JP2023086108A - Compounds and organic electroluminescent elements - Google Patents

Abstract

To provide compounds that have high solvent solubility and, when used in an emission layer of organic electroluminescent elements, realize an organic electroluminescent element with low voltage, high luminous efficiency, and a long life.SOLUTION: A compound is represented by the formula (1) in the figure. (In the formula, W1, W2 and W3 are each -CH or a nitrogen atom, provided that at least one of W1, W2 and W3 is a nitrogen atom; and Za2 is an N-carbazolyl group which may have a substituent)SELECTED DRAWING: Figure 1

Description

The present invention provides a compound that can be used in an organic electroluminescent device (hereinafter sometimes referred to as "OLED" or "device"), an organic electroluminescent device having the compound, and a display having the organic electroluminescent device. The present invention relates to a device and a lighting device, a composition containing the compound and an organic solvent, a method for forming a thin film using the composition, and a method for producing an organic electroluminescent device.

In recent years, as a thin-film type electroluminescence element, an organic electroluminescence element using an organic thin film has been developed in place of the one using an inorganic material. An organic electroluminescent device (OLED) typically has a hole-injection layer, a hole-transport layer, an organic light-emitting layer, an electron-transport layer, etc. between an anode and a cathode. Materials suitable for each of these layers are being developed, and the development of red, green, and blue emission colors is progressing. In addition, research is being conducted on coating-type OLEDs, which are more efficient in material utilization than conventional evaporation-type OLEDs and can reduce manufacturing costs.

Coating-type OLEDs are required to have a longer life and be driven with lower power consumption. There are various factors that can affect the life of an element and the improvement in power consumption, but with regard to life, for example, it is believed that the heat resistance and durability of the materials that make up the element and the crystallinity have a large effect. .

Moreover, in order to manufacture an organic electroluminescence device by a wet film-forming method, all the materials used must be soluble in an organic solvent and used as an ink. If the material to be used has poor solubility, the material may deteriorate before use because an operation such as heating for a long period of time is required. Furthermore, if the uniform state cannot be maintained for a long time in a solution state, the material will precipitate out of the solution, making it impossible to form a film using an inkjet device or the like. Materials used in the wet film-forming method are required to have solubility in two senses: rapid dissolution in an organic solvent and maintenance of a homogeneous state without precipitating after dissolution.

On the other hand, in order to form all the organic layers by a wet film-forming method and to produce an organic electroluminescence element by applying a multilayer lamination of organic layers to form a film, after the wet film-forming, a Solvent resistance to the applied ink is required.

Patent Document 1 reports that a triazine-based compound having a carbazolyl group is used as a charge-transporting material that is a host of a light-emitting layer.

WO2012/137958

Patent Document 1 does not discuss wet deposition of an electron transport layer on and in contact with a light-emitting layer containing a triazine-based compound. Moreover, the triazine-based compound having a carbazolyl group described in Patent Document 1 has low solvent solubility and poor film-forming properties by a wet film-forming method.

On the other hand, materials used in organic electroluminescent devices are always required to have not only suitability for wet film formation and solvent solubility, but also further improvement in device performance of organic electroluminescent devices using such materials. ing.

The present invention has been made in view of the above-described conventional circumstances, and provides an organic electroluminescent device that has high solvent solubility, low voltage, high luminous efficiency, and long life when used in the light-emitting layer of an organic electroluminescent device. An object of the present invention is to provide the resulting compound. Another object of the present invention is to provide a compound that renders a film containing the compound insoluble in a specific solvent in order to enable wet film formation of another layer on the film containing the compound. do.
Further, the present invention provides an organic electroluminescent device comprising the compound, a display device and a lighting device comprising the organic electroluminescent device, a composition containing the compound and an organic solvent, a method for forming a thin film using the composition, and an organic electric field. An object of the present invention is to provide a method for manufacturing a light emitting device.

As a result of intensive studies by the present inventors, they have found that the above problems can be solved by using a compound having a specific structure, and have completed the present invention.

That is, the gist of the present invention is as follows <1> to <11>.

<1> A compound represented by the following formula (1).

(In formula (1),
W ₁ , W ₂ and W ₃ each independently represent —CH or a nitrogen atom, at least one of W ₁ , W ₂ and W ₃ is a nitrogen atom;
Xa ¹ , Ya ¹ and Za ¹ each independently represent an optionally substituted 1,3-phenylene group or an optionally substituted 1,4-phenylene group,
at least one of Za ¹ is an optionally substituted 1,3-phenylene group,
Xa ² and Ya ² each independently represent a phenyl group which may have a substituent;
Za ² represents an optionally substituted N-carbazolyl group,
f11 is 1 or 2,
g11 is an integer from 1 to 5,
h11 is 1 or 2,
j11 is an integer from 1 to 5,
k11 is an integer from 2 to 5,
Each R ₁₁ independently represents a hydrogen atom or a substituent. )

<2> The compound according to <1>, wherein each R ₁₁ in formula (1) is independently a hydrogen atom, a phenyl group, or a naphthyl group.

<3> An organic electroluminescence device having an anode and a cathode on a substrate, and an organic layer between the anode and the cathode, wherein the organic layer contains the compound according to <1> or <2>. organic electroluminescent device, including

<4> The organic electroluminescence device according to <3>, wherein the organic layer includes a light-emitting layer, and the light-emitting layer includes the compound.

<5> A display device comprising the organic electroluminescence device according to <3> or <4>.

<6> A lighting device comprising the organic electroluminescent device according to <3> or <4>.

<7> A composition comprising at least the compound according to <1> or <2> and an organic solvent.

<8> The composition according to <7>, further comprising a luminescent material.

<9> A method for forming a thin film, comprising forming a film from the composition according to <7> or <8> by a wet film-forming method.

<10> A method for producing an organic electroluminescence device having an anode and a cathode on a substrate and an organic layer between the anode and the cathode, wherein the organic layer is formed in <7> or <8>. A method for producing an organic electroluminescence device, comprising a step of forming the composition by a wet film-forming method.

<11> The method for producing an organic electroluminescence device according to <10>, wherein the organic layer is a light-emitting layer.

According to the present invention, it is possible to provide a compound that has high solvent solubility and that, when used in the light-emitting layer of an organic electroluminescent device, provides an organic electroluminescent device with low voltage, high luminous efficiency, and long life.
In addition, since the compound of the present invention is insoluble in a specific solvent and has excellent solvent resistance, it is also possible to laminate another layer on the film containing the compound of the present invention by a wet film-forming method. becomes.

According to the present invention, an organic electroluminescent device having the compound, a display device and a lighting device having the organic electroluminescent device, a composition containing the compound and a solvent, a thin film forming method using the composition, and an organic electroluminescent device A manufacturing method can be provided.

FIG. 1 is a schematic cross-sectional view showing a structural example of the organic electroluminescence device of the present invention.

Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be modified in various ways within the scope of the gist thereof.

In the present invention, "optionally having a substituent" means that one or more substituents may be present.

[Compound represented by formula (1)]
The compound of the present invention is represented by the following formula (1).

(In formula (1),
W ₁ , W ₂ and W ₃ each independently represent —CH or a nitrogen atom, at least one of W ₁ , W ₂ and W ₃ is a nitrogen atom;
Xa ¹ , Ya ¹ and Za ¹ each independently represent an optionally substituted 1,3-phenylene group or an optionally substituted 1,4-phenylene group,
at least one of Za ¹ is an optionally substituted 1,3-phenylene group,
Xa ² and Ya ² each independently represent a phenyl group which may have a substituent;
Za ² represents an optionally substituted N-carbazolyl group,
f11 is 1 or 2,
g11 is an integer from 1 to 5,
h11 is 1 or 2,
j11 is an integer from 1 to 5,
k11 is an integer from 2 to 5,
Each R ₁₁ independently represents a hydrogen atom or a substituent. )

The compounds of the invention function as charge transport materials. That is, since the compound of the present invention has a 6-membered heterocyclic ring containing a nitrogen atom, it can function as an electron-transporting material.
Therefore, the compound of the present invention is preferably a charge-transporting compound, ie, a charge-transporting host material, and is preferably used as an electron-transporting host material for a light-emitting layer in an organic electroluminescent device.

The 1,3-phenylene group or 1,4-phenylene group of Xa ¹ , Ya ¹ and Za ¹ , the phenyl group of Xa ² and Ya ² , and the N-carbazolyl group of Za ² in the above formula (1) The optional substituents are selected from Substituent Group Q described later.

< _W1 , _W2 , _W3 >
W ₁ , W ₂ and W ₃ in formula (1) each independently represent —CH or a nitrogen atom, and at least one of W ₁ , W ₂ and W ₃ is a nitrogen atom. From the viewpoint of electron transportability and electron durability, at least W ₁ is preferably a nitrogen atom, at least W ₁ and W ₂ are preferably nitrogen atoms, and all of W ₁ , W ₂ and W ₃ are nitrogen atoms. Atoms are more preferred.
That is, from the viewpoint of improving the electron-transporting property, it is preferable that W ₁ is a nitrogen atom, and W ₁ is a nitrogen atom, in which two or three benzene rings are linked at the para position to widen the conjugation. In addition, a pyrimidine structure in which one of _W2 or _W3 is a nitrogen atom is more preferred, and a triazine structure in which all of _W1 , _W2 and _W3 are nitrogen atoms is most preferred.

<-(Xa ¹ ) _g11 -Xa ² >
—(Xa ¹ ) _g11 —Xa ² is preferably selected from the following structures.

In these structures, hydrogen atoms on all benzene rings may be substituted with substituents selected from Substituent Group Q described later. A structure in which hydrogen atoms are not substituted is preferred.

<−(Ya ¹ ) _j11 −Ya ² >
—(Ya ¹ ) _j11 —Ya ² is preferably selected from the following structures.

In these structures, hydrogen atoms on all benzene rings may be substituted with substituents selected from Substituent Group Q described later. A structure in which hydrogen atoms are not substituted is preferred.

<−(Za ¹ ) _k11 −Za ² >
—(Za ¹ ,) _k11 —Za ² is preferably selected from the following structures.

In these structures, all hydrogen atoms on the benzene ring including the hydrogen atom on the benzene ring of the N-carbazolyl group of Za ² may be substituted with a substituent selected from the substituent group Q described below. good. A structure in which hydrogen atoms are not substituted is preferred.

^<R11>
Examples of R ¹¹ , which is a substituent other than a hydrogen atom, include groups selected from the following substituent group Q. Among the substituent group Q, an optionally substituted aromatic hydrocarbon group having 6 to 30 carbon atoms or an optionally substituted aromatic heterocyclic group having 3 to 30 carbon atoms is preferable. is.
The substituent that the aromatic hydrocarbon group having 6 to 30 carbon atoms described above may have, the substituent that the aromatic heterocyclic group having 3 to 30 carbon atoms may have, and the substituent R ¹¹ The substituent that may have can be selected from the following substituent group Q.
When a plurality of R ¹¹ are present as substituents in the formula (1), the plurality of R ¹¹ may be the same or different from each other.

R ¹¹ is preferably a hydrogen atom, a phenyl group, or a naphthyl group, more preferably a hydrogen atom, from the viewpoints of durability improvement and charge transportability.

<Substituent group Q>
Substituent group Q includes an alkyl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an alkoxycarbonyl group, a dialkylamino group, a diarylamino group, an arylalkylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, A group consisting of an arylthio group, a heteroarylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. These substituents may contain any structure of linear, branched and cyclic.

More specific examples of the substituent group Q include the following structures.
The alkyl group has usually 1 or more carbon atoms, preferably 4 or more carbon atoms, usually 24 or less, preferably 12 or less, more preferably 8 or less, and still more preferably 6 or less. linear, branched or cyclic alkyl groups, preferably methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert- Butyl group, n-hexyl group, cyclohexyl group and dodecyl group.
The alkoxy group includes an alkoxy group having usually 1 or more carbon atoms, usually 24 or less, preferably 12 or less, preferably methoxy or ethoxy.
The aryloxy group and heteroaryloxy group include aryloxy groups and heteroaryloxy groups having usually 4 or more carbon atoms, preferably 5 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, Preferred are phenoxy group, naphthoxy group and pyridyloxy group.
The alkoxycarbonyl group includes an alkoxycarbonyl group having usually 2 or more carbon atoms, usually 24 or less carbon atoms, preferably 12 or less carbon atoms, preferably a methoxycarbonyl group or an ethoxycarbonyl group.
The dialkylamino group includes dialkylamino groups having usually 2 or more carbon atoms, usually 24 or less carbon atoms, preferably 12 or less carbon atoms, preferably dimethylamino group and diethylamino group.
The diarylamino group includes a diarylamino group having usually 10 or more carbon atoms, preferably 12 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, preferably a diphenylamino group or a ditolylamino group. Examples of the arylalkylamino group include arylalkylamino groups having usually 7 carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, preferably phenylmethylamino groups.
The acyl group usually has 2 carbon atoms, usually 24 or less, preferably 12 acyl groups, preferably acetyl group and benzoyl group.
A fluorine atom and a chlorine atom are mentioned as a halogen atom, A fluorine atom is preferable.
The haloalkyl group includes a haloalkyl group having usually 1 or more carbon atoms, usually 12 or less carbon atoms, preferably 6 or less carbon atoms, preferably a trifluoromethyl group.
The alkylthio group includes an alkylthio group having usually 1 or more carbon atoms, usually 24 or less carbon atoms, preferably 12 or less carbon atoms, preferably methylthio group or ethylthio group.
Arylthio groups and heteroarylthio groups include arylthio groups and heteroarylthio groups having usually 4 or more carbon atoms, preferably 5 or more carbon atoms, usually 36 or less carbon atoms, preferably 24 or less carbon atoms, preferably A phenylthio group, a naphthylthio group, and a pyridylthio group can be mentioned.
The silyl group includes silyl groups having usually 2 or more carbon atoms, preferably 3 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, preferably trimethylsilyl and triphenylsilyl groups. .
The siloxy group includes a siloxy group having usually 2 or more carbon atoms, preferably 3 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, preferably a trimethylsiloxy group or a triphenylsiloxy group. be done.
A cyano group is -CN.
The aromatic hydrocarbon group includes an aromatic hydrocarbon group having usually 6 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, preferably a phenyl group or a naphthyl group.
The aromatic heterocyclic group includes an aromatic heterocyclic group having usually 3 or more carbon atoms, preferably 4 or more carbon atoms, usually 36 or less, preferably 24 or less carbon atoms, preferably thienyl group, pyridyl groups.

Among the above substituent group Q, an alkyl group, an alkoxy group, an aromatic hydrocarbon group, or an aromatic heterocyclic group is preferable. From the viewpoint of charge transport properties, the substituent is preferably an aromatic hydrocarbon group or an aromatic heterocyclic group, more preferably an aromatic hydrocarbon group, and further preferably has no substituent. From the viewpoint of improving solubility, it is preferable to have an alkyl group or an alkoxy group as a substituent.

Further, each substituent in the substituent group Q may further have a substituent. Examples of these substituents include the same substituents as those described above (substituent group Q). Each substituent that the substituent of the above substituent group Q may further have is preferably an alkyl group having 8 or less carbon atoms, an alkoxy group having 8 or less carbon atoms, or a phenyl group, more preferably 6 or less carbon atoms. , an alkoxy group having 6 or less carbon atoms, or a phenyl group, and each substituent in the substituent group Q more preferably does not have a further substituent from the viewpoint of charge transport properties.

<Molecular weight>
The molecular weight of the compound of the present invention represented by formula (1) is preferably 3,000 or less, more preferably 2,500 or less, particularly preferably 2,000 or less, and most preferably 1,800 or less. The lower limit of the molecular weight of the compound of the present invention represented by formula (1) is preferably 1080 or more, more preferably 1200 or more.

<Specific examples of the compound of the present invention>
Although the specific structure of the compound of the present invention represented by the formula (1) is not particularly limited, examples thereof include the following compounds.

<Method for producing compound>
The compound of the present invention represented by the above formula (1) can be produced, for example, according to the method described in the Examples below.

[Reason why the compound of the present invention is effective]
In the compound of the present invention represented by the formula (1), the group bonded to the para position of W ₁ and W ₃ is a group in which two or three benzene rings are linked at the para position, so conjugation is extended. LUMO is distributed here, and it is considered that the electron transport property is excellent. In addition, since the number of benzene rings conjugated to the para-positions of W ₁ and W ₃ is 3 or less, the conjugation is not too long and has a wide energy gap when used as a host material for a light-emitting layer. , is considered preferable because it is difficult to quench the light-emitting material.

In the nitrogen-containing 6-membered ring containing W ₁ , W ₂ and W ₃ of the compound of the present invention represented by formula (1), the group bonded to the para position of W ₂ is a 1,3-phenylene group. , is not conjugated, the compound of the present invention represented by the formula (1) has a wide energy gap, and when used as a host material for a light-emitting layer, the light-emitting material is less likely to be quenched, which is considered preferable.

Since at least one of Za ¹ in the compound of the present invention represented by formula (1) is a 1,3-phenylene group, it is not conjugated with Za ² , which is an N-carbazolyl group, and in formula (1) The represented compound of the present invention has a wide energy gap, and when used as a host material for a light-emitting layer, it is considered preferable because the light-emitting material is less likely to be quenched.

Furthermore, when —(Xa ¹ ) _g11 —Xa ² , —(Ya ¹ ) _j11 —Ya ² , —(Za ¹ ) _k11 —Za ² are the preferred structures, they have a wide energy gap and When used as a material, it is difficult to quench light-emitting materials.
In addition, the number of phenylene groups between the N-carbazolyl group and the nitrogen-containing 6-membered ring containing W ₁ , W ₂ and W ₃ is 3 or more, contains a moderately large number of 1,3-phenylene groups, and Since it does not contain a 1,4-phenylene linked structure longer than a phenylene group, it has excellent solubility. On the other hand, since f11+g11+h11+j11+k11 is 6 or more, it is thought that after the film is formed, it is poorly soluble in alcoholic solvents, that is, has solvent resistance. f11+g11+h11+j11+k11 is preferably 7 or more, more preferably 9 or more, and preferably 15 or less from the viewpoint of stability, from the viewpoint of solvent resistance to alcohol-based solvents after film formation.

[Composition]
The composition of the present invention contains at least the compound of the present invention represented by formula (1) and an organic solvent.
The composition of the present invention may contain only one of the compounds of the present invention represented by formula (1), or may contain two or more of them.
The composition of the present invention preferably further contains a light-emitting material, and is suitably used as a composition for forming a light-emitting layer of an organic electroluminescence device.

<Organic solvent>
The organic solvent contained in the composition of the present invention is a volatile liquid component used for forming a layer containing the compound of the present invention by wet film formation.

The organic solvent is not particularly limited as long as it can satisfactorily dissolve the compound of the present invention as a solute and the luminescent material described below.

Preferred organic solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, mesitylene, phenylcyclohexane, tetralin and methylnaphthalene; Halogenated aromatic hydrocarbons such as chlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3 - aromatic ethers such as dimethylanisole, 2,4-dimethylanisole and diphenyl ether; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl p-methylbenzoate (ethyl p-toluate), benzoic acid Aromatic esters such as propyl and n-butyl benzoate; Alicyclic ketones such as cyclohexanone, cyclooctanone and fenchone; Alicyclic alcohols such as cyclohexanol and cyclooctanol; Aliphatic compounds such as methyl ethyl ketone and dibutyl ketone ketones; aliphatic alcohols such as butanol and hexanol; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether and propylene glycol-1-monomethyl ether acetate (PGMEA);

Among these, from the viewpoint of viscosity and boiling point, alkanes, aromatic hydrocarbons, aromatic ethers, and aromatic esters are preferred, and aromatic hydrocarbons, aromatic ethers, and aromatic esters are more preferred. , aromatic hydrocarbons and aromatic esters are particularly preferred.

One type of these organic solvents may be used alone, or two or more types may be used in any combination and ratio.

The boiling point of the organic solvent used is usually 80° C. or higher, preferably 100° C. or higher, more preferably 120° C. or higher, and usually 380° C. or lower, preferably 350° C. or lower, more preferably 330° C. or lower. If the boiling point of the organic solvent is below this range, the film formation stability may decrease due to evaporation of the solvent from the composition during wet film formation. If the boiling point of the organic solvent exceeds this range, there is a possibility that the film formation stability will decrease due to the solvent remaining after film formation during wet film formation.

In particular, by combining two or more organic solvents having a boiling point of 150° C. or higher among the above organic solvents, a uniform coating film can be produced. If the number of organic solvents having a boiling point of 150° C. or higher is one or less, a uniform film may not be formed during coating.

<Luminescent material>
The composition of the present invention is preferably a composition for forming a light-emitting layer, and in this case, it preferably further contains a light-emitting material. A luminescent material refers to a component that mainly emits light in the composition of the present invention, and corresponds to a dopant component in an organic electroluminescent device.

As the light-emitting material, a known material can be applied, and a fluorescent light-emitting material or a phosphorescent light-emitting material can be used singly or in combination. From the viewpoint of internal quantum efficiency, the phosphorescent light-emitting material is preferable.

(Phosphorescent material)
A phosphorescent material is a material that emits light from an excited triplet state. For example, metal complex compounds containing Ir, Pt, Eu, etc. are typical examples, and materials containing metal complexes are preferable as the structure of the material.

Among metal complexes, the long-period periodic table (unless otherwise specified, the long-period periodic table ) include Werner-type complexes or organometallic complex compounds containing a metal selected from Groups 7 to 11 as a central metal. As such a phosphorescent material, a compound represented by the following formula (201) or a compound represented by the following formula (205) is preferable, and a compound represented by the following formula (201) is more preferable. .

In the above formula (201), M is a metal selected from Groups 7 to 11 of the periodic table, such as ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, gold, and europium.

Ring A1 represents an optionally substituted aromatic hydrocarbon ring structure or an optionally substituted aromatic heterocyclic ring structure.
Ring A2 represents an aromatic heterocyclic structure which may have a substituent.

R ²⁰¹ and R ²⁰² each independently represent a structure represented by the above formula (202), and "*" represents the bonding position with ring A1 or ring A2. R ²⁰¹ and R ²⁰² may be the same or different, and when multiple R ²⁰¹ and R ²⁰² are present, they may be the same or different.

In formula (202), Ar ²⁰¹ and Ar ²⁰³ each independently represent an optionally substituted aromatic hydrocarbon ring structure or an optionally substituted aromatic heterocyclic ring structure. .
Ar ²⁰² is an optionally substituted aromatic hydrocarbon ring structure, an optionally substituted aromatic heterocyclic ring structure, or an optionally substituted aliphatic hydrocarbon structure represents
The substituents bonded to ring A1, the substituents bonded to ring A2, or the substituents bonded to ring A1 and the substituents bonded to ring A2 may be bonded to each other to form a ring.

B ²⁰¹ -L ²⁰⁰ -B ²⁰² represents an anionic bidentate ligand. B ²⁰¹ and B ²⁰² each independently represent a carbon atom, an oxygen atom or a nitrogen atom, and these atoms may be atoms constituting a ring. L ²⁰⁰ represents a single bond or an atomic group forming a bidentate ligand together with B ²⁰¹ and B ²⁰² . When there are multiple groups of B ²⁰¹ -L ²⁰⁰ -B ²⁰² , they may be the same or different.

In formulas (201) and (202),
i1 and i2 each independently represent an integer of 0 to 12,
i3 is an integer of 0 or more with an upper limit of the number that can be substituted for Ar ²⁰² ,
j is an integer greater than or equal to 0 up to the number that can be substituted for Ar ²⁰¹ .
k1 and k2 are each independently an integer of 0 or more, with the upper limit being the number that can be substituted on ring A1 and ring A2.
m is an integer of 1-3.

The aromatic hydrocarbon ring for ring A1 is preferably an aromatic hydrocarbon ring having 6 to 30 carbon atoms, and specifically includes a benzene ring, naphthalene ring, anthracene ring, triphenylyl ring, acenaphthene ring, fluoranthene ring, A fluorene ring is preferred.

The aromatic heterocyclic ring in ring A1 is preferably an aromatic heterocyclic ring having 3 to 30 carbon atoms containing any one of a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom, more preferably a furan ring or a benzofuran ring. , thiophene ring, and benzothiophene ring.

Ring A1 is more preferably a benzene ring, a naphthalene ring or a fluorene ring, particularly preferably a benzene ring or a fluorene ring, most preferably a benzene ring.

The aromatic heterocyclic ring in ring A2 is preferably an aromatic heterocyclic ring having 3 to 30 carbon atoms containing either a nitrogen atom, an oxygen atom, or a sulfur atom as a heteroatom,
Specifically, pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, imidazole ring, oxazole ring, thiazole ring, benzothiazole ring, benzoxazole ring, benzimidazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, quinazoline ring, Naphthyridine ring, phenanthridine ring,
more preferably pyridine ring, pyrazine ring, pyrimidine ring, imidazole ring, benzothiazole ring, benzoxazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, quinazoline ring,
More preferred are pyridine ring, imidazole ring, benzothiazole ring, quinoline ring, isoquinoline ring, quinoxaline ring and quinazoline ring,
Most preferred are pyridine ring, imidazole ring, benzothiazole ring, quinoline ring, quinoxaline ring and quinazoline ring.

Preferred combinations of ring A1 and ring A2 are represented by (ring A1-ring A2), (benzene ring-pyridine ring), (benzene ring-quinoline ring), (benzene ring-quinoxaline ring), (benzene ring- quinazoline ring), (benzene ring-imidazole ring), and (benzene ring-benzothiazole ring).

The substituents that the ring A1 and the ring A2 may have can be optionally selected, but are preferably one or more substituents selected from the group S of substituents described below.

When any one of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is an aromatic hydrocarbon ring structure which may have a substituent, the aromatic hydrocarbon ring structure is preferably an aromatic ring structure having 6 to 30 carbon atoms. is a hydrocarbon ring,
Specifically, benzene ring, naphthalene ring, anthracene ring, triphenylyl ring, acenaphthene ring, fluoranthene ring, and fluorene ring are preferred.
more preferably a benzene ring, a naphthalene ring or a fluorene ring,
A benzene ring is most preferred.

When any of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is a fluorene ring optionally having a substituent, the 9- and 9′-positions of the fluorene ring have a substituent or are bonded to the adjacent structure. preferably.

When any one of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is a benzene ring optionally having a substituent, at least one benzene ring is preferably bonded to the adjacent structure at the ortho- or meta-position. , more preferably, at least one benzene ring is attached to the adjacent structure at the meta position.

When any one of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is an aromatic heterocyclic structure which may have a substituent, the aromatic heterocyclic structure preferably contains a nitrogen atom, an oxygen atom, or an aromatic heterocyclic ring having 3 to 30 carbon atoms containing any of a sulfur atom,
Specifically, pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, imidazole ring, oxazole ring, thiazole ring, benzothiazole ring, benzoxazole ring, benzimidazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, quinazoline ring, naphthyridine ring, phenanthridine ring, carbazole ring, dibenzofuran ring, dibenzothiophene ring,
Preferred are pyridine ring, pyrimidine ring, triazine ring, carbazole ring, dibenzofuran ring and dibenzothiophene ring.

When any of Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ is a carbazole ring optionally having a substituent, the N-position of the carbazole ring may have a substituent or be bonded to an adjacent structure. preferable.

When Ar ²⁰² is an optionally substituted aliphatic hydrocarbon structure, the aliphatic hydrocarbon structure is an aliphatic hydrocarbon structure having a linear, branched, or cyclic structure, preferably It is an aliphatic hydrocarbon having 1 or more and 24 or less carbon atoms, more preferably an aliphatic hydrocarbon having 1 or more and 12 or less carbon atoms, and still more preferably an aliphatic hydrocarbon having 1 or more and 8 or less carbon atoms. .

i1 and i2 are each independently an integer of 0 to 12, preferably an integer of 1 to 12, more preferably an integer of 1 to 8, and still more preferably an integer of 1 to 6. Within this range, improved solubility and improved charge transport properties can be expected.

i3 is preferably an integer of 0-5, more preferably an integer of 0-2, still more preferably 0 or 1.

j preferably represents an integer of 0 to 2, more preferably 0 or 1;

k1 and k2 are each independently preferably an integer of 0 to 3, more preferably an integer of 1 to 3, still more preferably 1 or 2, and particularly preferably 1.

The substituents that Ar ²⁰¹ , Ar ²⁰² and Ar ²⁰³ may have can be arbitrarily selected, but are preferably one or more substituents selected from the group S of substituents described later, more preferably hydrogen It is an atom, an alkyl group or an aryl group, particularly preferably a hydrogen atom or an alkyl group, and most preferably unsubstituted (hydrogen atom).

Unless otherwise specified, the substituent is preferably a group selected from the following substituent group S.

<Substituent group S>
- an alkyl group, preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, particularly preferably an alkyl group having 1 to 6 carbon atoms .
- An alkoxy group, preferably an alkoxy group having 1 to 20 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and still more preferably an alkoxy group having 1 to 6 carbon atoms.
- an aryloxy group, preferably an aryloxy group having 6 to 20 carbon atoms, more preferably an aryloxy group having 6 to 14 carbon atoms, still more preferably an aryloxy group having 6 to 12 carbon atoms, particularly preferably an aryloxy group having 6 carbon atoms; aryloxy group.
- A heteroaryloxy group, preferably a heteroaryloxy group having 3 to 20 carbon atoms, more preferably a heteroaryloxy group having 3 to 12 carbon atoms.
- an alkylamino group, preferably an alkylamino group having 1 to 20 carbon atoms, more preferably an alkylamino group having 1 to 12 carbon atoms;
- An arylamino group, preferably an arylamino group having 6 to 36 carbon atoms, more preferably an arylamino group having 6 to 24 carbon atoms.
• an aralkyl group, preferably an aralkyl group having 7 to 40 carbon atoms, more preferably an aralkyl group having 7 to 18 carbon atoms, and still more preferably an aralkyl group having 7 to 12 carbon atoms;
- A heteroaralkyl group, preferably a heteroaralkyl group having 7 to 40 carbon atoms, more preferably a heteroaralkyl group having 7 to 18 carbon atoms.
- an alkenyl group, preferably an alkenyl group having 2 to 20 carbon atoms, more preferably an alkenyl group having 2 to 12 carbon atoms, still more preferably an alkenyl group having 2 to 8 carbon atoms, particularly preferably an alkenyl group having 2 to 6 carbon atoms .
- an alkynyl group, preferably an alkynyl group having 2 to 20 carbon atoms, more preferably an alkynyl group having 2 to 12 carbon atoms;
- An aryl group, preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 24 carbon atoms, still more preferably an aryl group having 6 to 18 carbon atoms, particularly preferably an aryl group having 6 to 14 carbon atoms .
- a heteroaryl group, preferably a heteroaryl group having 3 to 30 carbon atoms, more preferably a heteroaryl group having 3 to 24 carbon atoms, still more preferably a heteroaryl group having 3 to 18 carbon atoms, particularly preferably 3 to 3 carbon atoms 14 heteroaryl groups.
An alkylsilyl group, preferably an alkylsilyl group having 1 to 20 carbon atoms, more preferably an alkylsilyl group having 1 to 12 carbon atoms.
- An arylsilyl group, preferably an arylsilyl group in which the aryl group has 6 to 20 carbon atoms, more preferably an arylsilyl group in which the aryl group has 6 to 14 carbon atoms.
- an alkylcarbonyl group, preferably an alkylcarbonyl group having 2 to 20 carbon atoms;
- an arylcarbonyl group, preferably an arylcarbonyl group having 7 to 20 carbon atoms;
In the above groups, one or more hydrogen atoms may be replaced with fluorine atoms, or one or more hydrogen atoms may be replaced with deuterium atoms.
- A hydrogen atom, a deuterium atom, a fluorine atom, a cyano group, or -SF ₅ .
Unless otherwise specified, aryl groups are aromatic hydrocarbon groups and heteroaryl groups are aromatic heterocyclic groups.

(Preferred Group in Substituent Group S)
Among these substituent group S,
Preferably, an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkylsilyl group, an arylsilyl group, and at least one hydrogen atom of these groups is fluorine. a group substituted with an atom, a fluorine atom, a cyano group, or _-SF5 ,
More preferably, an alkyl group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, a group in which one or more hydrogen atoms of these groups are replaced with a fluorine atom, a fluorine atom, a cyano group, or , −SF ₅ , and
more preferably an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, an aralkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkylsilyl group, an arylsilyl group,
Particularly preferred are alkyl groups, arylamino groups, aralkyl groups, alkenyl groups, aryl groups and heteroaryl groups,
Most preferred are alkyl groups, arylamino groups, aralkyl groups, aryl groups and heteroaryl groups.

These substituent group S may further have a substituent selected from the substituent group S as a substituent. Preferred groups, more preferred groups, further preferred groups, particularly preferred groups, and most preferred groups of the substituents which may be present are the same as the preferred groups in Substituent Group S and the like.

(preferred structure of formula (201))
Among the structures represented by the above formula (202) in the above formula (201), (i) a structure having a group to which a benzene ring is linked, (ii) an alkyl group or an aralkyl group in ring A1 or ring A2 A structure having a bound aromatic hydrocarbon group or aromatic heterocyclic group, and (iii) a structure in which a dendron is bound to ring A1 or ring A2 are preferred.

(i) In the structure having a group to which benzene rings are linked, Ar ²⁰¹ is a benzene ring structure, i1 is 1 to 6, and at least one of the benzene rings is bonded to the adjacent structure at the ortho- or meta-position. are doing.
This structure is expected to improve the solubility and the charge transport property.

(ii) In a structure having an aromatic hydrocarbon group or aromatic heterocyclic group to which an alkyl group or an aralkyl group is bonded to ring A1 or ring A2, Ar ²⁰¹ is an aromatic hydrocarbon structure or an aromatic heterocyclic ring structure. , i1 is 1 to 6, Ar ²⁰² is an aliphatic hydrocarbon structure, i2 is 1 to 12, preferably 3 to 8, Ar ²⁰³ is a benzene ring structure, i3 is 0 or 1.
In this structure, Ar ²⁰¹ is preferably the above aromatic hydrocarbon structure, more preferably a structure in which 1 to 5 benzene rings are linked, and more preferably one benzene ring.
This structure is expected to improve the solubility and the charge transport property.

(iii) In the structure in which a dendron is bound to ring A1 or ring A2, Ar ²⁰¹ and Ar ²⁰² are a benzene ring structure, Ar ²⁰³ is a biphenyl or terphenyl structure, and i1 and i2 are 1 to 6. , i3 is 2 and j is 2.
This structure is expected to improve the solubility and the charge transport property.

Among the structures represented by B ²⁰¹ -L ²⁰⁰ -B ²⁰² in the formula (201), structures represented by the following formulas (203) and (204) are preferable.

In formula (203) above, R ²¹¹ , R ²¹² and R ²¹³ represent substituents.
Although the substituent is not particularly limited, it is preferably a group selected from the substituent group S described above.

In formula (204) above, ring B3 represents an aromatic heterocyclic structure containing a nitrogen atom, which may have a substituent. Ring B3 is preferably a pyridine ring.
Although the substituent that ring B3 may have is not particularly limited, it is preferably a group selected from the substituent group S described above.

Although the phosphorescent light-emitting material represented by the formula (201) is not particularly limited, specific examples include the following structures.
In the following, Me means a methyl group and Ph means a phenyl group.

Next, the compound represented by the following formula (205) will be explained.

In formula (205), ^M2 represents a metal and T represents a carbon or nitrogen atom. R ⁹² to R ⁹⁵ each independently represent a substituent. However, when T is a nitrogen atom, ^R94 and ^R95 do not exist.

In formula (205), ^M2 represents a metal. Specific examples include metals selected from groups 7 to 11 of the periodic table. Among them, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum and gold are preferred, and divalent metals such as platinum and palladium are particularly preferred.

In formula (205), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group;

Furthermore, when T is a carbon atom, ^R94 and ^R95 each independently represent a substituent represented by the same examples as ^R92 and ^R93 . Also, when T is a nitrogen atom, there is no ^R94 or ^R95 directly bonded to said T.

In addition, R ⁹² to R ⁹⁵ may further have a substituent. The substituents may be the aforementioned substituents exemplified for R ⁹² and R ⁹³ . Furthermore, any two or more groups selected from R ⁹² to R ⁹⁵ may be linked together to form a ring.

(molecular weight)
The molecular weight of the phosphorescent material is preferably 5,000 or less, more preferably 4,000 or less, and particularly preferably 3,000 or less. Further, the molecular weight of the phosphorescent material is usually 1000 or more, preferably 1100 or more, more preferably 1200 or more. It is believed that within this molecular weight range, the phosphorescent light-emitting materials do not aggregate with each other and are uniformly mixed with the compound of the present invention and/or other charge-transporting materials, so that a light-emitting layer with high light-emitting efficiency can be obtained.

The molecular weight of the phosphorescent light-emitting material has a high Tg, melting point, decomposition temperature, etc., and the phosphorescent light-emitting material and the formed light-emitting layer have excellent heat resistance, and the film quality due to gas generation, recrystallization, molecular migration, etc. A large value is preferable from the viewpoint that it is difficult to cause a decrease in the concentration of impurities and an increase in the concentration of impurities due to thermal decomposition of the material. On the other hand, the molecular weight of the phosphorescent light-emitting material is preferably small in terms of facilitating purification of the organic compound.

<Charge transport material>
When the composition of the present invention is a composition for forming a light-emitting layer, it preferably contains a charge-transporting material as an additional host material.

The charge-transporting material used as the host material of the light-emitting layer is a material having a skeleton with excellent charge-transporting properties, and is composed of an electron-transporting material, a hole-transporting material, and a bipolar material capable of transporting both electrons and holes. preferably selected.

Specific examples of skeletons with excellent charge transport properties include aromatic structures, aromatic amine structures, triarylamine structures, dibenzofuran structures, naphthalene structures, phenanthrene structures, phthalocyanine structures, porphyrin structures, thiophene structures, benzylphenyl structures, fluorene structure, quinacridone structure, triphenylene structure, carbazole structure, pyrene structure, anthracene structure, phenanthroline structure, quinoline structure, pyridine structure, pyrimidine structure, triazine structure, oxadiazole structure, imidazole structure, and the like.

Since the compound of the present invention represented by the formula (1) functions as an electron-transporting material, the composition of the present invention preferably further contains a hole-transporting material as a charge-transporting material. A hole-transporting material is a compound having a structure with excellent hole-transporting properties, and among the skeletons with excellent charge-transporting properties, a carbazole structure, a dibenzofuran structure, a triarylamine structure, a naphthalene structure, a phenanthrene structure, or a pyrene structure. is preferable as a structure having excellent hole-transporting properties, and a carbazole structure, a dibenzofuran structure, or a triarylamine structure is more preferable.

The charge-transporting material used as the host material of the light-emitting layer is preferably a compound having a condensed ring structure of three or more rings, and at least a compound having two or more condensed ring structures of three or more rings or a condensed ring of five or more rings. Compounds having one are more preferred. These compounds increase the rigidity of the molecules, making it easier to obtain the effect of suppressing the degree of molecular motion in response to heat. Furthermore, the 3 or more condensed rings and the 5 or more condensed rings preferably have an aromatic hydrocarbon ring or an aromatic heterocyclic ring from the viewpoint of charge transportability and material durability.

Specific examples of condensed ring structures having three or more rings include anthracene structure, phenanthrene structure, pyrene structure, chrysene structure, naphthacene structure, triphenylene structure, fluorene structure, benzofluorene structure, indenofluorene structure, indolofluorene structure, Carbazole structure, indenocarbazole structure, indolocarbazole structure, dibenzofuran structure, dibenzothiophene structure and the like.
At least one selected from the group consisting of a phenanthrene structure, a fluorene structure, an indenofluorene structure, a carbazole structure, an indenocarbazole structure, an indolocarbazole structure, a dibenzofuran structure, and a dibenzothiophene structure, from the viewpoints of charge transportability and solubility. A carbazole structure or an indolocarbazole structure is more preferred from the viewpoint of resistance to electric charge.

The charge-transporting material used as the host material of the light-emitting layer is preferably a polymeric material from the viewpoint of excellent flexibility. A light-emitting layer formed using a material having excellent flexibility is preferable as a light-emitting layer of an organic electroluminescent device formed on a flexible substrate. When the charge-transporting material used as the host material contained in the light-emitting layer is a polymeric material, the molecular weight is preferably 5,000 or more and 1,000,000 or less, more preferably 10,000 or more and 500,000 or less, It is more preferably 10,000 or more and 100,000 or less.

In addition, the charge transport material used as the host material of the light-emitting layer is easy to synthesize and purify, easy to design the electron transport performance and hole transport performance, and easy to adjust the viscosity when dissolved in an organic solvent. It is preferably a low-molecular-weight compound from the viewpoint of flexibility. When the charge-transporting material used as the host material contained in the light-emitting layer is a low-molecular-weight material, the molecular weight is preferably 5,000 or less, more preferably 4,000 or less, and particularly preferably 3,000 or less. , most preferably 2,000 or less, usually 800 or more, preferably 900 or more, and preferably 1000 or more when the layer formed in contact with the light emitting layer is formed by a wet film formation method. , more preferably 1100 or more, and particularly preferably 1200 or more.

<Other ingredients>
The composition of the present invention may optionally contain various other solvents in addition to the organic solvent and light-emitting material described above. Examples of such other solvents include amides such as N,N-dimethylformamide and N,N-dimethylacetamide, and dimethylsulfoxide.

Moreover, the composition of the present invention may contain various additives such as a leveling agent and an antifoaming agent.
Furthermore, when laminating two or more layers by a wet film formation method, in order to prevent these layers from becoming compatible, a photocurable resin or a thermosetting resin is used for the purpose of curing and insolubilizing after film formation. can also be included.

<Blending ratio>
Solid content concentration in the composition of the present invention (compound of the present invention, luminescent material, host material other than the compound of the present invention, and optionally additive components (leveling agent, etc.) Concentration of all solids ) is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.5% by mass or more, and most preferably 1% by mass or more, It is usually 80% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and most preferably 20% by mass or less.
When the solid content concentration is within this range, it is easy to form a thin film having a desired film thickness with a uniform thickness, which is preferable.

A preferred compounding ratio of the compound of the present invention and the light-emitting material to all the host materials contained in the composition of the present invention, that is, a light-emitting layer formed using the composition of the present invention (hereinafter referred to as the "light-emitting layer of the present invention") A preferred compounding ratio of the compound of the invention and the light-emitting material to the total host material contained in the compound is as follows. All host materials refer to the compounds of the present invention and all host materials other than the compounds of the present invention.

In the composition of the present invention and the light-emitting layer of the present invention, the mass ratio of the compound of the present invention to 100 mass of all host materials is usually 5 or more, preferably 10 or more, more preferably 15 or more, and usually 99 or less. It is preferably 95 or less, more preferably 90 or less, still more preferably 80 or less, and particularly preferably 70 or less.

In addition, in the composition of the present invention and the light emitting layer of the present invention, the molar ratio of the compound of the present invention to the total host material is usually 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, and still more preferably. is 25 mol% or more, particularly preferably 30 mol% or more, and usually 90 mol% or less, preferably 80 mol% or less, more preferably 70 mol% or less, and particularly preferably 60 mol% or less.

In the composition of the present invention and the light-emitting layer of the present invention, the mass ratio of the light-emitting material to 100 of the mass of all the host materials is usually 0.1 or more, preferably 0.5 or more, more preferably 1 or more, and particularly preferably 2. It is 100 or less, preferably 60 or less, more preferably 50 or less, and particularly preferably 40 or less. If this ratio falls below the above lower limit or exceeds the above upper limit, the luminous efficiency may significantly decrease.

<Method for preparing composition>
The composition of the present invention comprises the compound of the present invention, if necessary the light-emitting material described above and a host material other than the compound of the present invention, and various additive components such as a leveling agent and an antifoaming agent that can be added as necessary. It is prepared by dissolving the solute in a suitable organic solvent as described above.

In order to shorten the time required for this dissolving step and to keep the solute concentration in the composition of the present invention uniform, the solute is usually dissolved while stirring the liquid. The dissolution step may be performed at room temperature, but if the dissolution rate is slow, the dissolution may be performed by heating. After completion of the dissolving step, a filtering step such as filtering may be performed as necessary.

<Characteristics, physical properties, etc. of the composition>
(moisture concentration)
When an organic electroluminescence device is produced by forming layers by a wet film-forming method using the composition of the present invention, if water is present in the composition, the formed film will be contaminated with water, resulting in poor film uniformity. It is preferred that the water content in the compositions of the present invention is as low as possible, as this impairs the In general, organic electroluminescence devices use many materials such as cathodes that are significantly deteriorated by moisture. Possibility of deteriorating the characteristics is considered, which is not preferable.

Specifically, the amount of water contained in the composition of the present invention is usually 1% by mass or less, preferably 0.1% by mass or less, and more preferably 0.01% by mass or less.

As a method for measuring the water concentration in the composition, the method described in Japanese Industrial Standards "Method for Determining Moisture in Chemical Products" (JIS K0068: 2001) is preferable, for example, by the Karl Fischer reagent method (JIS K0211-1348). can be analyzed.

(uniformity)
The composition of the present invention is preferably in a uniform liquid state at room temperature in order to improve stability in a wet film formation process, for example, ejection stability from a nozzle in an inkjet film formation method. The uniform liquid state at normal temperature means that the composition is a liquid consisting of a uniform phase and does not contain a particle component having a particle size of 0.1 μm or more in the composition.

(physical properties)
When the viscosity of the composition of the present invention is extremely low, for example, excessive liquid film flow in the film formation process tends to cause non-uniformity of the coated surface, nozzle discharge failure in ink jet film formation, and the like. If the viscosity of the composition of the present invention is extremely high, nozzle clogging and the like tend to occur during inkjet film formation.
Therefore, the viscosity of the composition of the present invention at 25° C. is usually 2 mPa·s or more, preferably 3 mPa·s or more, more preferably 5 mPa·s or more, and usually 1000 mPa·s or less, preferably 100 mPa·s or less. , more preferably 50 mPa·s or less.

In addition, when the surface tension of the composition of the present invention is high, problems such as a decrease in wettability with respect to the substrate, poor leveling of the liquid film, and susceptibility to disturbance of the film formation surface during drying may occur. be.
Therefore, the surface tension at 20° C. of the composition of the invention is usually less than 50 mN/m, preferably less than 40 mN/m.

Furthermore, when the vapor pressure of the composition of the present invention is high, problems such as a change in solute concentration due to evaporation of the organic solvent may easily occur.
Therefore, the vapor pressure at 25° C. of the composition of the present invention is usually 50 mmHg or less, preferably 10 mmHg or less, more preferably 1 mmHg or less.

[Thin film formation method]
The film forming method using the composition of the present invention in the thin film forming method of the present invention is a wet film forming method.
The wet film-forming method is a method in which a composition is applied to form a liquid film, dried to remove the organic solvent, and a film is formed. If the composition of the present invention contains a light-emitting material, the light-emitting layer can be formed by this method.
Examples of coating methods include spin coating, dip coating, die coating, bar coating, blade coating, roll coating, spray coating, capillary coating, inkjet, nozzle printing, screen printing, and gravure. A wet film-forming method such as a printing method or a flexographic printing method is employed, and the coating film is dried to form a film. Among these film forming methods, the spin coating method, the spray coating method, the inkjet method, the nozzle printing method, and the like are preferable. When manufacturing an organic EL display device having an organic electroluminescence element, an inkjet method or a nozzle printing method is preferable, and an inkjet method is particularly preferable.

Although the drying method is not particularly limited, natural drying, drying under reduced pressure, drying by heating, or drying under reduced pressure while heating can be used as appropriate. Heat drying may be carried out in order to further remove residual organic solvents after natural drying or vacuum drying.
In drying under reduced pressure, it is preferable to reduce the pressure below the vapor pressure of the organic solvent contained in the composition of the present invention.
When drying by heating, the heating method is not particularly limited, but heating with a hot plate, heating in an oven, infrared heating, or the like can be used.
The heating temperature is usually 80° C. or higher, preferably 100° C. or higher, more preferably 110° C. or higher, and preferably 200° C. or lower, more preferably 150° C. or lower.
The heating time is generally 1 minute or longer, preferably 2 minutes or longer, generally 60 minutes or shorter, preferably 30 minutes or shorter, and more preferably 20 minutes or shorter.

As will be described later, in the organic electroluminescent device, an electron transport layer is formed on the light emitting layer. In the present invention, it is preferred that the composition of the present invention is used to form a light-emitting layer by a wet film-forming method, and a layer such as an electron transport layer is formed in contact with the light-emitting layer by a wet film-forming method.
The composition for forming an electron transport layer, which is used when the electron transport layer is formed in contact with the light-emitting layer by a wet film-forming method, contains at least an electron transport layer material and an organic solvent. As the organic solvent for the electron-transporting layer-forming composition, an alcohol-based solvent (a solvent having an alcoholic hydroxyl group) is preferable because the compound of the present invention is sparingly soluble and has excellent solvent resistance. As the electron transport layer material of the electron transport layer-forming composition, an electron transport material soluble in such an alcohol-based solvent is preferable.
The alcohol-based solvent used as the solvent for the electron-transporting layer-forming composition has 6 or more carbon atoms because it easily dissolves the electron-transporting material, has a moderately high boiling point, and is easy to form a flat film. Alkyl alcohols of are preferred.

As for the method for forming the electron transport layer by the wet film forming method, it is preferable to use the wet film forming method described in the method for forming the light emitting layer.

[Organic electroluminescent device]
As an example of the structure of the organic electroluminescence device of the present invention, FIG. 1 shows a schematic diagram (cross section) of a structural example of the organic electroluminescence device 8 . In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer, 6 is an electron transport layer, and 7 is a cathode.

<Substrate>
The substrate 1 serves as a support for the organic electroluminescence element, and is usually made of a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Among these, glass plates and transparent synthetic resin plates such as polyester, polymethacrylate, polycarbonate and polysulfone are preferred. The substrate is preferably made of a material having a high gas barrier property because deterioration of the organic electroluminescence element due to outside air is unlikely to occur. Therefore, especially when using a material having low gas barrier properties such as a synthetic resin substrate, it is preferable to provide a dense silicon oxide film or the like on at least one side of the substrate to improve the gas barrier properties.

<Anode>
The anode 2 has the function of injecting holes into the layer on the light-emitting layer 5 side.

Anode 2 is typically made of metals such as aluminum, gold, silver, nickel, palladium, platinum; metal oxides such as indium and/or tin oxide; metal halides such as copper iodide; carbon black and poly(3 -methylthiophene), polypyrrole, and polyaniline.

The anode 2 is usually formed by a dry method such as a sputtering method or a vacuum deposition method. In addition, when the anode is formed using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., an appropriate binder resin solution may be used. It can also be formed by dispersing and coating on a substrate. In the case of a conductive polymer, a thin film can be formed directly on a substrate by electrolytic polymerization, or an anode can be formed by coating a conductive polymer on a substrate (Appl. Phys. Lett., 60 2711, 1992).

The anode 2 usually has a single-layer structure, but may have a laminated structure as appropriate. When the anode 2 has a laminated structure, different conductive materials may be laminated on the first layer of the anode.

The thickness of the anode 2 may be determined according to the required transparency and material. When particularly high transparency is required, the thickness is preferably such that the visible light transmittance is 60% or more, and more preferably the thickness is such that the visible light transmittance is 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. On the other hand, when transparency is not required, the thickness of the anode 2 may be arbitrarily set according to the required strength, etc. In this case, the thickness of the anode 2 may be the same as that of the substrate.

When another layer is formed on the surface of the anode 2, the impurity on the anode 2 is removed and its ionization potential is changed by treating with ultraviolet rays/ozone, oxygen plasma, argon plasma, etc. before the film formation. is preferably adjusted to improve the hole injection property.

<Hole injection layer>
A layer that functions to transport holes from the anode 2 side to the light emitting layer 5 side is usually called a hole injection transport layer or a hole transport layer. When there are two or more layers that have a function of transporting holes from the anode 2 side to the light emitting layer 5 side, the layer closer to the anode 2 side may be called the hole injection layer 3 . The hole injection layer 3 is preferably formed in order to enhance the function of transporting holes from the anode 2 to the light emitting layer 5 side. When forming the hole injection layer 3 , the hole injection layer 3 is usually formed on the anode 2 .

The film thickness of the hole injection layer 3 is usually 1 nm or more, preferably 5 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

A method for forming the hole injection layer may be a vacuum deposition method or a wet film formation method. From the viewpoint of excellent film-forming properties, it is preferable to form the film by a wet film-forming method.

A general method for forming a hole injection layer will be described below. It is preferably formed by a method.

The composition for forming a hole injection layer usually contains a hole transporting compound for a hole injection layer which will become the hole injection layer 3 . In the case of the wet film-forming method, the hole injection layer-forming composition usually further contains an organic solvent. It is preferable that the composition for forming a hole injection layer has a high hole-transporting property and can efficiently transport the injected holes. For this reason, it is preferable that the hole mobility is large and that impurities that become traps are less likely to occur during manufacture or use. Moreover, it is preferable that it has excellent stability, a small ionization potential, and a high transparency to visible light. In particular, when the hole injection layer is in contact with the light-emitting layer, it is preferable to use a material that does not quench light emitted from the light-emitting layer or that forms an exciplex with the light-emitting layer so as not to lower the light emission efficiency.

As the hole-transporting compound for the hole-injection layer, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable from the viewpoint of a charge injection barrier from the anode to the hole-injection layer. Examples of such hole-transporting compounds include aromatic amine-based compounds, phthalocyanine-based compounds, porphyrin-based compounds, oligothiophene-based compounds, polythiophene-based compounds, benzylphenyl-based compounds, and tertiary amines linked with fluorene groups. compounds, hydrazone-based compounds, silazane-based compounds, quinacridone-based compounds, and the like.

Among the exemplified compounds described above, aromatic amine compounds are preferred, and aromatic tertiary amine compounds are particularly preferred, from the viewpoints of amorphousness and visible light transmittance. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.

The type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of easily obtaining uniform light emission due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1000 or more and 1000000 or less (polymeric compound in which repeating units are linked) ) is preferably used.

When the hole injection layer 3 is formed by a wet film-forming method, the film-forming composition (positive A composition for forming a hole injection layer) is prepared. Then, the hole injection layer 3 is formed by applying this composition for forming a hole injection layer onto a layer corresponding to the lower layer of the hole injection layer 3 (usually, the anode 2) to form a film, followed by drying. do.

The concentration of the hole-transporting compound in the hole-injection layer-forming composition is arbitrary as long as it does not significantly impair the effects of the present invention. , a higher value is preferable from the viewpoint that defects are less likely to occur in the hole injection layer 3 . Specifically, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly preferably 0.5% by mass or more. It is preferably 60% by mass or less, and particularly preferably 50% by mass or less.

Examples of organic solvents include ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, and amide-based solvents.

Examples of ether-based solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole. , phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole and 2,4-dimethylanisole.

Examples of ester solvents include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate and n-butyl benzoate.

Examples of aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. be done.

Examples of amide solvents include N,N-dimethylformamide and N,N-dimethylacetamide.

In addition to these, dimethyl sulfoxide and the like can also be used.

Formation of the hole injection layer 3 by a wet film-forming method is usually carried out by preparing a composition for forming a hole injection layer and then applying it on a layer corresponding to the lower layer of the hole injection layer 3 (usually the anode 2). It is carried out by coating and forming a film on the surface and drying it.

After forming the hole injection layer 3, the coating film is usually dried by heating, drying under reduced pressure, or the like.

When the hole injection layer 3 is formed by a vacuum deposition method, one or more of the constituent materials of the hole injection layer 3 are usually placed in a crucible placed in a vacuum vessel (two or more materials are placed in separate crucibles), and the inside of the vacuum chamber is evacuated to about 10 ⁻⁴ Pa by a vacuum pump. After that, the crucible is heated (usually each crucible is heated when two or more materials are used) to evaporate while controlling the amount of evaporation of the material in the crucible (when two or more materials are used, usually evaporate while independently controlling the amount of evaporation) to form a hole injection layer 3 on the anode 2 on the substrate 1 placed facing the crucible. When using two or more kinds of materials, the hole injection layer 3 can also be formed by putting a mixture of them in a crucible, heating and evaporating them.

The degree of vacuum during vapor deposition ^is not limited as long as ^it does not significantly impair the effects ^of the present invention. 12.0×10 ⁻⁴ Pa) or less. The vapor deposition rate is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1 Å/second or more and 5.0 Å/second or less. The film formation temperature during vapor deposition is not limited as long as the effects of the present invention are not significantly impaired, but is preferably 10° C. or higher and 50° C. or lower.

The hole injection layer 3 may be crosslinked in the same manner as the hole transport layer 4 described below.

<Hole transport layer>
The hole transport layer 4 is a layer that functions to transport holes from the anode 2 side to the light emitting layer 5 side. The hole transport layer 4 is not an essential layer in the organic electroluminescent device of the present invention, but it is preferable to form this layer in terms of enhancing the function of transporting holes from the anode 2 to the light emitting layer 5. . When forming the hole transport layer 4 , the hole transport layer 4 is usually formed between the anode 2 and the light emitting layer 5 . Further, when the hole injection layer 3 described above is present, it is formed between the hole injection layer 3 and the light emitting layer 5 .

A material for forming the hole transport layer 4 is preferably a material that has a high hole transport property and can efficiently transport the injected holes. Therefore, it is preferable that the ionization potential is low, the transparency to visible light is high, the hole mobility is high, the stability is excellent, and impurities that act as traps are less likely to occur during manufacture or use. In many cases, since the hole transport layer 4 is in contact with the light emitting layer 5, it does not quench the light emitted from the light emitting layer 5 or form an exciplex with the light emitting layer 5 to reduce the efficiency. is preferred.

The material for such a hole transport layer 4 may be any material that is conventionally used as a constituent material for a hole transport layer. Examples of compounds include those exemplified. Also, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatic group derivatives, metal complexes, and the like.

Materials for the hole transport layer 4 include, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, and polyarylene vinylene. derivatives, polysiloxane derivatives, polythiophene derivatives, poly(p-phenylene vinylene) derivatives and the like. These may be alternating copolymers, random polymers, block polymers or graft copolymers. Also, a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer may be used.

Among them, polyarylamine derivatives and polyarylene derivatives are preferred.
As the polyarylamine derivative, a polymer containing a repeating unit represented by the following formula (II) is preferred. In particular, a polymer composed of repeating units represented by the following formula (II) is preferable, and in this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In formula (II), Ar ^a and Ar ^b each independently represent an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group .)

Examples of polyarylene derivatives include polymers having arylene groups such as optionally substituted aromatic hydrocarbon groups or optionally substituted aromatic heterocyclic groups in their repeating units. .

As the polyarylene derivative, a polymer having repeating units represented by the following formula (III-1) and/or the following formula (III-2) is preferable.

(In formula (III-1), R ^a , R ^b , R ^c and R ^d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group or a carboxy group, and t and s each independently represents an integer of 0 to 3. When t or s is 2 or more, a plurality of groups contained in one molecule may be ^the same or different, and adjacent Ra ^{or Rb} may form a ring. ⁾

(In formula (III-2), R ^e and R ^f are each independently synonymous with R ^a , R ^b , R ^c or R ^d in formula (III-1) above. r and u are each independently represents an integer of 0 to 3. When r or u is 2 or more, a plurality of R ^e and R ^f contained in one molecule may be the same or different, and adjacent R ^e or R ^f may form a ring together, and X represents an atom or a group of atoms constituting a 5- or 6-membered ring.)

Specific examples of X include an oxygen atom, an optionally substituted boron atom, an optionally substituted nitrogen atom, an optionally substituted silicon atom, and an optionally substituted an optionally substituted phosphorus atom, an optionally substituted sulfur atom, an optionally substituted carbon atom, or a group formed by combining these atoms.

Further, the polyarylene derivative has a repeating unit represented by the following formula (III-3) in addition to the repeating unit represented by the above formula (III-1) and/or the above formula (III-2). is preferred.

(In formula (III-3), Ar ^c to Ar ⁱ each independently represent an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group; and v and w each independently represent 0 or 1.)

Specific examples of the above formulas (III-1) to (III-3) and specific examples of the polyarylene derivative include those described in JP-A-2008-98619.

When the hole transport layer 4 is formed by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as in the formation of the hole injection layer 3, and after wet film formation, heat drying is performed. .

The hole-transporting layer-forming composition contains an organic solvent in addition to the hole-transporting compound described above. The organic solvent to be used is the same as that used for the composition for forming the hole injection layer. Further, the film formation conditions, heat drying conditions, etc. are the same as in the case of forming the hole injection layer 3 .

When the hole transport layer 4 is formed by the vacuum vapor deposition method, the film forming conditions and the like are the same as those for forming the hole injection layer 3 described above.

The hole-transporting layer 4 may contain various light-emitting materials, electron-transporting compounds, binder resins, coatability improvers, etc., in addition to the hole-transporting compounds described above. Therefore, the composition for forming a hole transport layer may contain various luminescent materials, electron transport compounds, binder resins, coatability improvers, etc., in addition to the above hole transport compounds.

Further, the hole transport layer 4 may be a layer formed by cross-linking a cross-linking compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.

Examples of crosslinkable groups include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acryl, methacryloyl, and cinnamoyl; Examples thereof include groups derived from cyclobutene.

The crosslinkable compound may be a monomer, oligomer, or polymer. The crosslinkable compound may have only one type, or may have two or more types in any combination and ratio.

A hole-transporting compound having a crosslinkable group is preferably used as the crosslinkable compound.
Examples of the hole-transporting compound of the hole-transporting compound having a crosslinkable group include those exemplified above. or those bound to side chains. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole-transporting compound is preferably a polymer containing a repeating unit having a crosslinkable group, and is represented by the above formula (II) or formulas (III-1) to (III-3). It is preferably a polymer having repeating units in which a crosslinkable group is bonded directly or via a linking group to the repeating units.

In order to form the hole transport layer 4 by cross-linking a cross-linking compound, a composition for forming a hole transport layer is usually prepared by dissolving or dispersing a cross-linking compound in an organic solvent, and the composition is formed by a wet film forming method. Film and crosslink.

The thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

<Light emitting layer>
The light-emitting layer 5 is a layer that functions to emit light by being excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 7 when an electric field is applied between a pair of electrodes. .
The light-emitting layer 5 is a layer formed between the anode 2 and the cathode 7, and the light-emitting layer 5 is formed between the hole-injection layer 3 and the cathode 7 when the hole-injection layer 3 is on the anode 2. and between the hole-transport layer 4 and the cathode 7, if there is a hole-transport layer 4 on the anode 2;

The light-emitting layer 5 contains at least a material having light-emitting properties (light-emitting material) and preferably contains one or more host materials.
As described above, the light-emitting layer 5 of the organic electroluminescent device of the present invention is formed from the composition of the present invention by a wet film-forming method, and preferably contains the compound of the present invention and a light-emitting material.

The film thickness of the light-emitting layer 5 is arbitrary as long as it does not significantly impair the effects of the present invention, but a thicker film is preferable because defects are less likely to occur in the film. Therefore, the film thickness of the light-emitting layer 5 is preferably 3 nm or more, more preferably 5 nm or more, and is preferably 200 nm or less, more preferably 100 nm or less.

<Hole blocking layer>
A hole blocking layer may be provided between the light emitting layer 5 and the electron injection layer 6 described below. The hole-blocking layer is a layer laminated on the light-emitting layer 5 so as to be in contact with the interface of the light-emitting layer 5 on the cathode 7 side.

This hole-blocking layer has the role of blocking holes moving from the anode 2 from reaching the cathode 7 and the role of efficiently transporting electrons injected from the cathode 7 toward the light-emitting layer 5. have. Physical properties required for the material constituting the hole blocking layer include high electron mobility and low hole mobility, a large energy gap (difference between HOMO and LUMO), and an excited triplet level (T ₁ ). is high.

Examples of materials for the hole blocking layer that satisfy these conditions include bis(2-methyl-8-quinolinolato)(phenolato)aluminum and bis(2-methyl-8-quinolinolato)(triphenylsilanolate)aluminum. mixed ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives and the like Styryl compounds (JP-A-11-242996), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (JP-A-11-242996) 7-41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), and the like. Furthermore, the compound having at least one pyridine ring substituted at the 2,4,6 positions described in WO 2005/022962 is also preferable as a material for the hole blocking layer.

There are no restrictions on the method of forming the hole blocking layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

The thickness of the hole-blocking layer is arbitrary as long as it does not significantly impair the effects of the present invention. .

<Electron transport layer>
The electron transport layer 6 is provided between the light emitting layer 5 and the cathode 7 for the purpose of further improving the current efficiency of the device.

The electron transport layer 6 is formed of a compound capable of efficiently transporting electrons injected from the cathode 7 toward the light-emitting layer 5 between electrodes to which an electric field is applied. The electron-transporting compound used in the electron-transporting layer 6 is a compound that has high electron injection efficiency from the cathode 7, high electron mobility, and can efficiently transport the injected electrons. is necessary.

Specific examples of the electron-transporting compound used in the electron-transporting layer 6 include a metal complex such as an aluminum complex of 8-hydroxyquinoline (JP-A-59-194393) and a metal of 10-hydroxybenzo[h]quinoline. complexes, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948) book), quinoxaline compound (JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinone diimine, n-type hydrogen amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, and the like.

The electron transport layer 6 is formed on the hole blocking layer by a wet film forming method or a vacuum vapor deposition method in the same manner as described above. A vacuum deposition method is usually used, but in the present invention, as described above, the electron transport layer 6 can be formed on the light-emitting layer containing the compound of the present invention by a wet film-forming method.

The film thickness of the electron transport layer 6 is usually 1 nm or more, preferably 5 nm or more, and is usually 300 nm or less, preferably 100 nm or less.

<Electron injection layer>
An electron injection layer may be provided between the electron transport layer 6 and the cathode 7 in order to efficiently inject electrons injected from the cathode 7 into the electron transport layer 6 or the light emitting layer 5 .

In order to efficiently inject electrons, the material forming the electron injection layer is preferably a metal with a low work function. Examples thereof include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the like.
The film thickness of the electron injection layer is preferably 0.1 nm or more and 5 nm or less.

Furthermore, an organic electron-transporting material typified by a nitrogen-containing heterocyclic compound such as bathophenanthroline or a metal complex such as an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium or rubidium ( JP-A-10-270171, JP-A-2002-100478, JP-A-2002-100482, etc.) also improves the electron injection and transport properties and makes it possible to achieve both excellent film quality. preferable.
In this case, the thickness of the electron injection layer is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

The electron injection layer is formed by laminating the light emitting layer 5 or the hole blocking layer or the electron transport layer 6 thereon by a wet film forming method or a vacuum deposition method.
The details of the wet film formation method are the same as those of the light-emitting layer described above.

In some cases, the hole-blocking layer, the electron-transporting layer, and the electron-injecting layer are formed into a single layer by co-doping the electron-transporting material and the lithium complex.

<Cathode>
The cathode 7 plays a role of injecting electrons into a layer (an electron injection layer, a light-emitting layer, or the like) on the light-emitting layer 5 side.

As the material of the cathode 7, it is possible to use the material used for the anode 2, but in terms of efficient electron injection, it is preferable to use a metal with a low work function, such as tin or magnesium. , indium, calcium, aluminum, and silver, or alloys thereof. Specific examples include low work function alloy electrodes such as magnesium-silver alloys, magnesium-indium alloys, and aluminum-lithium alloys.

From the viewpoint of the stability of the organic electroluminescence device, it is preferable to protect the cathode made of a metal with a low work function by stacking a metal layer that has a high work function and is stable against the atmosphere on the cathode. Metals to be laminated include, for example, metals such as aluminum, silver, copper, nickel, chromium, gold, and platinum.

The film thickness of the cathode is generally similar to that of the anode.

<Other layers>
The organic electroluminescence device of the present invention may further have other layers as long as they do not significantly impair the effects of the present invention. That is, it may have any of the other layers described above between the anode and cathode.

<Other device configurations>
The organic electroluminescence device of the present invention has a structure opposite to that described above. It is also possible to laminate the injection layer and the anode in this order.

When the organic electroluminescent element of the present invention is applied to an organic electroluminescent device, it may be used as a single organic electroluminescent element or may be used in a configuration in which a plurality of organic electroluminescent elements are arranged in an array. A configuration in which anodes and cathodes are arranged in an XY matrix may also be used.

[Display device]
The display device of the present invention (organic electroluminescent element display device: organic EL display device) comprises the organic electroluminescent element of the present invention. The type and structure of the organic EL display device of the present invention are not particularly limited, and the organic electroluminescence device of the present invention can be assembled according to a conventional method.

For example, the organic EL display device of the present invention can be manufactured by the method described in "Organic EL Display" (Ohmsha, August 20, 2004, by Shizuo Tokito, Chihaya Adachi, and Hideyuki Murata). can be formed.

[Lighting device]
The lighting device of the present invention (organic electroluminescent element lighting device: organic EL lighting device) includes the organic electroluminescent element of the present invention. There are no particular restrictions on the type and structure of the organic EL lighting device of the present invention, and it can be assembled according to a conventional method using the organic electroluminescence device of the present invention.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Various conditions and values of evaluation results in the following examples have the meaning of preferable upper or lower limit values in the embodiments of the present invention. It may be a range defined by a value in an example or a combination of values between examples.

In the present specification, Ac means an acetyl group, Ph means a phenyl group, dppf means 1,1'-bis(diphenylphosphino)ferrocene, DMSO means dimethylsulfoxide, THF means tetrahydrofuran. Compound 1-e and Comparative Compound 1 were synthesized according to the method described in Patent Document 1 (International Publication No. 2012/137958).

[Compound synthesis and solubility evaluation]
<Example 1: Synthesis example of compound 1>
(Synthesis of compound 1-c)

Compound 1-a (11.6 g, 40.5 mmol) and compound 1-b (14.5 g, 40.5 mmol) were subjected to nitrogen bubbling toluene (100 mL), ethanol (50 mL), tripotassium phosphate aqueous solution (2 .0 mol/L, 50 mL) was sequentially added and heated to 50°C. PdCl ₂ (PPh ₃ ) ₂ (0.29 g, 0.41 mmol) was then added and stirred at 65° C. for 3 hours. After cooling to room temperature, a saturated sodium chloride aqueous solution was added, and extraction was performed using toluene. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain compound 1-c (15.7 g, 82% yield).

(Synthesis of compound 1-d)

Dehydrated DMSO (100 mL) was added to compound 1-c (11.6 g, 24.5 mmol), bis(pinacolatodiboron) (9.3 g, 36.7 mmol) and potassium acetate (7.2 g, 73.5 mmol). , and heated to 50°C. PdCl ₂ (dppf)CH ₂ Cl ₂ (1.0 g, 1.2 mmol) was added thereto and stirred at 90° C. for 8 hours. After cooling to room temperature, distilled water was added and suction filtration was performed. The filtrate was dissolved in toluene, washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain compound 1-d (8.0 g, 63% yield).

(Synthesis of Compound 1)

Compound 1-e (2.8 g, 3.9 mmol) and compound 1-d (2.4 g, 4.7 mmol) synthesized according to the method described in Patent Document 1 (International Publication No. 2012/137958) were subjected to nitrogen bubbling. THF (30 mL) and tripotassium phosphate aqueous solution (2.0 mol/L, 10 mL) were added in order. Then Pd(PPh ₃ ) ₄ (45 mg, 0.039 mmol) was added and stirred at 70° C. for 2 hours. After cooling to room temperature, a saturated aqueous sodium chloride solution and 1N dilute hydrochloric acid were added, and extraction was performed using dichloromethane. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain compound 1 (1.2 g, 29% yield).

<Comparative Example 1: Synthesis Example of Comparative Compound 1>

Comparative compound 1 was synthesized according to the method described in Patent Document 1 (International Publication No. 2012/137958).

<Comparative Example 2: Synthesis Example of Comparative Compound 2>

Compound 1-e (0.66 g, 0.91 mmol) and compound C2-a (0.49 g, 1.37 mmol) synthesized according to the method described in Patent Document 1 (International Publication No. 2012/137958) were subjected to nitrogen bubbling. THF (15 mL) and tripotassium phosphate aqueous solution (2.0 mol/L, 5 mL) were added in order. Then Pd(PPh ₃ ) ₄ (11 mg, 0.0091 mmol) was added and stirred at 70° C. for 3 hours. After cooling to room temperature, 100 mL of dichloromethane was added to the reaction solution and filtered. The filtered product was washed with ethanol, acetone and dichloromethane and dried to obtain Comparative Compound 2 (0.90 g, 98% yield).

<Solubility evaluation>

Compound 1, Comparative Compound 1, and Comparative Compound 2 were evaluated for solubility in ethyl p-toluate (EpT).
For the solubility in ethyl p-toluate (EpT), prepare a p-ethyl toluate solution (compound concentration: 3.0% by mass) of about 1 to 2 mL, and add compound 1, comparative compound 1, and comparative It was judged whether compound 2 was dissolved or not. In addition, the number of days for precipitation of Compound 1 and Comparative Compound 1 in the solution adjusted to a concentration of 3.0% by mass was evaluated.
Table 1 shows the results. ">3.0% by mass" in Table 1 means that the compound was dissolved in the solution.

From Table 1, it can be seen that compound 1, which is the compound of the present invention, is excellent in solvent solubility in two senses, namely, that it dissolves quickly in an organic solvent and that it maintains a homogeneous state without precipitating after dissolution. .

[Preparation and Performance Evaluation of Organic Electroluminescent Device]
<Example 2>
An organic electroluminescence device was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate to a thickness of 50 nm (manufactured by Geomatec, a sputter-deposited product) was subjected to a 2 mm-wide stripe using ordinary photolithography and etching with hydrochloric acid. was patterned to form an anode. The substrate on which the ITO pattern is formed in this manner is washed with ultrasonic waves using an aqueous solution of surfactant, washed with ultrapure water, ultrasonically washed with ultrapure water, and washed with ultrapure water in this order, and then dried with compressed air. , and finally performed ultraviolet ozone cleaning.

As a composition for forming a hole injection layer, 3.0% by weight of a hole-transporting polymer compound having a repeating structure of the following formula (P-1) and 0 of an electron-accepting compound of the following structural formula (HI-1) A composition was prepared by dissolving .6% by weight in ethyl benzoate.

This solution was spin-coated on the substrate in the atmosphere and dried on a hot plate in the atmosphere at 240° C. for 30 minutes to form a uniform thin film with a thickness of 40 nm, which was used as a hole injection layer.
Next, a charge-transporting polymer compound having the following structural formula (HT-1) was dissolved in 1,3,5-trimethylbenzene to prepare a 2.0% by weight solution.

This solution was spin-coated on the substrate on which the hole injection layer had been applied and formed in a nitrogen glove box, and dried on a hot plate in the nitrogen glove box at 230° C. for 30 minutes to form a uniform thin film with a thickness of 40 nm. was formed to form a hole transport layer.

Subsequently, as materials for the light-emitting layer, 2.3% by weight of the compound 1 of the present invention synthesized in Example 1, 2.3% by weight of the compound of the following structural formula (H-1), and the following structural formula (D-1 ) was dissolved in cyclohexylbenzene at a concentration of 1.4% by weight to prepare a composition for forming a light-emitting layer.

This solution was spin-coated in a nitrogen glove box onto the substrate on which the hole transport layer had been coated, and dried on a hot plate in the nitrogen glove box at 120° C. for 20 minutes to form a uniform thin film with a thickness of 40 nm. was formed to form a light-emitting layer.
The substrate on which up to the light-emitting layer was formed was placed in a vacuum deposition apparatus, and the inside of the apparatus was evacuated to 2×10 ⁻⁴ Pa or less.

Next, a compound of the following structural formula (ET-1) and 8-hydroxyquinolinolatritium are co-deposited on the light-emitting layer at a film thickness ratio of 2:3 by a vacuum vapor deposition method to form an electron film having a film thickness of 30 nm. A transport layer was formed.

Subsequently, as a mask for cathode deposition, a striped shadow mask with a width of 2 mm was adhered to the substrate so as to be perpendicular to the ITO stripes of the anode, and aluminum was heated with a molybdenum boat to form an aluminum layer with a thickness of 80 nm. formed to form the cathode.
As described above, an organic electroluminescence device having a light-emitting area of 2 mm×2 mm was obtained.

<Comparative Example 3>
An organic electroluminescence device was produced in the same manner as in Example 1, except that Comparative Compound 1 synthesized in Comparative Example 1 was used instead of Compound 1 as a material for the light-emitting layer.

<Evaluation of element>
Voltage (V), current efficiency (cd/A), and external quantum efficiency (%) were measured when the organic electroluminescent devices obtained in Example 2 and Comparative Example 3 were caused to emit light at 1,000 cd/m ^{2 .} bottom. These measurement results are shown in Table 2. In Table 2, the value of Example 2 indicates a relative value with the value of Comparative Example 3 set to 1.

From the results in Tables 1 and 2, it can be seen that the compound of the present invention can improve the solvent solubility while ensuring the device performance of the organic electroluminescence device using the compound.

REFERENCE SIGNS LIST 1 substrate 2 anode 3 hole injection layer 4 hole transport layer 5 light emitting layer 6 electron transport layer 7 cathode 8 organic electroluminescence device

Claims (11)

A compound represented by the following formula (1).

(In formula (1),
W ₁ , W ₂ and W ₃ each independently represent —CH or a nitrogen atom, at least one of W ₁ , W ₂ and W ₃ is a nitrogen atom;
Xa ¹ , Ya ¹ and Za ¹ each independently represent an optionally substituted 1,3-phenylene group or an optionally substituted 1,4-phenylene group,
at least one of Za ¹ is an optionally substituted 1,3-phenylene group,
Xa ² and Ya ² each independently represent a phenyl group which may have a substituent;
Za ² represents an optionally substituted N-carbazolyl group,
f11 is 1 or 2,
g11 is an integer from 1 to 5,
h11 is 1 or 2,
j11 is an integer from 1 to 5,
k11 is an integer from 2 to 5,
Each R ₁₁ independently represents a hydrogen atom or a substituent. ) 2. The compound according to claim 1, wherein each _R11 in formula (1) is independently a hydrogen atom, a phenyl group or a naphthyl group. An organic electroluminescence device having an anode and a cathode on a substrate and an organic layer between the anode and the cathode,
An organic electroluminescent device, wherein the organic layer comprises the compound according to claim 1 or 2. 4. The organic electroluminescent device according to claim 3, wherein said organic layer comprises a light-emitting layer, and said light-emitting layer comprises said compound. A display device comprising the organic electroluminescence device according to claim 3 or 4. A lighting device comprising the organic electroluminescence device according to claim 3 or 4. A composition comprising at least a compound according to claim 1 or 2 and an organic solvent. 8. The composition of claim 7, further comprising a luminescent material. A method for forming a thin film, comprising the step of forming a film from the composition according to claim 7 or 8 by a wet film-forming method. A method for producing an organic electroluminescence device having an anode and a cathode on a substrate and an organic layer between the anode and the cathode, the method comprising:
A method for producing an organic electroluminescence device, comprising the step of forming the organic layer using the composition according to claim 7 or 8 by a wet film-forming method. 11. The method of manufacturing an organic electroluminescence device according to claim 10, wherein the organic layer is a light-emitting layer.

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