JP2024115515A - Polycyclic aromatic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound suitable as a material for organic devices such as an organic electroluminescence element.

SOLUTION: The present invention provides a polycyclic aromatic compound represented by formula (1), where A ring and B ring each represent a substituted/unsubstituted aryl ring or a substituted/unsubstituted heteroaryl ring, C ring represents a ring represented by formula (1C), R^c1-R^c4 and R^d1-R^d2 independently represent hydrogen or a substituent, wherein at least one selected from the group consisting of R^c1-R^c4 is a substituent, and at least one hydrogen in the structure may be substituted with deuterium.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a polycyclic aromatic compound. In particular, the present invention relates to a polycyclic aromatic compound containing nitrogen and boron. The present invention also relates to a material for an organic device, an organic electroluminescent device, and a display device and a lighting device, each containing the polycyclic aromatic compound.

Display devices using electroluminescent light-emitting elements have been extensively studied because they can be made thin and energy-efficient. Furthermore, organic electroluminescent devices made from organic materials have been actively studied because they can be easily made large and lightweight. In particular, there has been active research into the development of organic materials that have the luminescence properties of blue, one of the three primary colors of light, and organic materials that have the ability to transport charges such as holes and electrons (potential to become semiconductors or superconductors), regardless of whether they are polymeric or low molecular weight compounds.

An organic electroluminescent element has a structure consisting of a pair of electrodes consisting of an anode and a cathode, and one or more layers containing an organic compound that are disposed between the pair of electrodes. Layers containing organic compounds include a light-emitting layer and a charge transport/injection layer that transports or injects charges such as holes and electrons, and various organic materials suitable for these layers have been developed.

Among them, Patent Document 1 discloses that polycyclic aromatic compounds containing boron are useful as materials for organic electroluminescent devices, etc.

International Publication No. 2015/102118

As described above, various materials have been developed for use in organic EL elements. However, in order to increase the options for materials for organic EL elements, it is desirable to develop materials made of novel compounds.
An object of the present invention is to provide a novel compound useful as a material for organic devices such as organic EL elements.

The present inventors have conducted extensive research to solve the above problems, and have succeeded in producing a novel polycyclic aromatic compound having a structure similar to that of the compound described in Patent Document 1, which has superior light-emitting properties. The inventors have also found that an excellent organic EL element can be obtained by disposing a layer containing this polycyclic aromatic compound between a pair of electrodes to form an organic EL element, and have completed the present invention. That is, the present invention provides the following polycyclic aromatic compound, and further provides a material for an organic device containing the following polycyclic aromatic compound, etc.
Specifically, the present invention has the following configuration.

<1> A polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1);

In formula (1),
ring A and ring B each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring;
Ring C is a substituted indene ring represented by formula (1C),
R ^c1 , R ^c2 , R ^c3 , and R ^c4 are each independently hydrogen or a substituent, provided that at least one selected from the group consisting of R ^c1 , R ^c2 , R ^c3 , and R ^c4 is a substituent;
R ^c5 and R ^c6 are bonds to Y ¹ and X ² in formula (1),
R ^d1 and R ^d2 each independently represent hydrogen or a substituent, and may be bonded to each other to form a ring;
^Y1 is B, P, P=O, P=S, Al, Ga, As, Si-R ^YI , or Ge-R ^YG , where R ^YI and R ^YG are each substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl;
^X1 and ^X2 are each independently >O, >N- ^RNX , >C( ^-RCX ) ₂ , >Si( ^-RIX ) ₂ , >S, or >Se; ^RNX , ^RCX , and ^RIX are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; two ^RCX in >C(-RCX) ₂ may be bonded to each other to form a ring; two ^RIX in >Si(-R) ₂ may be bonded to each other to form ^a ring; ^RNX , at least one ^RCX , and at least one ^RIX may be bonded to at least one of the A ring or B ring or at least one of the A ring or C ring via a single bond or a linking group;
At least one of the aryl or heteroaryl rings in said structure may be fused with at least one cycloalkane, said cycloalkane may be substituted with at least one substituent, and at least one _-CH2- in said cycloalkane may be replaced with -O-;
In said structure, at least one hydrogen may be replaced by deuterium, at least one nitrogen may be replaced by nitrogen-15 ( ¹⁵ N), at least one sulfur may be replaced by sulfur-33 ( ³³ S), sulfur-34 ( ³⁴ S) or sulfur-36 ( ³⁶ S), at least one oxygen may be replaced by oxygen-17 ( ¹⁷ O) or oxygen-18 ( ¹⁸ O), at least one carbon may be replaced by carbon-13 ( ¹³ C), and at least one boron may be replaced by boron-11 ( ¹¹ B).

<2> The polycyclic aromatic compound according to <1>, having a structure consisting of one or more structural units represented by formula (1XC1);

In formula (1XC1),
R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 are each independently a hydrogen atom or a substituent;
any two adjacent groups among R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 may be bonded to each other to form a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring together with the two carbon atoms to which they are bonded,
R ^c1 , R ^c2 , R ^c3 and R ^c4 are each independently hydrogen or a substituent, provided that at least one of R ^c1 to R ^c4 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl;
R ^d1 and R ^d2 are the same as R ^d1 and R ^d2 in formula (1C),
Y ¹ , X ¹ and X ² have the same meanings as Y ¹ , X ¹ and X ² in formula (1), respectively.
<3> The polycyclic aromatic compound according to <2>, wherein R ^c2 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (the two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl.

<4> The polycyclic aromatic compound according to <2>, wherein R ^c2 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, or a substituted or unsubstituted diarylamino.

<5> The polycyclic aromatic compound according to <3>, represented by any one of the following formulas:

式中、Ｍｅはメチル、ｔＢｕはｔ－ブチル、Ｄは重水素である。

In the formula, Me is methyl, tBu is t-butyl, and D is deuterium.

<6> The polycyclic aromatic compound according to <5>, represented by formula (2-013), formula (2-019), or formula (2-025).
<7> The polycyclic aromatic compound according to <2>, wherein R ^c2 is a substituted or unsubstituted alkyl, and none of R ^NX , R ^CX , and R ^IX is bonded to any of ring A, ring B, or ring C via a single bond or a linking group.

<8> The polycyclic aromatic compound according to <7>, represented by any one of the following formulas:

式中、Ｍｅはメチル、ｔＢｕはｔ－ブチルである。

In the formula, Me is methyl and tBu is t-butyl.

<9> A polycyclic aromatic compound according to <8>, represented by formula (2-001) or formula (2-007).

<10> The polycyclic aromatic compound according to <2>, wherein R ^c3 is a substituted or unsubstituted aryl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (the two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl.

<11> The polycyclic aromatic compound according to <2>, wherein R ^c3 is a substituted or unsubstituted heteroaryl.
<12> The polycyclic aromatic compound according to <2>, wherein R ^c3 is a substituted or unsubstituted diarylamino.

式中、Ｍｅはメチル、ｔＢｕはｔ－ブチルである。 <13> The polycyclic aromatic compound according to <12>, represented by any one of the following formulas:

In the formula, Me is methyl and tBu is t-butyl.

<14> A polycyclic aromatic compound according to <13>, represented by formula (1-034).

<15> The polycyclic aromatic compound according to <10>, represented by any one of the following formulas:

式中、Ｍｅはメチル、ｔＢｕはｔ－ブチルである。

In the formula, Me is methyl and tBu is t-butyl.

<16> A polycyclic aromatic compound according to <15>, represented by formula (1-001), formula (1-016), formula (1-017), formula (1-028), formula (1-037), formula (1-043), or formula (1-065).

<17> The polycyclic aromatic compound according to <2>, represented by any one of the following formulas:

式中、Ｍｅはメチル、ｔＢｕはｔ－ブチルである。

In the formula, Me is methyl and tBu is t-butyl.

<18> The polycyclic aromatic compound according to <17>, represented by formula (1-002), formula (1-003), formula (1-013), formula (1-018), formula (1-025), or formula (1-031).
<19> The polycyclic aromatic compound according to <2>, wherein R ^c1 or R ^c4 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (the two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl.

<20> The polycyclic aromatic compound according to <19>, represented by any one of the following formulas:

式中、Ｍｅはメチル、ｔＢｕはｔ－ブチルである。

In the formula, Me is methyl and tBu is t-butyl.

<21> The polycyclic aromatic compound according to <1>, having a structure consisting of one or more structural units represented by formula (1XC2);

In formula (1XC2),
R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 are each independently a hydrogen atom or a substituent;
any two adjacent groups among R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 may be bonded to each other to form a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring together with the two carbon atoms to which they are bonded,
R ^c1 , R ^c2 , R ^c3 , R ^c4 , R ^d1 , and R ^d2 are each defined as R ^c1 , R ^c2 , R ^c3 , R ^c4 , R ^d1 , and R ^d2 in formula (1C), respectively;
Y ¹ , X ¹ and X ² have the same meanings as Y ¹ , X ¹ and X ² in formula (1), respectively.

<22> The polycyclic aromatic compound according to <21>, represented by any one of the following formulas:

式中、Ｍｅはメチル、ｔＢｕはｔ－ブチルである。

In the formula, Me is methyl and tBu is t-butyl.

<23> The polycyclic aromatic compound according to <22>, represented by formula (5-036):
<24> A material for an organic device, comprising the polycyclic aromatic compound according to any one of <1> to <23>.
<25> An organic electroluminescence device comprising a pair of electrodes consisting of an anode and a cathode, and a light-emitting layer disposed between the pair of electrodes, the light-emitting layer containing the polycyclic aromatic compound according to any one of <1> to <23>.
<26> The organic electroluminescent device according to <25>, wherein the light-emitting layer contains a host and the polycyclic aromatic compound as a dopant.
<27> The organic electroluminescent device according to <26>, wherein the host is an anthracene compound, a fluorene compound, a pyrene compound, or a dibenzochrysene compound.
<28> A display device or a lighting device comprising the organic electroluminescent device according to any one of <25> to <27>.

The present invention provides a novel polycyclic aromatic compound that is useful as a material for organic devices such as organic electroluminescent devices. The polycyclic aromatic compound of the present invention can be used in the manufacture of organic devices such as organic electroluminescent devices.

FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescent device.

The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment or a specific example, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range including the numerical values before and after "to" as the lower and upper limits. In this specification, "hydrogen" in the explanation of the structural formula means "hydrogen atom (H)". Similarly, "carbon atom (C)" may be referred to as "carbon".
In this specification, the term "adjacent groups" refers to two groups bonded to two adjacent atoms (two atoms directly bonded by a covalent bond) in a structural formula.

In this specification, "Me" is methyl, "Et" is ethyl, "nBu" is n-butyl (normal butyl), "tBu" is t-butyl (tertiary butyl), "iBu" is isobutyl, "secBu" is secondary butyl, "nPr" is n-propyl (normal propyl), "iPr" is isopropyl, "tAm" is t-amyl, "2EH" is 2-ethylhexyl, "tOct" is t-octyl, "Ph" is phenyl, "Mes" is mesityl (2,4,6-trimethylphenyl), "Ad" is 1-adamantyl, "Tf" is trifluoromethanesulfonyl, "TMS" is trimethylsilyl, and "D" is deuterium.
In this specification, the organic electroluminescent element may be referred to as an "organic EL element."

In this specification, chemical structures and substituents are sometimes expressed by the number of carbon atoms, but when a chemical structure is substituted with a substituent or when a substituent is further substituted with a substituent, the number of carbon atoms means the number of carbon atoms in each of the chemical structure and the substituent, and does not mean the total number of carbon atoms in the chemical structure and the substituent, or the total number of carbon atoms in the substituent and the substituent. For example, "substituent B of carbon number Y substituted with substituent A of carbon number X" means that "substituent B of carbon number Y" is substituted with "substituent A of carbon number X", and the carbon number Y is not the total number of carbon atoms in the substituents A and B. Also, for example, "substituent B of carbon number Y substituted with substituent A" means that "substituent B of carbon number Y" is substituted with "substituent A (with no carbon number limit)", and the carbon number Y is not the total number of carbon atoms in the substituents A and B.

This specification describes many structural formulas of aromatic compounds. Aromatic compounds are described as a combination of double bonds and single bonds, but in reality, because pi electrons resonate, a single substance can have multiple equivalent resonance structures in which double bonds and single bonds alternate. This specification describes only one resonance structural formula for each substance, but unless otherwise specified, other resonance structural formulas that are organically equivalent are also included.

In this specification, the expression "may be" is sometimes used, but this has the same meaning as "not being, or being."

<Explanation of Rings and Substituents>
First, the rings and substituents used in the present specification will be described in detail below.
As used herein, the "aryl ring" includes, for example, an aryl ring having 6 to 30 carbon atoms, preferably an aryl ring having 6 to 16 carbon atoms, more preferably an aryl ring having 6 to 12 carbon atoms, and particularly preferably an aryl ring having 6 to 10 carbon atoms.

Specific examples of "aryl rings" include a monocyclic benzene ring, a bicyclic bicyclic bicyclic naphthalene ring and an indene ring, a tricyclic terphenyl ring (m-terphenyl, o-terphenyl, p-terphenyl), a fused tricyclic acenaphthylene ring, a fluorene ring, a phenalene ring, a phenanthrene ring, and an anthracene ring, a fused tetracyclic tricyclic triphenylene ring, a pyrene ring, a naphthacene ring, and a chrysene ring, and a fused pentacyclic perylene ring and a pentacene ring. In addition, the fluorene ring, benzofluorene ring, and indene ring each include a structure in which a fluorene ring, a benzofluorene ring, and a cyclopentane ring are spiro-bonded. In addition, the fluorene ring, benzofluorene ring, and indene ring also include those in which two of the two hydrogen atoms of the methylene in the structure are replaced by alkyl such as methyl as the first substituent described below, resulting in a dimethylfluorene ring, dimethylbenzofluorene ring, dimethylindene ring, etc.

In this specification, examples of the "heteroaryl ring" include heteroaryl rings having 2 to 30 carbon atoms, preferably heteroaryl rings having 2 to 25 carbon atoms, more preferably heteroaryl rings having 2 to 20 carbon atoms, still more preferably heteroaryl rings having 2 to 15 carbon atoms, and particularly preferably heteroaryl rings having 2 to 10 carbon atoms. In addition, examples of the "heteroaryl ring" include heterocycles containing, in addition to carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, nitrogen, boron, selenium, phosphorus, and tellurium as ring-constituting atoms.

Specific examples of the "heteroaryl ring" include a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, an oxadiazole ring (such as a furazan ring), a thiadiazole ring, a triazole ring, a tetrazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, an indole ring, an isoindole ring, a 1H-indazole ring, a benzimidazole ring, a benzoxazole ring, a benzothiazole ring, a 1H-benzotriazole ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinazoline ring, a quinoxaline ring, a phthalazine ring, a naphthyridine ring, a purine ring, a pteridine ring, a carbazole ring, an acridine ring, a phenoxathiin ring, a phenoxazine ring, a phenothiazine ring, a phenazine ring, a phenazasiline ring, an indolizine ring, a furan ring, a benzofuran ring, an isobenzofuran ring, a dibenzofuran ring, and a thiophene ring. , a benzothiophene ring, a dibenzothiophene ring, a thianthrene ring, an indolocarbazole ring, a benzoindolocarbazole ring, a dibenzoindolocarbazole ring, a naphthobenzofuran ring, a dioxin ring, a dihydroacridine ring, a xanthene ring, a thioxanthene ring, a dibenzodioxin ring, a dioxaboranaphthoanthracene ring (such as a 5,9-dioxa-13b-bora-13bH-naphtho[3,2,1-de]anthracene ring), a benzoselenophene ring, Examples of the ring include an aryl ring, a dibenzoselenophene ring, an azacarbazole ring, an azadibenzothiophene ring, an azadibenzofuran ring, an azadibenzoselenophene ring, an azatriphenylene ring, an imidazoimidazole ring, an indoloindole ring, a benzofurocarbazole ring, a benzothienocarbazole ring, an indenocarbazole ring, a selenophenocarbazole ring, a spiro[fluorene-9,9'-xanthene] ring, a spirobi[silafluorene] ring, etc. In addition, it is also preferable that the dihydroacridine ring, the xanthene ring, and the thioxanthene ring have two of the two hydrogen atoms of the methylene in the structure replaced by an alkyl such as methyl as the first substituent described later, to form a dimethyldihydroacridine ring, a dimethylxanthene ring, a dimethylthioxanthene ring, etc. In addition, bicyclic rings such as bipyridine ring, phenylpyridine ring, and pyridylphenyl ring, and tricyclic rings such as terpyridyl ring, bispyridylphenyl ring, and pyridylbiphenyl ring are also included as "heteroaryl rings." In addition, "heteroaryl ring" also includes a pyran ring.

In this specification, a substituent may be substituted with a further substituent. For example, a particular substituent may be described as "substituted or unsubstituted". This means that the particular substituent is substituted with at least one further substituent, or is not substituted. In a similar sense, the term "optionally substituted" may also be used. In this specification, the particular substituent may be referred to as a "first substituent" and the further substituent may be referred to as a "second substituent".

In this specification, the substituent group Zα consists of the substituents of the substituent group Z and the substituents represented by the formula (A30) described below.

In the present specification, the substituent group Z is
an aryl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen;
heteroaryl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen;
diarylamino which may be substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (two aryls may be bonded to each other via a linking group);
diheteroarylamino optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (two heteroaryls may be bonded to each other via a linking group);
arylheteroarylamino which may be substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (the aryl and heteroaryl may be bonded to each other via a linking group);
diarylboryl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen (two aryls may be bonded via a single bond or a linking group);
an alkyl group optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, cycloalkyl, cyano, and halogen;
cycloalkyl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen;
alkoxy optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, cycloalkyl, cyano, and halogen;
aryloxy optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen;
an arylthio group optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen;
alkenyl optionally substituted with at least one group selected from the group consisting of aryl, heteroaryl, alkyl, cycloalkyl, cyano, and halogen;
Consists of substituted silyl, cyano, and halogen.
The aryl as the second substituent in each group of the substituent group Z may be further substituted with an aryl, heteroaryl, alkyl, cycloalkyl, cyano, or halogen; similarly, the heteroaryl as the second substituent may be substituted with an aryl, heteroaryl, alkyl, cycloalkyl, cyano, or halogen.

In this specification, when the term "substituent" is used, the type of the substituent is not particularly limited, but unless otherwise specified, it may be any group selected from the substituent group Z. For example, when a group that is "substituted or unsubstituted" is substituted, the group may be substituted with at least one group selected from the substituent group Z.

In this specification, "aryl" refers to, for example, an aryl having 6 to 30 carbon atoms, and preferably an aryl having 6 to 20 carbon atoms, an aryl having 6 to 16 carbon atoms, an aryl having 6 to 12 carbon atoms, or an aryl having 6 to 10 carbon atoms.

Specific examples of "aryl" include monovalent groups obtained by removing one hydrogen from the above-mentioned "aryl ring." For example, phenyl is a monocyclic ring system, biphenylyl (2-biphenylyl, 3-biphenylyl, or 4-biphenylyl) is a bicyclic ring system, naphthyl (1-naphthyl or 2-naphthyl) is a condensed bicyclic ring system, terphenylyl (m-terphenyl-2'-yl, m-terphenyl-4'-yl, m-terphenyl-5'-yl, o-terphenyl-3'-yl, o-terphenyl-4'-yl, p-terphenyl-2'-yl, m-terphenyl-2-yl, m-terphenyl-3-yl, m-terphenyl-4-yl, o-terphenyl-2-yl, o-terphenyl-3-yl, o-terphenyl-4-yl, p-terphenyl-2-yl, p-terphenyl-3-yl, or p-terphenyl-4-yl) is a condensed tricyclic ring system, acenaphthylene-(1-, 3-, 4-, or 5- -)yl, fluoren-(1-, 2-, 3-, 4-, or 9-)yl, phenalen-(1- or 2-)yl, phenanthrene-(1-, 2-, 3-, 4-, or 9-)yl, or anthracene-(1-, 2-, or 9-)yl, the tetracyclic ring system quaterphenylyl (5'-phenyl-m-terphenyl-2-yl, 5'-phenyl-m-terphenyl-3-yl, 5'-phenyl -m-terphenyl-4-yl, or m-quaterphenyl), fused tetracyclic ring systems such as triphenylene-(1- or 2-)yl, pyrene-(1-, 2-, or 4-)yl, or naphthacene-(1-, 2-, or 5-)yl, or fused pentacyclic ring systems such as perylene-(1-, 2-, or 3-)yl, or pentacene-(1-, 2-, 5-, or 6-)yl. Other examples include monovalent groups of spirofluorene.

The aryl as the second substituent also includes a structure in which the aryl is substituted with at least one group selected from the group consisting of aryl such as phenyl (specific examples are the groups described above), alkyl such as methyl (specific examples are the groups described later), and cycloalkyl such as cyclohexyl or adamantyl (specific examples are the groups described later).
An example of such a group is a group in which the 9-position of fluorenyl as the second substituent is substituted with an aryl such as phenyl, an alkyl such as methyl, or a cycloalkyl such as cyclohexyl or adamantyl.

The "arylene" is, for example, an arylene having 6 to 30 carbon atoms, and preferably an arylene having 6 to 20 carbon atoms, an arylene having 6 to 16 carbon atoms, an arylene having 6 to 12 carbon atoms, or an arylene having 6 to 10 carbon atoms.
Specific examples of "arylene" include divalent groups obtained by removing one hydrogen from the above-mentioned "aryl" (monovalent group).

"Heteroaryl" is, for example, a heteroaryl having 2 to 30 carbon atoms, and preferably a heteroaryl having 2 to 25 carbon atoms, a heteroaryl having 2 to 20 carbon atoms, a heteroaryl having 2 to 15 carbon atoms, or a heteroaryl having 2 to 10 carbon atoms. "Heteroaryl" contains, in addition to carbon, one or more heteroatoms selected from oxygen, sulfur, nitrogen, etc., as ring-constituting atoms, preferably 1 to 5 heteroatoms.

Specific examples of "heteroaryl" include monovalent groups obtained by removing one hydrogen from the above-mentioned "heteroaryl ring". For example, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, oxadiazolyl, thiadiazolyl, triazolyl, tetrazolyl, pyrazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, indolyl, isoindolyl, 1H-indazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, 1H-benzotriazolyl, quinolinyl, isoquinolinyl, cinnolinyl, quinazolinyl, quinoxalinyl, phenanthrolinyl, phthalazinyl, naphthyridinyl, purinyl, pteridinyl, carbazolyl, Acridinyl, phenoxathiinyl, phenoxazinyl, phenothiazinyl, phenazinyl, phenazasilinyl, indolizinyl, furanyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl, naphthobenzofuranyl, thienyl, benzothienyl, isobenzothienyl, dibenzothienyl, naphthobenzothienyl, monovalent groups of benzophosphole oxide rings, monovalent groups of dibenzophosphole oxide rings, furazanyl, thianthrenyl, indolocarbazolyl, benzoindolocarbazolyl, dibenzoindolocarbazolyl, imidazolinyl, or oxazolinyl. Other examples include monovalent groups of spiro[fluorene-9,9'-xanthene], monovalent groups of spirobi[silafluorene], and monovalent groups of benzoselenophene.

The heteroaryl as the second substituent also includes a structure in which the heteroaryl is substituted with at least one group selected from the group consisting of aryl such as phenyl (specific examples are the groups described above), alkyl such as methyl (specific examples are the groups described below), and cycloalkyl such as cyclohexyl or adamantyl (specific examples are the groups described below).
An example of such a group is a group in which the 9-position of the carbazolyl as the second substituent is substituted with an aryl such as phenyl, an alkyl such as methyl, or a cycloalkyl such as cyclohexyl or adamantyl.Furthermore, the heteroaryl as the second substituent also includes groups in which a nitrogen-containing heteroaryl such as pyridyl, pyrimidinyl, triazinyl, or carbazolyl is further substituted with phenyl or biphenylyl.

The "heteroarylene" is, for example, a heteroarylene having 2 to 30 carbon atoms, and preferably a heteroarylene having 2 to 25 carbon atoms, a heteroarylene having 2 to 20 carbon atoms, a heteroarylene having 2 to 15 carbon atoms, or a heteroarylene having 2 to 10 carbon atoms. In addition, the "heteroarylene" is, for example, a divalent group such as a heterocycle containing, in addition to carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, and nitrogen as ring-constituting atoms.
Specific examples of "heteroarylene" include divalent groups obtained by removing one hydrogen atom from the above-mentioned "heteroaryl" (monovalent group).

The term "diarylamino" refers to an amino group substituted with two aryl groups, and the details of the aryl group can be found in the above description of the "aryl".
The term "diheteroarylamino" refers to an amino group substituted with two heteroaryls. For details of the heteroaryl, the above description of the "heteroaryl" can be cited.
The term "arylheteroarylamino" refers to an amino group substituted with an aryl and a heteroaryl. For details of the aryl and the heteroaryl, the above descriptions of "aryl" and "heteroaryl" can be cited.

The two aryls in the diarylamino as the first substituent may be bonded to each other via a linking group, the two heteroaryls in the diheteroarylamino as the first substituent may be bonded to each other via a linking group, and the aryl and heteroaryl in the arylheteroarylamino as the first substituent may be bonded to each other via a linking group. Here, the expression "bonded via a linking group" means that, for example, the two phenyls in diphenylamino form a bond with a linking group as shown below. This explanation also applies to diheteroarylamino and arylheteroarylamino formed by aryls and heteroaryls.

Specific examples of the linking group include >O, >N-R ^X , >C(-R ^X ) ₂ , -C(-R ^X )=C(-R ^X )-, >Si(-R ^X ) ₂ , >S, >CO, >CS, >SO, >SO ₂ , >SeO, >SeO ₂ , >PO, >B(-R ^X ), and >Se. Each R ^X is independently an alkyl, cycloalkyl, aryl, or heteroaryl, which may be substituted with an alkyl, cycloalkyl, aryl, or heteroaryl. Furthermore, the two R ^Xs in each of >C(-R ^X ) ₂ , -C(-R ^X )=C(-R ^X )-, and >Si(-R ^X ) ₂ may be bonded to each other via a single bond or a linking group X ^Y to form a ring. Examples of X ^Y include >O, >N-R ^Y , >C(-R ^Y ) ₂ , >Si(-R ^Y ) ₂ , >S, >CO, >CS, >SO, >SO ₂ , and >Se, and R ^Y is independently alkyl, cycloalkyl, aryl, or heteroaryl, which may be substituted with alkyl, cycloalkyl, aryl, or heteroaryl. However, when X ^Y is >C(-R ^Y ) ₂ or >Si(-R ^Y ) ₂ , the two R ^Ys do not bond to form a ring. Examples of the linking group include alkenylene. Any hydrogen of the alkenylene may be independently substituted with R ^2X , and each R ^2X is independently alkyl, cycloalkyl, substituted silyl, aryl, or heteroaryl, which may be substituted with alkyl, cycloalkyl, substituted silyl, or aryl. The two R ^X 's in -C(-R ^X )=C(-R ^X )- may be bonded to each other to form an aryl ring (such as a benzene ring) or a heteroaryl ring together with the C=C to which they are bonded. That is, -C(-R ^X )=C(-R ^X )- may be an arylene (such as 1,2-phenylene) or a heteroarylene.

In addition, in this specification, when the term "diarylamino", "diheteroarylamino", or "arylheteroarylamino" is used, unless otherwise specified, it is assumed that the following explanation is added: "The two aryls of the diarylamino may be bonded to each other via a linking group", "The two heteroaryls of the diheteroarylamino may be bonded to each other via a linking group", and "The aryl and heteroaryl of the arylheteroarylamino may be bonded to each other via a linking group", respectively.

"Diarylboryl" is a boryl substituted with two aryls, and the above description of "aryl" can be cited for details of the aryls. The two aryls may be bonded via a single bond or a linking group (e.g., -CH=CH-, -CR=CR-, -C≡C-, >N-R, >O, >S, >CO, >C=S, >S=O, >S(=O) ₂ , >Se(=O), >Se(=O) ₂ , >P(=O), >B(-R), >C(-R) ₂ , >Si(-R) ₂ , or >Se). Here, R in -CR=CR-, R in >N-R, R in >B(-R), R in >C(-R) ₂ , and R in >Si(-R) are aryl, heteroaryl, diarylamino, alkyl, alkenyl, alkynyl, cycloalkyl, alkoxy, or aryloxy, and at least one hydrogen in the R may be further substituted with aryl, heteroaryl, alkyl, alkenyl, alkynyl, or cycloalkyl. In addition, two adjacent R may be bonded to each other to form a ring, forming a cycloalkylene, arylene, or heteroarylene. For details of the substituents listed here, the explanations of "aryl", "arylene", "heteroaryl", "heteroarylene", and "diarylamino" above, and the explanations of "alkyl", "alkenyl", "alkynyl", "cycloalkyl", "cycloalkylene", "alkoxy", and "aryloxy" below can be cited. In addition, when the term "diarylboryl" is used simply in this specification, unless otherwise specified, it is assumed that the explanation that "the two aryls of the diarylboryl may be bonded to each other via a single bond or a linking group" is added.

"Alkyl" may be either straight-chain or branched-chain, for example, straight-chain alkyl having 1 to 24 carbon atoms or branched-chain alkyl having 3 to 24 carbon atoms, and preferably alkyl having 1 to 18 carbon atoms (branched-chain alkyl having 3 to 18 carbon atoms), alkyl having 1 to 12 carbon atoms (branched-chain alkyl having 3 to 12 carbon atoms), alkyl having 1 to 6 carbon atoms (branched-chain alkyl having 3 to 6 carbon atoms), alkyl having 1 to 5 carbon atoms (branched-chain alkyl having 3 to 5 carbon atoms), alkyl having 1 to 4 carbon atoms (branched-chain alkyl having 3 to 4 carbon atoms), etc.

Specific examples of "alkyl" include methyl, ethyl, n-propyl, isopropyl, 1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1,2-trimethylpropyl, 1,1,2,2-tetramethylpropyl, 1-ethyl-1,2,2-trimethylpropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-ethylbutyl, 1,1-dimethylbutyl, 3,3-dimethylbutyl, 1,1-diethylbutyl, 1-ethyl-1-methylbutyl, 1-propyl-1-methylbutyl, 1,1,3-trimethylbutyl, 1-ethyl-1,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, t-pentyl (t-amyl), 1-methylpentyl, 2-propylpentyl, 1,1-dimethylpentyl, 1-ethyl-1-methylpentyl, 1-propyl-1 -methylpentyl, 1-butyl-1-methylpentyl, 1,1,4-trimethylpentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 1,1-dimethylhexyl, 1-ethyl-1-methylhexyl, 1,1,5-trimethylhexyl, 3,5,5-trimethylhexyl, n-heptyl, 1-methylheptyl, 1-hexylheptyl, 1,1-dimethylheptyl, 2,2-dimethylhexyl, Methylheptyl, 2,6-dimethyl-4-heptyl, n-octyl, t-octyl (1,1,3,3-tetramethylbutyl), 1,1-dimethyloctyl, n-nonyl, n-decyl, 1-methyldecyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, or n-eicosyl.

"Alkylene" is a divalent group obtained by removing one of the hydrogen atoms from "alkyl", such as methylene, ethylene, and propylene.

For "alkenyl," please refer to the explanation of "alkyl" above. It is a group in which the C-C single bond in the "alkyl" structure is replaced with a C=C double bond, and includes groups in which not only one but two or more single bonds are replaced with double bonds (also called alkadien-yl or alkatriene-yl).

Specific examples of "alkenyl" include alkenyl having 2 to 30 carbon atoms, preferably alkenyl having 2 to 20 carbon atoms, more preferably alkenyl having 2 to 10 carbon atoms, further preferably alkenyl having 2 to 6 carbon atoms, and particularly preferably alkenyl having 2 to 4 carbon atoms. Preferred alkenyls are vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl.

"Alkenylene" is a divalent group obtained by removing one of the hydrogen atoms from "alkenyl", for example vinylene.

For "alkynyl," please refer to the explanation of "alkyl" above. It is a group in which the C-C single bond in the "alkyl" structure is replaced with a C≡C triple bond, and also includes groups in which not only one but two or more single bonds are replaced with triple bonds (also called alkadiyn-yl or alkatriyn-yl).

"Cycloalkyl" is, for example, cycloalkyl having 3 to 24 carbon atoms, and preferably cycloalkyl having 3 to 20 carbon atoms, cycloalkyl having 3 to 16 carbon atoms, cycloalkyl having 3 to 14 carbon atoms, cycloalkyl having 3 to 12 carbon atoms, cycloalkyl having 5 to 10 carbon atoms, cycloalkyl having 5 to 8 carbon atoms, cycloalkyl having 5 to 6 carbon atoms, or cycloalkyl having 5 carbon atoms.

Specific examples of "cycloalkyl" include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, or alkyl (especially methyl) substituted derivatives of these having 1 to 5 or 1 to 4 carbon atoms, bicyclo[1.1.0]butyl, bicyclo[1.1.1]pentyl, bicyclo[2.1.0]pentyl, bicyclo[2.1.1]hexyl, bicyclo[3.1.0]hexyl, bicyclo[2.2.1]heptyl (norbornyl), bicyclo[2.2.2]octyl, adamantyl, diamantyl, decahydronaphthalenyl, and decahydroazulenyl.

The "cycloalkylene" is, for example, a cycloalkylene having 3 to 24 carbon atoms, and preferably a cycloalkylene having 3 to 20 carbon atoms, a cycloalkylene having 3 to 16 carbon atoms, a cycloalkylene having 3 to 14 carbon atoms, a cycloalkylene having 3 to 12 carbon atoms, a cycloalkylene having 5 to 10 carbon atoms, a cycloalkylene having 5 to 8 carbon atoms, a cycloalkylene having 5 to 6 carbon atoms, or a cycloalkylene having 5 carbon atoms.
Specific examples of "cycloalkylene" include structures obtained by removing one hydrogen from the above-mentioned "cycloalkyl" (monovalent group) to form a divalent group.

"Cycloalkenyl" refers to a group having a structure in which at least one pair of single bonds between two carbons in the above-mentioned "cycloalkyl" has become a double bond (for example, a group in which --CH ₂ --CH ₂ -- is replaced with --CH=CH--), and does not fall under the category of aryl. Specific examples include 1-cyclohexenyl and 1-cyclopentenyl.

"Alkoxy" is a group represented by "Alk-O- (Alk is alkyl)" and the details of this alkyl can be found in the explanation of "alkyl" above.

"Aryloxy" is a group represented by "Ar-O- (Ar is aryl)". For details of the aryl, the above explanation of "aryl" can be cited.
"Arylthio" is a group represented by "Ar-S-(Ar is aryl)". For details of the aryl, the above explanation of "aryl" can be cited.

"Substituted silyl" is, for example, a silyl substituted with at least one of aryl, alkyl, and cycloalkyl, and is preferably triarylsilyl, trialkylsilyl, tricycloalkylsilyl, dialkylcycloalkylsilyl, or alkyldicycloalkylsilyl.

The "triarylsilyl" is a silyl group substituted with three aryl groups. For details of the aryl groups, see the above description of the "aryl".
Specific "triarylsilyl" includes, for example, triphenylsilyl, diphenylmononaphthylsilyl, monophenyldinaphthylsilyl, trinaphthylsilyl, and the like.

The term "trialkylsilyl" refers to a silyl group substituted with three alkyl groups. For details of this alkyl group, see the above description of "alkyl."
Specific examples of "trialkylsilyl" include trimethylsilyl, triethylsilyl, tri-n-propylsilyl, triisopropylsilyl, tri-n-butylsilyl, triisobutylsilyl, tri-s-butylsilyl, tri-t-butylsilyl, ethyldimethylsilyl, n-propyldimethylsilyl, isopropyldimethylsilyl, n-butyldimethylsilyl, isobutyldimethylsilyl, s-butyldimethylsilyl, t-butyldimethylsilyl, methyldiethylsilyl, n-propyldiethylsilyl, isopropyldiethylsilyl, n-butyldiethylsilyl, s-butyldiethylsilyl, t-butyldiethylsilyl, methyldi-n-propylsilyl, ethyldi-n-propylsilyl, n-butyldi-n-propylsilyl, s-butyldi-n-propylsilyl, t-butyldi-n-propylsilyl, methyldiisopropylsilyl, ethyldiisopropylsilyl, n-butyldiisopropylsilyl, s-butyldiisopropylsilyl, and t-butyldiisopropylsilyl.

The term "tricycloalkylsilyl" refers to a silyl group substituted with three cycloalkyl groups. For details of this cycloalkyl, see the above description of the "cycloalkyl".
Specific "tricycloalkylsilyl" includes, for example, tricyclopentylsilyl or tricyclohexylsilyl.

"Dialkylcycloalkylsilyl" is a silyl group substituted with two alkyls and one cycloalkyl. For details on the alkyl and cycloalkyl, see the explanations of "alkyl" and "cycloalkyl" above.

"Alkyldicycloalkylsilyl" is a silyl group substituted with one alkyl and two cycloalkyl. For details of the alkyl and cycloalkyl, see the explanations of "alkyl" and "cycloalkyl" above.

"Halogen" is fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine, more preferably fluorine or chlorine, and even more preferably fluorine.

When cyano or halogen is substituted, it is also preferred that all or some of the hydrogen atoms in the aryl or heteroaryl in the structure are replaced with cyano or halogen.

The substituent represented by formula (A30) has the following structure.

In formula (A30),
Ak is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted cycloalkyl, or substituted or unsubstituted cycloalkenyl, in which at least one -CH ₂ - may be replaced by -O- or -S-;
R ^Ak is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, or a substituted or unsubstituted cycloalkyl, and R ^Ak may be bonded to Ak via a linking group or a single bond, and * indicates the bonding position.

In formula (A30), since Ak is the above-mentioned substituent, it does not conjugate with the unshared electron pair on N, and therefore the unshared electron pair can be conjugated with the π electron of the bonded group, allowing for a greater wavelength change than when an aryl or the like is present at the same position. The same applies to the effect on the multiple resonance effect, allowing for a greater improvement in thermally activated delayed fluorescence (TADF) properties.

R is ^preferably aryl optionally substituted with alkyl or cycloalkyl, heteroaryl optionally substituted with alkyl or cycloalkyl, alkyl or cycloalkyl, more preferably aryl optionally substituted with alkyl, heteroaryl optionally substituted with alkyl, alkyl or cycloalkyl, further preferably aryl optionally substituted with alkyl, and particularly preferably phenyl optionally substituted with methyl.

In formula (A30), Ak is preferably an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 3 to 14 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 3 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably methyl.

R ^Ak and Ak may be the same or different, and are preferably different.

R ^Ak may be bonded to Ak via a linking group or a single bond. In this case, examples of the linking group include >O, >S, and >Si(-R) _2. R in >Si(-R) ₂ is hydrogen, an aryl having 6 to 12 carbon atoms, an alkyl having 1 to 6 carbon atoms, or a cycloalkyl having 3 to 14 carbon atoms. Examples of the structure in which R ^Ak is bonded to Ak via a linking group or a single bond include the following.

上記各式中、＊は結合位置である。

In the above formulas, * indicates a bonding position.

[When two groups bonded to the same atom are bonded to each other]
In this specification, when it is stated that two groups bonded to the same atom may be bonded to each other to form a ring, it is sufficient that they are bonded by a single bond or a linking group (collectively also referred to as a linking group). Examples of the linking group include _-CH2 - _CH2- , -CHR-CHR-, _-CR2 -CR2-, -CH=CH-, -CR=CR- _, -C≡C-, -N(-R)-, -O-, -S-, -C(-R) _2- , -C(=O)-, -C(=S)-, -S(=O)-, -S(=O) _2- , -Se(=O)-, -Se(=O) _2- , -P(=O)-, -B(-R)-, -Si(-R) _2- or -Se-, for example, the following structure. The R of -CHR-CHR-, the R of _{-CR2- CR2-} , the R of -CR=CR-, the R of -N(-R)-, the R of -C(-R) _2- , the R of -B(-R)-, and the R of -Si(-R) _2- are each independently hydrogen, aryl which may be substituted with alkyl or cycloalkyl, heteroaryl which may be substituted with alkyl or cycloalkyl, alkyl which may be substituted with cycloalkyl, alkenyl which may be substituted with alkyl or cycloalkyl, alkynyl which may be substituted with alkyl or cycloalkyl, or cycloalkyl which may be substituted with alkyl or cycloalkyl. Two adjacent Rs may be bonded to form a ring, forming a cycloalkylene, arylene, or heteroarylene.

As the bonding group, a single bond and the linking groups -CR=CR-, -N(-R)-, -O-, -S-, -C(-R) ₂ -, -Si(-R) ₂ -, and -Se- are preferred, a single bond and the linking groups -CR=CR-, -N(-R)-, -O-, -S-, and -C(-R) ₂ - are more preferred, a single bond and the linking groups -CR=CR-, -N(-R)-, -O-, and -S- are even more preferred, and a single bond is most preferred.

The position where the two R's are bonded by the linking group is not particularly limited as long as it is a position where bonding is possible, but it is preferable for them to be bonded at the most adjacent positions. For example, if the two groups are phenyl, it is preferable for them to be bonded at the ortho (2nd) positions based on the bonding position (1st position) of "C" or "Si" in the phenyl (see the structural formula above).

<Stereoisomers, etc.>
The polycyclic aromatic compound of the present invention may exist as an enantiomer or diastereomer depending on the type of substituents, etc., but regardless of the structural formula described, any stereoisomer in any pure form, any mixture of stereoisomers, racemates, etc. are all intended to be included within the scope of the present invention.

<1. Polycyclic aromatic compounds>
<Overall structure>
It has already been found that polycyclic aromatic compounds in which aromatic rings are linked by heteroatoms such as boron, nitrogen, oxygen, and sulfur have a large HOMO-LUMO gap (band gap Eg in a thin film). This is because the six-membered ring containing a heteroatom has low aromaticity, and the decrease in the HOMO-LUMO gap due to the expansion of the conjugated system is suppressed. It was found that the LUMO gap can be changed arbitrarily. This is believed to be because the HOMO and LUMO energies can be moved arbitrarily depending on the spatial extent and energy of the unoccupied orbitals or lone pairs of the heteroatoms. .

In these polycyclic aromatic compounds, the excited states SOMO1 and SOMO2 are localized on each atom due to electronic perturbation of the heteroatom, so that the half-width of the fluorescence emission peak is narrow, and when used as a dopant in an organic EL device, light emission with high color purity can be obtained. For the same reason, ΔE _S1T1 is small, and the compound exhibits thermally activated delayed fluorescence, and when used as an emitting dopant in an organic EL device, high efficiency can be obtained.
Furthermore, the introduction of a substituent group allows the HOMO and LUMO energies to be freely adjusted, making it possible to optimize the ionization potential and electron affinity depending on the surrounding materials.

In the present invention, it has been found that polycyclic aromatic compounds in which aromatic rings such as benzene rings and indene rings are linked by hetero elements such as boron and nitrogen, and which have a structure consisting of one or more structural units represented by formula (1) having substituents at specific positions, enable the manufacture of organic electroluminescent devices with higher light emission efficiency than polycyclic aromatic compounds of similar structures.

The polycyclic aromatic compound of the present invention is a polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1).

In formula (1), ring A and ring B are each independently a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring, and ring C is an indene ring having a substituent represented by formula (1C).

<Explanation of ring structure in compound>
In formula (1), "A", "B", and "C" in the circles are symbols indicating the ring structure shown by each circle. The structure represented by formula (1) has a structure in which at least two aromatic rings in ring A and ring B and an indene ring in ring C are linked by a hetero element such as boron, oxygen, sulfur, or nitrogen to form a further ring structure. The formed ring structure is a fused ring structure composed of at least six rings.

[A ring]
In formula (1), ring A is a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring.
The A ring forms a trivalent group having bonds to three consecutive atoms (preferably carbon) on the aryl ring or heteroaryl ring in the structure. These three bonds are bonded to X ¹ , X ² , and B (boron), respectively. The ring in the A ring, in which the element having the above three bonds is a ring constituent element, is preferably a five-membered ring or a six-membered ring, more preferably a six-membered ring. This ring may be further condensed with another ring. Examples of the six-membered ring include a benzene ring, a pyridine ring, a pyrazine ring, and a pyrimidine ring. Examples of the six-membered ring further condensed with another ring include a naphthalene ring, a quinoline ring, a dibenzofuran ring, a dibenzothiophene ring, and a carbazole ring. Examples of the five-membered ring include a furan ring, a thiophene ring, a pyrrole ring, and a thiazole ring. Examples of the five-membered ring further condensed with another ring include a benzofuran ring, a benzothiophene ring, and an indole ring. The aryl ring or heteroaryl ring in ring A is preferably a benzene ring.

In the case of the substituted or unsubstituted aryl ring or substituted or unsubstituted heteroaryl ring which is the A ring, the substituent when it is referred to as "substituted or unsubstituted (substituted or unsubstituted)" is preferably at least one substituent selected from the substituent group Zα. The substituent may also be a substituted or unsubstituted diarylphosphino such as diphenylphosphino. When there are multiple substituents, the multiple substituents may be the same or different from each other. The substituent is preferably a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted diarylamino.

[B Ring]
In formula (1), ring B is a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring.

The ring B forms a divalent group having bonds to two atoms (preferably carbon) adjacent to each other on the ring of the aryl ring or heteroaryl ring in the structure. The ring B is bonded to ^X1 and B (boron) by the above-mentioned two bonds. The ring in the ring B having the element having the above-mentioned two bonds as a ring constituent element is preferably a 5-membered ring or a 6-membered ring. This ring may be further condensed with another ring. Examples of the 6-membered ring include a benzene ring, a pyridine ring, a pyrazine ring, and a pyrimidine ring. Examples of the 6-membered ring further condensed with another ring include a naphthalene ring, a quinoline ring, a benzofuran ring, a benzothiophene ring, an indole ring, a benzoselenophene ring, a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, and a dibenzoselenophene ring. Examples of the 5-membered ring include a furan ring, a thiophene ring, a pyrrole ring, a thiazole ring, and a selenophene ring. Examples of the 5-membered ring further condensed with another ring include a benzofuran ring, a benzothiophene ring, an indole ring, a benzoselenophene ring, etc. The aryl ring or heteroaryl ring in ring B is preferably a benzene ring, a benzofuran ring, a benzothiophene ring, or a benzoselenophene ring, more preferably a benzene ring, a benzofuran ring, or a benzothiophene ring, and further preferably a benzene ring.

In the case of the substituted or unsubstituted aryl ring or substituted or unsubstituted heteroaryl ring which is the B ring, the substituent when it is referred to as "substituted or unsubstituted (substituted or unsubstituted)" is preferably at least one substituent selected from the substituent group Zα. The substituent may also be a substituted or unsubstituted diarylphosphino such as diphenylphosphino. When multiple substituents are present, the multiple substituents may be the same or different from each other. The substituent is preferably a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted diarylamino.

[C Ring]
In formula (1), ring C is a substituted indene ring represented by formula (1C).
In formula (1C), R ^c5 and R ^c6 are bonds to Y ¹ and X ^2. R ^c6 may be a bond to Y ¹ and R ^c5 may be a bond to X ² , or R ^c5 may be a bond to Y ¹ and R ^c6 may be a bond to X ^2. From the viewpoint of ease of synthesis, however, it is preferable that R ^c6 is a bond to Y ¹ and R ^c5 is a bond to X ² .

In formula (1C), R ^c1 , R ^c2 , R ^c3 , and R ^c4 are each independently hydrogen or a substituent, provided that at least one selected from the group consisting of R ^c1 , R ^c2 , R ^c3 , and R ^c4 is a substituent. With such a structure, it becomes easier to obtain blue light emission in an organic EL device using the compound of the present invention as a light-emitting material, and the luminous efficiency is improved. It is preferable that one of R ^c1 , R ^c2 , R ^c3 , and R ^c4 is a substituent, and the others are hydrogen.

The substituents R ^c1 , R ^c2 , R ^c3 , and R ^c4 are preferably at least one substituent selected from the substituent group Zα. The substituent may be a substituted or unsubstituted diarylphosphino such as diphenylphosphino. When a plurality of R ^c1 , R ^c2 , R ^c3 , and R ^c4 are substituents, the plurality of substituents may be the same or different from each other.

Preferred examples of the substituent when R ^c1 , R ^c2 , R ^c3 , or R ^c4 is a substituent include substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted diarylamino, substituted or unsubstituted diheteroarylamino, substituted or unsubstituted arylheteroarylamino, substituted or unsubstituted diarylboryl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, or substituted silyl.

In particular, preferred examples of the substituent when R ^c2 or R ^c3 is a substituent include substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted diarylamino, substituted or unsubstituted diheteroarylamino, substituted or unsubstituted arylheteroarylamino, substituted or unsubstituted diarylboryl), substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, or substituted silyl, and more preferred examples include substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, or substituted or unsubstituted diarylamino (diphenylamino which may be substituted with alkyl or biphenylylphenylamino which may be substituted with alkyl, etc.).

Preferred specific examples of the substituent when R ^c1 , R ^c2 , R ^c3 or R ^c4 , particularly R ^c2 or R ^c3 , is substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl include any substituent selected from the following substituent group C. In the following formulae, * represents a bonding position, and Ak is alkyl, preferably methyl or t-butyl.

(Substituent Group C)

In formula (1C), among R ^c1 , R ^c2 , R ^c3 , and R ^c4 , when R ^c2 or R ^c3 is a substituted or unsubstituted alkyl and the others are hydrogen, it is preferable that none of R ^NX , R ^CX , and R ^IX in X ¹ and X ² of formula (1) is bonded to any of ring A, ring B, or ring C via a single bond or a linking group. In addition, in the above case, when X ¹ or X ² are both >N-R ^NX , from the viewpoint of efficiency, it is preferable that R ^NX is each independently a group containing a phenyl ring, a benzofuran ring, a benzothiophene ring, an adamantane ring, or a tetrahydronaphthalene ring, and specifically, it is preferable that it is selected from the substituent group X1 described later, more preferably from the substituent group X2 described later, and further preferably from the substituent group X3 described later.

In formula (1C), among R ^c1 , R ^c2 , R ^c3 , and R ^c4 , when R ^c2 is unsubstituted phenyl and the others are hydrogen, and when X ¹ and X ² are both >N-R ^NX , from the viewpoint of efficiency, it is preferable that R ^NX is each independently substituted or unsubstituted aryl (excluding unsubstituted phenyl) or substituted or unsubstituted heteroaryl, more preferably any group selected from the following substituent group X1, further preferably any group selected from the following substituent group X2, and particularly preferably any group selected from the following substituent group X3.

In formula (1C), when R ^c3 is N-carbazolyl and the others are hydrogen, it is preferable that none of R ^NX , R ^CX , and R ^IX in X ¹ and X ² is bonded to any of ring A, ring B, or ring C via a single bond or a linking group. In addition, in the above case, when X ¹ or X ² are both >N-R ^NX , at least one R ^NX is preferably any group selected from the substituent group X1 described below, more preferably any group selected from the substituent group X2 described below, and further preferably any group selected from the substituent group X3 described below.

In formula (1C), when R ^c3 is t-butyl and the others are hydrogen, and both X ¹ and X ² are >N—R ^NX , it is preferable that at least one of R ^NX is selected from the substituent group X3 described later.

R ^d1 and R ^d2 are each independently hydrogen or a substituent, and may be bonded to each other to form a ring. The substituent R ^d1 or R ^d2 is preferably an alkyl group, more preferably a methyl group. It is preferable that both R ^d1 and R ^d2 are methyl.

<Structure consisting of one or more structural units>
The polycyclic aromatic compound of the present invention is a polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1). Examples of polycyclic aromatic compounds having a structure consisting of one of the structural units include polycyclic aromatic compounds represented by formula (1). Examples of polycyclic aromatic compounds having a structure consisting of two or more structural units represented by formula (1) include compounds corresponding to the multimers of polycyclic aromatic compounds represented by the formulas described above as the structural unit represented by formula (1). The multimer is preferably a dimer to a hexamer, more preferably a dimer to a trimer, and particularly preferably a dimer. The multimer may be in a form having a plurality of the above unit structures in one compound, and may be in a form in which any ring (aryl ring or heteroaryl ring in ring A, ring B, or ring C) contained in the above structural unit is bonded so as to be shared by a plurality of unit structures, or may be in a form in which any ring (aryl ring or heteroaryl ring in ring A, ring B, or ring C) contained in the above unit structure is bonded so as to be condensed with each other. The above unit structures may be bonded together via a linking group such as a single bond, an alkylene having 1 to 3 carbon atoms, phenylene, or naphthylene. Among these, the unit structures are preferably bonded together so as to share a ring. In a polycyclic aromatic compound having a structure consisting of two or more structural units represented by formula (1), the structural units may be the same or different from each other.

<Y ¹ >
In formula (1), Y ¹ is B, P, P═O, P═S, Al, Ga, As, Si-R ^YI , or Ge-R ^YG , and R ^YI and R ^YG are each a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, or a substituted or unsubstituted cycloalkyl. R ^YI and R ^YG are particularly preferably an aryl having 6 to 10 carbon atoms (e.g., phenyl, naphthyl, etc.), an alkyl having 1 to 5 carbon atoms (e.g., methyl, ethyl, etc.), or a cycloalkyl having 5 to 10 carbon atoms (preferably cyclohexyl or adamantyl).
Y ¹ is preferably B, P═O or P═S, and more preferably B.

< ^X1 and ^X2 >
X ¹ and X ² in formula (1) are each independently >O, >NR ^NX , >C(-R ^CX ) ₂ , >Si(-R ^IX ) ₂ , >S, or >Se.

Each R ^CX is independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, and two R ^CX may be bonded to each other to form a ring. Preferably, R ^CX is methyl or phenyl. Each R ^IX is independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, and two R ^IX may be bonded to each other to form a ring.

R ^NX is hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, and is preferably substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl.

Examples of the substituted or unsubstituted aryl represented by R ^NX include any group selected from the above-mentioned Substituent Group C. In the following formula, Ak is alkyl, and is preferably methyl or t-butyl. * indicates a bonding position.

It is preferable that both ^X1 and ^X2 are >N- ^RNX , and in this case, it is preferable that ^RNX is each independently substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl, and more preferably any group selected from the above-mentioned substituent group C. Furthermore, in a specific case (for example, when ^Rc2 or ^Rc3 is substituted or unsubstituted alkyl), from the viewpoint of efficiency, it is preferable that ^RNX is each independently any group selected from the following substituent group X1, more preferably any group selected from the following substituent group X2, and particularly preferably any group selected from the following substituent group X3.

(Substituent Group X1)

(Substituent Group X2)

(Substituent Group X3)

In the above formula, * indicates the bond position. Ak is alkyl, preferably methyl or t-butyl.

<Explanation of change in ring structure due to bonding between ^X1 or ^X2 and the ring>
R ^NX , at least one R ^CX , and at least one R ^IX in each of X ¹ and X ² may be bonded to at least one of ring A or ring B, or at least one of ring A or ring C via a single bond or a linking group.

Examples of the linking group when R ^NX , R ^CX and R ^IX are each bonded to a ring include -CH ₂ -CH ₂ -, -CHR-CHR-, -CR ₂ -CR ₂ -, -CH=CH-, -CR=CR-, -C≡C-, -N(-R)-, -O-, -S-, -C(-R) ₂ -, -C(=O)-, -C(=S)-, -S(=O)-, -S(=O) ₂ -, -Se(=O)-, -Se(=O) ₂ -, -P(=O)-, -B(-R)-, -Si(-R) ₂ - and -Se-. Of these, -CH=CH-, -CR=CR-, -N(-R)-, -O-, -S- and -C(-R) ₂ - are preferred, -CH=CH-, -CR=CR-, -N(-R)-, -O- and -S- are more preferred, and -CR=CR-, -N(-R)-, -O- and -S- are even more preferred. The R of "-CHR-CHR-", the R of "-CR ₂ -CR ₂ -", the R of "-CR=CR-", the R of "-N(-R)-", the R of "-C(-R) ₂ -", the R of "-B(-R)-", and the R of "-Si(-R) ₂ -" are each independently hydrogen, aryl which may be substituted with an alkyl or cycloalkyl, heteroaryl which may be substituted with an alkyl or cycloalkyl, alkyl which may be substituted with an alkyl or cycloalkyl, alkenyl which may be substituted with an alkyl or cycloalkyl, alkynyl which may be substituted with an alkyl or cycloalkyl, or cycloalkyl which may be substituted with an alkyl or cycloalkyl. Two Rs bonded to the same element may be bonded to each other to form a ring. Furthermore, two adjacent Rs may be bonded to each other to form a cycloalkylene ring, an arylene ring, or a heteroarylene ring. These rings may also be substituted with an alkyl or cycloalkyl.

Examples of the fused ring formed by R ^NX in >N-R ^NX bonding to a benzene ring as an aryl ring in ring A, ring B, or ring C include a carbazole ring (R ^NX which is a phenyl is bonded via a single bond), a phenoxazine ring (R ^NX which is a phenyl is bonded via -O-), a phenothiazine ring (R ^NX which is a phenyl is bonded via -S-), or an acridone ring (R ^NX which is a phenyl is bonded via -C(=O)-).

Furthermore, the following partial structure (A10) may be formed by the above-mentioned linkage.

In formula (A10), R ^A1 to R ^A4 are each independently hydrogen, an optionally substituted alkyl, or an optionally substituted cycloalkyl, and any two to four of R ^A1 to R ^A4 may be bonded to each other by a linking group or a single bond, and are bonded to one of the two rings to which X ¹ or X ² is bonded at the two * positions, and to the other ring at the ** position. That is, N in formula (A10) is N of >N-R ^NX when X ¹ or X ² is >N-R ^NX . The atoms on the rings bonded at the two * positions may be adjacent atoms (preferably carbon atoms). When the polycyclic aromatic compound contains a structure represented by formula (A10), the number of such atoms may be one or two (preferably one).

In formula (A10), any two to four of R ^A1 to R ^A4 may be linked to each other via a linking group.
Of R ^A1 to R ^A4 , any two (R ^A1 and R ^A4 , R ^A1 and R ^A4 and R ^A2 and R ^A3 , R ^A1 and R ^A2 , R ^A3 and R ^A4 , R ^A1 and R ^A2 and R ^A3 and R ^A4 ) are preferably bonded to each other via a linking group or a single bond, and it is more preferable that R ^A1 and R ^A4 are bonded to each other via a linking group or a single bond. Examples of the divalent group formed by bonding to each other include alkylene and cycloalkylene. At least one hydrogen atom in the alkylene may be substituted with an alkyl or cycloalkyl, and at least one (preferably one) -CH ₂ - in the alkylene may be substituted with -O- and -S-. The divalent group formed by bonding to each other is preferably a straight-chain alkylene having 2 to 5 carbon atoms, more preferably a straight-chain alkylene having 3 or 4 carbon atoms, and even more preferably a straight-chain alkylene having 4 carbon atoms (-(CH ₂ ) ₄ -). It is particularly preferable that the straight-chain alkylene having 4 carbon atoms (-(CH ₂ ) ₄ -) is unsubstituted.

The remaining R ^A1 to R ^A4 that are not involved in the linking through the linking group are each preferably independently hydrogen or an alkyl which may be substituted, more preferably an alkyl having 1 to 6 carbon atoms which may be substituted, further preferably an unsubstituted alkyl having 1 to 6 carbon atoms, and most preferably methyl.
That is, the partial structure represented by formula (A10) is preferably a structure represented by the following formula (A11).

式（Ａ１１）中、Ｍｅはメチルであり、２つの＊の位置でＸが結合する２つの環の一方の環に、＊＊の位置で他方の環に結合している。

In formula (A11), Me is methyl and is bonded to one of the two rings to which X is bonded at the two * positions and to the other ring at the ** position.

<Formula (1XC1) and Formula (1XC2)>
Specific examples of formula (1) include formula (1XC1) and formula (1XC2).

In formula (1XC1) and formula (1XC2), R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 each independently represent hydrogen or a substituent.

In each of formulas (1XC1) and (1XC2), R ^c1 , R ^c2 , R ^c3 , R ^c4 , R ^d1 , and R ^d2 are the same as R ^c1 , R ^c2 , R ^c3 , R ^c4 , R ^d1 , and R ^d2 in formula (1C), and the preferred ranges are also the same. In each of formulas (1XC1) and (1XC2), Y ¹ , X ¹ , and X ² are the same as Y ¹ , X ¹ , and X ² in formula (1), and the preferred ranges are also the same.

In each of formulas (1XC1) and (1XC2), R ^a1 , R ^a2 , and R ^a3 are each independently hydrogen or a substituent, R ^a2 is a substituent, and R ^a1 and R ^a3 are both preferably hydrogen. The substituent represented by R ^a1 , R ^a2 , or R ^a3 is preferably a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted diarylamino, more preferably an alkyl, a cycloalkyl which may be substituted with an alkyl, or a diarylamino which may be substituted with an alkyl, and even more preferably a diphenylamino which may be substituted with methyl, t-butyl, isopropyl, methyl, or t-butyl.

In each of formulas (1XC1) and (1XC2), among R ^b1 , R ^b2 , R ^b3 , and R ^b4 , two adjacent groups may be bonded to each other to form a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring together with the two carbon atoms to which they are bonded. The ring formed by bonding two adjacent groups among R ^b1 to R ^b4 to each other together with the two carbon atoms to which they are bonded is not particularly limited, and examples thereof include a benzene ring, a naphthalene ring, an indene ring, a fluorene ring, a pyridine ring, a furan ring, a thiophene ring, a pyrrole ring, a benzofuran ring, a benzothiophene ring, an indole ring, a selenophene ring, and a benzoselenophene ring. Any of these may have a substituent.

In each formula (1XC1) and formula (1XC2), when R ^b1 , R ^b2 , R ^b3 , and R ^b4 are substituents, and when the above-formed aryl ring or heteroaryl ring has a substituent, the substituent is preferably at least one substituent selected from the substituent group Zα. The substituent may be a substituted or unsubstituted diarylphosphino such as diphenylphosphino. When a plurality of R ^c1 to R ^c4 are substituents, and when the formed ring has a plurality of substituents, the plurality of substituents may be the same or different from each other. As the substituent, a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted diarylamino is preferable.

In each of formulas (1XC1) and (1XC2), in R ^b1 , R ^b2 , R ^b3 , and R ^b4 , it is preferable that R ^b2 or R ^b3 is hydrogen or a substituent and the others are each hydrogen, and it is more preferable that R ^b2 or R ^b3 is a substituent and the others are each hydrogen.

In each of formulas (1XC1) and (1XC2), R ^c1 , R ^c2 , R ^c3 , and R ^c4 are each independently hydrogen or a substituent, provided that at least one selected from the group consisting of R ^c1 , R ^c2 , R ^c3 , and R ^c4 is a substituent. It is preferable that one of R ^c1 , R ^c2 , R ^c3 , and R ^c4 is a substituent, and the others are hydrogen.

In each of formulas (1XC1) and (1XC2), when R ^c1 is a substituent and R ^c2 , R ^c3 , and R ^c4 are all hydrogen, R ^c1 is particularly preferably a substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, and more preferably methyl, t-butyl, phenyl (optionally substituted with methyl, t-butyl, cyano, or halogen), or diarylamino (optionally substituted with phenyl, methyl, t-butyl, cyano, or halogen).

In each formula of formula (1XC1) and formula (1XC2), R ^c2 is a substituent, and R ^c1 , R ^c3 , and R ^c4 are all hydrogen when R ^c2 is particularly preferably substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted diarylamino, substituted or unsubstituted diheteroarylamino, substituted or unsubstituted arylheteroarylamino, substituted or unsubstituted diarylboryl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, or substituted silyl, and more preferably substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, or substituted or unsubstituted diarylamino (diphenylamino which may be substituted with alkyl or biphenylylphenylamino which may be substituted with alkyl). A preferred specific example of the substituent when it is substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl is any of the substituents selected from the above-mentioned substituent group C (preferably excluding unsubstituted phenyl).

In formula (1XC1), when R ^c2 is a substituent, and when R ^c1 , R ^c3 , and R ^c4 are all hydrogen, and R ^c2 is unsubstituted phenyl, and X ¹ and X ² are both >N-R ^NX , R ^NX is preferably each independently any group selected from the above-mentioned substituent group X1, more preferably any group selected from the above-mentioned substituent group X2, and further preferably any group selected from the above-mentioned substituent group X3.

In formula (1XC1), when R ^c2 is a substituent and R ^c1 , R ^c3 , and R ^c4 are all hydrogen and R ^c2 is a substituted or unsubstituted alkyl, it is preferable that none of R ^NX , R ^CX , and R ^IX in X ¹ and X ² is bonded to any of ring A, ring B, or ring C via a single bond or a linking group. In addition, in the above case, when X ¹ and X ² are all >N-R ^NX , at least one R ^NX is preferably a substituted or unsubstituted heteroaryl, a substituted or unsubstituted cycloalkyl, or a cycloalkane-condensed substituted or unsubstituted aryl or a cycloalkane-condensed substituted or unsubstituted heteroaryl as described below. Among them, substituted or unsubstituted dibenzofuranyl (or other groups containing a substituted or unsubstituted dibenzofuran ring), substituted or unsubstituted adamantyl (or other groups containing a substituted or unsubstituted adamantane), and substituted or unsubstituted tetrahydronaphthalene group (or other groups containing a substituted or unsubstituted tetrahydronaphthalene ring) are particularly preferred.Specific examples include groups described in the above-mentioned Substituent Group X1, and any group selected from the above-mentioned Substituent Group X2 is more preferred, and any group selected from the above-mentioned Substituent Group X3 is even more preferred.

In each formula of formula (1XC1) and formula (1XC2), R ^c3 is a substituent, and R ^c1 , R ^c2 , and R ^c4 are all hydrogen. When R ^c3 is hydrogen, it is particularly preferably substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted diarylamino, substituted or unsubstituted diheteroarylamino, substituted or unsubstituted arylheteroarylamino, substituted or unsubstituted diarylboryl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, or substituted silyl, and more preferably substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, or substituted or unsubstituted diarylamino (diphenylamino which may be substituted with alkyl or biphenylylphenylamino which may be substituted with alkyl). Specific examples of the preferred substituent when it is substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl include any of the substituents selected from the above-mentioned substituent group C.

In each of formulas (1XC1) and (1XC2), when R ^c3 is a substituent and R ^c1 , R ^c3 , and R ^c4 are all hydrogen, and R ^c3 is a substituted or unsubstituted alkyl, it is preferable that none of R ^NX , R ^CX , and R ^IX in X ¹ and X ² is bonded to any of ring A, ring B, or ring C via a single bond or a linking group. In addition, when X ¹ and X ² are both >N-R ^NX , at least one R ^NX is preferably any group selected from the above-mentioned substituent group X1, more preferably any group selected from the above-mentioned substituent group X2, and even more preferably any group selected from the above-mentioned substituent group X3.

In formula (1XC1), when R ^c3 is a substituent and R ^c1 , R ^c3 , and R ^c4 are all hydrogen, and R ^c3 is N-carbazolyl, it is preferable that none of R ^NX , R ^CX , and R ^IX in X ¹ and X ² is bonded to any of ring A, ring B, or ring C via a single bond or a linking group. In addition, when X ¹ and X ² are all >N-R ^NX , at least one R ^NX is preferably any group selected from the above-mentioned substituent group X1, more preferably any group selected from the above-mentioned substituent group X2, and further preferably any group selected from the above-mentioned substituent group X3.

In each of formulas (1XC1) and (1XC2), when R ^c4 is a substituent and R ^c1 , R ^c2 , and R ^c3 are all hydrogen, R ^c4 is particularly preferably a substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, and more preferably methyl, t-butyl, phenyl (optionally substituted with methyl, t-butyl, cyano, or halogen), or diarylamino (optionally substituted with phenyl, methyl, t-butyl, cyano, or halogen).

<Preferable Substituents>
In polycyclic aromatic compounds used as emitting dopants (and in other compounds used as dopants), a tertiary alkyl represented by the following formula (tR) is one of the particularly preferred substituents containing an "alkyl". This is because such a bulky substituent increases the intermolecular distance, thereby improving the light emission quantum yield (PLQY). Also preferred are substituents in which the tertiary alkyl represented by formula (tR) is substituted with another substituent as a second substituent. Specifically, examples include diarylamino substituted with a tertiary alkyl represented by formula (tR), carbazolyl (preferably N-carbazolyl) substituted with a tertiary alkyl represented by formula (tR), or benzocarbazolyl (preferably N-benzocarbazolyl) substituted with a tertiary alkyl represented by formula (tR). Substitution of the group of formula (tR) on diarylamino, carbazolyl and benzocarbazolyl includes examples in which some or all of the hydrogen atoms on the aryl ring or benzene ring in these groups are replaced with the group of formula (tR).

In formula (tR), R ^a , R ^b , and R ^c each independently represent an alkyl group having 1 to 24 carbon atoms, any —CH ₂ — in the alkyl group may be replaced by —O—, and the group represented by formula (tR) has * as the bonding position.

The "alkyl having 1 to 24 carbon atoms" of R ^a , R ^b and R ^c may be either linear or branched, and examples thereof include linear alkyl having 1 to 24 carbon atoms or branched alkyl having 3 to 24 carbon atoms, alkyl having 1 to 18 carbon atoms (branched alkyl having 3 to 18 carbon atoms), alkyl having 1 to 12 carbon atoms (branched alkyl having 3 to 12 carbon atoms), alkyl having 1 to 6 carbon atoms (branched alkyl having 3 to 6 carbon atoms), and alkyl having 1 to 4 carbon atoms (branched alkyl having 3 to 4 carbon atoms).

The total number of carbon atoms of R ^a , R ^b and R ^c in formula (tR) is preferably 3 to 20, and particularly preferably 3 to 10.

Specific examples of alkyl for R ^a , R ^b , and R ^c include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, 1-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, n-heptyl, 1-methylhexyl, n-octyl, t-octyl, 1-methylheptyl, Examples include 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 2,6-dimethyl-4-heptyl, 3,5,5-trimethylhexyl, n-decyl, n-undecyl, 1-methyldecyl, n-dodecyl, n-tridecyl, 1-hexylheptyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, and n-eicosyl.

Examples of groups represented by formula (tR) include t-butyl, t-amyl, 1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1-dimethylbutyl, 1-ethyl-1-methylbutyl, 1,1,3,3-tetramethylbutyl, 1,1,4-trimethylpentyl, 1,1,2-trimethylpropyl, 1,1-dimethyloctyl, 1,1-dimethylpentyl, 1,1-dimethylheptyl, 1,1,5-trimethylhexyl, 1-ethyl- Examples include 1-methylhexyl, 1-ethyl-1,3-dimethylbutyl, 1,1,2,2-tetramethylpropyl, 1-butyl-1-methylpentyl, 1,1-diethylbutyl, 1-ethyl-1-methylpentyl, 1,1,3-trimethylbutyl, 1-propyl-1-methylpentyl, 1,1,2-trimethylpropyl, 1-ethyl-1,2,2-trimethylpropyl, 1-propyl-1-methylbutyl, and 1,1-dimethylhexyl. Of these, t-butyl and t-amyl are preferred.

The substituent is preferably a substituent represented by formula (A30).

The emission wavelength can be adjusted by the steric hindrance, electron donating property and electron withdrawing property of the structure of the substituent possessed by the compound used as a dopant (assisting dopant or emitting dopant). The groups represented by the following structural formulas are preferred, and more preferred are methyl, t-butyl, t-amyl, t-octyl, neopentyl, adamantyl, phenyl, o-tolyl, p-tolyl, 2,4-xylyl, 2,5-xylyl, 2,6-xylyl, 2,4,6-mesityl, diphenylamino, di-p-tolylamino, bis(p-(t-butyl)phenyl)amino, carbazolyl, 3,6-dimethylcarbazolyl, 3,6-di-t-butyl and more preferably, methyl, t-butyl, t-amyl, t-octyl, neopentyl, adamantyl, phenyl, o-tolyl, 2,6-xylyl, 2,4,6-mesityl, diphenylamino, di-p-tolylamino, bis(p-(t-butyl)phenyl)amino, carbazolyl, 3,6-dimethylcarbazolyl, 3,6-di-t-butylcarbazolyl, and tribenzoazepinyl. From the viewpoint of ease of synthesis, a larger steric hindrance is preferred for selective synthesis, and specifically, t-butyl, t-amyl, t-octyl, adamantyl, o-tolyl, p-tolyl, 2,4-xylyl, 2,5-xylyl, 2,6-xylyl, 2,4,6-mesityl, di-p-tolylamino, bis(p-(t-butyl)phenyl)amino, 3,6-dimethylcarbazolyl, and 3,6-di-t-butylcarbazolyl are preferred.

In the following structural formula, * represents a bond position.

The polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1) is preferably a structure containing at least one tertiary alkyl (such as t-butyl or t-amyl), neopentyl or adamantyl represented by the above formula (tR), and preferably contains a tertiary alkyl (such as t-butyl or t-amyl) represented by formula (tR). This is because such bulky substituents increase the intermolecular distance, improving the luminescence quantum yield (PLQY). Diarylamino is also preferred as a substituent. Furthermore, diarylamino substituted with a group represented by formula (tR), carbazolyl (preferably N-carbazolyl) substituted with a group represented by formula (tR), or benzocarbazolyl (preferably N-benzocarbazolyl) substituted with a group represented by formula (tR) are also preferred. Examples of the substitution of the group of formula (tR) on diarylamino, carbazolyl, and benzocarbazolyl include those in which some or all of the hydrogen atoms on the aryl ring or benzene ring in these groups are substituted with the group of formula (tR).

In the structure consisting of one or more structural units represented by formula (1), the substituent on the aryl ring or heteroaryl ring may be a substituent represented by the following formula (A20).

The substituent represented by formula (A20) is bonded to two adjacent atoms on the ring of the aryl ring or heteroaryl ring at two *'s, respectively. In formula (A20), L is >N-R, >O, >Si(-R) ₂ or >S, R of the >N-R is substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl or substituted or unsubstituted cycloalkyl, R of the >Si(-R) ₂ is hydrogen, optionally substituted aryl, optionally substituted alkyl or optionally substituted cycloalkyl, and may be bonded to each other by a linking group, and at least one of R of the >N-R and the >Si(-R) ₂ may be bonded to the aryl ring or heteroaryl ring by a linking group or a single bond,
r is an integer from 1 to 4;
Each R ^A is independently hydrogen, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, and any R ^A may be bonded to any other R ^A via a linking group or a single bond.

Examples of the above-mentioned substituent include any of the following substituents.

In each formula, * may be bonded to two or three consecutive (adjacent) atoms on any aryl or heteroaryl ring.

<Cycloalkane condensation>
At least one selected from the group consisting of aryl rings and heteroaryl rings in the polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1) may be condensed with at least one cycloalkane.

The cycloalkane may be a cycloalkane having 3 to 24 carbon atoms. In this case, at least one hydrogen atom in the cycloalkane may be substituted with an aryl having 6 to 30 carbon atoms, a heteroaryl having 2 to 30 carbon atoms, an alkyl having 1 to 24 carbon atoms, or a cycloalkyl having 3 to 24 carbon atoms, and at least one -CH ₂ - in the cycloalkane may be replaced with -O-.

The cycloalkane is preferably a cycloalkane having 3 to 20 carbon atoms, in which at least one hydrogen atom may be substituted with an aryl having 6 to 16 carbon atoms, a heteroaryl having 2 to 22 carbon atoms, an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms.

Examples of "cycloalkanes" include cycloalkanes with 3 to 24 carbon atoms, cycloalkanes with 3 to 20 carbon atoms, cycloalkanes with 3 to 16 carbon atoms, cycloalkanes with 3 to 14 carbon atoms, cycloalkanes with 5 to 10 carbon atoms, cycloalkanes with 5 to 8 carbon atoms, cycloalkanes with 5 to 6 carbon atoms, and cycloalkanes with 5 carbon atoms.

Specific examples of cycloalkanes include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, norbornane (bicyclo[2.2.1]heptane), bicyclo[1.1.0]butane, bicyclo[1.1.1]pentane, bicyclo[2.1.0]pentane, bicyclo[2.1.1]hexane, bicyclo[3.1.0]hexane, bicyclo[2.2.2]octane, adamantane, diamantane, decahydronaphthalene, and decahydroazulene, as well as alkyl (especially methyl) substituted, halogen (especially fluorine) substituted, and deuterium substituted derivatives of these having 1 to 5 carbon atoms.

Among the above examples, a structure having at least one substituent on the α-position carbon of the cycloalkane (in a cycloalkane fused to an aryl ring or heteroaryl ring, the carbon adjacent to the carbon at the condensation site), such as that shown in the structural formula below, is preferred, a structure having two substituents on the α-position carbon is more preferred, and a structure having two substituents on each of the two α-position carbons (four substituents in total) is even more preferred. Examples of such substituents include alkyl groups having 1 to 5 carbon atoms (especially methyl), halogens (especially fluorine), and deuterium. In particular, a structure in which a partial structure represented by the following formula (B) is bonded to adjacent carbon atoms in an aryl ring or heteroaryl ring is preferred.

式（Ｂ）中、＊は結合位置を示す。

In formula (B), * indicates a bonding position.

The number of cycloalkanes fused to one aryl ring or heteroaryl ring is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. For example, the following shows an example in which one or more cycloalkanes are fused to one benzene ring (phenyl). * indicates the bonding position, and the position may be any carbon that constitutes the benzene ring but does not constitute the cycloalkane. Cycloalkanes fused to each other as in formula (Cy-1-4) and formula (Cy-2-4) may be fused together. The same applies when the fused ring (group) is an aryl ring or heteroaryl ring other than a benzene ring (phenyl), or when the fused cycloalkane is a cycloalkane other than cyclopentane or cyclohexane.

At least one -CH ₂ - in a cycloalkane may be replaced with -O-. For example, examples in which one or more -CH ₂ - in a cycloalkane fused to a benzene ring (phenyl) are replaced with -O- are shown below. The same applies when the fused ring (group) is an aryl ring or heteroaryl ring other than a benzene ring (phenyl) or when the fused cycloalkane is a cycloalkane other than cyclopentane or cyclohexane.

The cycloalkane may be substituted with at least one substituent, and the substituent may be any of the substituents selected from the group Z of substituents. Among these substituents, alkyl (e.g., alkyl having 1 to 6 carbon atoms) and cycloalkyl (e.g., cycloalkyl having 3 to 14 carbon atoms) are preferred. It is also preferred that any hydrogen atom is replaced with a halogen (e.g., fluorine) or deuterium. In addition, when cycloalkyl is substituted, it may be a substitution form that forms a spiro structure. For example, an example of a spiro structure formed in a cycloalkane condensed to one benzene ring (phenyl) is shown below. In each structural formula, * means that in the case of a benzene ring, it is a benzene ring included in the skeletal structure of the compound, and in the case of phenyl, it means a bond that substitutes in the skeletal structure of the compound.

Examples of cycloalkane condensation include a form in which an aryl ring or heteroaryl ring in ring A and ring B or an indene ring in ring C in a polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1) is condensed with a cycloalkane, and a form in which an aryl ring or heteroaryl ring in R ^a1 to R ^a3 , R ^b1 to R ^b4 , and R ^c1 to R ^c4 is condensed with a cycloalkane.

Other forms of cycloalkane condensation include examples of polycyclic aromatic compounds having a structure consisting of one or more structural units represented by formula (1), such as >N-R ^NX , where R ^NX is an aryl fused with a cycloalkane, a diarylamino fused with a cycloalkane (condensed to the aryl portion), a carbazolyl fused with a cycloalkane (condensed to the benzene ring portion), or a benzocarbazolyl fused with a cycloalkane (condensed to the benzene ring portion).

By introducing a cycloalkane structure into a polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1), a further reduction in melting point and sublimation temperature can be expected. This means that in sublimation purification, which is almost essential as a purification method for materials for organic devices such as organic EL elements that require high purity, purification can be performed at a relatively low temperature, and thermal decomposition of the material can be avoided. This is also true for the vacuum deposition process, which is a powerful means for producing organic devices such as organic EL elements, and since the process can be performed at a relatively low temperature, thermal decomposition of the material can be avoided, resulting in a high-performance organic device. In addition, since the introduction of a cycloalkane structure improves solubility in organic solvents, it can also be applied to the production of elements using a coating process. However, the present invention is not particularly limited to these principles.

<Replacement with heavy stable isotopes>
Unless otherwise specified, each element in a polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1) contains a plurality of naturally occurring isotopes in the natural abundance ratio. However, all or a portion of the elements in each structural formula may contain a heavy stable isotope in excess of the natural abundance ratio (for example, 90 atom % or more for boron-11 (11B)). In this specification, this is simply referred to as being "replaced" with a "heavy stable isotope". More specifically, at least one hydrogen can be replaced with deuterium, at least one nitrogen can be replaced with nitrogen-15 ( ¹⁵ N), at least one sulfur can be replaced with sulfur-33 ( ³³ S), sulfur-34 ( ³⁴ S) or sulfur-36 ( ³⁶ S), at least one oxygen can be replaced with oxygen-17 ( ¹⁷ O) or oxygen-18 ( ¹⁸ O), at least one carbon can be replaced with carbon-13 ( ¹³ C), and at least one boron can be replaced with boron-11 ( ¹¹ B). By replacing at least a part of the elements with heavy stable isotopes, particularly by replacing at least one boron with boron-11 ( ¹¹ B), it is possible to extend the life of an organic electroluminescent device using a polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1) as a dopant.

<Replacement with deuterium>
All or a part of the hydrogen atoms in the polycyclic aromatic compound having a structure consisting of one or two or more structural units represented by formula (1) may be deuterium.

For example, hydrogen atoms in the rings and the aryl or heteroaryl rings in ring B, or the indene ring in ring C of a polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1), and in the substituents thereof, may be replaced with deuterium atoms. Among these, there are embodiments in which all or part of the hydrogen atoms in the aryl or heteroaryl rings are replaced with deuterium atoms. From the viewpoint of durability, it is also preferable that all or part of the hydrogen atoms in the polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1) are deuterated.

<Specific examples of polycyclic aromatic compounds>
Further specific examples of the polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1) include the following compounds.

<Method of producing polycyclic aromatic compound>
Polycyclic aromatic compounds having a structure consisting of one or more structural units represented by formula (1) can be basically produced by first bonding fused rings including A ring, B ring, and C ring with a bonding group (a group including ^X1 or ^X2 ) to produce an intermediate (first reaction), and then bonding fused rings including A ring, B ring, and C ring with a bonding group (a group including ^Y1 ) to produce a final product (second reaction). In the first reaction, for example, general reactions such as Buchwald-Hartwig reaction, nucleophilic substitution reaction, and Goldberg amination can be used as an amination reaction. In the second reaction, a tandem hetero Friedel-Crafts reaction (successive aromatic electrophilic substitution reaction, the same applies below) can be used. The desired compound can be produced by using a raw material having a desired fused ring somewhere in the reaction process or by adding a process of condensing the rings.

[Production method via intermediate 1]
The polycyclic aromatic compound of the present invention can be produced by a production method including the following steps. For each of the steps, the description in WO 2015/102118 can be referred to.

The reaction includes the steps of synthesizing the following intermediate 1 from a halogenated precursor, metallating the halogen atom (Hal) between ^X1 and ^X2 in the following intermediate 1 using an organic alkali compound, exchanging the metal with ^Y1 using a reagent selected from the group consisting of halides of ^Y1 , aminated halides of ^Y1 , alkoxylated compounds of ^Y1 , and aryloxylated compounds of ^Y1 , and bonding the b ring and the c ring at ^Y1 by successive aromatic electrophilic substitution reactions using a Bronsted base, as shown below. The halogen atom (Hal) in the formula may be any of F, Cl, Br, and I, and can be appropriately selected in consideration of the reactivity of the substrate.

Metalation reagents used in the halogen-metal exchange reactions in the schemes described so far include alkyllithium such as methyllithium, n-butyllithium, sec-butyllithium, and t-butyllithium, isopropylmagnesium chloride, isopropylmagnesium bromide, phenylmagnesium chloride, phenylmagnesium bromide, and lithium chloride complexes of isopropylmagnesium chloride, known as turboGrignard reagents.

In addition to the above-mentioned reagents, the metallation reagents used in the orthometal exchange reactions in the schemes described so far include organic alkaline compounds such as lithium diisopropylamide, lithium tetramethylpiperidide, lithium hexamethyldisilazide, potassium hexamethyldisilazide, lithium tetramethylpiperidinylmagnesium chloride-lithium chloride complex, and lithium tri-n-butylmagnesium oxide.

Additionally, when using alkyllithium as a metalation reagent, additives that promote the reaction include N,N,N',N'-tetramethylethylenediamine, 1,4-diazabicyclo[2.2.2]octane, and N,N-dimethylpropyleneurea.

Lewis acids used in the schemes described so far include _AlCl3 , _AlBr3 , _AlF3 , _BF3.OEt2 , _BCl3 , _BBr3 , _BI3 , _GaCl3 , _GaBr3 , _InCl3 , _InBr3 , In(OTf) ₃ , _SnCl4 , _SnBr4 , _AgOTf , _{ScCl3 ,} Sc(OTf) ₃ , _ZnCl2 , ZnBr2, Zn(OTf) ₂ , MgCl2, MgBr2 _{, Mg(OTf)2, LiOTf, NaOTf, KOTf, Me3SiOTf, Cu(OTf)2 , CuCl2 , YCl3 , Y} (OTf) ₃ , TiCl ₄ , TiBr ₄ , ZrCl ₄ , ZrBr ₄ , FeCl ₃ , FeBr ₃ , CoCl ₃ , CoBr ₃ and the like. Furthermore, these Lewis acids supported on a solid can also be used in the same manner.

The Bronsted acids used in the schemes explained so far include p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, fluorosulfonic acid, carborane acid, trifluoroacetic acid, (trifluoromethanesulfonyl)imide, tris(trifluoromethanesulfonyl)methane, hydrogen chloride, hydrogen bromide, and hydrogen fluoride. The solid Bronsted acids include Amberlyst (trade name: Dow Chemical), Nafion (trade name: DuPont), zeolite, and Teikacure (trade name: Teika Corporation).

In addition, amines that may be added in the schemes described above include diisopropylethylamine, triethylamine, tributylamine, 1,4-diazabicyclo[2.2.2]octane, N,N-dimethyl-p-toluidine, N,N-dimethylaniline, pyridine, 2,6-lutidine, and 2,6-di-t-butylamine.

In addition, solvents used in the schemes described so far include o-dichlorobenzene, chlorobenzene, toluene, benzene, methylene chloride, chloroform, dichloroethylene, benzotrifluoride, decalin, cyclohexane, hexane, heptane, 1,2,4-trimethylbenzene, xylene, diphenyl ether, anisole, cyclopentyl methyl ether, tetrahydrofuran, dioxane, and methyl t-butyl ether.

Here, an example in which ^Y1 is B is described, but by appropriately changing the raw materials, a compound in which ^Y1 is P, P=O, P=S, Al, Ga, As, Si-R, or Ge-R can also be synthesized.

In the above scheme, a Bronsted base or Lewis acid may be used to promote the tandem hetero Friedel-Crafts reaction. However, when ^a halide of ^Y1 such as trifluoride of Y1, trichloride of ^Y1 , tribromide of ^Y1 , or triiodide of ^Y1 is used, acids such as hydrogen fluoride, hydrogen chloride, hydrogen bromide, and hydrogen iodide are generated as the aromatic electrophilic substitution reaction proceeds, so it is effective to use a Bronsted base to capture the acid. On the other hand, when an amino halide of ^Y1 or an alkoxylated product of ^Y1 is used, amines and alcohols are generated as the aromatic electrophilic substitution reaction proceeds, so in many cases it is not necessary to use a Bronsted base, but since the elimination ability of amino and alkoxy is low, it is effective to use a Lewis acid to promote the elimination.

The polycyclic aromatic compounds of the present invention also include compounds in which at least some of the hydrogen atoms are replaced with deuterium or are replaced with various substituents. Such compounds can be synthesized in the same manner as above by using raw materials in which the desired positions are deuterated or derivatized.

2. Organic Devices
The polycyclic aromatic compound of the present invention can be used as a material for an organic device, such as an organic electroluminescent device, an organic field effect transistor, or an organic thin-film solar cell.

The polycyclic aromatic compound and its multimer according to the present invention can be used as a material for an organic device. Examples of organic devices include organic electroluminescent devices, organic field effect transistors, and organic thin-film solar cells, and organic electroluminescent devices are preferred. The polycyclic aromatic compound according to the present invention is preferably a material for an organic electroluminescent device, more preferably a material for a light-emitting layer (light-emitting material), and most preferably a dopant material for the light-emitting layer.

<2-1. Organic electroluminescent element>
<2-1-1. Structure of organic electroluminescent element>
FIG. 1 is a schematic cross-sectional view showing an example of an organic EL element.
The organic EL element 100 shown in FIG. 1 has a substrate 101, an anode 102 provided on the substrate 101, a hole injection layer 103 provided on the anode 102, a hole transport layer 104 provided on the hole injection layer 103, a light emitting layer 105 provided on the hole transport layer 104, an electron transport layer 106 provided on the light emitting layer 105, an electron injection layer 107 provided on the electron transport layer 106, and a cathode 108 provided on the electron injection layer 107.

The organic EL element 100 may be fabricated in the reverse order, for example, with a substrate 101, a cathode 108 provided on the substrate 101, an electron injection layer 107 provided on the cathode 108, an electron transport layer 106 provided on the electron injection layer 107, a light-emitting layer 105 provided on the electron transport layer 106, a hole transport layer 104 provided on the light-emitting layer 105, a hole injection layer 103 provided on the hole transport layer 104, and an anode 102 provided on the hole injection layer 103.

Not all of the above layers are essential, and the minimum structural unit is the anode 102, the light-emitting layer 105, and the cathode 108, with the hole injection layer 103, the hole transport layer 104, the electron transport layer 106, and the electron injection layer 107 being layers that may be provided optionally. Each of the above layers may consist of a single layer or multiple layers.

In addition to the above-mentioned "substrate/anode/hole injection layer/hole transport layer/light-emitting layer/electron transport layer/electron injection layer/cathode" configuration, the layers constituting the organic EL element may be "substrate/anode/hole transport layer/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole injection layer/hole transport layer/light-emitting ... transport", The configuration may be "transport layer/cathode", "substrate/anode/light-emitting layer/electron transport layer/electron injection layer/cathode", "substrate/anode/hole transport layer/light-emitting layer/electron injection layer/cathode", "substrate/anode/hole transport layer/light-emitting layer/electron transport layer/cathode", "substrate/anode/hole transport layer/light-emitting layer/electron injection layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron injection layer/cathode", "substrate/anode/hole injection layer/light-emitting layer/electron transport layer/cathode", "substrate/anode/light-emitting layer/electron transport layer/cathode", "substrate/anode/light-emitting layer/electron transport layer/cathode", or "substrate/anode/light-emitting layer/electron injection layer/cathode".

<2-1-2. Light-emitting layer in organic electroluminescent device>
The polycyclic aromatic compound of the present invention is preferably used as a material for forming one or more organic layers in an organic electroluminescent device, and more preferably used as a material for forming a light-emitting layer. The light-emitting layer 105 is a layer that emits light by recombining holes injected from the anode 102 and electrons injected from the cathode 108 between electrodes to which an electric field is applied. The material for forming the light-emitting layer 105 may be a compound (light-emitting compound) that is excited by the recombination of holes and electrons to emit light, and is preferably a compound that can form a stable thin film shape and shows strong light-emitting (fluorescence) efficiency in a solid state. The polycyclic aromatic compound of the present invention can be used as a material for a light-emitting layer, may be used as a dopant material, or may be used as a host material, but is preferably used as a material for a light-emitting layer, and more preferably used as a dopant material.

Note that, although there are cases where the dopant is used in combination with an assisting dopant and an emitting dopant, in this specification, when the term "dopant" is used simply, it refers to a light-emitting dopant used alone.

The light-emitting layer may be a single layer or multiple layers, each of which is formed from light-emitting layer materials (host material, dopant material). The host material and dopant material may each be one type, or a combination of multiple types. The dopant material may be contained entirely in the host material, or may be contained partially in the host material. As a doping method, the dopant material may be formed by co-evaporation with the host material, but it may also be mixed with the host material in advance and then vapor-deposited simultaneously. Specific examples of dopants to be combined with the compound of the present invention when multiple dopants are used in combination are shown below.

The amount of the host material used varies depending on the type of host material, and may be determined according to the characteristics of the host material. The amount of the host material used is preferably 50 to 99.999% by mass, more preferably 80 to 99.95% by mass, and even more preferably 90 to 99.9% by mass, of the total mass of the materials for the light-emitting layer.

The amount of dopant material used varies depending on the type of dopant material, and may be determined according to the characteristics of the dopant material. The amount of dopant used is preferably 0.001 to 50% by mass of the total mass of the light-emitting layer material, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 10% by mass. The above ranges are preferable in that, for example, concentration quenching can be prevented.

<Host Material>
Examples of the host material include condensed ring derivatives of anthracene, pyrene, dibenzochrysene, fluorene, and the like, which have long been known as light-emitting bodies; bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives; tetraphenylbutadiene derivatives; cyclopentadiene derivatives; fluorene derivatives; and benzofluorene derivatives.

As the host material, for example, a compound represented by any one of the following formulas (H1), (H2), and (H3) can be used.

In formulae (H1), (H2) and (H3), L ¹ is a single bond or a divalent group containing at least an arylene or heteroarylene. Specifically, L ¹ may be a single bond, or may be an arylene having 6 to 24 carbon atoms, a heteroarylene having 2 to 24 carbon atoms, a heteroarylenearylene having 6 to 24 carbon atoms, or an aryleneheteroarylenearylene having 6 to 24 carbon atoms, or a divalent group formed by linking any two of these with -O-, -S-, -CH ₂ -, -Si(-Arx) ₂ - (Arx is aryl), or a cycloalkylene. The arylene in L ¹ is preferably an arylene having 6 to 16 carbon atoms, more preferably an arylene having 6 to 12 carbon atoms, and particularly preferably an arylene having 6 to 10 carbon atoms, and specifically includes divalent groups such as a benzene ring, a biphenyl ring, a terphenyl ring and a fluorene ring. L The heteroarylene in ¹ is preferably a heteroarylene having 2 to 24 carbon atoms, more preferably a heteroarylene having 2 to 20 carbon atoms, still more preferably a heteroarylene having 2 to 15 carbon atoms, and particularly preferably a heteroarylene having 2 to 10 carbon atoms, and specifically, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, an oxadiazole ring (such as a furazan ring), a thiadiazole ring, a triazole ring, a tetrazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, an indole ring, or an isoindole ring. , 1H-indazole ring, benzimidazole ring, benzoxazole ring, benzothiazole ring, 1H-benzotriazole ring, quinoline ring, isoquinoline ring, cinnoline ring, quinazoline ring, quinoxaline ring, phthalazine ring, naphthyridine ring, purine ring, pteridine ring, carbazole ring, acridine ring, phenoxathiin ring, phenoxazine ring, phenothiazine ring, phenazine ring, indolizine ring, furan ring, benzofuran ring, isobenzofuran ring, dibenzofuran ring, thiophene ring, benzothiophene ring, dibenzothiophene ring, and thianthrene ring. At least one hydrogen atom in the compound represented by each of the above formulae may be substituted with at least one group selected from the substituent group Z or deuterium, and may be substituted with, for example, an alkyl group having 1 to 6 carbon atoms, a cyano group, a halogen group, or a deuterium group.

Preferred specific examples include compounds represented by any of the structural formulas listed below. In the structural formulas listed below, at least one hydrogen may be substituted with halogen, cyano, alkyl having 1 to 4 carbon atoms (e.g., methyl or t-butyl), phenyl, naphthyl, or the like.

<Anthracene Compounds>
Examples of the anthracene compound as a host include a compound represented by the formula (3-H) and a compound represented by the formula (3-H2).

In formula (3-H),
X and ^Ar4 are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted diarylamino, optionally substituted diheteroarylamino, substituted or unsubstituted arylheteroarylamino, substituted or unsubstituted alkyl, optionally substituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkoxy, substituted or unsubstituted aryloxy, substituted or unsubstituted arylthio, or substituted silyl, and all of X and ^Ar4 are not hydrogen at the same time.
At least one hydrogen in the compound represented by formula (3-H) may be substituted with halogen, cyano, deuterium or an optionally substituted heteroaryl.

A polymer (preferably a dimer) may be formed using the structure represented by formula (3-H) as a unit structure. In this case, for example, the unit structures represented by formula (3-H) may be bonded to each other via X, where X may be a single bond, an arylene (phenylene, biphenylene, naphthylene, etc.), or a heteroarylene (a pyridine ring, a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, a benzocarbazole ring, a phenyl-substituted carbazole ring, etc., having a divalent bond).

Preferred embodiments of the above anthracene compound are described below. The symbols in the following structures are defined as above.

In formula (3-H), X is each independently a group represented by formula (3-X1), formula (3-X2) or formula (3-X3), and the group represented by formula (3-X1), formula (3-X2) or formula (3-X3) is bonded to the anthracene ring of formula (3-H) at *. Preferably, two Xs are not simultaneously a group represented by formula (3-X3). More preferably, two Xs are not simultaneously a group represented by formula (3-X2).

A polymer (preferably a dimer) may be formed using the structure represented by formula (3-H) as a unit structure. In this case, for example, the unit structures represented by formula (3-H) may be bonded to each other via X, where X may be a single bond, an arylene (phenylene, biphenylene, naphthylene, etc.), or a heteroarylene (a pyridine ring, a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, a benzocarbazole ring, a phenyl-substituted carbazole ring, etc., having a divalent bond).

The naphthylene moieties in formula (3-X1) and formula (3-X2) may be condensed with one benzene ring. The condensed structures are as follows:

Ar ¹ and Ar ² are each independently hydrogen, phenyl, biphenylyl, terphenylyl, quaterphenylyl, naphthyl, phenanthryl, fluorenyl, benzofluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by formula (A) (including carbazolyl, benzocarbazolyl, and phenyl-substituted carbazolyl). When Ar ¹ or Ar ² is a group represented by formula (A), the group represented by formula (A) is bonded to the naphthalene ring in formula (3-X1) or formula (3-X2) at the *.

Ar ³ is phenyl, biphenylyl, terphenylyl, quaterphenylyl, naphthyl, phenanthryl, fluorenyl, benzofluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by formula (A) (including carbazolyl, benzocarbazolyl, and phenyl-substituted carbazolyl). When Ar ³ is a group represented by formula (A), the group represented by formula (A) is bonded to the single bond represented by a straight line in formula (3-X3) at the *. That is, the anthracene ring of formula (3-H) and the group represented by formula (A) are directly bonded.

In addition, Ar ³ may have a substituent, and at least one hydrogen atom in Ar ³ may be further substituted with an alkyl having 1 to 4 carbon atoms, a cycloalkyl having 5 to 10 carbon atoms, phenyl, biphenylyl, terphenylyl, naphthyl, phenanthryl, fluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by formula (A) (including carbazolyl and phenyl-substituted carbazolyl). When the substituent in Ar ³ is a group represented by formula (A), the group represented by formula (A) bonds to Ar ³ in formula (3-X3) at the *.

Each Ar ⁴ is independently hydrogen, phenyl, biphenylyl, terphenylyl, naphthyl, or silyl substituted with alkyl having 1 to 4 carbon atoms (eg, methyl, ethyl, t-butyl) and/or cycloalkyl having 5 to 10 carbon atoms.

In addition, hydrogen in the chemical structure of the anthracene compound represented by formula (3-H) may be replaced by a group represented by formula (A). When replaced by a group represented by formula (A), the group represented by formula (A) replaces at least one hydrogen in the compound represented by formula (3-H) at the *.

The group represented by formula (A) is one of the substituents that the anthracene compound represented by formula (3-H) may have.

In formula (A), Y is -O-, -S- or >N-R ²⁹ , R ²¹ to R ²⁸ are each independently hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted arylthio, trialkylsilyl, tricycloalkylsilyl, dialkylcycloalkylsilyl, alkyldicycloalkylsilyl, optionally substituted amino, halogen, hydroxy or cyano, adjacent groups among R ²¹ to R ²⁸ may be bonded to each other to form a hydrocarbon ring, an aryl ring or a heteroaryl ring, and R ²⁹ is hydrogen or optionally substituted aryl.
In formula (A), Y is preferably --O--.

The "substituted amino" of the "optionally substituted amino" in R ²¹ to R ²⁸ includes diarylamino, diheteroarylamino, arylheteroarylamino, and the like.

In “>N—R ²⁹ ” as Y, R ²⁹ is hydrogen or an optionally substituted aryl.

Adjacent groups among R ²¹ to R ²⁸ may be bonded to each other to form a hydrocarbon ring, an aryl ring, or a heteroaryl ring. The group represented by the following formula (A-1) does not form a ring, and examples of the group that forms a ring include the groups represented by the following formulas (A-2) to (A-14). At least one hydrogen atom in the group represented by any of formulas (A-1) to (A-14) may be substituted with alkyl, cycloalkyl, aryl, heteroaryl, alkoxy, aryloxy, arylthio, trialkylsilyl, tricycloalkylsilyl, dialkylcycloalkylsilyl, alkyldicycloalkylsilyl, diaryl (the two aryls may be bonded to each other via a linking group), substituted amino, diheteroaryl substituted amino, arylheteroaryl substituted amino, halogen, hydroxy, or cyano.

Examples of rings formed by bonding adjacent groups to each other include hydrocarbon rings such as cyclohexane rings, and examples of aryl rings and heteroaryl rings include the ring structures explained above for "aryl" and "heteroaryl" in R ^{to R} , and these rings are formed so as to be condensed with one or two benzene rings in formula (A-1).

The group represented by formula (A) is a group obtained by removing one hydrogen atom at any position of formula (A), and * indicates the position. That is, the group represented by formula (A) may have any position as a bonding position. For example, it may be any carbon atom on the two benzene rings in the structure of formula (A), an atom on any ring formed by bonding adjacent groups among R ²¹ to R ²⁸ in the structure of formula (A), any position in R ²⁹ in “>N-R ²⁹ ” as Y in the structure of formula (A), or a group directly bonded to N in “>N-R ²⁹ ” (R ²⁹ is a bond). The same applies to the groups represented by any of formulas (A-1) to (A-14).

Examples of the group represented by formula (A) include groups represented by any of formulas (A-1) to (A-14), with groups represented by any of formulas (A-1) to (A-5) and (A-12) to (A-14) being preferred, groups represented by any of formulas (A-1) to (A-4) being more preferred, groups represented by any of formulas (A-1), (A-3) and (A-4) being even more preferred, and groups represented by formula (A-1) being particularly preferred.

Examples of the group represented by formula (A) include the following groups: In the formula, Y and * are defined as above.

In the compound represented by formula (3-H), the group represented by formula (A) is preferably bonded to any one of the naphthalene ring in formula (3-X1) or formula (3-X2), the single bond in formula (3-X3), and Ar ³ in formula (3-X3).

In addition, all or some of the hydrogen atoms in the chemical structure of the anthracene compound represented by formula (3-H) may be deuterium atoms.

The anthracene compound as the host may be, for example, a compound represented by the following formula (3-H2).

In formula (3-H2), Ar ^c is optionally substituted aryl or optionally substituted heteroaryl, R ^c is hydrogen, alkyl, or cycloalkyl, Ar ¹¹ , Ar ¹² , Ar ¹³ , Ar ¹⁴ , Ar ¹⁵ , Ar ¹⁶ , Ar ¹⁷ , and Ar ¹⁸ are each independently hydrogen, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted diarylamino (two aryls may be bonded to each other via a linking group), optionally substituted diheteroarylamino (two heteroaryls may be bonded to each other via a linking group), optionally substituted arylheteroarylamino (aryl and heteroaryl may be bonded to each other via a linking group), optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted arylthio, or optionally substituted silyl, and at least one hydrogen in the compound represented by formula (3-H2) may be replaced by halogen, cyano, or deuterium.

The "optionally substituted aryl" is preferably a group represented by any one of the following formulas (3-H2-X1) to (3-H2-X8).

In formulae (3-H2-X1) to (3-H2-X8), * indicates a bonding position. In formulae (3-H2-X1) to (3-H2-X3), Ar ²¹ , Ar ²² , and Ar ²³ are each independently hydrogen, phenyl, biphenylyl, terphenylyl, quaterphenylyl, naphthyl, phenanthryl, fluorenyl, benzofluorenyl, chrysenyl, triphenylenyl, pyrenyl, anthracenyl, or a group represented by formula (A). In the explanation of formula (3-H2), the group represented by formula (A) is the same as that explained in the anthracene compound represented by formula (3-H).

In formulae (3-H2-X4) to (3-H2-X8), Ar ²⁴ , Ar ²⁵ , Ar ²⁶ , Ar ²⁷ , Ar ²⁸ , Ar ²⁹ , and Ar ³⁰ are each independently hydrogen, phenyl, biphenylyl, terphenylyl, naphthyl, phenanthryl, fluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by formula (A). In addition, any one or more hydrogen atoms in each of the groups represented by formulae (3-H2-X1) to (3-H2-X8) may be substituted by alkyl having 1 to 6 carbon atoms (preferably methyl or t-butyl).

Furthermore, preferred examples of "optionally substituted aryl" include phenyl, biphenylyl, terphenylyl, naphthyl, phenanthryl, fluorenyl, chrysenyl, triphenylenyl, pyrenyl, and terphenylyl (particularly m-terphenyl-5'-yl) which may be substituted with one or more substituents selected from the group consisting of groups represented by formula (A).

An example of an "optionally substituted heteroaryl" is a group represented by formula (A). Other examples of "optionally substituted aryl" and "optionally substituted heteroaryl" include dibenzofuryl, naphthobenzofuryl, and phenyl-substituted dibenzofuryl.

At least one hydrogen atom in the compound represented by formula (3-H2) may be replaced by a halogen atom, cyano, or deuterium. In this case, "halogen" includes fluorine, chlorine, bromine, and iodine. In particular, a compound in which all hydrogen atoms in the compound represented by formula (3-H2) are replaced by deuterium is preferred.

In formula (3-H2), R ^c is hydrogen, alkyl or cycloalkyl, preferably hydrogen, methyl or t-butyl, and more preferably hydrogen.
In formula (3-H2), it is preferable that at least two of Ar ¹¹ to Ar ¹⁸ are optionally substituted aryl or optionally substituted heteroaryl. That is, it is preferable that the anthracene compound represented by formula (3-H2) has a structure in which at least three substituents selected from the group consisting of optionally substituted aryl and optionally substituted heteroaryl are bonded to an anthracene ring.

In the anthracene compound represented by formula (3-H2), two of Ar ¹¹ to Ar ¹⁸ are optionally substituted aryl or optionally substituted heteroaryl, and the remaining six are hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, or optionally substituted alkoxy. In other words, it is more preferable that the anthracene compound represented by formula (3-H2) has a structure in which three substituents selected from the group consisting of optionally substituted aryl and optionally substituted heteroaryl are bonded to the anthracene ring.

In the anthracene compound represented by formula (3-H2), any two of Ar ¹¹ to Ar ¹⁸ are optionally substituted aryl or optionally substituted heteroaryl, and the other six are hydrogen, methyl, or t-butyl.

Furthermore, in formula (3-H2), it is preferred that R ^c is hydrogen and any six of Ar ¹¹ to Ar ¹⁸ are hydrogen.

The anthracene compound represented by formula (3-H2) is preferably an anthracene compound represented by the following formula (3-H2-A), (3-H2-B), (3-H2-C), (3-H2-D), or (3-H2-E).

In formula (3-H2-A), (3-H2-B), (3-H2-C), (3-H2-D) or (3-H2-E), Ar ^c ', Ar ¹¹ ', Ar ¹² ', Ar ¹³ ', Ar ¹⁴ ', Ar ¹⁵ ', Ar ¹⁷ ' and Ar ¹⁸ ' are each independently phenyl, biphenylyl, terphenylyl, quaterphenylyl, naphthyl, phenanthryl, fluorenyl, benzofluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by formula (A), and at least one hydrogen atom in these groups may be substituted by phenyl, biphenylyl, terphenylyl, quaterphenylyl, naphthyl, phenanthryl, fluorenyl, benzofluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by formula (A). When all of the hydrogen atoms of the methylene in fluorenyl and benzofluorenyl are replaced by phenyl, these phenyls may be bonded to each other via a single bond. Methyl or t-butyl may be bonded to the carbon atom of the anthracene ring to which Ar ^c ', Ar ¹¹ ', Ar ¹² ', Ar ¹³ ', Ar ¹⁴ ', Ar ¹⁵ ', Ar ¹⁷ ', and Ar ¹⁸ ' are not bonded, instead of hydrogen.

When Ar ^c ', Ar ¹¹ ', Ar ¹² ', Ar ¹³ ', Ar ¹⁴ ', Ar ¹⁵ ', Ar ¹⁷ ', and Ar ¹⁸ ' are each substituted or unsubstituted phenyl or substituted or unsubstituted naphthyl, they are preferably a group represented by any of the above formulae (3-H2-X1) to (3-H2-X8).

It is more preferable that Ar ^c ', Ar ¹¹ ', Ar ¹² ', Ar ¹³ ', Ar ¹⁴ ', Ar ¹⁵ ', Ar ¹⁷ ', and Ar ¹⁸ ' are each independently phenyl, biphenylyl (particularly biphenyl-2-yl or biphenyl-4-yl), terphenylyl (particularly m-terphenyl-5'-yl), naphthyl, phenanthryl, fluorenyl, or a group represented by any of the above formulas (A-1) to (A-4), in which case at least one hydrogen atom in these groups may be substituted by phenyl, biphenylyl, naphthyl, phenanthryl, fluorenyl, or a group represented by any of the above formulas (A-1) to (A-4).

In addition, at least one hydrogen atom in the compound represented by formula (3-H2-A), (3-H2-B), (3-H2-C), (3-H2-D), or (3-H2-E) may be replaced with a halogen atom, a cyano atom, or a deuterium atom. Deuterated forms are preferred, and it is preferable that all anthracene rings are deuterated, or that all hydrogen atoms are deuterated.

Particularly preferred anthracene compounds represented by formula (3-H2) include those represented by formula (3-H2-Aa) below.

In formula (3-H2-Aa), Ar ^c ', Ar ¹⁴ ', and Ar ¹⁵ ' are each independently phenyl, biphenylyl, terphenylyl, naphthyl, phenanthryl, fluorenyl, benzofluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by any one of formulas (A-1) to (A-11), and at least one hydrogen atom in these groups may be substituted by phenyl, biphenylyl, terphenylyl, naphthyl, phenanthryl, fluorenyl, benzofluorenyl, chrysenyl, triphenylenyl, pyrenyl, or a group represented by any one of formulas (A-1) to (A-11). When both hydrogen atoms of methylene groups in fluorenyl and benzofluorenyl are substituted by phenyl, these phenyl groups may be bonded to each other by a single bond. Furthermore, the carbon atoms on the anthracene ring to which Ar ^c ', Ar ¹⁴ ', and Ar ¹⁵ ' are not bonded may be substituted with methyl or t-butyl in place of hydrogen. At least one hydrogen in the compound represented by formula (3-H2-Aa) may be substituted with halogen or cyano, and at least one hydrogen in the compound represented by formula (3-H2-Aa) is substituted with deuterium.

In formula (3-H2-Aa), it is preferable that Ar ^c ', Ar ¹⁴ ', and Ar ¹⁵ ' are each independently phenyl, biphenylyl, terphenylyl, naphthyl, phenanthryl, fluorenyl, or a group represented by any one of the above formulas (A-1) to (A-4), and at least one hydrogen atom in these groups may be substituted by phenyl, naphthyl, phenanthryl, fluorenyl, or a group represented by any one of the above formulas (A-1) to (A-4).

In the compound represented by formula (3-H2-Aa), it is preferable that at least the hydrogen bonded to the carbon at the 10th position of the anthracene ring (the carbon bonded to Ar ^c ' is the 9th position) is substituted with deuterium. That is, the compound represented by formula (3-H2-Aa) is preferably a compound represented by the following formula (3-H2-Ab). In formula (3-H2-Ab), D is deuterium, and Ar ^c ', Ar ¹⁴ ', and Ar ¹⁵ ' are the same as those in formula (3-H2-Aa). D in formula (3-H2-Ab) indicates that at least this position is deuterium, and any one or more other hydrogen atoms in formula (3-H2-Ab) may be deuterium at the same time, and it is also preferable that all hydrogen atoms in formula (3-H2-Ab) are deuterium.

Specific examples of the anthracene compound include compounds represented by formulae (3-131-Y) to (3-182-Y), (3-183-N), (3-184-Y) to (3-284-Y), (3-500) to (3-557), (3-600) to (3-605), and (3-606-Y) to (3-626-Y). The hydrogen atoms in these formulae may be partially or completely replaced with deuterium, and particularly preferred forms of deuterium replacement are listed individually. Y in the formulae may be any of -O-, -S-, >N-R ²⁹ (R ²⁹ is the same as above) or >C(-R ³⁰ ) ₂ (R ³⁰ is an aryl or alkyl group which may be linked), where R ²⁹ is, for example, phenyl, and R ³⁰ is, for example, methyl. For example, when Y is O, the formula (3-131-Y) is made into the formula (3-131-O), and when Y is -S- or >N-R ²⁹ , it is made into the formula (3-131-S) or the formula (3-131-N), respectively.

上記式中、Ｄは重水素である。

In the above formula, D is deuterium.

Among these compounds, the compounds of the formula (3-131-Y) to the formula (3-134-Y), the formula (3-138-Y), the formula (3-140-Y) to the formula (3-143-Y), the formula (3-150-Y), the formula (3-153-Y) to the formula (3-156-Y), the formula (3-166-Y), the formula (3-168-Y), the formula (3-173-Y), the formula (3-177-Y), the formula (3-180-Y) to the formula (3-183-N), the formula (3-185-Y), the formula (3-190-Y), the formula (3-223-Y), the formula (3-241- Y), the formula (3-250-Y), the formula (3-252-Y) to the formula (3-254-Y), the formula (3-270-Y) to the formula (3-284-Y), the formula (3-501), the formula (3-507), the formula (3-508), the formula (3-509), the formula (3-513), the formula (3-514), the formula (3-519), the formula (3-521), the formula (3-538) to the formula (3-547), or the formula (3-600) to the formula (3-605), and the formula (3-606-Y) to the formula (3-626-Y) are preferred. Y is preferably -O- or >N-R ²⁹ , more preferably -O-. Deuterium substitution is also preferred.

The above anthracene compounds can be produced by applying Suzuki coupling, Negishi coupling, or other known coupling reactions using as starting materials a compound having a reactive group at a desired position of the anthracene skeleton, and a compound having a reactive group in a partial structure such as X, Ar ⁴ , and the structure of formula (A) in the case of an anthracene compound represented by formula (3-H). Examples of reactive groups in these reactive compounds include halogens and boronic acids. As a specific production method, for example, the synthesis method in paragraphs [0089] to [0175] of WO 2014/141725 can be referred to.

<Fluorene Compound>
The compound represented by the formula (4-H) basically functions as a host.

In formula (4-H),
R ¹ to R ¹⁰ are each independently hydrogen, aryl, heteroaryl (the heteroaryl may be bonded to the fluorene skeleton in formula (4-H) via a linking group), diarylamino (two aryls may be bonded to each other via a linking group), diheteroarylamino (two heteroaryls may be bonded to each other via a linking group), arylheteroarylamino (aryl and heteroaryl may be bonded to each other via a linking group), alkyl, cycloalkyl, alkenyl, alkoxy, or aryloxy, in which at least one hydrogen may be substituted with an aryl, heteroaryl, alkyl, or cycloalkyl, and R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , R ⁷ and R ⁸ , or R ⁹ and R ¹⁰ may each independently bond to form a fused ring or a spiro ring, and at least one hydrogen atom in the formed ring may be substituted with an aryl, a heteroaryl (the heteroaryl may be bonded to the formed ring via a linking group), a diarylamino (two aryls may be bonded to each other via a linking group), a diheteroarylamino (two heteroaryls may be bonded to each other via a linking group), an arylheteroarylamino (an aryl and a heteroaryl may be bonded to each other via a linking group), an alkyl, a cycloalkyl, an alkenyl, an alkoxy, or an aryloxy, and at least one hydrogen atom in these may be substituted with an aryl, a heteroaryl, an alkyl, or a cycloalkyl; and at least one hydrogen atom in the compound represented by formula (4-H) may be substituted with a halogen, a cyano, or a deuterium.

Specific examples of heteroaryl include monovalent groups represented by removing any one hydrogen atom from the compounds of the following formula (4-Ar1), (4-Ar2), (4-Ar3), (4-Ar4), or (4-Ar5).

In formulae (4-Ar1) to (4-Ar5), ^Y1 's are each independently O, S, or N-R, where R is phenyl, biphenylyl, naphthyl, anthracenyl, or hydrogen, and at least one hydrogen in the structures of formulae (4-Ar1) to (4-Ar5) may be substituted with phenyl, biphenylyl, naphthyl, anthracenyl, phenanthryl, methyl, ethyl, propyl, or butyl.

These heteroaryls may be bonded to the fluorene skeleton in formula (4-H) via a linking group. That is, the fluorene skeleton in formula (4-H) and the heteroaryl may be bonded directly or via _a linking group. Examples of the linking group include phenylene, biphenylene, naphthylene, anthracenylene _, methylene, ethylene, _{-OCH2CH2- , -CH2CH2O-} , and _-OCH2CH2O- .

In addition, R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ in formula (4-H) may each independently bond to a fused ring, and R ⁹ and R ¹⁰ may bond to a spiro ring. The fused ring formed by R ¹ to R ⁸ is a ring fused to the benzene ring in formula (4-H), and is an aliphatic ring or an aromatic ring. It is preferably an aromatic ring, and examples of the structure including the benzene ring in formula (4-H) include a naphthalene ring and a phenanthrene ring. The spiro ring formed by R ⁹ and R ¹⁰ is a ring spiro-bonded to the 5-membered ring in formula (4-H), and is an aliphatic ring or an aromatic ring. It is preferably an aromatic ring, and examples of the structure including the benzene ring in formula (4-H) include a fluorene ring.

The compound represented by formula (4-H) is preferably a compound represented by the following formula (4-H-1), formula (4-H-2) or formula (4-H-3), which is a compound in which R ¹ and R ² in formula (4-H) are bonded to form a condensed benzene ring, a compound in which R ³ and R ⁴ in formula (4-H) are bonded to form a condensed benzene ring, and a compound in which none of R ¹ to R ⁸ in formula (4-H) are bonded.

The definitions of R ¹ to R ¹⁰ in formulas (4-H-1), (4-H-2) and (4-H-3) are the same as the corresponding R ¹ to R ¹⁰ in formula (4-H), and the definitions of R ¹¹ to R ¹⁴ in formulas (4-H-1) and (4-H-2) are the same as the corresponding R ¹ to R ¹⁰ in formula (4-H).

The compound represented by formula (4-H) is more preferably a compound represented by the following formula (4-H-1A), formula (4-H-2A) or formula (4-H-3A), which is a compound in which R ⁹ and R ¹⁰ are bonded to form a spiro-fluorene ring in formula (4-H-1), formula (4-H-2) or formula (4-H-3), respectively.

The definitions of ^R2 to ^R7 in formulae (4-H-1A), (4-H-2A) and (4-H-3A) are the same as the corresponding ^R2 to R7 in formulae (4-H-1), (4-H-2) and (4-H-3), and the definitions of ^R11 to ^R14 in formulae (4-H-1A) and (4-H-2A) are the same as ^R11 to ^R14 in formulae (4-H- ¹ ) and (4-H-2).

In addition, all or some of the hydrogen atoms in the compound represented by formula (4-H) may be replaced with halogen, cyano, or deuterium.

More specific examples of the fluorene compound as the host of the present invention include compounds represented by the following structural formulas.

<Pyrene Compounds>
Examples of the pyrene compound include the pyrene compounds described in WO 2021/210304, WO 2021/210305, or WO 2021/049659.

Specific examples of the pyrene compound include the following compounds.

<Dibenzochrysene Compound>
The dibenzochrysene compound as the host is, for example, a compound represented by the following formula (5-H).

In formula (5-H), R ¹ to R ¹⁶ are each independently hydrogen, aryl, heteroaryl (the heteroaryl may be bonded to the dibenzochrysene skeleton in formula (5-H) via a linking group), diarylamino, diheteroarylamino, arylheteroarylamino, alkyl, cycloalkyl, alkenyl, alkoxy, or aryloxy, in which at least one hydrogen may be substituted with an aryl, heteroaryl, alkyl, or cycloalkyl, or adjacent groups among R ¹ to R ¹⁶ may be bonded to each other to form a condensed ring, in which at least one hydrogen in the formed ring may be substituted with an aryl, heteroaryl (the heteroaryl may be bonded to the formed ring via a linking group), diarylamino, diheteroarylamino, arylheteroarylamino, alkyl, cycloalkyl, alkenyl, alkoxy, or aryloxy, in which at least one hydrogen may be substituted with an aryl, heteroaryl, alkyl, or cycloalkyl, or in which at least one hydrogen in the compound represented by formula (5-H) may be substituted with a halogen, cyano, or deuterium.

The alkenyl in the definition of formula (5-H) is, for example, an alkenyl having 2 to 30 carbon atoms, preferably an alkenyl having 2 to 20 carbon atoms, more preferably an alkenyl having 2 to 10 carbon atoms, even more preferably an alkenyl having 2 to 6 carbon atoms, and particularly preferably an alkenyl having 2 to 4 carbon atoms. Preferred alkenyls are vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl.

Specific examples of heteroaryl include monovalent groups represented by removing any one hydrogen atom from the compounds of the following formula (5-Ar1), (5-Ar2), (5-Ar3), (5-Ar4), or (5-Ar5).

In formulae (5-Ar1) to (5-Ar5), ^Y1 's are each independently O, S or N-R, R is phenyl, biphenylyl, naphthyl, anthracenyl or hydrogen, and at least one hydrogen in the structures of formulae (5-Ar1) to (5-Ar5) may be substituted with phenyl, biphenylyl, naphthyl, anthracenyl, phenanthryl, methyl, ethyl, propyl or butyl.

These heteroaryls may be bonded to the dibenzochrysene skeleton in formula (5-H) via a linking group. That is, the dibenzochrysene skeleton in formula (5-H) and the heteroaryl may be bonded directly or via _a linking group. Examples of the linking group include phenylene, biphenylene, naphthylene, _{anthracenylene} , methylene, ethylene, _{-OCH2CH2- , -CH2CH2O-} , and _-OCH2CH2O- .

In the compound represented by formula (5-H), R ¹ , R ⁴ , R ⁵ , R ⁸ , R ⁹ , R ¹² , R ¹³ and R ¹⁶ are preferably hydrogen. In this case, it is preferable that R ² , R ³ , R ⁶ , R ⁷ , R ¹⁰ , R ¹¹ , R ¹⁴ and R ¹⁵ in formula (5-H) are each independently hydrogen, phenyl, biphenylyl, naphthyl, anthracenyl, phenanthryl, a monovalent group having a structure of formula (5-Ar1), formula (5-Ar2), formula (5-Ar3), formula (5-Ar4) or formula (5-Ar5) (the monovalent group having the structure may be bonded to the dibenzochrysene skeleton in formula (5-H) via phenylene, biphenylene, naphthylene, anthracenylene, methylene, ethylene, -OCH ₂ CH ₂ -, -CH ₂ CH ₂ O- or -OCH ₂ CH ₂ O-), methyl, ethyl, propyl or butyl.

In the compound represented by formula (5-H), R ¹ , R ² , R ⁴ , R ⁵ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹² , R ¹³ , R ¹⁵ and R ¹⁶ are more preferably hydrogen. In this case, at least one (preferably one or two, more preferably one) of R ³ , R ⁶ , R ¹¹ and R ¹⁴ in formula (5-H) is a single bond, phenylene, biphenylene, naphthylene, anthracenylene, methylene, ethylene, -OCH ₂ CH ₂ -, -CH ₂ CH ₂ O-, or -OCH ₂ CH ₂ A monovalent group having a structure of formula (5-Ar1), (5-Ar2), (5-Ar3), (5-Ar4) or (5-Ar5) via O-, wherein the other than the at least one (i.e., other than the position substituted by the monovalent group having the structure) is hydrogen, phenyl, biphenylyl, naphthyl, anthracenyl, methyl, ethyl, propyl or butyl, and at least one hydrogen in these may be substituted with phenyl, biphenylyl, naphthyl, anthracenyl, methyl, ethyl, propyl or butyl.

In addition, when a monovalent group having a structure represented by formula (5-Ar1) to formula (5-Ar5) is selected as R ² , R ³ , R ⁶ , R ⁷ , R ¹⁰ , R ¹¹ , R ¹⁴ and R ¹⁵ in formula (5-H), at least one hydrogen atom in the structure may be bonded to any one of R ¹ to R ¹⁶ in formula (5-H) to form a single bond.

More specific examples of the dibenzochrysene compound as the host of the present invention include compounds represented by the following structural formulas.

The above-mentioned light-emitting layer materials (host material and dopant material) can be used as light-emitting layer materials as polymer compounds obtained by polymerizing a reactive compound substituted with a reactive substituent as a monomer, or as crosslinked polymers thereof, or as pendant polymer compounds obtained by reacting a main-chain polymer with the reactive compound, or as crosslinked pendant polymers thereof. In this case, the explanation for the polycyclic aromatic compound represented by formula (1) can be cited as the reactive substituent.

<Light-emitting layer containing an assisting dopant and an emitting dopant>
The light-emitting layer in the organic electroluminescent device may contain a host compound as a first component, an assisting dopant (compound) as a second component, and an emitting dopant (compound) as a third component. The polycyclic aromatic compound of the present invention is also preferably used as an emitting dopant. A thermally activated delayed phosphor can be used as the assisting dopant (compound).

In the following description, an organic electroluminescent device that uses a thermally activated delayed fluorescent material as an assisting dopant may be referred to as a "TAF element" (TADF Assisting Fluorescence element). The "host compound" in a TAF element refers to a compound whose lowest excited singlet energy level, determined from the shoulder on the short-wavelength side of the peak of the fluorescence spectrum, is higher than that of the thermally activated delayed fluorescent material as the second component and the emitting dopant as the third component.

"Thermally activated delayed fluorescent material" means a compound that can absorb thermal energy, undergo reverse intersystem crossing from the lowest excited triplet state to the lowest excited singlet state, and then radiatively deactivate from the lowest excited singlet state to emit delayed fluorescence. However, "thermally activated delayed fluorescent material" also includes compounds that undergo higher triplets in the process of excitation from the lowest excited triplet state to the lowest excited singlet state. For example, there are a paper by Monkman et al. of Durham University (NATURE COMMUNICATIONS, 7:13680, DOI: 10.1038/ncomms13680), a paper by Hosokai et al. of the National Institute of Advanced Industrial Science and Technology (Hosokai et al., Sci. Adv. 2017;3: e1603282), a paper by Sato et al. of Kyoto University (Scientific Reports, 7:4820, DOI:10.1038/s41598-017-05007-7), and an academic presentation by Sato et al. of Kyoto University (98th Annual Meeting of the Chemical Society of Japan, presentation number: 2I4-15, Mechanism of highly efficient light emission in organic electroluminescence using DABNA as an emitting molecule, Graduate School of Engineering, Kyoto University). In the present invention, when a sample containing a target compound is measured for its fluorescence lifetime at 300K, if a slow fluorescent component is observed, the target compound is determined to be a "thermally activated delayed fluorescent substance." Here, a slow fluorescent component refers to one whose fluorescence lifetime is 0.1 μsec or longer. The fluorescence lifetime can be measured, for example, using a fluorescence lifetime measuring device (manufactured by Hamamatsu Photonics, C11367-01).

The polycyclic aromatic compound of the present invention can function as an emitting dopant, and the "thermally activated delayed phosphor" can function as an assisting dopant that assists the emission of the polycyclic aromatic compound of the present invention.

In this embodiment, known host compounds can be used, such as compounds having at least one of a carbazole ring and a furan ring. Among them, it is preferable to use a compound in which at least one of furanyl and carbazolyl is bonded to at least one of arylene and heteroarylene. Specific examples include mCP and mCBP.

From the viewpoint of promoting TADF generation in the light-emitting layer without inhibiting it, the lowest excited triplet energy level E(1,T,Sh) of the host compound, which is determined from the shoulder on the short wavelength side of the peak of the phosphorescence spectrum, is preferably higher than the lowest excited triplet energy levels E(2,T,Sh) and E(3,T,Sh) of the emitting dopant or assisting dopant having the highest lowest excited triplet energy level in the light-emitting layer. Specifically, the lowest excited triplet energy level E(1,T,Sh) of the host compound is preferably 0.01 eV or more, more preferably 0.03 eV or more, and even more preferably 0.1 eV or more, compared to E(2,T,Sh) and E(3,T,Sh). A TADF-active compound may also be used as the host compound.

The host compound may be, for example, a compound represented by any one of the above formulas (H1), (H2), and (H3).

<Thermally activated delayed phosphor (assisting dopant)>
The thermally activated delayed fluorescent substance (TADF compound) used in the TAF element is preferably a donor-acceptor type thermally activated delayed fluorescent substance (DA type TADF compound) designed to localize the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) in the molecule using an electron-donating substituent called a donor and an electron-accepting substituent called an acceptor, so that efficient reverse intersystem crossing occurs. Here, in this specification, the term "electron-donating substituent" (donor) refers to a substituent and partial structure in which the HOMO is localized in the thermally activated delayed fluorescent substance molecule, and the term "electron-accepting substituent" (acceptor) refers to a substituent and partial structure in which the LUMO is localized in the thermally activated delayed fluorescent substance molecule.

In general, a thermally activated delayed phosphor using a donor or an acceptor has a large spin orbit coupling (SOC) due to its structure, and has a small exchange interaction between HOMO and LUMO, and therefore has a small ΔE(ST), so that a very fast reverse intersystem crossing rate can be obtained. By using a thermally activated delayed phosphor using a donor or an acceptor as an assisting dopant together with a suitable emitting dopant such as the polycyclic aromatic compound of the present invention, a device that satisfies any one or all of high efficiency, high color purity, and long life can be provided.
The thermally activated delayed phosphor may be a compound whose emission spectrum overlaps at least partially with the absorption spectrum of the polycyclic aromatic compound of the present invention. The polycyclic aromatic compound of the present invention and the thermally activated delayed phosphor may be contained in the same layer, or may be contained in an adjacent layer or other adjacent layers.

As the thermally activated delayed phosphor in the TAF element, for example, a compound in which a donor and an acceptor are bonded directly or via a spacer can be used. As the electron donor group (donor structure) and the electron acceptor group (acceptor structure) used in the thermally activated delayed phosphor of the present invention, for example, the structures described in Chemistry of Materials, 2017, 29, 1946-1963 can be used. Examples of the donor structure include carbazole, dimethylcarbazole, di-tert-butylcarbazole, dimethoxycarbazole, tetramethylcarbazole, benzofluorocarbazole, benzothienocarbazole, phenyldihydroindolocarbazole, phenylbicarbazole, bicarbazole, tercarbazole, diphenylcarbazolylamine, tetraphenylcarbazolyldiamine, phenoxazine, dihydrophenazine, phenothiazine, dimethyldihydroacridine, diphenylamine, bis(tert-butylphenyl)amine, N1-(4-(diphenylamino)phenyl)-N4,N4-diphenylbenzene-1,4-diamine, dimethyltetraphenyldihydroacridinediamine, tetramethyl-dihydro-indenoacridine, and diphenyl-dihydrodibenzoazasiline. Examples of the acceptor structure include sulfonyldibenzene, benzophenone, phenylenebis(phenylmethanone), benzonitrile, isonicotinonitrile, phthalonitrile, isophthalonitrile, paraphthalonitrile, benzenetricarbonitrile, triazole, oxazole, thiadiazole, benzothiazole, benzobis(thiazole), benzoxazole, benzobis(oxazole), quinoline, benzimidazole, dibenzoquinoxaline, heptaazaphenalene, thioxanthone dioxide, dimethylanthracenone, anthracenedione, 5H-cyclopenta[1,2-b:5,4-b']dipyridine, fluorene dicarbonitrile, triphenyltriazine, pyrazine dicarbonitrile, pyrimidine, phenylpyrimidine, methylpyrimidine, pyridine dicarbonitrile, dibenzoquinoxaline dicarbonitrile, bis(phenylsulfonyl)benzene, dimethylthioxanthene dioxide, thianthrene tetraoxide, and tris(dimethylphenyl)borane. In particular, the compound having thermally activated delayed fluorescence in the TAF element is preferably a compound having at least one partial structure selected from carbazole, phenoxazine, acridine, triazine, pyrimidine, pyrazine, thioxanthene, benzonitrile, phthalonitrile, isophthalonitrile, diphenylsulfone, triazole, oxadiazole, thiadiazole, and benzophenone.

The compound used as the second component of the light-emitting layer in the TAF element is preferably a thermally activated delayed phosphor, the emission spectrum of which at least partially overlaps with the absorption peak of the emitting dopant. Below, examples of compounds that can be used as the second component (thermally activated delayed phosphor) of the light-emitting layer in the TAF element are given. However, the compounds that can be used as the thermally activated delayed phosphor in the TAF element are not limited to the following example compounds.

Furthermore, as the thermally activated delayed phosphor, a compound represented by any one of the following formulae (AD1), (AD2) and (AD3) can also be used.

In the above formulas (AD1), (AD2) and (AD3), M is each independently a single bond, -O-, >N-Ar or > _CAR2 , and is preferably a single bond, -O- or >N-Ar from the viewpoint of the HOMO depth and the height of the lowest excited singlet energy level and the lowest excited triplet energy level of the partial structure to be formed. J is a spacer structure separating the donor partial structure and the acceptor partial structure, and is each independently an arylene having 6 to 18 carbon atoms, and is preferably an arylene having 6 to 12 carbon atoms from the viewpoint of the magnitude of conjugation exuding from the donor partial structure and the acceptor partial structure. More specifically, phenylene, methylphenylene and dimethylphenylene are exemplified. Q is each independently ═C(—H)— or ═N—, and is preferably ═N— from the viewpoint of the shallowness of the LUMO and the height of the lowest excited singlet energy level and the lowest excited triplet energy level of the partial structure to be formed. Ar are each independently hydrogen, an aryl having 6 to 24 carbon atoms, a heteroaryl having 2 to 24 carbon atoms, an alkyl having 1 to 12 carbon atoms, or a cycloalkyl having 3 to 18 carbon atoms, and from the viewpoint of the HOMO depth and the height of the lowest excited singlet energy level and the lowest excited triplet energy level of the partial structure to be formed, preferably hydrogen, an aryl having 6 to 12 carbon atoms, a heteroaryl having 2 to 14 carbon atoms, an alkyl having 1 to 4 carbon atoms, or a cycloalkyl having 6 to 10 carbon atoms, more preferably hydrogen, phenyl, tolyl, xylyl, mesityl, biphenyl, pyridyl, bipyridyl, triazinyl, carbazolyl, dimethylcarbazolyl, di-tert-butylcarbazolyl, benzimidazolyl, or phenylbenzimidazolyl, and even more preferably hydrogen, phenyl, or carbazolyl. m is 1 or 2. n is an integer of (6-m) or less, and from the viewpoint of steric hindrance, preferably an integer of 4 to (6-m). Furthermore, at least one hydrogen atom in the compounds represented by the above formulas may be substituted with a halogen or deuterium.

More specifically, the compounds used as the second component in this embodiment are preferably 4CzBN, 4CzBN-Ph, 5CzBN, 3Cz2DPhCzBN, 4CzIPN, 2PXZ-TAZ, Cz-TRZ3, BDPCC-TPTA, MA-TA, PA-TA, FA-TA, PXZ-TRZ, DMAC-TRZ, BCzT, DCzTrz, DDCzTRz, spiroAC-TRZ, Ac-HPM, Ac-PPM, Ac-MPM, TCzTrz, TmCzTrz and DCzmCzTrz.

The compound used as the second component in this embodiment may be a donor-acceptor type TADF compound represented by D-A in which one donor D and one acceptor A are bonded directly or via a linking group, but it is preferable that the compound has a structure represented by the following formula (DAD1) in which multiple donors D are bonded directly or via a linking group to one acceptor A, because this will result in better properties for the organic electroluminescent device.

(D ¹ -L ¹ )n-A ¹ (DAD1)

Formula (DAD1) includes compounds represented by the following formula (DAD2).

D ² -L ² -A ² -L ³ -D ³ (DAD2)

In formula (DAD1) and formula (DAD2), D ¹ , D ² and D ³ each independently represent a donor group. The donor group may have the above-mentioned donor structure. A ¹ and A ² each independently represent an acceptor group. The acceptor group may have the above-mentioned acceptor structure. L ¹ , L ² and L ³ each independently represent a single bond or a conjugated linking group. The conjugated linking group is a spacer structure that separates the donor group and the acceptor group, and is preferably an arylene having 6 to 18 carbon atoms, more preferably an arylene having 6 to 12 carbon atoms. It is more preferable that L ¹ , L ² and L ³ each independently represent phenylene, methylphenylene or dimethylphenylene. In formula (DAD1), n represents an integer of 2 or more and not more than the maximum number that A ¹ can substitute. For example, n may be selected within the range of 2 to 10, or within the range of 2 to 6. When n is 2, the compound is represented by formula (DAD2). The n D ^1s may be the same or different, and the n L ^1s may be the same or different. Preferable specific examples of the compounds represented by formula (DAD1) and formula (DAD2) include 2PXZ-TAZ and the following compounds, but the second component that can be employed in the present invention is not limited to these compounds.

In this embodiment, the light-emitting layer may be a single layer or multiple layers. The host compound, the thermally activated delayed phosphor, and the polycyclic aromatic compound of the present invention may be contained in the same layer, or at least one component may be contained in each of the multiple layers. The host compound, the thermally activated delayed phosphor, and the polycyclic aromatic compound of the present invention contained in the light-emitting layer may each be one type or a combination of multiple types. The assisting dopant and the emitting dopant may be entirely or partially contained in the host compound as a matrix. The light-emitting layer doped with the assisting dopant and the emitting dopant can be formed by a method of forming a film by a ternary co-evaporation method of the host compound, the assisting dopant, and the emitting dopant, a method of mixing the host compound, the assisting dopant, and the emitting dopant in advance and then simultaneously evaporating them, a wet film formation method in which a composition for forming a light-emitting layer (paint) prepared by dissolving the host compound, the assisting dopant, and the emitting dopant in an organic solvent is applied, or the like.

The amount of the host compound used varies depending on the type of host compound, and may be determined according to the properties of the host compound. The amount of the host compound used is preferably 40 to 99% by mass, more preferably 50 to 98% by mass, and even more preferably 60 to 95% by mass, of the total mass of the materials for the light-emitting layer. The above ranges are preferable, for example, in terms of efficient charge transport and efficient energy transfer to the dopant.

The amount of assisting dopant (thermally activated delayed phosphor) used varies depending on the type of assisting dopant, and may be determined according to the characteristics of the assisting dopant. The amount of assisting dopant used is preferably 1 to 60% by mass of the total mass of the material for the light-emitting layer, more preferably 2 to 50% by mass, and even more preferably 5 to 30% by mass. The above ranges are preferable, for example, in that energy can be efficiently transferred to the emitting dopant.

The amount of emitting dopant (a compound having a boron atom) used varies depending on the type of emitting dopant, and may be determined according to the characteristics of the emitting dopant. The amount of emitting dopant used is preferably 0.001 to 30% by mass of the total mass of the material for the light-emitting layer, more preferably 0.01 to 20% by mass, and even more preferably 0.1 to 10% by mass. The above range is preferable in that, for example, concentration quenching can be prevented.

A low concentration of the emitting dopant is preferred in terms of preventing concentration quenching. A high concentration of the assisting dopant is preferred in terms of the efficiency of the thermally activated delayed fluorescence mechanism. Furthermore, a low concentration of the emitting dopant is preferred in terms of the efficiency of the thermally activated delayed fluorescence mechanism of the assisting dopant compared to the amount of the assisting dopant.

<2-1-3. Substrate in organic electroluminescent device>
The substrate 101 is a support for the organic EL element 100, and is usually made of quartz, glass, metal, plastic, or the like. The substrate 101 is formed into a plate, film, or sheet shape depending on the purpose, and for example, a glass plate, a metal plate, a metal foil, a plastic film, a plastic sheet, or the like is used. Among them, a glass plate and a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone are preferable. For a glass substrate, soda-lime glass or alkali-free glass is used, and the thickness is sufficient to maintain mechanical strength, so that it may be, for example, 0.2 mm or more. The upper limit of the thickness is, for example, 2 mm or less, preferably 1 mm or less. As for the material of the glass, it is better to have fewer ions eluted from the glass, so alkali-free glass is preferable, but soda-lime glass with a barrier coat such as SiO ₂ is also commercially available, and this can be used. In addition, in order to improve the gas barrier properties, the substrate 101 may be provided with a gas barrier film such as a dense silicon oxide film on at least one side, and it is preferable to provide a gas barrier film, especially when a synthetic resin plate, film or sheet with poor gas barrier properties is used as the substrate 101.

<2-1-4. Anode in organic electroluminescent device>
The anode 102 plays a role in injecting holes into the light-emitting layer 105. When either one of the hole injection layer 103 and the transport layer 104 is provided between the anode 102 and the light-emitting layer 105, holes are injected into the light-emitting layer 105 via the hole injection layer 103 or the transport layer 104.

Materials for forming the anode 102 include inorganic and organic compounds. Inorganic compounds include, for example, metals (aluminum, gold, silver, nickel, palladium, chromium, etc.), metal oxides (indium oxide, tin oxide, indium-tin oxide (ITO), indium-zinc oxide (IZO), etc.), metal halides (copper iodide, etc.), copper sulfide, carbon black, ITO glass, and Nesa glass. Organic compounds include, for example, polythiophenes such as poly(3-methylthiophene), polypyrrole, polyaniline, and other conductive polymers. In addition, materials that are used as anodes in organic EL elements can be appropriately selected and used.

The resistance of the transparent electrode is not limited as long as it can supply sufficient current to light the light-emitting element, but a low resistance is desirable from the viewpoint of the power consumption of the light-emitting element. For example, an ITO substrate of 300 Ω/□ or less will function as an element electrode, but since it is now possible to supply substrates of around 10 Ω/□, it is particularly desirable to use a low resistance product of, for example, 100 to 5 Ω/□, preferably 50 to 5 Ω/□. The thickness of the ITO can be selected arbitrarily according to the resistance value, but it is usually used in the range of 50 to 300 nm.

<2-1-5. Hole injection layer and hole transport layer in organic electroluminescence element>
The hole injection layer 103 plays a role of efficiently injecting holes moving from the anode 102 into the light emitting layer 105 or the hole transport layer 104. The hole transport layer 104 plays a role of efficiently transporting holes injected from the anode 102 or holes injected from the anode 102 through the hole injection layer 103 to the light emitting layer 105. The hole injection layer 103 and the hole transport layer 104 are each formed by laminating and mixing one or more types of hole injection/transport materials, or by a mixture of a hole injection/transport material and a polymer binder. Alternatively, a layer may be formed by adding an inorganic salt such as iron (III) chloride to the hole injection/transport material.

The hole injection/transport material must be able to efficiently inject and transport holes from the positive electrode between electrodes to which an electric field is applied, and it is desirable for the hole injection efficiency to be high and for the injected holes to be efficiently transported. For this purpose, it is preferable for the material to have a small ionization potential, a large hole mobility, and excellent stability, and to be unlikely to generate impurities that act as traps during manufacture and use.

As the material for forming the hole injection layer 103 and the hole transport layer 104, any compound can be selected from compounds conventionally used as charge transport materials for holes in photoconductive materials, p-type semiconductors, and known compounds used in hole injection layers and hole transport layers of organic EL elements. Specific examples thereof include carbazole derivatives (N-phenylcarbazole, polyvinylcarbazole, etc.), biscarbazole derivatives such as bis(N-arylcarbazole) or bis(N-alkylcarbazole), triarylamine derivatives (4,4',4"-tris(N-carbazolyl)triphenylamine, polymers having aromatic tertiary amino in the main chain or side chain, 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diaminobiphenyl, N,N'-diphenyl-N,N'-dinaphthyl-4,4'-diaminobiphenyl, N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine, N,N'-dinaphthyl-N,N'-diphenyl-4,4'-diphenyl-1,1'-diamine, N ⁴ , N ^{4 '} -diphenyl- ^{N 4} , N ^{4 '} -bis(9-phenyl-9H-carbazol-3-yl)-[1,1'-biphenyl]-4,4'-diamine, N ⁴ , N ⁴ , N ^{4 '} , N ^{4 '} -tetra[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine, triphenylamine derivatives such as 4,4',4"-tris(3-methylphenyl(phenyl)amino)triphenylamine, starburst amine derivatives, etc.), stilbene derivatives, phthalocyanine derivatives (metal-free, copper phthalocyanine, etc.), pyrazoline derivatives, hydrazone compounds, benzofuran derivatives, thiophene derivatives, oxadiazole derivatives, quinoxaline derivatives (for example, 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-hexacarbonitrile, etc.), heterocyclic compounds such as porphyrin derivatives, polysilanes, etc. As the polymer, polycarbonate, styrene derivatives, polyvinylcarbazole, polysilane, and the like having the above-mentioned monomer in the side chain are preferable, but there is no particular limitation as long as the compound can form a thin film required for producing a light-emitting element, can inject holes from the anode, and can transport holes.

It is also known that the electrical conductivity of organic semiconductors is strongly influenced by their doping. Such organic semiconductor matrix substances consist of compounds with good electron donating or accepting properties. For doping with electron donating substances, strong electron acceptors such as tetracyanoquinone dimethane (TCNQ) or 2,3,5,6-tetrafluorotetracyano-1,4-benzoquinone dimethane (F4TCNQ) are known (see, for example, the literature "M. Pfeiffer, A. Beyer, T. Fritz, K. Leo, Appl. Phys. Lett., 73(22), 3202-3204 (1998)" and the literature "J. Blochwitz, M. Pfeiffer, T. Fritz, K. Leo, Appl. Phys. Lett., 73(6), 729-731 (1998)"). These generate so-called holes by an electron transfer process in an electron-donating base material (hole transport material). The conductivity of the base material varies considerably depending on the number and mobility of the holes. Known matrix materials with hole transport properties include, for example, benzidine derivatives (TPD, etc.) or starburst amine derivatives (TDATA, etc.), or specific metal phthalocyanines (especially zinc phthalocyanine (ZnPc) and the like) (JP Patent Publication 2005-167175). The polycyclic aromatic compound of the present invention may be used as a material for forming a hole injection layer or a material for forming a hole transport layer.

<2-1-6. Electron blocking layer in organic electroluminescent device>
An electron blocking layer for preventing diffusion of electrons from the light emitting layer may be provided between the hole injection/transport layer and the light emitting layer. The electron blocking layer may be formed using a compound represented by any one of the above formulas (H1), (H2) and (H3). The polycyclic aromatic compound of the present invention may be used as a material for forming the electron blocking layer.

<2-1-7. Electron injection layer and electron transport layer in organic electroluminescent device>
The electron injection layer 107 plays a role of efficiently injecting electrons moving from the cathode 108 into the light emitting layer 105 or the electron transport layer 106. The electron transport layer 106 plays a role of efficiently transporting electrons injected from the cathode 108 or electrons injected from the cathode 108 via the electron injection layer 107 to the light emitting layer 105. The electron transport layer 106 and the electron injection layer 107 are each formed by laminating or mixing one or more types of electron transport/injection materials, or by a mixture of an electron transport/injection material and a polymer binder.

The electron injection/transport layer is a layer that is responsible for injecting electrons from the cathode and transporting the electrons. It is desirable for the electron injection layer to have a high electron injection efficiency and efficiently transport the injected electrons. For this purpose, it is preferable for the material to have a large electron affinity, a large electron mobility, and excellent stability, and to be a material that is unlikely to generate impurities that become traps during manufacture and use. However, when considering the balance between the transport of holes and electrons, if the material mainly plays a role in efficiently preventing holes from the anode from flowing to the cathode without recombining, even if the electron transport ability is not that high, it has the effect of improving the luminous efficiency equivalent to a material with a high electron transport ability. Therefore, the electron injection/transport layer in this embodiment may also include the function of a layer that can efficiently block the movement of holes.

The material (electron transport material) forming the electron transport layer 106 or the electron injection layer 107 can be arbitrarily selected from compounds conventionally used as electron transport compounds in photoconductive materials and known compounds used in the electron injection layer and electron transport layer of organic EL elements.

Materials used in the electron transport layer or electron injection layer preferably contain at least one selected from compounds consisting of aromatic rings or heteroaromatic rings composed of one or more atoms selected from carbon, hydrogen, oxygen, sulfur, silicon, and phosphorus, pyrrole derivatives and their condensed ring derivatives, and metal complexes having electron-accepting nitrogen. Specific examples include condensed ring aromatic ring derivatives such as naphthalene and anthracene, styryl aromatic ring derivatives such as 4,4'-bis(diphenylethenyl)biphenyl, perinone derivatives, coumarin derivatives, naphthalimide derivatives, quinone derivatives such as anthraquinone and diphenoquinone, phosphine oxide derivatives, arylnitrile derivatives, and indole derivatives. Examples of metal complexes having electron-accepting nitrogen include hydroxyazole complexes such as hydroxyphenyloxazole complexes, azomethine complexes, tropolone metal complexes, flavonol metal complexes, and benzoquinoline metal complexes. These materials can be used alone or in combination with different materials.

Specific examples of other electron transport compounds include pyridine derivatives, naphthalene derivatives, fluoranthene derivatives, BO derivatives, anthracene derivatives, phenanthroline derivatives, perinone derivatives, coumarin derivatives, naphthalimide derivatives, anthraquinone derivatives, diphenoquinone derivatives, diphenylquinone derivatives, perylene derivatives, oxadiazole derivatives (such as 1,3-bis[(4-t-butylphenyl)1,3,4-oxadiazolyl]phenylene), thiophene derivatives, triazole derivatives (such as N-naphthyl-2,5-diphenyl-1,3,4-triazole), thiadiazole derivatives, metal complexes of oxine derivatives, quinolinol metal complexes, quinoxaline derivatives, polymers of quinoxaline derivatives, benzazole compounds, gallium complexes, pyrazole derivatives, perfluorinated phenylene derivatives, triazine derivatives, pyrazine derivatives, benzoquinol Examples of such compounds include benzene derivatives (such as 2,2'-bis(benzo[h]quinolin-2-yl)-9,9'-spirobifluorene), imidazopyridine derivatives, borane derivatives, benzimidazole derivatives (such as tris(N-phenylbenzimidazol-2-yl)benzene), benzoxazole derivatives, thiazole derivatives, benzothiazole derivatives, quinoline derivatives, oligopyridine derivatives such as terpyridine, bipyridine derivatives, terpyridine derivatives (such as 1,3-bis(2,2':6',2"-terpyridin-4'-yl)benzene), naphthyridine derivatives (such as bis(1-naphthyl)-4-(1,8-naphthyridin-2-yl)phenylphosphine oxide), aldazine derivatives, pyrimidine derivatives, arylnitrile derivatives, indole derivatives, phosphine oxide derivatives, bisstyryl derivatives, silole derivatives, and azoline derivatives.

Metal complexes having an electron-accepting nitrogen can also be used, such as quinolinol metal complexes, hydroxyazole complexes such as hydroxyphenyloxazole complexes, azomethine complexes, tropolone metal complexes, flavonol metal complexes, and benzoquinoline metal complexes.

The above materials can be used alone or in combination with other materials.

Among the above-mentioned materials, borane derivatives, pyridine derivatives, fluoranthene derivatives, BO-based derivatives, anthracene derivatives, benzofluorene derivatives, phosphine oxide derivatives, pyrimidine derivatives, arylnitrile derivatives, triazine derivatives, benzimidazole derivatives, phenanthroline derivatives, quinolinol-based metal complexes, thiazole derivatives, benzothiazole derivatives, silole derivatives and azoline derivatives are preferred.

The polycyclic aromatic compound of the present invention may be used as a material for forming an electron injection layer or an electron transport layer.

The electron transport layer or the electron injection layer may further contain a substance capable of reducing the material forming the electron transport layer or the electron injection layer. As the reducing substance, various substances can be used as long as they have a certain degree of reducing ability. For example, at least one selected from the group consisting of alkali metals, alkaline earth metals, rare earth metals, oxides of alkali metals, halides of alkali metals, oxides of alkaline earth metals, halides of alkaline earth metals, oxides of rare earth metals, halides of rare earth metals, organic complexes of alkali metals, organic complexes of alkaline earth metals, and organic complexes of rare earth metals can be preferably used.

Preferred reducing substances include alkali metals such as Na (work function 2.36 eV), K (2.28 eV), Rb (2.16 eV), or Cs (1.95 eV), and alkaline earth metals such as Ca (2.9 eV), Sr (2.0-2.5 eV), or Ba (2.52 eV), with substances with a work function of 2.9 eV or less being particularly preferred. Of these, more preferred reducing substances are alkali metals such as K, Rb, or Cs, more preferably Rb or Cs, and most preferably Cs. These alkali metals have particularly high reducing ability, and by adding a relatively small amount to the material forming the electron transport layer or electron injection layer, the luminance of the organic EL element can be improved and the lifespan can be extended. In addition, as a reducing substance having a work function of 2.9 eV or less, a combination of two or more of these alkali metals is also preferred, and in particular, a combination containing Cs, such as a combination of Cs and Na, Cs and K, Cs and Rb, or Cs, Na and K, is preferred. By containing Cs, the reducing ability can be efficiently exerted, and by adding it to the material forming the electron transport layer or electron injection layer, the luminance of the light emitted by the organic EL element can be improved and the life span can be extended.

<2-1-8. Cathode in organic electroluminescent device>
The cathode 108 serves to inject electrons into the light-emitting layer 105 via the electron injection layer 107 and the electron transport layer 106 .

The material for forming the cathode 108 is not particularly limited as long as it is a substance that can efficiently inject electrons into the organic layer, but the same material as the material for forming the anode 102 can be used. Among them, metals such as tin, indium, calcium, aluminum, silver, copper, nickel, chromium, gold, platinum, iron, zinc, lithium, sodium, potassium, cesium, and magnesium, or alloys thereof (magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy such as lithium fluoride/aluminum, etc.), etc. are preferable. In order to increase the electron injection efficiency and improve the device characteristics, lithium, sodium, potassium, cesium, calcium, magnesium, or alloys containing these low work function metals are effective. However, these low work function metals are generally unstable in air. To improve this point, for example, a method is known in which a trace amount of lithium, cesium, or magnesium is doped into the organic layer to use a highly stable electrode. Other dopants that can be used include inorganic salts such as lithium fluoride, cesium fluoride, lithium oxide, and cesium oxide. However, they are not limited to these.

Furthermore, preferred examples include laminating metals such as platinum, gold, silver, copper, iron, tin, aluminum, and indium, or alloys using these metals, as well as inorganic materials such as silica, titania, and silicon nitride, polyvinyl alcohol, vinyl chloride, and hydrocarbon polymer compounds, in order to protect the electrodes. There are no particular limitations on the method of producing these electrodes, and they can be produced by resistance heating, electron beam deposition, sputtering, ion plating, coating, or the like, as long as electrical conductivity can be obtained.

<2-1-9. Binder that may be used in each layer>
The materials used for the hole injection layer, hole transport layer, light emitting layer, electron transport layer and electron injection layer can form each layer alone, but they can also be used as a polymer binder by dispersing them in a solvent-soluble resin such as polyvinyl chloride, polycarbonate, polystyrene, poly(N-vinylcarbazole), polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate resin, ABS resin, polyurethane resin, or a curable resin such as phenol resin, xylene resin, petroleum resin, urea resin, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicone resin, or the like.

<2-1-10. Method for producing organic electroluminescent device>
Each layer constituting an organic EL element can be formed by forming the material to be formed into a thin film by a method such as vapor deposition, resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination, printing, inkjet, spin coating or casting, coating, etc. The thickness of each layer thus formed is not particularly limited and can be set appropriately according to the properties of the material, but is usually in the range of 2 nm to 5000 nm. The thickness can usually be measured with a quartz crystal oscillation type film thickness measuring device, etc. When forming a thin film by vapor deposition, the vapor deposition conditions vary depending on the type of material, the intended crystal structure and association structure of the film, etc. The vapor deposition conditions are generally preferably set appropriately in the range of boat heating temperature +50 to +400°C, vacuum degree 10 ^-6 to 10 ^-3 Pa, vapor deposition rate 0.01 to 50 nm/sec, substrate temperature -150 to +300°C, and film thickness 2 nm to 5 μm.

Next, as an example of a method for producing an organic EL element, a method for producing an organic EL element consisting of an anode, a hole injection layer, a hole transport layer, a light-emitting layer consisting of a host material and a dopant material, an electron transport layer, an electron injection layer, and a cathode will be described. After forming a thin film of an anode material on a suitable substrate by a deposition method or the like to produce an anode, a thin film of a hole injection layer and a hole transport layer is formed on the anode. A host material and a dopant material are co-deposited on the anode to form a thin film to produce a light-emitting layer, an electron transport layer and an electron injection layer are formed on the light-emitting layer, and a thin film of a cathode material is further formed by a deposition method or the like to produce a cathode, thereby obtaining the desired organic EL element. It is also possible to reverse the order of production in the above-mentioned organic EL element, producing the elements in the order of cathode, electron injection layer, electron transport layer, light-emitting layer, hole transport layer, hole injection layer, and anode.

When applying a DC voltage to the organic EL element obtained in this way, the anode should be set to + and the cathode to -. When a voltage of about 2 to 40 V is applied, light emission can be observed from the transparent or semi-transparent electrode side (anode or cathode, or both). This organic EL element also emits light when a pulsed current or AC current is applied. The waveform of the applied AC current can be any waveform.

<2-1-11. Application examples of organic electroluminescent devices>
The organic EL element can also be applied to a display device or a lighting device.
A display device or lighting device equipped with an organic EL element can be manufactured by a known method, such as by connecting the organic EL element to a known driving device, and can be driven appropriately using a known driving method such as DC driving, pulse driving, or AC driving.

Display devices include, for example, panel displays such as color flat panel displays, and flexible displays such as flexible color organic electroluminescent (EL) displays (see, for example, JP-A-10-335066, JP-A-2003-321546, JP-A-2004-281086, etc.). Display methods include, for example, either a matrix or segment method. Note that matrix display and segment display may coexist in the same panel.

In a matrix, the pixels for display are arranged two-dimensionally, such as in a grid or mosaic pattern, and a collection of pixels displays characters and images. The shape and size of the pixels are determined by the application. For example, square pixels with sides of 300 μm or less are usually used to display images and characters on computers, monitors, and televisions, and pixels with sides on the order of mm are used for large displays such as display panels. For monochrome display, pixels of the same color can be arranged, but for color display, red, green, and blue pixels are displayed side by side. In this case, there are typically delta types and stripe types. The driving method for this matrix can be either line sequential driving method or active matrix. Line sequential driving has the advantage of being simpler in structure, but when considering operating characteristics, active matrix may be superior, so it is necessary to use it according to the application.

In the segment method, a pattern is formed to display predetermined information, and a specific area is illuminated. Examples include the time and temperature displays on digital clocks and thermometers, the operating status displays on audio equipment and induction cookers, and panel displays on automobiles.

Examples of lighting devices include lighting devices for indoor lighting, backlights for liquid crystal display devices, etc. (see, for example, JP-A-2003-257621, JP-A-2003-277741, JP-A-2004-119211, etc.). Backlights are mainly used for the purpose of improving the visibility of non-self-luminous display devices, and are used in liquid crystal display devices, clocks, audio devices, automobile panels, display boards, signs, etc. In particular, for backlights for liquid crystal display devices, especially for personal computers where thinning is an issue, backlights using organic EL elements are characterized by their thinness and light weight, considering that conventional methods are made up of fluorescent lamps and light guide plates and therefore difficult to make thin.

<2-2. Other organic devices>
The polycyclic aromatic compound according to the present invention can be used for producing the above-mentioned organic electroluminescent device, as well as an organic field effect transistor or an organic thin-film solar cell.

An organic field-effect transistor is a transistor that controls current by generating an electric field through voltage input, and has a gate electrode in addition to a source electrode and a drain electrode. When a voltage is applied to the gate electrode, an electric field is generated, and the flow of electrons (or holes) between the source electrode and drain electrode can be arbitrarily blocked to control the current. Field-effect transistors are easier to miniaturize than simple transistors (bipolar transistors), and are often used as elements in integrated circuits.

The structure of an organic field effect transistor may be such that a source electrode and a drain electrode are provided in contact with an organic semiconductor active layer formed using the polycyclic aromatic compound according to the present invention, and a gate electrode is provided sandwiching an insulating layer (dielectric layer) in contact with the organic semiconductor active layer. Examples of the element structure include the following structure.
(1) Substrate/gate electrode/insulator layer/source electrode/drain electrode/organic semiconductor active layer (2) Substrate/gate electrode/insulator layer/organic semiconductor active layer/source electrode/drain electrode (3) Substrate/organic semiconductor active layer/source electrode/drain electrode/insulator layer/gate electrode (4) Substrate/source electrode/drain electrode/organic semiconductor active layer/insulator layer/gate electrode An organic field effect transistor configured in this manner can be used as a pixel driving switching element for active matrix driving liquid crystal displays and organic electroluminescence displays.

An organic thin-film solar cell has a structure in which an anode such as ITO, a hole transport layer, a photoelectric conversion layer, an electron transport layer, and a cathode are laminated on a transparent substrate such as glass. The photoelectric conversion layer has a p-type semiconductor layer on the anode side and an n-type semiconductor layer on the cathode side. The polycyclic aromatic compound according to the present invention can be used as a material for a hole transport layer, a p-type semiconductor layer, an n-type semiconductor layer, and an electron transport layer depending on its physical properties. The polycyclic aromatic compound according to the present invention can function as a hole transport material or an electron transport material in an organic thin-film solar cell. In addition to the above, the organic thin-film solar cell may appropriately include a hole blocking layer, an electron blocking layer, an electron injection layer, a hole injection layer, a smoothing layer, and the like. For the organic thin-film solar cell, known materials used in organic thin-film solar cells can be appropriately selected and combined for use.

3. Wavelength conversion materials
The polycyclic aromatic compound of the present invention can be used as a wavelength converting material.
Currently, the application of multi-coloring technology using color conversion methods to liquid crystal displays, organic EL displays, lighting, and the like is being actively studied. Color conversion refers to wavelength conversion of light emitted from a light emitter to light with a longer wavelength, for example, converting ultraviolet light or blue light to green light or red light emission. By forming a wavelength conversion material having this color conversion function into a film and combining it with, for example, a blue light source, it becomes possible to extract the three primary colors of blue, green, and red from the blue light source, that is, to extract white light. By combining such a white light source, which is a combination of a blue light source and a wavelength conversion film having a color conversion function, with a liquid crystal driving part and a color filter as a light source unit, it becomes possible to manufacture a full-color display. Furthermore, if there is no liquid crystal driving part, it can be used as a white light source as it is, and can be applied as a white light source such as LED lighting. Furthermore, by using a blue organic EL element as a light source in combination with a wavelength conversion film that converts blue light into green light and red light, it becomes possible to manufacture a full-color organic EL display without using a metal mask. Furthermore, by using blue micro-LEDs as a light source in combination with wavelength conversion films that convert blue light into green and red light, it becomes possible to create low-cost full-color micro-LED displays.

The polycyclic aromatic compound of the present invention can be used as this wavelength conversion material. By using a wavelength conversion material containing the polycyclic aromatic compound of the present invention, light from a light source or a light-emitting element that generates ultraviolet light or shorter wavelength blue light can be converted into blue light or green light with high color purity suitable for use in a display device (a display device using an organic EL element or a liquid crystal display device). The converted color can be adjusted by appropriately selecting the substituent of the polycyclic aromatic compound of the present invention, the binder resin used in the wavelength conversion composition described below, and the like. The wavelength conversion material can be prepared as a wavelength conversion composition containing the polycyclic aromatic compound of the present invention. In addition, a wavelength conversion film may be formed using this wavelength conversion composition.

The wavelength conversion composition may contain, in addition to the polycyclic aromatic compound of the present invention, a binder resin, other additives, and a solvent. As the binder resin, for example, those described in paragraphs 0173 to 0176 of WO 2016/190283 can be used. As the other additives, the compounds described in paragraphs 0177 to 0181 of WO 2016/190283 can be used. As the solvent, the description of the solvent contained in the composition for forming the light-emitting layer above can be referred to.

The wavelength conversion film includes a wavelength conversion layer formed by curing the wavelength converting composition. Known film formation methods can be referred to as a method for producing a wavelength conversion layer from a wavelength converting composition. The wavelength conversion film may consist only of a wavelength conversion layer formed from a composition containing the polycyclic aromatic compound of the present invention, or may include other wavelength conversion layers (e.g., a wavelength conversion layer that converts blue light into green light or red light, or a wavelength conversion layer that converts blue light or green light into red light). The wavelength conversion film may further include a substrate layer and a barrier layer for preventing deterioration of the color conversion layer due to oxygen, moisture, or heat.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.
In the examples, APCI-MS means atmospheric pressure chemical ionization mass spectrometry.

<<Synthesis Example>>
Synthesis Example (1):
Synthesis of compound (1-001)

Under a nitrogen atmosphere, intermediate (X-1) (41.4 g), 1-t-butyl-3,4,5-trichlorobenzene (23.8 g), dichlorobis[di-t-butyl(4-dimethylaminophenyl)phosphino]palladium(II) (Pd-132) (0.909 g) as a palladium catalyst, sodium t-butoxide (NaOtBu, 14.4 g), and toluene (500 ml) were placed in a flask and heated at 120°C for 5 hours. After the reaction was completed, water and ethyl acetate were added to the reaction solution and stirred, and the organic layer was separated and washed with water. The organic layer was then concentrated to obtain a crude product, which was purified using a silica gel short-path column (eluent: toluene) to obtain 49.1 g of intermediate (X-2).

Under a nitrogen atmosphere, intermediate (X-2) (30.7 g), intermediate (X-3) (21.8 g), Pd-132 (0.719 g) as a palladium catalyst, NaOtBu (7.21 g), and toluene (300 ml) were placed in a flask and heated at 120°C for 3 hours. After the reaction was completed, water and ethyl acetate were added to the reaction solution and stirred, and the organic layer was separated and washed with water. The organic layer was then concentrated to obtain a crude product, which was purified using a silica gel short-path column (eluent: toluene/heptane = 1/4 (volume ratio)) to obtain 30.0 g of intermediate (X-4).

A 1.60M tert-butyllithium pentane solution ( ^t BuLi, 12.5 ml) was added to a flask containing intermediate (X-4) (10.5 g) and tert-butylbenzene ( ^t Bu-benzene, 100 ml) under a nitrogen atmosphere at 0°C. After the dropwise addition, the temperature was raised to 70°C and stirred for 0.5 hours, and then components with a boiling point lower than that of tert-butylbenzene were distilled off under reduced pressure. The mixture was cooled to -50°C and boron tribromide (5.0 g) was added, and the mixture was heated to room temperature and stirred for 0.5 hours. Thereafter, the mixture was cooled again to 0°C and N,N-diisopropylethylamine (EtN ⁱ Pr ₂ , 2.6 g) was added, and the mixture was stirred at room temperature until the heat generation subsided, and then the mixture was heated to 100°C and stirred for 1 hour. The reaction solution was cooled to room temperature, and an aqueous sodium acetate solution cooled in an ice bath and then ethyl acetate were added to separate the liquids. The organic layer was concentrated and then purified with a silica gel short-path column (eluent: chlorobenzene). The resulting crude product was recrystallized from toluene to obtain 1.5 g of compound (1-001).

APCI-MS showed that the m/z (M+H) was 973.6, confirming that the compound was the target (1-001).

Synthesis Example (2): Synthesis of Compound (1-002) Compound (1-002) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-2).
APCI-MS revealed that the m/z (M+H) was 953.7, confirming that the compound was the target (1-002).

Synthesis Example (3): Synthesis of Compound (1-003) Compound (1-003) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-3).
APCI-MS revealed that the m/z (M+H) was 965.6, confirming that the compound was the target (1-003).

Synthesis Example (4): Synthesis of Compound (1-013) Compound (1-013) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-4).
APCI-MS revealed that the m/z (M+H) was 1099.8, confirming that the compound was the target (1-013).

Synthesis Example (5): Synthesis of Compound (1-016) Compound (1-016) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-5).
APCI-MS revealed that the m/z (M+H) was 1098.6, confirming that the compound was the target (1-016).

Synthesis Example (6): Synthesis of Compound (1-017) Compound (1-017) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-6).
APCI-MS revealed that the m/z (M+H) was 877.5, confirming that the compound was the target (1-017).

Synthesis Example (7): Synthesis of Compound (1-018) Compound (1-018) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-7).
APCI-MS revealed that the m/z (M+H) was 1009.7, confirming that the compound was the target (1-018).

Synthesis Example (8): Synthesis of Compound (1-025) Compound (1-025) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-8).
APCI-MS revealed that the m/z (M+H) was 815.5, confirming that the compound was the target (1-025).

Synthesis Example (9): Synthesis of Compound (1-031) Compound (1-031) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-9).
APCI-MS revealed that the m/z (M+H) was 1002.5, confirming that the compound was the target (1-031).

Synthesis Example (10): Synthesis of Compound (1-037) Compound (1-037) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-10).
APCI-MS revealed that the m/z (M+H) was 909.6, confirming that the compound was the target (1-037).

Synthesis Example (11): Synthesis of Compound (1-043) Compound (1-043) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-11).
APCI-MS revealed that the m/z (M+H) was 787.5, confirming that the compound was the target (1-043).

Synthesis Example (12): Synthesis of Compound (1-028) Compound (1-028) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-12).
APCI-MS revealed that the m/z (M+H) was 1010.6, confirming that the compound was the target (1-028).

Synthesis Example (13): Synthesis of Compound (1-034) Compound (1-034) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-13).
APCI-MS revealed that the m/z (M+H) was 984.6, confirming that the compound was the target (1-034).

Synthesis Example (14): Synthesis of Compound (2-001) Compound (2-001) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-14).
APCI-MS revealed that the m/z (M+H) was 857.6, confirming that the compound was the target (2-001).

Synthesis Example (15): Synthesis of Compound (2-007) Compound (2-007) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-15).
APCI-MS revealed that the m/z (M+H) was 939.5, confirming that the compound was the target (2-007).

Synthesis Example (16): Synthesis of Compound (2-013) Compound (2-013) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-16).
APCI-MS revealed that the m/z (M+H) was 987.7, confirming that the compound was the target (2-013).

Synthesis Example (17): Synthesis of Compound (2-019) Compound (2-019) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-17).
APCI-MS revealed that the m/z (M+H) was 1044.6, confirming that the compound was the target (2-019).

Synthesis Example (18): Synthesis of Compound (2-025) Compound (2-025) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-18).
APCI-MS revealed that the m/z (M+H) was 1142.7, confirming that the compound was the target (2-025).

Synthesis Example (19): Synthesis of Compound (1-065) Compound (1-065) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-19).
APCI-MS revealed that the m/z (M+H) was 1081.9, confirming that the compound was the target (1-065).

Synthesis Example (20): Synthesis of Compound (5-036) Compound (5-036) was obtained in the same manner as in Synthesis Example 1, except that compound (X-4) was changed to compound (X-4-20).
APCI-MS revealed that the m/z (M+H) was 1117.2, confirming that the compound was the target (5-036).

By appropriately changing the raw material compounds, other compounds of the present invention can be synthesized in a manner similar to the above synthesis examples.

<<Fabrication and evaluation of deposition-type organic EL elements>>
Next, the preparation and evaluation of an organic EL device using the polycyclic aromatic compound of the present invention will be described.

<Preparation of Organic EL Element>
An organic EL device was produced using the polycyclic aromatic compound of the present invention.
The material configurations of the layers in the organic EL devices of Examples 1 to 20 and Comparative Examples 1 to 5 are shown in Table 1 below.

The chemical structures of "HI", "HAT-CN", "HT-1", "HT-2", "BH", "ET-1", "ET-2", "BH", "Liq", "Comparative compound (1)" described in WO 2021/150026, "Comparative compound (2)" described in Chinese Patent Application Publication No. 113045595, "Comparative compound (3)" described in WO 2021/107728, "Comparative compound (4)" described in Korean Patent Publication No. 2094830, and "Comparative compound (5)" described in U.S. Patent Application Publication No. 20210167293 in Tables 1 and 3 are shown below.

[Example 1]
A 26 mm x 28 mm x 0.7 mm glass substrate (manufactured by Optoscience Co., Ltd.) on which an ITO film having a thickness of 180 nm was formed by sputtering and polished to 150 nm was used as a transparent support substrate. This transparent support substrate was fixed to a substrate holder of a commercially available deposition apparatus (manufactured by Showa Vacuum Co., Ltd.), and a molybdenum deposition boat containing HI, HAT-CN, HT-1, HT-2, BH, (1-001), ET-1, and ET-2, and an aluminum nitride deposition boat containing Liq, LiF, and aluminum were attached.

The following layers are formed in sequence on the ITO film of the transparent support substrate. The vacuum chamber is depressurized to 5×10 ⁻⁴ Pa, and first, HI is heated and evaporated to a thickness of 40 nm, then HAT-CN is heated and evaporated to a thickness of 5 nm, then HT-1 is heated and evaporated to a thickness of 45 nm, then HT-2 is heated and evaporated to a thickness of 10 nm to form a hole layer consisting of four layers. Next, BH and (1-001) are heated simultaneously and evaporated to a thickness of 25 nm to form a light-emitting layer. The evaporation rate was adjusted so that the mass ratio of BH to (1-001) was approximately 98:2. Furthermore, ET-1 was heated and evaporated to a thickness of 5 nm, and then ET-2 and Liq were heated simultaneously and evaporated to a thickness of 25 nm to form an electronic layer consisting of two layers. The evaporation rate was adjusted so that the mass ratio of ET-2 to Liq was approximately 50:50. The deposition rate of each layer was 0.01 to 1 nm/sec. LiF was heated and deposited at a deposition rate of 0.01 to 0.1 nm/sec to a thickness of 1 nm, and then aluminum was heated and deposited to a thickness of 100 nm to form a cathode, thereby obtaining an organic EL element.

[Examples 2 to 20, Comparative Examples 1 to 5]
Organic EL devices of Examples 2 to 20 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that each material shown in Table 2 or Table 3 was used instead of compound (1-001).

<Evaluation of Organic EL Device>
The quantum efficiency of a light-emitting element includes internal quantum efficiency and external quantum efficiency, and the internal quantum efficiency indicates the ratio of the external energy injected as electrons (or holes) into the light-emitting layer of the light-emitting element that is converted purely into photons. On the other hand, the external quantum efficiency is calculated based on the amount of these photons that are emitted to the outside of the light-emitting element, and since some of the photons generated in the light-emitting layer are absorbed or continue to be reflected inside the light-emitting element and are not emitted to the outside of the light-emitting element, the external quantum efficiency is lower than the internal quantum efficiency.

The method for measuring the external quantum efficiency is as follows. Using an Advantest voltage/current generator R6144, a voltage was applied to make the element emit light at a luminance of 1000 cd/ ^m2 . Using a TOPCON spectroradiometer SR-3AR, the spectral radiance in the visible light region was measured from a direction perpendicular to the light-emitting surface. Assuming that the light-emitting surface is a completely diffusing surface, the measured spectral radiance value of each wavelength component was divided by the wavelength energy and multiplied by π to obtain the number of photons at each wavelength. Next, the number of photons was integrated over the entire wavelength range observed to obtain the total number of photons emitted from the element. The value obtained by dividing the applied current value by the elementary charge was taken as the number of carriers injected into the element, and the value obtained by dividing the total number of photons emitted from the element by the number of carriers injected into the element was taken as the external quantum efficiency.

The organic EL elements according to Examples 1 to 20 and Comparative Examples 1 to 5 produced above were measured for the emission color, driving voltage (V), and external quantum efficiency (%), which are characteristics at 10 mA/ ^cm2 emission. The results are shown in Tables 2 and 3.

The organic EL elements of Examples 1 to 20 were driven at a lower voltage and had higher external quantum efficiency than the organic EL elements of Comparative Examples 1 to 5.

The polycyclic aromatic compound of the present invention is useful as a material for organic devices, particularly as a material for forming a light-emitting layer in an organic electroluminescent device. By using the polycyclic aromatic compound of the present invention as a dopant for the light-emitting layer, an organic electroluminescent device with low driving voltage and high light emission efficiency can be obtained.

REFERENCE SIGNS LIST 100 Organic electroluminescent element 101 Substrate 102 Anode 103 Hole injection layer 104 Hole transport layer 105 Light-emitting layer 106 Electron transport layer 107 Electron injection layer 108 Cathode

Claims (28)

A polycyclic aromatic compound having a structure consisting of one or more structural units represented by formula (1);

In formula (1),
ring A and ring B each independently represent a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring;
Ring C is a substituted indene ring represented by formula (1C),
R ^c1 , R ^c2 , R ^c3 , and R ^c4 are each independently hydrogen or a substituent, provided that at least one selected from the group consisting of R ^c1 , R ^c2 , R ^c3 , and R ^c4 is a substituent;
R ^c5 and R ^c6 are bonds to Y ¹ and X ² in formula (1),
R ^d1 and R ^d2 each independently represent hydrogen or a substituent, and may be bonded to each other to form a ring;
^Y1 is B, P, P=O, P=S, Al, Ga, As, Si-R ^YI , or Ge-R ^YG , where R ^YI and R ^YG are each substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl;
^X1 and ^X2 are each independently >O, >N- ^RNX , >C( ^-RCX ) ₂ , >Si( ^-RIX ) ₂ , >S, or >Se; ^RNX , ^RCX , and ^RIX are each independently hydrogen, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl; two ^RCX in >C(-RCX) ₂ may be bonded to each other to form a ring; two ^RIX in >Si(-R) ₂ may be bonded to each other to form ^a ring; ^RNX , at least one ^RCX , and at least one ^RIX may be bonded to at least one of the A ring or B ring or at least one of the A ring or C ring via a single bond or a linking group;
At least one of the aryl or heteroaryl rings in said structure may be fused with at least one cycloalkane, said cycloalkane may be substituted with at least one substituent, and at least one _-CH2- in said cycloalkane may be replaced with -O-;
In said structure, at least one hydrogen may be replaced by deuterium, at least one nitrogen may be replaced by nitrogen-15 ( ¹⁵ N), at least one sulfur may be replaced by sulfur-33 ( ³³ S), sulfur-34 ( ³⁴ S) or sulfur-36 ( ³⁶ S), at least one oxygen may be replaced by oxygen-17 ( ¹⁷ O) or oxygen-18 ( ¹⁸ O), at least one carbon may be replaced by carbon-13 ( ¹³ C), and at least one boron may be replaced by boron-11 ( ¹¹ B). The polycyclic aromatic compound according to claim 1, having a structure composed of one or more structural units represented by formula (1XC1);

In formula (1XC1),
R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 are each independently a hydrogen atom or a substituent;
any two adjacent groups among R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 may be bonded to each other to form a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring together with the two carbon atoms to which they are bonded,
R ^c1 , R ^c2 , R ^c3 and R ^c4 are each independently hydrogen or a substituent, provided that at least one of R ^c1 to R ^c4 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl;
R ^d1 and R ^d2 are defined the same as R ^d1 and R ^d2 in formula (1C),
Y ¹ , X ¹ and X ² have the same meanings as Y ¹ , X ¹ and X ² in formula (1), respectively. The polycyclic aromatic compound according to claim 2, wherein R ^c2 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (the two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl. The polycyclic aromatic compound according to claim 2, wherein R ^c2 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, or a substituted or unsubstituted diarylamino. The polycyclic aromatic compound according to claim 3, which is represented by any one of the following formulas:

In the formula, Me is methyl, tBu is t-butyl, and D is deuterium. The polycyclic aromatic compound according to claim 5, represented by formula (2-013), formula (2-019), or formula (2-025). The polycyclic aromatic compound according to claim 2, wherein R ^c2 is a substituted or unsubstituted alkyl, and none of R ^NX , R ^CX , and R ^IX is bonded to any of ring A, ring B, or ring C via a single bond or a linking group. The polycyclic aromatic compound according to claim 7, which is represented by any one of the following formulas:

In the formula, Me is methyl and tBu is t-butyl. The polycyclic aromatic compound according to claim 8, represented by formula (2-001) or formula (2-007). The polycyclic aromatic compound according to claim 2, wherein R is a substituted or unsubstituted ^aryl , a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (wherein the two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl. The polycyclic aromatic compound according to claim 2, wherein R ^c3 is a substituted or unsubstituted heteroaryl. The polycyclic aromatic compound according to claim 2, wherein R ^c3 is a substituted or unsubstituted diarylamino. The polycyclic aromatic compound according to claim 12, represented by any one of the following formulas:

In the formula, Me is methyl and tBu is t-butyl. The polycyclic aromatic compound according to claim 13, represented by formula (1-034). The polycyclic aromatic compound according to claim 10, represented by any one of the following formulas:

In the formula, Me is methyl and tBu is t-butyl. The polycyclic aromatic compound according to claim 15, represented by formula (1-001), formula (1-016), formula (1-017), formula (1-028), formula (1-037), formula (1-043), or formula (1-065). The polycyclic aromatic compound according to claim 2, which is represented by any one of the following formulas:

In the formula, Me is methyl and tBu is t-butyl. The polycyclic aromatic compound according to claim 17, represented by formula (1-002), formula (1-003), formula (1-013), formula (1-018), formula (1-025), or formula (1-031). The polycyclic aromatic compound according to claim 2, wherein R ^c1 or R ^c4 is a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted diarylamino, a substituted or unsubstituted diheteroarylamino, a substituted or unsubstituted arylheteroarylamino, a substituted or unsubstituted diarylboryl (the two aryls may be bonded via a single bond or a linking group), a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryloxy, or a substituted silyl. The polycyclic aromatic compound according to claim 19, represented by any one of the following formulas:

In the formula, Me is methyl and tBu is t-butyl. The polycyclic aromatic compound according to claim 1, having a structure consisting of one or more structural units represented by formula (1XC2);

In formula (1XC2),
R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 are each independently a hydrogen atom or a substituent;
any two adjacent groups among R ^a1 , R ^a2 , R ^a3 , R ^b1 , R ^b2 , R ^b3 , and R ^b4 may be bonded to each other to form a substituted or unsubstituted aryl ring or a substituted or unsubstituted heteroaryl ring together with the two carbon atoms to which they are bonded,
R ^c1 , R ^c2 , R ^c3 , R ^c4 , R ^d1 , and R ^d2 are each defined as R ^c1 , R ^c2 , R ^c3 , R ^c4 , R ^d1 , and R ^d2 in formula (1C), respectively;
Y ¹ , X ¹ and X ² have the same meanings as Y ¹ , X ¹ and X ² in formula (1), respectively. The polycyclic aromatic compound according to claim 21, represented by any one of the following formulas:

In the formula, Me is methyl and tBu is t-butyl. The polycyclic aromatic compound according to claim 22, represented by formula (5-036). A material for organic devices containing the polycyclic aromatic compound according to any one of claims 1 to 23. An organic electroluminescent device comprising a pair of electrodes consisting of an anode and a cathode, and a light-emitting layer disposed between the pair of electrodes, the light-emitting layer containing the polycyclic aromatic compound according to any one of claims 1 to 23. The organic electroluminescent device according to claim 25, wherein the light-emitting layer contains a host and the polycyclic aromatic compound as a dopant. The organic electroluminescent device according to claim 26, wherein the host is an anthracene compound, a fluorene compound, a pyrene compound, or a dibenzochrysene compound. A display device or lighting device comprising the organic electroluminescent device according to claim 25.