TWI862602B - Composition for organic electroluminescent element, organic electroluminescent element and manufacturing method thereof, display device and lighting device - Google Patents

Abstract

A composition for an organic electroluminescent element, comprising a compound represented by the following formula (1), a polymer compound having a repeating unit having a structure represented by the following formula (2), a compound represented by the following formula (3), and a solvent. An organic electroluminescent element, comprising a light-emitting layer formed using the composition for an organic electroluminescent element.

Description

Composition for organic electroluminescent element, organic electroluminescent element and its manufacturing method, display device and lighting device

The present invention relates to an organic electroluminescent element composition useful for forming a light-emitting layer of an organic electroluminescent element (hereinafter sometimes referred to as an "organic EL (Electro-Luminescence) element"). The present invention also relates to an organic electroluminescent element having a light-emitting layer formed using the organic electroluminescent element composition, a method for manufacturing the same, and a display device and a lighting device having the organic electroluminescent element.

Various electronic devices using organic EL elements, such as organic EL lighting and organic EL displays, are becoming practical. Organic electroluminescent elements consume little power due to low applied voltage, and can emit light in three primary colors. Therefore, they are beginning to be used not only in large display monitors, but also in small and medium-sized displays such as mobile phones and smartphones.

Organic electroluminescent devices are manufactured by stacking multiple layers such as a light-emitting layer or a charge injection layer, a charge transport layer, etc. Currently, most organic electroluminescent devices are manufactured by evaporating organic materials under vacuum.

In the vacuum evaporation method, the evaporation process is complicated and the productivity is poor.

Organic electroluminescent devices manufactured by vacuum evaporation are extremely difficult to achieve large-scale lighting or display panels.

In recent years, wet film forming (coating) has been studied as a process for efficiently manufacturing organic electroluminescent elements that can be used in large displays or lighting. Compared with vacuum evaporation, wet film forming has the advantage of being able to easily form a stable layer, so it is expected to be applied to mass production of displays or lighting devices or large displays.

In order to manufacture organic electroluminescent elements by wet film forming, all materials used must be soluble in organic solvents and used as ink. If the solubility of the used material is poor, operations such as heating are required for a long time, so there is a possibility that the material will deteriorate before use. Furthermore, if the solution cannot be kept uniform for a long time, the material will precipitate from the solution, making it impossible to form a film using an inkjet device, etc. The materials used in the wet film forming method are required to be soluble in two senses: to dissolve quickly in the organic solvent and to maintain a uniform state without precipitation after dissolution.

In recent years, attempts have been made to improve the performance of organic electroluminescent elements by increasing the luminescent efficiency or reducing the driving voltage of organic electroluminescent elements by using compounds containing an organic metal complex structure containing iridium as the central metal, which is widely used as a luminescent dopant, and inks containing polymer compounds having a fluorene structure (for example, Patent Documents 1 and 2).

Another advantage of the wet film forming method over the vacuum evaporation method is that more materials can be used in one layer. In the vacuum evaporation method, it is difficult to control the evaporation rate to be constant as the number of materials increases. On the other hand, in the wet film forming method, even if the number of materials increases, as long as each material is dissolved in an organic solvent, it is possible to prepare an ink with a fixed composition ratio to form a layer.

In recent years, attempts have been made to use a specific compound containing a triazine ring or a pyrimidine ring as one of the multiple components contained in the ink used to form the light-emitting layer for the purpose of electron transport (for example, Patent Document 3 and Patent Document 4). [Prior Art Document] [Patent Document]

[Patent Document 1] International Publication No. 2017/154884 [Patent Document 2] Japanese Patent Publication No. 2018-83941 [Patent Document 3] International Publication No. 2014/024889 [Patent Document 4] International Publication No. 2017/178311

However, in the above-mentioned prior art, although the solubility of the luminescent dopant is improved and the stability of the ink is improved due to the introduction of the specific substituent, the electron conductivity of the luminescent material is reduced due to the introduction of the specific substituent. Therefore, the performance of the organic electroluminescent element is not sufficient for display or lighting applications, and it is required to further reduce the driving voltage and improve the luminescent efficiency and driving life.

The subject of the present invention is to provide a composition for an organic electroluminescent element which can produce an organic electroluminescent element having a lower driving voltage, higher luminous efficiency and longer driving life than conventional organic electroluminescent elements by a wet film forming method.

The inventors of the present invention have conducted in-depth research on the above-mentioned topic in order to flexibly apply the advantages of the wet film-forming method that can use more types of materials in one layer. As a result, they found that by using an iridium complex with a high solubility in an organic solvent and introducing a specific substituent as a luminescent dopant, and using a specific compound containing a triazine ring or a pyrimidine ring that is responsible for electron transport as a main material in addition to a polymer containing a fluorene structure, dissolving these in a solvent to prepare a composition for an organic electroluminescent element, and using the composition to prepare an organic electroluminescent element, the performance of the organic electroluminescent element is improved.

The composition for an organic electroluminescent element of the present invention uses an iridium complex with high solubility in an organic solvent and introduced with a specific substituent as a luminescent dopant, so that the luminescent material is not easily precipitated and has excellent storage stability. In addition, since a specific compound containing a triazine ring or a pyrimidine ring that is responsible for electron transport is contained, an organic electroluminescent element with improved electron transport capability in the luminescent layer, low driving voltage, high luminescent efficiency, and long driving life can be produced compared to the prior art.

The gist of the present invention is as follows.

[1] A composition for an organic electroluminescent element, comprising: a compound represented by the following formula (1); a polymer compound having a repeating unit having a structure represented by the following formula (2); a compound represented by the following formula (3), and a solvent.

[Chemistry 1] [In the formula (1), R ¹ and R ² are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent; when there are a plurality of R ¹ and R ² , the plurality of R ¹ and R ² may be the same or different; adjacent R ¹ or R 2 bonded to the benzene ring may be ² can bond with each other to form a ring condensed to the benzene ring; a is an integer of 0 to 4; b is an integer of 0 to 3; m is an integer of 1 to 20; n is an integer of 0 to 2; Ring A is any one of a pyridine ring, a pyrazine ring, a pyrimidine ring, an imidazole ring, an oxazole ring, a thiazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an nitrogen-doped tris-benzene ring, and a carboline ring; Ring A may also have a substituent; the substituent is any one of a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 2 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 20 carbon atoms, or a combination thereof; adjacent substituents bonded to ring A may bond to each other to form a ring condensed to ring A; Z ¹ represents a direct bond or an m+1-valent aromatic linking group; L ¹ represents an auxiliary ligand; l is an integer from 1 to 3; if there are multiple auxiliary ligands, they can be different or the same]

[Chemistry 2]

[In formula (2), R ³ and R ⁴ are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent]

[Chemistry 3]

[In formula (3), ^X1 represents C or N; ^R5 to ^R7 are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent; when there are multiple ^R5 groups, the multiple ^{R5 groups} may be the same or different; the adjacent R5 groups bonded to the benzene ring may be any one of the following: ⁵ can be bonded to each other to form a ring condensed to the benzene ring; c is an integer from 0 to 5; wherein, when c is 0, R ⁶ and R ⁷ are not both unsubstituted phenyl groups]

[2] The composition for an organic electroluminescent device as described in [1], wherein ^Z1 in the formula (1) is a direct bond.

[3] The composition for an organic electroluminescent device according to [1], wherein the compound represented by the formula (1) is a compound represented by the following formula (1-1).

[Chemistry 4]

[In formula (1-1), three ^X2s simultaneously represent C or N; ^Z2 represents a direct bond or a p+1-valent aromatic linking group; ^Z3 represents a direct bond or a q+1-valent aromatic linking group; p and q are integers of 1 to 10; ^R1 , ^R2 , a, b, n, m, ring A, ^L1 , and l have the same meanings as ^R1 , ^R2 , a, b, m, n, ring A, ^L1 , and l in formula (1)]

[4] The composition for an organic electroluminescent device according to [1] or [2], wherein the compound represented by the formula (1) is a compound represented by the formula (1-2).

[Chemistry 5]

[In formula (1-2), R ¹ , a, m, n, ring A, Z ¹ , L ¹ , and l have the same meanings as R ¹ , a, m, n, ring A, Z ¹ , L ¹ , and l in formula (1); R ¹⁵ to R ¹⁷ are substituents]

[5] The composition for an organic electroluminescent device according to any one of [1] to [4], wherein l in the formula (1) is 3.

[6] The composition for an organic electroluminescent device according to any one of [1] to [5], wherein the polymer compound having a repeating unit having a structure represented by the formula (2) comprises a repeating unit represented by the following formula (2-1).

[Chemistry 6]

[In formula (2-1), Ar ²¹ to Ar ²³ each independently represent a divalent (hetero)arylene group having 3 to 30 carbon atoms which may have a substituent; Ar ²⁴ and Ar ²⁵ each independently represent a (hetero)arylene group having 3 to 30 carbon atoms which may have a substituent; r represents an integer of 0 to 2]

[7] The composition for an organic electroluminescent device according to any one of [1] to [6], wherein in the compound represented by the formula (3), the three partial structures of [phenylene-(R ⁵ )c], R ⁶ and R ⁷ are not the same structure, and when the partial structures have substituents, the substituents are also included.

[8] The composition for an organic electroluminescent device according to any one of [1] to [7], wherein the terminals of R ⁵ to R ⁷ in the compound represented by the formula (3) independently contain a phenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, an indolecarbazolyl group, an indenocarbazolyl group or an indenofluorenyl group.

[9] A method for manufacturing an organic electroluminescent element, comprising the step of forming a light-emitting layer by a wet film-forming method using the composition for an organic electroluminescent element as described in any one of [1] to [8].

[10] An organic electroluminescent element having a light-emitting layer formed using the composition for an organic electroluminescent element as described in any one of [1] to [8].

[11] A display device having an organic electroluminescent element as described in [10].

[12] A lighting device having an organic electroluminescent element as described in [10].

According to the present invention, a wet film forming method can be used to provide an organic electroluminescent element with lower driving voltage, higher luminous efficiency, and longer driving life than before.

The following describes the embodiments of the present invention in detail. The present invention is not limited to the following embodiments, and can be implemented in various modifications within the scope of the gist.

In this specification, (hetero)aralkyl, (hetero)aryloxy, and (hetero)aryl represent aralkyl that may contain heteroatoms, aryloxy that may contain heteroatoms, and aryl that may contain heteroatoms, respectively. "May contain heteroatoms" means that one or more carbon atoms in the carbon atoms forming the main skeleton of the aryl, aralkyl, or aryloxy group are substituted with heteroatoms. As heteroatoms, nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, silicon atoms, etc. can be listed. Among them, nitrogen atoms are preferred from the viewpoint of durability. The same is true for (hetero)aryl groups.

In the present specification, the "aromatic linking group" refers not only to an aromatic hydrocarbon linking group, that is, a linking group having an aromatic hydrocarbon ring, but also to an aromatic linking group in a broad sense including a heteroaromatic linking group, that is, a linking group having a heteroaromatic ring.

[Luminescent dopant] The composition for an organic electroluminescent element of the present invention contains a compound represented by the following formula (1) as a luminescent dopant.

[Chemistry 7]

[In the formula (1), R ¹ and R ² are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent; when there are a plurality of R ¹ and R ² , the plurality of R ¹ and R ² may be the same or different; adjacent R ¹ or R 2 bonded to the benzene ring may be ² can bond with each other to form a ring condensed to the benzene ring; a is an integer of 0 to 4; b is an integer of 0 to 3; m is an integer of 1 to 20; n is an integer of 0 to 2; Ring A is any one of a pyridine ring, a pyrazine ring, a pyrimidine ring, an imidazole ring, an oxazole ring, a thiazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an nitrogen-doped tris-benzene ring, and a carboline ring; Ring A may also have a substituent; the substituent is any one of a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 2 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 20 carbon atoms, or a combination thereof; adjacent substituents bonded to ring A may bond to each other to form a ring condensed to ring A; Z ¹ represents a direct bond or an m+1-valent aromatic linking group; L ¹ represents an auxiliary ligand; l is an integer from 1 to 3; if there are multiple auxiliary ligands, they can be different or the same]

In formula (1), from the viewpoint of durability, R ¹ and R ² are preferably independently an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero)aryl group having 3 to 30 carbon atoms, and more preferably an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, or a (hetero)aryl group having 3 to 20 carbon atoms. Two adjacent R ² groups may be linked to each other to form a ring.

Regarding a, from the perspective of easy production, it is preferably 0, from the perspective of improving solubility, it is preferably 1 or 2, and more preferably 1. Regarding b, from the perspective of easy production, it is preferably 0, from the perspective of improving durability and solubility, it is preferably 1 or 2, and more preferably 1. When two adjacent ^R2s are linked to each other to form a ring, b is preferably 2 or 3.

In order to improve the solubility of the phenyl group having a tert-butyl group at the end in an organic solvent, m is preferably 2 or more. The phenyl group having a tert-butyl group at the end does not participate much in charge transport or luminescence, so if there are too many of them, there is a concern that the driving voltage will increase or the luminescence efficiency will decrease. Therefore, m is preferably 8 or less, and more preferably 4 or less.

In terms of achieving a balance between solubility, low driving voltage and high luminescence efficiency, the compound represented by formula (1) preferably has 4 or more, particularly 6 or more, and 48 or less, particularly 24 or less, such terminal t-butyl groups in the entire compound.

From the viewpoint of easy production, n is preferably 0 or 1. From the viewpoint of less concern about an increase in driving voltage, n is preferably 0. From the viewpoint of improving solubility, n is preferably 1 or 2.

In terms of durability, Ring A is preferably a pyridine ring, a pyrimidine ring or an imidazole ring, and more preferably a pyridine ring.

In terms of durability and improved solubility, the hydrogen atom on ring A is preferably substituted with an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, or a (hetero)aryl group having 3 to 20 carbon atoms. In terms of ease of production, the hydrogen atom on ring A is preferably unsubstituted. If the hydrogen atom on ring A is substituted with a phenyl group or a naphthyl group which may have a substituent, excitons are easily generated when used in an organic electroluminescent element, and thus it is preferred in terms of improved luminescence efficiency.

In ring A, if substituents on ring A are bonded to each other to form a condensed ring condensed to ring A, thereby forming a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an azotriphenyl ring, or a carboline ring, the luminescent wavelength becomes longer, and thus it is useful in applications of red luminescence. Among them, in terms of durability and the display of red luminescence, ring A is preferably formed with a quinoline ring, an isoquinoline ring, or a quinazoline ring.

From the viewpoint of easy production, ^Z1 is preferably a direct bond. From the viewpoint of less concern about an increase in driving voltage, ^Z1 is preferably an m+1-valent aromatic linking group.

When m is 1, Z ¹ is preferably a phenylene group, a biphenylene group, a terphenylene group, or a fluorenediyl group, and particularly preferably a p-phenylene group, from the viewpoint of durability.

When m is 2 or more, ^Z1 is preferably a benzene ring having 1,3,5-positions as bonding positions or a triazine ring having 2,4,6-positions as bonding positions from the viewpoint of durability.

^Z1 is preferably a trivalent group represented by the following formula (1-2A) or (1-2B).

[Chemistry 8]

The group represented by formula (1-2A) or formula (1-2B) is preferably bonded to the benzene ring or ring A bonded to iridium. In this case, the compound represented by formula (1) is preferably a compound represented by the following formula (1-1).

[Chemistry 9]

[In formula (1-1), three ^X2s simultaneously represent C or N; ^Z2 represents a direct bond or a p+1-valent aromatic linking group; ^Z3 represents a direct bond or a q+1-valent aromatic linking group; p and q are integers of 1 to 10; ^R1 , ^R2 , a, b, n, m, ring A, ^L1 , and l have the same meanings as ^R1 , ^R2 , a, b, m, n, ring A, ^L1 , and l in formula (1)]

In the above formula (1-1), Z ² and Z ³ are preferably direct bonds in terms of easy production.

In terms of less concern about the increase in driving voltage, ^Z2 and ^Z3 are preferably p+1 and q+1 valent aromatic linking groups. In this case, for example, when p and q are 1, in terms of durability, ^Z2 and ^Z3 are preferably phenylene, biphenylene, terphenylene, fluorene diyl, and particularly preferably p-phenylene.

In terms of durability, ^Z2 when p is 2 or more and ^Z3 when q is 2 or more preferably include a benzene ring having 1,3,5-positions as bonding positions or a triazine ring having 2,4,6-positions as bonding positions. That is, ^Z2 and ^Z3 preferably include a trivalent group represented by the following formula (1-2A) or (1-2B).

[Chemistry 10]

^L1 is an auxiliary ligand. Although not particularly limited, ^L1 is preferably a monovalent bidentate ligand, and more preferably selected from the ligands represented by the following formula (1A), formula (1B), and formula (1C). The dashed lines in the following formulas (1A) to (1C) represent coordination bonds. When l is 1 and there are two auxiliary ligands ^L1 , the auxiliary ligands ^L1 may be the same as each other or have different structures. When l is 3, ^L1 does not exist.

[Chemistry 11]

In the formula (1A) and (1B), R ⁹ and R ¹⁰ are selected from the same group as R ¹ and R ² , and preferred examples are the same. g is an integer of 0 to 4. h is an integer of 0 to 4. For g and h, 0 is preferred from the viewpoint of easy production, and 1 or 2 is preferred from the viewpoint of improving solubility, and 1 is further preferred.

Ring B is any one of a pyridine ring, a pyrimidine ring, an imidazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an azotriazole ring, a carboline ring, a benzothiazole ring, and a benzoxazole ring, and these may also have a substituent. In terms of durability, Ring B is preferably a pyridine ring, a pyrimidine ring, or an imidazole ring, and more preferably a pyridine ring.

In terms of durability and improved solubility, the hydrogen atom on ring B is preferably substituted with an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, or a (hetero)aryl group having 3 to 20 carbon atoms. In terms of ease of production, the hydrogen atom on ring B is preferably unsubstituted. If the hydrogen atom on ring B is substituted with a phenyl group or a naphthyl group which may have a substituent, excitons are easily generated when used in an organic electroluminescent element, and thus it is preferred in terms of improved luminescence efficiency.

In ring B, if the substituents on ring B are bonded to each other to form a condensed ring condensed to ring B, thereby forming a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, a nitrogen-doped tert-benzene ring, or a carboline ring, it is easy to generate excitons on the auxiliary dopant, so it is preferred from the perspective of improving the luminescence efficiency. Among them, in terms of durability and the aspect of showing red luminescence, ring B is preferably formed with a quinoline ring, an isoquinoline ring, or a quinazoline ring.

In formula (1C), ^R11 to ^R13 each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may be substituted with a fluorine atom, a phenyl group which may be substituted with an alkyl group having 1 to 20 carbon atoms, or a halogen atom. More preferably, ^R11 and ^R13 are methyl or t-butyl, and ^R12 is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group.

The compound represented by formula (1) is preferably a compound represented by the following formula (1-2) in which adjacent R ^2's are bonded to each other to form a fluorene ring.

[Chemistry 12]

[In formula (1-2), R ¹ , a, m, n, ring A, Z ¹ , L ¹ , and l have the same meanings as R ¹ , a, m, n, ring A, Z ¹ , L ¹ , and l in formula (1); R ¹⁵ to R ¹⁷ are substituents]

As R ¹⁵ , the substituents that may be possessed by the above R ² can be listed. More preferably, R ¹⁵ is an alkyl group having 1 to 20 carbon atoms, or an aromatic alkyl group having 6 to 30 carbon atoms which may be substituted by one or two alkyl groups having 1 to 20 carbon atoms. Here, the aromatic alkyl group having 6 to 30 carbon atoms refers to a monocyclic ring, a bicyclic condensed ring, or a tricyclic condensed ring, or a group in which a plurality of monocyclic rings, bicyclic condensed rings, or tricyclic condensed rings are linked. ^{R 15} is further preferably an alkyl group having 1 to 20 carbon atoms, and particularly preferably an alkyl group having 1 to 8 carbon atoms.

R ¹⁶ and R ¹⁷ are a part of the above R ² or a substituent that the above R ² may have, and are preferably independently an alkyl group having 1 to 12 carbon atoms, an aromatic alkyl group having 6 to 20 carbon atoms that may be substituted by one or two alkyl groups having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an aromatic alkyl group having 6 to 20 carbon atoms that may be substituted by one or two alkoxy groups having 1 to 12 carbon atoms. Here, the aromatic alkyl group having 6 to 20 carbon atoms refers to a monocyclic, bicyclic condensed ring, or tricyclic condensed ring, or a group in which a plurality of monocyclic, bicyclic, or tricyclic condensed rings are linked. ^R16 and ^R17 are further preferably independently an alkyl group having 1 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 or 12 carbon atoms which may be substituted by one or two alkyl groups having 1 to 8 carbon atoms, and are particularly preferably an alkyl group having 1 to 8 carbon atoms, or an aromatic hydrocarbon group having 6 carbon atoms which may be substituted by one or two alkyl groups having 1 to 8 carbon atoms. Here, the aromatic hydrocarbon structure having 6 carbon atoms is a benzene structure, and the aromatic hydrocarbon structure having 12 carbon atoms is a biphenyl structure.

Preferred specific examples of the luminescent dopant, that is, the compound represented by formula (1) contained in the composition for an organic electroluminescent device of the present invention are shown below. The present invention is not limited to these.

[Chemistry 13]

[Chemistry 14]

[Chemistry 15]

[Polymer compound] The composition for an organic electroluminescent element of the present invention comprises a polymer compound having a repeating unit having a structure represented by the following formula (2) (hereinafter, sometimes referred to as "repeating unit (2)").

[Chemistry 16]

[In formula (2), R ³ and R ⁴ are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent]

In formula (2), R ³ and R ⁴ are each independently preferably an alkyl group having 1 to 20 carbon atoms or a (hetero)aralkyl group having 7 to 40 carbon atoms, from the viewpoint of self-solubility. In terms of heat resistance, R ³ and R ⁴ are each independently preferably a (hetero)aryl group having 3 to 30 carbon atoms.

In terms of improving the charge transport property, the polymer compound contained in the composition for an organic electroluminescent device of the present invention preferably contains, in addition to the repeating unit (2), a repeating unit having a structure represented by the following formula (2-1) (hereinafter, sometimes referred to as "repeating unit (2-1)"). In this case, the repeating unit (2) may also be contained in the repeating unit (2-1) described below.

[Chemistry 17]

[In formula (2-1), Ar ²¹ to Ar ²³ each independently represent a divalent (hetero)arylene group having 3 to 30 carbon atoms which may have a substituent; Ar ²⁴ and Ar ²⁵ each independently represent a (hetero)arylene group having 3 to 30 carbon atoms which may have a substituent; r represents an integer of 0 to 2]

In terms of durability, Ar ²¹ to Ar ²³ are each independently preferably a phenylene group, a biphenylene group, a terphenylene group, a fluorene diyl group, or a divalent group having 30 or less carbon atoms formed by arbitrarily selecting these groups and linking them, and are particularly preferably p-phenylene group and biphenylene group. These groups may have a substituent. When formula (2-1) includes the structure represented by formula (2), when Ar ²¹ , Ar ²² or r is 1 or more, at least one selected from at least one Ar ²³ is a fluorene group represented by formula (2) which may have a substituent at the 9,9' position.

In view of durability, Ar ²⁴ and Ar ²⁵ are each independently preferably a phenyl group, a biphenyl group, a terphenyl group, or a fluorenyl group, and particularly preferably a phenyl group or a fluorenyl group. These groups may have a substituent.

The polymer compound contained in the composition for an organic electroluminescent device of the present invention may contain only one type of repeating unit (2) or two or more types. In addition, the polymer compound may contain only one type of repeating unit (2-1) or two or more types.

The weight average molecular weight (Mw) of the polymer compound contained in the organic electroluminescent device composition of the present invention is usually 2,000,000 or less, preferably 500,000 or less, more preferably 100,000 or less, and further preferably 50,000 or less, and is usually 2,500 or more, preferably 5,000 or more, more preferably 10,000 or more, and further preferably 20,000 or more.

When the weight average molecular weight is below the upper limit, the solubility in the solvent is excellent and the film-forming property is also excellent. When the weight average molecular weight is above the lower limit, the glass transition temperature, melting point and vaporization temperature of the polymer compound are high and the heat resistance is excellent.

The number average molecular weight (Mn) of the polymer compound contained in the composition for an organic electroluminescent device of the present invention is usually 1,000,000 or less, preferably 250,000 or less, more preferably 50,000 or less, and further preferably 25,000 or less, and is usually 2,000 or more, preferably 4,000 or more, more preferably 8,000 or more, and further preferably 15,000 or more.

The dispersion degree (Mw/Mn) of the polymer compound contained in the composition for an organic electroluminescent element of the present invention is preferably 3.5 or less, more preferably 2.5 or less, and particularly preferably 2.0 or less. The smaller the dispersion degree value, the better, so the lower limit is preferably 1. If the dispersion degree of the polymer compound is below the upper limit, it is easy to purify, and the solubility in the solvent or the charge transfer ability is good.

Usually, the weight average molecular weight of polymer compounds is determined by size exclusion chromatography (SEC). In SEC measurement, the higher the molecular weight, the shorter the dissolution time, while the lower the molecular weight, the longer the dissolution time. Using a calibration curve calculated from the dissolution time of polystyrene (standard sample) with a known molecular weight, the dissolution time of the sample is converted into molecular weight to calculate the weight average molecular weight. The number average molecular weight is also calculated in the same way.

The method for producing the polymer compound contained in the composition for an organic electroluminescent device of the present invention is not particularly limited, and any method is applicable as long as a polymer compound having repeating units (2) can be obtained. For example, the polymer compound can be produced by a polymerization method based on a Suzuki reaction, a polymerization method based on a Grignard reaction, a polymerization method based on a Yamamoto reaction, a polymerization method based on an Ullmann reaction, a polymerization method based on a Buchwald-Hartwig reaction, or the like.

Preferred specific examples of the repeating units of the polymer compound having the repeating units (2) and combinations thereof contained in the composition for an organic electroluminescent device of the present invention other than those shown in the Examples are shown below. The present invention is not limited to these.

[Chemistry 18]

[Charge transport material] The composition for an organic electroluminescent element of the present invention contains a compound represented by the following formula (3) as a charge transport material.

[Chemistry 19]

[In formula (3), ^X1 represents C or N; ^R5 to ^R7 are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent; when there are multiple ^R5 groups, the multiple ^{R5 groups} may be the same or different; the adjacent R5 groups bonded to the benzene ring may be any one of the following: ⁵ can be bonded to each other to form a ring condensed to the benzene ring; c is an integer from 0 to 5; wherein, when c is 0, R ⁶ and R ⁷ are not both unsubstituted phenyl groups]

In formula (3), from the viewpoint of durability, R ⁵ to R ⁷ are each independently preferably an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero)aryl group having 3 to 30 carbon atoms, more preferably an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, or a (hetero)aryl group having 3 to 20 carbon atoms, and still more preferably an aryl group having 6 to 20 carbon atoms.

In terms of charge transport properties, R ⁵ to R ⁷ are preferably independently a (hetero)aryl group having 3 to 20 carbon atoms. The (hetero)aryl group having 3 to 20 carbon atoms includes a monocyclic or condensed aryl group, a monocyclic or condensed heteroaryl group, a structure in which a plurality of monocyclic or condensed aryl groups are linked, a structure in which a plurality of monocyclic or condensed heteroaryl groups are linked, and a structure in which a plurality of monocyclic or condensed aryl groups or monocyclic or condensed heteroaryl groups are randomly linked. It is further preferred that R ⁵ to R ⁷ are independently a group selected from phenyl, naphthyl, fluorenyl, carbazolyl, indolocarbazolyl, indenocarbazolyl, indenofluorenyl, or a group having 3 to 20 carbon atoms formed by arbitrarily linking a plurality of groups selected from phenyl, naphthyl, fluorenyl, and carbazolyl. It is particularly preferred to be a group formed by linking two or three indolocarbazolyl, indenocarbazolyl, indenofluorenyl, phenyl, or phenyl groups. These groups may further have a substituent.

From the viewpoint of charge transportability, luminous efficiency of the device and driving life of the device, the terminals of R ⁵ to R ⁷ preferably independently contain a phenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, an indolecarbazolyl group, an indenocarbazolyl group or an indenofluorenyl group. When these groups are present, the following embodiment (i) is preferred, the following embodiment (ii) is more preferred, and the following embodiment (iii) is further preferred. (i) When c is 1 or more, at least one of the one or more R ⁵ , R ⁶ and R ⁷ contains a carbazolyl group, an indolecarbazolyl group, an indenocarbazolyl group or an indenofluorenyl group at the terminal. (ii) When c is 1 or more, only one or two of one or more R ⁵ , R ⁶ and R ⁷ contain a naphthyl group, a fluorenyl group, a carbazolyl group, an indolocarbazolyl group, an indenocarbazolyl group or an indenofluorenyl group at the terminal. (iii) When c is 1 or more, only one or two of one or more R ⁵ , R ⁶ and R ⁷ contain a naphthyl group, a fluorenyl group or a carbazolyl group at the terminal, or only one contains an indolocarbazolyl group, an indenocarbazolyl group or an indenofluorenyl group at the terminal. The terminal of R ⁵ to R ⁷ mentioned here may be a substituent group possessed by R ⁵ to R ⁷ .

These structures may further have substituents. As examples of these terminal structures, the structures shown in the figure below can be cited.

[Chemistry 20]

[In the above structures, * represents a bonding position; Ar ²⁰ represents an aromatic hydrocarbon group having 6 to 20 carbon atoms; R ¹⁴ represents a substituent; these structures may further have a substituent]

The substituents which these structures may have are the same as the substituents which R ⁵ to R ⁷ may have.

^Ar20 is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms, more preferably a phenyl group or a biphenyl group, and further preferably a phenyl group.

In the structure having two R ¹⁴ 's, the two R ^14's may be the same or different. R ¹⁴ is preferably an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms which may be substituted by an alkyl group having 1 to 8 carbon atoms, or a heteroaryl group having 3 to 30 carbon atoms which may be substituted by an alkyl group having 1 to 8 carbon atoms; more preferably an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, or an aryl group having 6 to 30 carbon atoms which may be substituted by an alkyl group having 1 to 8 carbon atoms; further preferably an alkyl group having 1 to 8 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an aryloxy group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms which may be substituted by an alkyl group having 1 to 8 carbon atoms.

From the viewpoint of improving solubility in a solvent and amorphous properties, when c is 1 or more, at least one of R ⁵ , R ⁶ and R ⁷ preferably has a 1,2-phenylene group or a 1,3-phenylene group. Furthermore, from the viewpoint of ease of synthesis, at least one preferably contains a 1,3-phenylene group.

From the viewpoint of durability, c is preferably an integer of 0 to 2.

In the compound represented by formula (3), when the benzene ring having R ⁵ is represented by "Bz", the three partial structures of Bz-(R ⁵ )c, R ⁶ and R ⁷ may all be the same structure, or only one may be a different structure, or all three may be different structures. When the partial structure has a substituent, the substituent is also included. It is preferably only one different structure or all three different structures, and more preferably all three different structures. The reason for this will be described later.

The compound represented by formula (3) contained as the charge transport material is a low molecular weight compound, and its molecular weight is preferably 400 or more, more preferably 450 or more, further preferably 500 or more, particularly preferably 600 or more, preferably 3000 or less, more preferably 2000 or less, further preferably 1500 or less, and particularly preferably 1200 or less.

Preferred specific examples of the compound represented by formula (3) contained as a charge transport material in the composition for an organic electroluminescent device of the present invention other than those described in the Examples are shown below. The present invention is not limited to these.

[Chemistry 21]

[Specific Examples of Each Structure] Specific examples and preferred structures of various structures of R 1 to R 7 , R 9 to R ¹³ , Ar ²¹ to Ar ²⁵ , Ring A and Ring B in Formula (1), Formula (1-1), Formula ( ^1-2 ), Formula (1A) to Formula ( ^1C ), Formula ( ² ), Formula (2-1) and Formula (3) are listed below.

The alkyl group having 1 to 20 carbon atoms may be any of linear, branched or cyclic alkyl groups, and specifically, may include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, isopropyl, isobutyl, isopentyl, t-butyl, cyclohexyl, etc. Among them, linear alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, n-butyl, n-hexyl, and n-octyl, are preferred.

The (hetero)aralkyl group having 7 to 40 carbon atoms refers to a group in which a part of the hydrogen atoms constituting a linear, branched or cyclic alkyl group is substituted with a (hetero)aryl group. Specifically, 2-phenyl-1-ethyl, cumyl, 5-phenyl-1-pentyl, 6-phenyl-1-hexyl, 7-phenyl-1-heptyl, tetrahydronaphthyl and the like can be mentioned. Among them, 5-phenyl-1-pentyl, 6-phenyl-1-hexyl and 7-phenyl-1-heptyl are preferred.

Specific examples of the alkoxy group having 1 to 20 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy, hexyloxy, cyclohexyloxy, octadecyloxy, etc. Among them, hexyloxy is preferred.

Specific examples of the (hetero)aryloxy group having 3 to 20 carbon atoms include phenoxy group and 4-methylphenyloxy group. Among them, phenoxy group is preferred.

Specific examples of the alkylsilyl group having 1 to 20 carbon atoms include trimethylsilyl, triethylsilyl, triisopropylsilyl, dimethylphenyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, etc. Among them, triisopropylsilyl, t-butyldimethylsilyl, and t-butyldiphenylsilyl are preferred.

Specific examples of the arylsilyl group having 6 to 20 carbon atoms include diphenylpyridylsilyl group and triphenylsilyl group, among which triphenylsilyl group is preferred.

Specific examples of the alkylcarbonyl group having 2 to 20 carbon atoms include acetyl, propionyl, trimethylacetyl, hexyl, decanoyl, and cyclohexylcarbonyl groups. Among them, acetyl and trimethylacetyl are preferred.

Specific examples of the arylcarbonyl group having 7 to 20 carbon atoms include benzoyl, naphthyl, anthracenyl, etc. Among them, benzoyl is preferred.

Specific examples of the alkylamino group having 1 to 20 carbon atoms include methylamino, dimethylamino, diethylamino, ethylmethylamino, dihexylamino, dioctylamino, dicyclohexylamino, etc. Among them, dimethylamino and dicyclohexylamino are preferred.

Specific examples of the arylamino group having 6 to 20 carbon atoms include phenylamino, diphenylamino, di(4-tolyl)amino, di(2,6-dimethylphenyl)amino, etc. Among them, diphenylamino and di(4-tolyl)amino are preferred.

The (hetero)aryl group having 3 to 30 carbon atoms refers to an aromatic alkyl group and an aromatic heterocyclic group having one free atomic valence, or a linked aromatic alkyl group formed by linking a plurality of aromatic alkyl groups, a linked aromatic heterocyclic group formed by linking a plurality of aromatic heterocyclic groups, or a group formed by arbitrarily linking one or more aromatic alkyl groups and one or more aromatic heterocyclic groups.

Specific examples of the (hetero)aryl group having 3 to 30 carbon atoms include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a fused tetraphenyl ring, a pyrene ring, a benzopyrene ring, a chrysene ring, a trisphenyl ring, an anthracene ring, a furan ring, a benzofuran ring, a dibenzofuran ring, a thiophene ring, a benzothiophene ring, a dibenzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolo A pyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furanopyrrole ring, a furanofuran ring, a thienofuran ring, a benzoisoxazole ring, a benzoisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a oxazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like. Examples of linked aromatic hydrocarbon groups in which a plurality of aromatic hydrocarbons are linked include biphenyl and terphenyl.

Among the (hetero)aryl groups, benzene ring, naphthalene ring, dibenzofuran ring, dibenzothiophene ring, carbazole ring, pyridine ring, pyrimidine ring, triazine ring having one free atomic valence are preferred from the viewpoint of durability. Among them, aryl groups having 6 to 18 carbon atoms, such as benzene ring, naphthalene ring or phenanthrene ring, which may be substituted by an alkyl group having 1 to 8 carbon atoms, or pyridine ring, which may be substituted by an alkyl group having 1 to 4 carbon atoms, are more preferred. Further preferred are aryl groups having 6 to 18 carbon atoms, such as benzene ring, naphthalene ring or phenanthrene ring, which may be substituted by an alkyl group having 1 to 8 carbon atoms, are more preferred.

The divalent (hetero)arylene group having 3 to 30 carbon atoms is the same as the examples of the (hetero)arylene group having 3 to 30 carbon atoms, except that it has two free atomic valences, and the preferred examples are also the same.

As the combination of these substituents, for example, a combination of an aryl group and an alkyl group, a combination of an aryl group and an aralkyl group, or a combination of an aryl group and an alkyl group or an aralkyl group can be used. As the combination of an aryl group and an aralkyl group, for example, a combination of a phenyl group, a biphenyl group or a terphenyl group and a 5-phenyl-1-pentyl group or a 6-phenyl-1-hexyl group can be used.

[Specific Examples of Substituents] In the following formulas (1), (1-1), (1-2), (1A) to (1C), (2), (2-1) and (3), R ¹ to R ⁷ , R ⁹ to R ¹³ , Ar ²¹ to Ar ²⁵ , Ring A and Ring B may have a substituent which is an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, a (hetero)aryl group having 3 to 30 carbon atoms or a crosslinking group. List specific examples of various substituents.

The alkyl group having 1 to 20 carbon atoms may be any of linear, branched or cyclic alkyl groups, and specifically, may include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, isopropyl, isobutyl, isopentyl, t-butyl, cyclohexyl, etc. Among them, linear alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, n-butyl, n-hexyl, and n-octyl, are preferred.

The (hetero)aralkyl group having 7 to 40 carbon atoms refers to a group in which a part of the hydrogen atoms constituting a linear, branched or cyclic alkyl group is substituted with a (hetero)aryl group, and specifically, 2-phenyl-1-ethyl, cumyl, 5-phenyl-1-pentyl, 6-phenyl-1-hexyl, 7-phenyl-1-heptyl, tetrahydronaphthyl, etc. are exemplified. Among them, 5-phenyl-1-pentyl, 6-phenyl-1-hexyl, and 7-phenyl-1-heptyl are preferred.

Specific examples of the alkoxy group having 1 to 20 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy, hexyloxy, cyclohexyloxy, octadecyloxy, etc. Among them, hexyloxy is preferred.

Specific examples of the (hetero)aryloxy group having 3 to 20 carbon atoms include phenoxy group and 4-methylphenyloxy group. Among them, phenoxy group is preferred.

Specific examples of the alkylsilyl group having 1 to 20 carbon atoms include trimethylsilyl, triethylsilyl, triisopropylsilyl, dimethylphenyl, t-butyldimethylsilyl, t-butyldiphenylsilyl, etc. Among them, triisopropylsilyl, t-butyldimethylsilyl, and t-butyldiphenylsilyl are preferred.

Specific examples of the arylsilyl group having 6 to 20 carbon atoms include diphenylpyridylsilyl group and triphenylsilyl group, among which triphenylsilyl group is preferred.

Specific examples of the alkylcarbonyl group having 2 to 20 carbon atoms include acetyl, propionyl, trimethylacetyl, hexyl, decanoyl, and cyclohexylcarbonyl groups. Among them, acetyl and trimethylacetyl are preferred.

Specific examples of the arylcarbonyl group having 7 to 20 carbon atoms include benzoyl, naphthyl, anthracenyl, etc. Among them, benzoyl is preferred.

Specific examples of the alkylamino group having 1 to 20 carbon atoms include methylamino, dimethylamino, diethylamino, ethylmethylamino, dihexylamino, dioctylamino, dicyclohexylamino, etc. Among them, dimethylamino and dicyclohexylamino are preferred.

Specific examples of the arylamino group having 6 to 20 carbon atoms include phenylamino, diphenylamino, di(4-tolyl)amino, di(2,6-dimethylphenyl)amino, etc. Among them, diphenylamino and di(4-tolyl)amino are preferred.

The (hetero)aryl group having 3 to 30 carbon atoms refers to an aromatic alkyl group and an aromatic heterocyclic group having one free atomic valence, or a linked aromatic alkyl group formed by linking a plurality of aromatic alkyl groups, a linked aromatic heterocyclic group formed by linking a plurality of aromatic heterocyclic groups, or a group formed by arbitrarily linking one or more aromatic alkyl groups and one or more aromatic heterocyclic groups.

Specific examples of the (hetero)aryl group having 3 to 30 carbon atoms include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a fused tetraphenyl ring, a pyrene ring, a benzopyrene ring, a chrysene ring, a trisphenyl ring, an anthracene ring, a furan ring, a benzofuran ring, a dibenzofuran ring, a thiophene ring, a benzothiophene ring, a dibenzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolo A pyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furanopyrrole ring, a furanofuran ring, a thienofuran ring, a benzoisoxazole ring, a benzoisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a oxazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like. Examples of linked aromatic hydrocarbon groups in which a plurality of aromatic hydrocarbons are linked include biphenyl and terphenyl.

Among the (hetero)aryl groups, benzene ring, naphthalene ring, dibenzofuran ring, dibenzothiophene ring, carbazole ring, pyridine ring, pyrimidine ring, triazine ring having one free atomic valence are preferred from the viewpoint of durability. Among them, aryl groups having 6 to 18 carbon atoms, such as benzene ring, naphthalene ring or phenanthrene ring, which may be substituted by an alkyl group having 1 to 8 carbon atoms, or pyridine ring, which may be substituted by an alkyl group having 1 to 4 carbon atoms, are more preferred. Further preferred are aryl groups having 6 to 18 carbon atoms, such as benzene ring, naphthalene ring or phenanthrene ring, which may be substituted by an alkyl group having 1 to 8 carbon atoms, are more preferred.

As the combination of these substituents, for example, a combination of an aryl group and an alkyl group, a combination of an aryl group and an aralkyl group, or a combination of an aryl group and an alkyl group or an aralkyl group can be used. As the combination of an aryl group and an aralkyl group, for example, a combination of a phenyl group, a biphenyl group or a terphenyl group and a 5-phenyl-1-pentyl group or a 6-phenyl-1-hexyl group can be used.

Among these substituents, preferred are alkyl groups having 1 to 20 carbon atoms, aralkyl groups having 7 to 40 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, aryloxy groups having 3 to 20 carbon atoms, alkylsilanyl groups having 1 to 20 carbon atoms, arylsilanyl groups having 6 to 20 carbon atoms, arylamine groups having 6 to 20 carbon atoms, and (hetero)aryl groups having 3 to 30 carbon atoms. Further preferred are alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, alkylsilanyl groups having 1 to 20 carbon atoms, arylsilanyl groups having 6 to 20 carbon atoms, arylamine groups having 6 to 20 carbon atoms, and (hetero)aryl groups having 3 to 30 carbon atoms. Particularly preferred are alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, and (hetero)aryl groups having 3 to 30 carbon atoms. The specific structure and preferred carbon number of each of these preferred substituents are as described in the specific examples of the substituents.

When these substituents further have a substituent, the substituents exemplified above can be cited as the substituent.

[Mechanism by which the composition for an organic electroluminescent element of the present invention exerts the effect of the present invention] The light-emitting layer of an organic electroluminescent element produced using the composition for an organic electroluminescent element of the present invention comprises a light-emitting dopant represented by formula (1), a polymer compound having a repeating unit having a structure represented by formula (2) (polymer compound having repeating units (2)), and a compound represented by formula (3).

In the light-emitting layer of the organic electroluminescent element of the present invention, the polymer compound having the repeating unit (2) is mainly responsible for hole transport. In the case of a structure in which the repeating unit (2) is contained in the repeating unit (2-1), the hole transport property is greatly improved due to the aromatic amine structure. The compound represented by formula (3) has high electron transport property. Therefore, the charge transport property in the light-emitting layer is improved, and the voltage is lowered. In addition, it is believed that the charge balance between holes and electrons becomes good, and the light-emitting efficiency is improved. Here, the light-emitting dopant represented by formula (1) has an alkyl group containing a tert-butyl group. The tert-butyl group is large in volume and thus becomes a stereo hindrance. Therefore, the charge-transporting compound is usually present at a certain distance from the charge-receiving site of the luminescent dopant, and the charge is not easy to move from the charge-transporting compound to the luminescent dopant. Here, in the present invention, the material responsible for hole transport is mainly a polymer compound, and holes are easy to move on the polymer chain, so holes exist in a relatively wide range of the polymer chain. It is believed that in the polymer chain where holes exist in a wide range, there is a site where holes are relatively easy to move to the luminescent dopant represented by formula (1), and the holes will move from the site to the luminescent dopant represented by formula (1). In this way, in the luminescent layer of the organic electroluminescent element of the present invention, it is believed that the holes first move to the neutral luminescent dopant. It is thought that: Secondly, electrons move from the compound represented by formula (3) to the luminescent dopant and recombine to emit light. It is thought that the luminescent dopant represented by formula (1) has low durability to electrons but high durability to holes, so the device life is prolonged.

Furthermore, in the compound represented by the formula (3), the three partial structures of [phenylene-(R ⁵ )c], R ⁶ and R ⁷ (including their substituents (if present)) are preferably not the same structure. Furthermore, the three partial structures are preferably different from each other. In the present invention, such a structure is referred to as an asymmetric structure.

The compound represented by the formula (3) is preferably an asymmetric structure in which only one or two of R ⁵ to R ⁷ contain a naphthyl, fluorenyl, carbazolyl, indolecarbazolyl, indenocarbazolyl, or indenofluorenyl at the terminal. By adopting such an asymmetric structure, the amorphous property is improved to form a uniform and stable film, and it is easy to form a film uniformly mixed with other materials. In addition, it is more preferred from the viewpoint of improving solubility in a solvent and improving stability in a solution. In particular, the aspect of easy uniform mixing with other materials is particularly effective when a polymer material is further included as a charge transport material.

The reason for this is considered to be that when a composition for an organic electroluminescent element prepared by dissolving the compound represented by the formula (3) and the polymer compound having the repeating unit (2) in a solvent is used as a composition for forming a light-emitting layer for wet film formation, the solvent evaporates during drying and the composition for forming a light-emitting layer is in a concentrated state. Since the compound represented by the formula (3) is asymmetric, it is easy to directly form a film in a state where the polymer chain rings of the polymer compound having the repeating unit (2) are uniformly mixed.

In particular, when at least one of one or more (when present) R ⁵ , R ⁶ and R ⁷ contains a carbazolyl group, an indolecarbazolyl group, an indenocarbazolyl group or an indenofluorene group at the terminal, it is believed that since the carbazolyl group, the indolecarbazolyl group, the indenocarbazolyl group or the indenofluorene group has a hole transporting ability (although the degree varies), it has a high affinity with the hole transporting polymer compound and is easily mixed with the hole transporting polymer compound to form a stable film. Among these, the carbazolyl group is considered to be preferred because it has a small structural tolerance and is more easily mixed with the polymer compound.

In addition, it is considered that the compound represented by the formula (3) as the charge transport material is asymmetric, and thus the luminescence efficiency of the compound represented by the formula (1) as the luminescent dopant can be improved. The reason is described below.

The luminescent dopant represented by formula (1) has an alkyl group including a tert-butyl group. Usually, since the tert-butyl group acts as a stereohindrance, the charge transport material is present at a certain distance from the luminescent dopant represented by formula (1). In the present invention, since the material responsible for hole transport is mainly a polymer compound, holes exist in a relatively wide range of positions on the polymer chain, and therefore holes are easily transferred to the luminescent dopant represented by formula (1). On the other hand, since the tert-butyl group of the luminescent dopant represented by formula (1) acts as a stereohindrance, the low molecular weight compound is usually present at a certain distance from the luminescent dopant, and charges are not easily transferred from the low molecular weight compound to the luminescent dopant. However, when the electron-transmitting material represented by formula (3) of the present invention has an asymmetric structure, the distribution of LUMO is biased, and it is believed that there is a site where electrons can easily move. Therefore, it is believed that electrons can easily move to the luminescent dopant having a stereohindrance such as tert-butyl, thereby lowering the voltage and emitting light with high efficiency, thereby extending the life of the device.

In addition, when at least one of the terminals of R ⁵ to R ⁷ in the compound represented by the formula (3) includes a carbazolyl group, an indolecarbazolyl group, an indenocarbazolyl group, or an indenofluorene group, it is believed that the compound represented by the formula (3) easily accepts electrons and holes, and thus easily accepts both electrons and holes to form an excited state. In this case, it is believed that the excitation energy is directly transferred to the luminescent dopant, and it is believed that even if the luminescent dopant has a tert-butyl group as in the formula (1), the excitation energy is efficiently transferred. As a result, it is believed that the luminescent efficiency is improved and the driving life of the device is prolonged.

Furthermore, even if the compound represented by the formula (3) is symmetrical, when all of the terminals R ⁵ to R ⁷ are carbazolyl groups, the luminous efficiency is improved and the driving life of the device is prolonged for the same reason, which is considered to be preferable. The molecular structure of the carbazolyl group is relatively small, so even if all of the terminals R ⁵ to R ⁷ have carbazolyl groups, the stereostructure of the compound represented by the formula (3) is less affected, which is preferable. The compound represented by the formula (3) is symmetrical when c=1 in the compound represented by the formula (3), and the three partial structures of [phenylene-R ⁵ ], R ⁶ and R ⁷ (including the substituents when there are substituents) are the same structure.

[Synthesis method of the compound represented by formula (1)] The compound represented by formula (1) contained as a luminescent dopant in the composition for an organic electroluminescent device of the present invention is an iridium complex. The synthesis method of the iridium complex is shown below.

The ligand of the iridium complex can be synthesized by combining known methods. The ligand can be synthesized by known reactions such as Suzuki-Miyaura coupling reaction of arylboronic acids with halogenated heteroaryls, and Friedlaender cyclization reaction of 2-formyl or acylanilines or acyl-aminopyridines located at adjacent positions (Chem. Rev. 2009, 109, 2652 or Organic Reactions, 28 (2), 37-201).

<Synthesis method of iridium complex> Iridium complex can be synthesized by combining known methods using ligands and iridium chloride n-hydrate as raw materials. The following is an explanation.

As a method for synthesizing an iridium complex, for ease of understanding, there can be exemplified a method of crosslinking an iridium binuclear complex as shown in the following formula [A] via chlorine using a phenylpyridine ligand as an example (M. G. Colombo, T. C. Brunold, T. Riedener, H. U. Gudel, Inorganic Chemistry (Inorg. Chem.) 1994, 33, 545-550); and a method of converting a binuclear complex of the following formula [B] into a mononuclear complex by further crosslinking the chlorine with acetylacetone to obtain the target product (S. Lamansky, P. Djurovich, D. Murphy, F. Abdel-Razzaq, R. Kwong, I. Tsyba, M. Borz, B. Mui, R. Bau, M. Thompson, Inorganic Chemistry (Inorg. Chem.) 1994, 33, 545-550). Chem.), 2001, 40, 1704-1711), etc., but not limited to these.

For example, the typical reaction conditions represented by the following formula [A] are as follows.

As the first stage, a chlorine-crosslinked iridium binuclear complex is synthesized by reacting two equivalents of the first ligand with one equivalent of iridium chloride n-hydrate. The solvent is usually a mixture of 2-ethoxyethanol and water, but no solvent or other solvents can also be used. The ligand can also be used in excess, or an additive such as an alkali can be used to promote the reaction. Other crosslinking anionic ligands such as bromine can also be used instead of chlorine.

The reaction temperature is not particularly limited, but is usually preferably 0° C. or higher, more preferably 50° C. or higher, preferably 250° C. or lower, and more preferably 150° C. or lower. When the reaction temperature is within this temperature range, only the target reaction proceeds without the production of byproducts or decomposition reactions, and there is a tendency to obtain high selectivity.

[Chemistry 22]

In the second stage, a halogen ion scavenger such as silver trifluoromethanesulfonate is added to bring it into contact with the second ligand to obtain the target complex. Ethoxyethanol or diglyme is usually used as the solvent, but depending on the type of ligand, no solvent or other solvents may be used, or multiple solvents may be mixed and used. Even if a halogen ion scavenger is not added, the reaction sometimes proceeds, so it is not necessarily necessary, but in order to increase the reaction yield and selectively synthesize facial isomers with higher quantum yields, it is beneficial to add the scavenger. The reaction temperature is not particularly limited, and is usually carried out in the range of 0°C to 250°C.

Typical reaction conditions represented by the following formula [B] are described.

The binuclear complex of the first stage can be synthesized in the same manner as that of formula [A].

In the second stage, the binuclear complex is converted into a mononuclear complex coordinated by a 1,3-diketone ligand by reacting the binuclear complex with more than 1 equivalent of a 1,3-diketone compound such as acetylacetone and more than 1 equivalent of an alkaline compound such as sodium carbonate that can extract active hydrogen from the 1,3-diketone compound. Usually, a solvent such as ethoxyethanol or dichloromethane that can dissolve the binuclear complex as a raw material is used, and when the ligand is in liquid form, it can also be carried out without a solvent. The reaction temperature is not particularly limited, and is usually carried out in the range of 0°C to 200°C.

[Chemistry 23]

In the third stage, one equivalent or more of the second ligand is reacted. The type and amount of the solvent are not particularly limited, and when the second ligand is liquid at the reaction temperature, no solvent may be used. The reaction temperature is also not particularly limited, but since the reactivity is slightly insufficient, the reaction is usually carried out at a relatively high temperature of 100°C to 300°C. Therefore, a solvent with a high boiling point such as glycerol is preferably used.

After the final reaction, purification is performed to remove unreacted raw materials, reaction by-products and solvents. The purification operation in common organic synthetic chemistry can be applied, but as described in the non-patent literature, purification is mainly performed by parallel phase silica gel column chromatography. The developing liquid can use a single or mixed solution of hexane, heptane, dichloromethane, chloroform, ethyl acetate, toluene, methyl ethyl ketone, and methanol. Purification can also be performed multiple times by changing the conditions. Other chromatographic techniques (reversed phase silica gel chromatography, size exclusion chromatography, paper chromatography) or liquid separation washing, reprecipitation, recrystallization, suspension washing of powders, reduced pressure drying and other purification operations can be implemented as needed.

[Solvent] The composition for the organic electroluminescent element of the present invention contains a solvent.

The solvent contained in the composition for an organic electroluminescent device of the present invention is a volatile liquid component used to form a layer containing a luminescent dopant by wet film formation.

The solvent is not particularly limited as long as it is a solvent in which the compound represented by formula (1) as a luminescent dopant, the polymer compound having repeating units (2), the compound represented by formula (3), and other luminescent materials or charge transport materials described below that may be contained as necessary are well dissolved as a solute.

Preferred solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decahydronaphthalene, and dicyclohexane; aromatic hydrocarbons such as toluene, xylene, mesitylene, cyclohexylbenzene (phenylcyclohexane), and tetrahydronaphthalene; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethoxybenzene, and the like. Aromatic ethers such as methyl anisole and diphenyl ether; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; aliphatic cycloketones such as cyclohexanone, cyclooctanone, and fenchone; aliphatic cycloalcohols such as cyclohexanol and cyclooctanol; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; 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), etc. Among them, alkanes or aromatic hydrocarbons are preferred. In particular, cyclohexylbenzene has a better viscosity and boiling point in the wet film forming process.

These solvents may be used alone or in any combination and ratio.

The boiling point of the solvent is usually 80° C. or higher, preferably 100° C. or higher, more preferably 150° C. or higher, particularly preferably 200° C. or higher, and usually 270° C. or lower, preferably 250° C. or lower, and more preferably 240° C. or lower. If the boiling point is lower than this range, the film formation stability may be reduced due to evaporation of the solvent from the composition during wet film formation.

[Composition] The composition for an organic electroluminescent element of the present invention is usually used to form a layer or film using a wet film-forming method, and is particularly preferably used to form a light-emitting layer of an organic electroluminescent element.

The content of the compound represented by the formula (1) as a luminescent dopant in the composition for an organic electroluminescent element is usually 0.01 mass % or more, preferably 0.1 mass % or more, and usually 20 mass % or less, preferably 10 mass % or less. By setting the content of the compound represented by the formula (1) to be within this range, when the composition is used for an organic electroluminescent element, the excitation energy is less likely to move to an adjacent layer (e.g., a hole transport layer or a hole blocking layer), and the extinction due to the interaction between excitons is reduced, thereby improving the luminescent efficiency.

The composition for an organic electroluminescent device of the present invention may contain only one kind of the compound represented by formula (1), or may contain two or more kinds in combination.

The content of the polymer compound having the repeating unit (2) in the composition for an organic electroluminescent device of the present invention is usually 0.01 mass % or more, preferably 0.1 mass % or more, and usually 20 mass % or less, preferably 10 mass % or less. By setting the content of the polymer compound to this range, when the composition is used for an organic electroluminescent device, the excitation energy is less likely to move to an adjacent layer (e.g., a hole transport layer or a hole blocking layer), and the extinction due to the interaction between excitons is reduced, thereby improving the luminescence efficiency.

The composition for an organic electroluminescent device of the present invention may contain only one type of polymer compound having the repeating unit (2), or may contain two or more types in combination.

The content of the compound represented by formula (3) in the composition for an organic electroluminescent device of the present invention is usually 0.005 mass % or more, preferably 0.05 mass % or more, and usually 10 mass % or less, preferably 5 mass % or less. By setting the content of the compound represented by formula (3) to be within this range, when the composition is used for an organic electroluminescent device, electrons can be efficiently injected from the layer on the cathode side (e.g., the hole blocking layer) into the light-emitting layer, thereby reducing the driving voltage.

The composition for an organic electroluminescent device of the present invention may contain only one compound represented by formula (3), or may contain two or more compounds in combination.

From the viewpoint of luminous efficiency, the composition for an organic electroluminescent device of the present invention preferably contains 5 to 100 parts by mass, particularly 15 to 60 parts by mass, of the compound represented by formula (1) relative to 100 parts by mass of the total of the polymer compound having the repeating unit (2) and the compound represented by formula (3). If the amount of the compound represented by formula (1) responsible for luminescence is too small, the efficiency is reduced, and if it is too large, the light is easily extinguished, thereby reducing the efficiency.

From the viewpoint of reasonable charge balance and improved efficiency, the composition for an organic electroluminescent device of the present invention preferably contains 20 to 98 parts by mass, particularly 50 to 90 parts by mass, of the polymer compound having the repeating unit (2) per 100 parts by mass of the total of the polymer compound having the repeating unit (2) and the compound represented by the formula (3).

The content of the solvent in the composition for an organic electroluminescent device of the present invention is preferably 10 parts by mass or more, more preferably 50 parts by mass or more, particularly preferably 80 parts by mass or more, and preferably 99.95 parts by mass or less, more preferably 99.9 parts by mass or less, and particularly preferably 99.8 parts by mass or less in 100 parts by mass of the composition.

As described later, the thickness of the luminescent layer is usually about 3 nm to 200 nm, but if the content of the solvent is above the lower limit, the viscosity of the composition does not become too high, and the film forming workability becomes good. On the other hand, if the content of the solvent is below the upper limit, after film formation, the thickness of the film obtained by removing the solvent can be obtained, so there is a tendency for film formation to become easy.

As described above, the composition for an organic electroluminescent device of the present invention may contain only one solvent or a combination of two or more solvents.

[Organic electroluminescent element] The organic electroluminescent element of the present invention includes a luminescent layer formed by a wet film-forming method using the composition for an organic electroluminescent element of the present invention.

The organic electroluminescent device of the present invention preferably has at least an anode, a cathode, and at least one organic layer between the anode and the cathode on a substrate, and includes a luminescent layer formed by a wet film-forming method using the composition for an organic electroluminescent device of the present invention as at least one of the organic layers.

In the present invention, the so-called wet film-forming method refers to a method of forming a film by wet method such as spin coating, dip coating, die coating, rod coating, doctor blade coating, roller coating, spray coating, capillary coating, ink jet coating, nozzle printing, screen printing, gravure printing, flexographic printing, etc. as a film-forming method, i.e., a coating method, and a method of forming a film by drying the film formed by these methods.

Fig. 1 is a schematic diagram showing a cross-section of a preferred structural example of an organic electroluminescent element 10 of the present invention. In Fig. 1, reference numeral 1 denotes a substrate, reference numeral 2 denotes an anode, reference numeral 3 denotes a hole injection layer, reference numeral 4 denotes a hole transport layer, reference numeral 5 denotes a light-emitting layer, reference numeral 6 denotes a hole blocking layer, reference numeral 7 denotes an electron transport layer, reference numeral 8 denotes an electron injection layer, and reference numeral 9 denotes a cathode.

The materials used in these structures can be known materials without any particular limitation. The representative materials or production methods for each layer are described below as an example. When citing a gazette or paper, the corresponding contents can be appropriately applied within the common knowledge of a person skilled in the art.

<Substrate 1> The substrate 1 is a support for the organic electroluminescent element, and is usually made of a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, etc. Among these, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferred. From the perspective of preventing the organic electroluminescent element from being easily deteriorated by external gas, the substrate 1 is preferably made of a material with high gas barrier properties. In particular, when using a material with low gas barrier properties such as a synthetic resin substrate, it is preferred to provide a dense silicon oxide film on at least one side of the substrate 1 to improve the gas barrier properties.

<Anode 2> Anode 2 is responsible for injecting holes into the layer on the side of the light-emitting layer. Anode 2 usually includes: metals such as aluminum, gold, silver, nickel, palladium, platinum; metal oxides such as indium and/or tin oxides; halogenated metals such as copper iodide; carbon black or conductive polymers such as poly(3-methylthiophene), polypyrrole, and polyaniline.

The formation of the anode 2 is usually carried out by a dry method such as sputtering or vacuum evaporation. When the anode 2 is formed using metal particles such as silver, copper iodide, carbon black, conductive metal oxide particles, conductive polymer powder, etc., it can also be formed by dispersing them in a suitable binder resin solution and applying them to a substrate. In the case of a conductive polymer, the anode 2 can also be formed by directly forming a thin film on the substrate by electrolytic polymerization, or by applying a conductive polymer on the substrate (Applied Physics Letters (Appl. Phys. Lett.), Vol. 60, p. 2711, 1992).

The anode 2 is usually a single-layer structure, but a laminated structure may also be used. In the case where the anode 2 is a laminated structure, different conductive materials may be laminated on the first layer of the anode.

The thickness of the anode 2 can be determined according to the required transparency and material, etc. In particular, when high transparency is required, it is preferred to have a thickness that allows the transmittance of visible light to be 60% or more, and more preferably 80% or more. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, usually 1000 nm or less, and preferably 500 nm or less. When transparency is not required, the thickness of the anode 2 can be set to any thickness according to the required strength, etc. In this case, the anode 2 can also be the same thickness as the substrate 1.

When forming a film on the surface of the anode 2, it is preferred to perform a treatment such as ultraviolet ray + ozone, oxygen plasma, or argon plasma before film formation to remove impurities on the anode and adjust its ionization potential to improve hole injection properties.

<Hole injection layer 3> A layer that performs the function of transporting holes from the anode 2 side to the light-emitting layer 5 side is generally referred to as a hole injection transport layer or a hole transport layer. When there are two or more layers that perform the function of transporting holes from the anode 2 side to the light-emitting layer 5 side, the layer closer to the anode 2 side is sometimes referred to as the hole injection layer 3. In terms of strengthening the function of transporting holes from the anode 2 to the light-emitting layer 5 side, it is preferable to use the hole injection layer 3. When the hole injection layer 3 is used, the hole injection layer 3 is generally formed on the anode 2.

The 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.

The hole injection layer 3 may be formed by vacuum evaporation or wet film formation. In terms of excellent film forming properties, the wet film formation is preferred.

The hole injection layer 3 preferably contains a hole transporting compound, more preferably contains a hole transporting compound and an electron accepting compound. Furthermore, the hole injection layer 3 preferably contains a cationic radical compound, particularly preferably contains a cationic radical compound and a hole transporting compound.

(Hole transport compound) The hole injection layer forming composition usually contains a hole transport compound to be the hole injection layer 3.

In the case of a wet film forming method, a solvent is usually further contained. The composition for forming the hole injection layer preferably has high hole transport properties and can efficiently transport the injected holes. Therefore, it is preferred that the hole mobility is large and impurities that do not easily form traps are not easily generated during manufacturing or use. In addition, it is preferred that the stability is excellent, the ionization potential is small, and the transparency to visible light is high. In particular, when the hole injection layer 3 is in contact with the light-emitting layer 5, it is preferred that the light from the light-emitting layer 5 is not extinguished or that the light-emitting efficiency is not reduced by forming an exciplex with the light-emitting layer 5.

As the hole transport compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferred from the viewpoint of hindering charge injection from the anode 2 to the hole injection layer 3. Examples of the hole transport compound include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds formed by linking tertiary amines with fluorene groups, hydrazone compounds, silazane compounds, and quinacridone compounds.

Among the above-mentioned exemplary compounds, aromatic amine compounds are preferred in terms of amorphousness and visible light transmittance, and aromatic tertiary amine compounds are particularly preferred. The aromatic tertiary amine compounds also include compounds having an aromatic tertiary amine structure and having a group derived from an aromatic tertiary amine.

The type of aromatic tertiary amine compound is not particularly limited. In terms of obtaining uniform luminescence by surface smoothing effect, it is preferred to use a polymer compound (a polymer compound in which repeating units are linked) having a weight average molecular weight of 1000 to 1000000. Preferred examples of aromatic tertiary amine polymer compounds include polymer compounds having repeating units represented by the following formula (I).

[Chemistry 24]

[In formula (I), ^Ar1 and ^Ar2 each independently represent an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent; ^Ar3 to ^Ar5 each independently represent an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent; Q represents a linking group selected from the following linking group group; and, among ^Ar1 to ^Ar5 , two groups bonded to the same N atom may bond to each other to form a ring]

The linking groups are shown below.

[Chemistry 25]

[In the above formulae, Ar ⁶ to Ar ¹⁶ each independently represent an aromatic group which may have a substituent or a heteroaromatic group which may have a substituent; ^Ra to ^Rb each independently represent a hydrogen atom or an arbitrary substituent]

The aromatic group and heteroaromatic group represented by Ar ¹ to Ar ¹⁶ are preferably groups derived from a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring or a pyridine ring, and more preferably groups derived from a benzene ring or a naphthalene ring, from the viewpoint of solubility, heat resistance and hole injection transport properties of the polymer compound.

Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by formula (I) include compounds described in International Publication No. 2005/089024.

(Electron-accepting compound) The hole injection layer 3 preferably contains an electron-accepting compound so that the conductivity of the hole injection layer 3 can be increased by oxidation of the hole transporting compound.

The electron-accepting compound is preferably a compound having an oxidizing ability and an ability to accept a single electron from the hole-transporting compound. Specifically, a compound having an electron affinity of 4 eV or more is preferred, and a compound having an electron affinity of 5 eV or more is more preferred.

Examples of such electron-accepting compounds include one or more compounds selected from the group consisting of triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Specifically, there can be cited: onium salts substituted with organic groups such as 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate and triphenylphosphine tetrafluoroborate (International Publication No. 2005/089024); high-valence inorganic compounds such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067) and ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; aromatic boron compounds such as tris(pentafluorophenyl)borane (Japanese Patent Laid-Open No. 2003-31365); fullerene derivatives and iodine, etc.

(Cationic radical compound) As the cationic radical compound, it is preferred to use an ionic compound containing a cationic radical as a chemical species that has removed one electron from a hole-transporting compound, and a counter anion. When the cationic radical is derived from a hole-transporting polymer compound, the cationic radical has a structure in which one electron has been removed from a repeating unit of the polymer compound.

As the cation radical, a chemical species obtained by removing one electron from the compound described above as the hole transporting compound is preferred. From the viewpoints of amorphousness, transmittance of visible light, heat resistance, solubility, etc., a chemical species obtained by removing one electron from a compound preferred as the hole transporting compound is preferred.

The cationic radical compound can be generated by mixing the hole transport compound and the electron accepting compound. By mixing the hole transport compound and the electron accepting compound, electrons move from the hole transport compound to the electron accepting compound, thereby generating a cationic radical of the hole transport compound and a counter anion.

Cationic radical compounds derived from polymer compounds such as PEDOT/PSS (Advanced Materials (Adv. Mater.), 2000, Vol. 12, p. 481) or emeraldine hydrochloride (J. Phys. Chem., 1990, Vol. 94, p. 7716) can also be generated by oxidative polymerization (dehydrogenation polymerization). The oxidative polymerization mentioned here is to chemically or electrochemically oxidize the monomer in an acidic solution using peroxodisulfate or the like. In the case of this oxidative polymerization (dehydrogenation polymerization), the monomer is polymerized by oxidation, and cationic radicals are generated that remove one electron from the repeating unit of the polymer, using anions derived from the acidic solution as counter anions.

(Formation of hole injection layer 3 by wet film formation) When the hole injection layer 3 is formed by wet film formation, a material to be the hole injection layer 3 is usually mixed with a soluble solvent (hole injection layer solvent) to prepare a film-forming composition (hole injection layer forming composition), and this hole injection layer forming composition is formed on a layer (usually anode 2) corresponding to the lower layer of the hole injection layer 3 by wet film formation, and then dried. The formed film can be dried in the same manner as the drying method in the formation of the light-emitting layer 5 by wet film formation.

The concentration of the hole transporting compound in the hole injection layer forming composition is arbitrary as long as the effect of the present invention is not significantly impaired. Regarding this concentration, a low concentration is preferred in terms of uniformity of film thickness, and a high concentration is preferred in terms of less likely defects to occur in the hole injection layer 3. The concentration of the hole transporting compound in the hole injection layer forming composition is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, particularly preferably 0.5 mass % or more, preferably 70 mass % or less, further preferably 60 mass % or less, and particularly preferably 50 mass % or less.

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

Examples of the ether solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); and aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, and 2,4-dimethylanisole.

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

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

Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide.

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

The hole injection layer 3 is formed by a wet film formation method generally by preparing a hole injection layer forming composition, applying the composition to a layer (generally the anode 2) corresponding to the lower layer of the hole injection layer 3, and drying the composition. The hole injection layer 3 is generally dried by heating or reduced pressure drying after film formation.

(Formation of the hole injection layer 3 by vacuum evaporation) When the hole injection layer 3 is formed by vacuum evaporation, one or more constituent materials of the hole injection layer 3 (the hole transporting compound, the electron accepting compound, etc.) are usually placed in a crucible set in a vacuum container (when more than two materials are used, they are usually placed in different crucibles respectively), and after the vacuum container is evacuated to about ^10-4 Pa by a vacuum pump, the crucible is heated (when more than two materials are used, the crucibles are usually heated separately), and the material in the crucible is evaporated while controlling the evaporation amount (when more than two materials are used, the evaporation amounts are usually controlled independently to evaporate), and the hole injection layer 3 is formed on the anode 2 on the substrate placed facing the crucible. When two or more materials are used, a mixture of these materials may be placed in a crucible and heated to evaporate the mixture to form the hole injection layer 3 .

The degree of vacuum during evaporation is not particularly limited unless it significantly impairs the effect of the present invention, and is usually 0.1×10 ^-6 Torr (0.13×10 ^-4 Pa) or more and 9.0×10 ^-6 Torr (12.0×10 ^-4 Pa) or less. The evaporation rate is not particularly limited unless it significantly impairs the effect of the present invention, and is usually 0.1 Å/sec or more and 5.0 Å/sec or less. The film-forming temperature during evaporation is not particularly limited unless it significantly impairs the effect of the present invention, and is preferably 10°C or more and 50°C or less.

<Hole transport layer 4> The hole transport layer 4 is a layer that has the function of transporting holes from the anode 2 side to the light-emitting layer 5 side. The hole transport layer 4 is not an essential layer for the organic electroluminescent element of the present invention, but it is preferably provided in terms of strengthening the function of transporting holes from the anode 2 to the light-emitting layer 5. When the hole transport layer 4 is provided, the hole transport layer 4 is usually formed between the anode 2 and the light-emitting layer 5. When the hole injection layer 3 is present, the hole transport layer 4 is formed between the hole injection layer 3 and the light-emitting layer 5.

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

The hole transport layer 4 may be formed by vacuum evaporation or wet film formation. In terms of excellent film forming properties, the wet film formation is preferred.

The hole transport layer 4 usually contains a hole transport compound forming the hole transport layer 4. Examples of the hole transport compound contained in the hole transport layer 4 include: aromatic diamines represented by 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl containing two or more tertiary amines and two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), aromatic amine compounds having a starburst structure such as 4,4',4''-tri(1-naphthylphenylamino)triphenylamine (J. Lumin., Vol. 72-74, p. 985, 1997), aromatic amine compounds containing tetramers of triphenylamine (Chem. Commun., 2175 pages, 1996), spirocyclic compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, 91 volumes, 209 pages, 1997), carbazole derivatives such as 4,4'-N,N'-dicarbazole biphenyl, etc. Polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Publication No. 7-53953), polyarylether sulfone containing tetraphenylbenzidine (Polym. Adv. Tech., 7 volumes, 33 pages, 1996), etc. can also be preferably used.

(Formation of hole transport layer 4 by wet film formation) When the hole transport layer 4 is formed by wet film formation, it is usually formed by using a hole transport layer forming composition instead of a hole injection layer forming composition, similarly to the case of forming the hole injection layer 3 by wet film formation.

When the hole transport layer 4 is formed by a wet film forming method, the hole transport layer forming composition generally further contains a solvent. The solvent used in the hole transport layer forming composition can be the same solvent as the solvent used in the hole injection layer forming composition. The concentration of the hole transport compound in the hole transport layer forming composition can be set to the same range as the concentration of the hole transport compound in the hole injection layer forming composition.

The hole transport layer 4 can be formed by a wet film formation method in the same manner as the film formation method of the hole injection layer 3 described above.

(Formation of hole transport layer 4 by vacuum evaporation) When forming hole transport layer 4 by vacuum evaporation, similarly to the case of forming hole injection layer 3 by wet film formation, hole transport layer 4 can be formed by using constituent materials instead of constituent materials of hole injection layer 3. Film formation conditions such as vacuum degree, evaporation speed and temperature during evaporation can be formed by using the same conditions as those for vacuum evaporation of hole injection layer 3.

<Luminescent layer 5> The luminescent layer 5 is a layer that emits light when an electric field is applied between a pair of electrodes and holes injected from the anode 2 and electrons injected from the cathode 9 are excited to recombine and emit light.

The light-emitting layer 5 is a layer formed between the anode 2 and the cathode 9. When the hole injection layer 3 is present on the anode 2, the light-emitting layer 5 is formed between the hole injection layer 3 and the cathode 9. When the hole transport layer 4 is present on the anode 2, the light-emitting layer 5 is formed between the hole transport layer 4 and the cathode 9.

The film thickness of the light-emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired. However, a thicker film is preferred in terms of less likely to cause defects in the film, and a thinner film is preferred in terms of easily achieving a low driving voltage. The film thickness of the light-emitting layer 5 is preferably 3 nm or more, more preferably 5 nm or more, and is usually preferably 200 nm or less, more preferably 100 nm or less.

In the organic electroluminescent device of the present invention, the light-emitting layer 5 is formed by using the composition for an organic electroluminescent device of the present invention, preferably by a wet film-forming method.

When a light-emitting layer is formed by a wet film-forming method using the composition for an organic electroluminescent device of the present invention, the composition for an organic electroluminescent device of the present invention may contain other light-emitting materials and charge transporting materials in addition to the compound represented by the formula (1), the polymer compound having the repeating unit (2) and the compound represented by the formula (3).

Other luminescent materials and charge transport materials are described in detail below.

(Luminescent material) Luminescent materials other than the compound represented by formula (1) emit light at a desired wavelength, and are not particularly limited as long as the effect of the present invention is not impaired, and known luminescent materials can be applied. The luminescent material may be a fluorescent luminescent material or a phosphorescent luminescent material, but preferably a material with good luminescent efficiency. From the viewpoint of internal quantum efficiency, a phosphorescent luminescent material is preferred.

As the fluorescent light-emitting material, for example, the following materials can be cited.

Examples of the fluorescent material providing blue luminescence (blue fluorescent material) include naphthalene, perylene, pyrene, anthracene, coumarin, chrysene, p-bis(2-phenylvinyl)benzene, and derivatives thereof.

Examples of the fluorescent material that provides green luminescence (green fluorescent material) include quinacridone derivatives, coumarin derivatives, and aluminum complexes such as Al(C ₉ H ₆ NO) ₃ .

Examples of the fluorescent material that provides yellow luminescence (yellow fluorescent material) include rubrene and perimidone derivatives.

Examples of the fluorescent material that provides red luminescence (red fluorescent material) include DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran) compounds, benzopyran derivatives, rose bengal derivatives, benzothiadone derivatives, and nitrogen-doped benzothiadone.

Examples of phosphorescent materials include organic metal complexes containing metals selected from Groups 7 to 11 of the long-term periodic table (hereinafter, "periodic table" refers to the long-term periodic table unless otherwise specified). Preferred examples of metals selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, yttrium, nirium, iridium, platinum, and gold.

As the ligand of the organometallic complex, a ligand formed by linking a (hetero)aryl group with pyridine, pyrazole, phenanthroline, etc., such as a (hetero)arylpyridine ligand and a (hetero)arylpyrazole ligand is preferred, and a phenylpyridine ligand and a phenylpyrazole ligand are particularly preferred. Here, the (hetero)aryl group represents an aryl group or a heteroaryl group.

Preferred phosphorescent materials include, specifically, phenylpyridine complexes such as tris(2-phenylpyridine)iridium, tris(2-phenylpyridine)ruthenium, tris(2-phenylpyridine)palladium, bis(2-phenylpyridine)platinum, tris(2-phenylpyridine)barium, and tris(2-phenylpyridine)rhodium, and porphyrin complexes such as octaethylplatinumporphyrin, octaphenylplatinumporphyrin, octaethylpalladiumporphyrin, and octaphenylpalladiumporphyrin.

Examples of polymer-based luminescent materials include polyfluorene-based materials such as poly(9,9-dioctylfluorene-2,7-diyl), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)], and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(1,4-benzo-2{2,1'-3}-triazole)], and polystyrene-based materials such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-styrene-ethylene].

(Charge transport material) The charge transport material is a material that has the property of transporting positive charges (holes) or negative charges (electrons). As a charge transport material other than the compound represented by formula (3), there is no particular limitation as long as the effect of the present invention is not impaired, and known materials can be applied.

As the charge transport material, a compound that has been used in the light-emitting layer of an organic electroluminescent device can be used. In particular, a compound that is used as a host material of the light-emitting layer is preferred.

As the charge transport material, specifically, there can be listed: aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds formed by linking tertiary amines with fluorene groups, hydrazone compounds, silazane compounds, silaneamine compounds, phosphamide compounds, quinacridone compounds and the like, which are exemplified as the hole transport compounds for the hole injection layer 3, and in addition, there can also be listed electron transport compounds such as anthracene compounds, pyrene compounds, carbazole compounds, pyridine compounds, phenanthroline compounds, oxadiazole compounds, and silole compounds.

As the charge transport material, preferably used are: aromatic diamines represented by 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl containing two or more tertiary amines and two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), aromatic amine compounds having a starburst structure such as 4,4',4''-tri(1-naphthylphenylamino)triphenylamine (J. Lumin., Vol. 72-74, p. 985, 1997), aromatic amine compounds containing a tetramer of triphenylamine (Chem. Commun., p. 2175, 1996), fluorene compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals), Vol. 91, p. 209, 1997), carbazole compounds such as 4,4'-N,N'-dicarbazolebiphenyl, and the like, and the compounds exemplified as the hole-transporting compounds of the hole-transporting layer 4. In addition, the following can be cited: oxadiazole compounds such as 2-(4-biphenyl)-5-(p-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD) and 2,5-bis(1-naphthyl)-1,3,4-oxadiazole (BND); silole compounds such as 2,5-bis(6'-(2',2''-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy); phenanthroline compounds such as 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline, BPhen) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproin, BCP).

(Formation of the light-emitting layer 5 by wet film forming method) The organic electroluminescent element of the present invention has a light-emitting layer formed by a wet film forming method using the organic electroluminescent element composition of the present invention. The organic electroluminescent element of the present invention may have a light-emitting layer other than the light-emitting layer formed by a wet film forming method using the organic electroluminescent element composition of the present invention as the light-emitting layer 5. The light-emitting layer may be formed by a vacuum evaporation method or a wet film forming method, but the wet film forming method is preferred in terms of excellent film forming properties.

When the light-emitting layer 5 is formed by a wet film-forming method, the hole injection layer 3 is formed by using the composition for the organic electroluminescent element of the present invention or a light-emitting layer forming composition prepared by mixing a material for the light-emitting layer 5 with a soluble solvent (light-emitting layer solvent) instead of the hole injection layer forming composition.

As the solvent, for example, in addition to the ether solvent, ester solvent, aromatic hydrocarbon solvent, and amide solvent listed for the formation of the hole injection layer 3, alkane solvents, halogenated aromatic hydrocarbon solvents, aliphatic alcohol solvents, alicyclic alcohol solvents, aliphatic ketone solvents, and alicyclic ketone solvents can also be listed. The solvent used is also exemplified as the solvent of the composition for the organic electroluminescent device of the present invention. Specific examples of the solvent are listed below, but they are not limited to these as long as the effects of the present invention are not impaired.

For example, aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); aromatic ether solvents such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and diphenyl ether; aromatic ester solvents such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; toluene, xylene, mesitylene, cyclohexylbenzene, tetrahydronaphthalene, 3-isobutylene, and the like. Aromatic hydrocarbon solvents such as propylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, and methylnaphthalene; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; alkane solvents such as n-decane, cyclohexane, ethylcyclohexane, decahydronaphthalene, and bicyclohexane; halogenated aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; aliphatic alcohol solvents such as butanol and hexanol; aliphatic alcohol solvents such as cyclohexanol and cyclooctanol; aliphatic ketone solvents such as methyl ethyl ketone and dibutyl ketone; aliphatic ketone solvents such as cyclohexanone, cyclooctanone, and fenchone, etc. Among these, alkane-based solvents and aromatic hydrocarbon-based solvents are particularly preferred.

In order to obtain a more uniform film, it is preferred that the solvent evaporates at an appropriate rate from the liquid film just formed. Therefore, the boiling point of the solvent used is usually 80°C or higher, preferably 100°C or higher, more preferably 120°C or higher, and usually 270°C or lower, preferably 250°C or lower, and more preferably 230°C or lower, as described above.

The amount of the solvent used is arbitrary as long as the effect of the present invention is not significantly impaired, but as described above, the total content in the composition for forming the light-emitting layer, i.e., the composition for the organic electroluminescent element, is preferably more because the film formation operation is easy due to low viscosity, and preferably less because the film is easy to form a thick film. As described above, the content of the solvent in the composition for the organic electroluminescent element is preferably 1% by mass or more, more preferably 10% by mass or more, particularly preferably 50% by mass or more, preferably 99.99% by mass or less, more preferably 99.9% by mass or less, and particularly preferably 99% by mass or less.

As a method for removing the solvent after wet film formation, heating or decompression can be adopted. As a heating means used in the heating method, a clean oven or a heating plate is preferred in terms of providing heat uniformly to the entire film.

The heating temperature in the heating step is arbitrary as long as it does not significantly damage the effect of the present invention, but a high temperature is preferred in terms of shortening the drying time, and a low temperature is preferred in terms of less damage to the material. The upper limit of the heating temperature is usually below 250°C, preferably below 200°C, and further preferably below 150°C. The lower limit of the heating temperature is usually above 30°C, preferably above 50°C, and further preferably above 80°C. The heating temperature exceeding the upper limit is higher in heat resistance than the commonly used charge transport material or phosphorescent material, and there is a possibility of decomposition or crystallization, so it is not preferred. If the heating temperature is less than the lower limit, it takes a long time to remove the solvent, so it is not preferred. The heating time in the heating step can be reasonably determined according to the boiling point or vapor pressure of the solvent in the composition for forming the light-emitting layer, the heat resistance of the material and the heating conditions.

(Formation of the luminescent layer 5 by vacuum evaporation) When the luminescent layer 5 is formed by vacuum evaporation, one or more constituent materials of the luminescent layer 5 (the luminescent material, charge transport compound, etc.) are usually placed in a crucible set in a vacuum container (when using more than two materials, they are usually placed in different crucibles respectively), and after the vacuum container is evacuated to about ^10-4 Pa by a vacuum pump, the crucible is heated (when using more than two materials, the crucibles are usually heated separately), and the material in the crucible is evaporated while controlling the evaporation amount (when using more than two materials, the evaporation amounts are usually controlled independently to evaporate), and the luminescent layer 5 is formed on the hole injection layer 3 or the hole transport layer 4 placed facing the crucible. When two or more materials are used, a mixture of these materials may be placed in a crucible and heated to evaporate them to form the light-emitting layer 5 .

The degree of vacuum during evaporation is not limited unless it significantly impairs the effect of the present invention, and is usually 0.1×10 ^-6 Torr (0.13×10 ^-4 Pa) or more and 9.0×10 ^-6 Torr (12.0×10 ^-4 Pa) or less. The evaporation rate is not limited unless it significantly impairs the effect of the present invention, and is usually 0.1 Å/sec or more and 5.0 Å/sec or less. The film-forming temperature during evaporation is not limited unless it significantly impairs the effect of the present invention, and is preferably 10°C or more and 50°C or less.

<Hole blocking layer 6> The hole blocking layer 6 may be provided between the light emitting layer 5 and the electron injection layer 8 described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 in contact with the interface on the cathode 9 side of the light emitting layer 5.

The hole blocking layer 6 has the function of blocking holes moving from the anode 2 from reaching the cathode 9 and efficiently transferring electrons injected from the cathode 9 to the light-emitting layer 5. The physical properties required of the material constituting the hole blocking layer 6 include high electron mobility and low hole mobility, a large energy gap (difference between HOMO and LUMO), and a high excited triplet energy level (T1).

Examples of materials for the hole blocking layer 6 that meet this condition include bis(2-methyl-8-hydroxyquinolinolato)(phenol)aluminum, bis(2-methyl-8-hydroxyquinolinolato)(triphenylsilanol)aluminum, Mixed ligand complexes such as silanolato)aluminum), metal complexes such as bis(2-methyl-8-hydroxyquinolinolato)aluminum-μ-oxo-bis-(2-methyl-8-hydroxyquinolinolato)aluminum dinuclear metal complexes, styryl compounds such as distyrylbiphenyl derivatives (Japanese Patent Laid-Open No. 11-242996), triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (Japanese Patent Laid-Open No. 7-41759), phenanthroline derivatives such as bathocuproin (Japanese Patent Laid-Open No. 10-79297), etc. The compound having at least one 2, 4, 6-position substituted pyridine ring described in International Publication No. 2005/022962 is also preferred as the material of the hole blocking layer 6.

The method for forming the hole blocking layer 6 is not limited and can be formed in the same way as the method for forming the light-emitting layer 5.

As long as the effect of the present invention is not significantly impaired, the thickness of the hole blocking layer 6 is arbitrary, usually 0.3 nm or more, preferably 0.5 nm or more, usually 100 nm or less, preferably 50 nm or less.

<Electronic transmission layer 7>

In order to further improve the current efficiency of the element, the electron transport layer 7 is disposed between the light-emitting layer 5 or the hole blocking layer 6 and the electron injection layer 8.

The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode 9 between electrodes to which an electric field is applied in the direction of the light-emitting layer 5. The electron transport compound used in the electron transport layer 7 needs to have a high efficiency of electron injection from the cathode 9 or the electron injection layer 8, a high electron mobility, and be able to efficiently transport the injected electrons.

Examples of electron-transmitting compounds that satisfy this condition include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Publication No. 59-194393), metal complexes of 10-hydroxybenzo[h]quinoline, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone gold complexes, and the like. metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, tribenzimidazolylbenzene (U.S. Patent No. 5645948), quinoxaline compounds (Japanese Patent Laid-Open No. 6-207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinone diimide, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide, etc.

The film thickness of the electron transport layer 7 is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

The electron transport layer 7 is formed by laminating on the light emitting layer 5 or the hole blocking layer 6 by a wet film forming method or a vacuum evaporation method, similarly to the light emitting layer 5. Usually, the vacuum evaporation method is used.

<Electron injection layer 8> The electron injection layer 8 plays the role of efficiently injecting electrons injected from the cathode 9 into the electron transport layer 7 or the light-emitting layer 5.

In order to efficiently inject electrons, the material forming the electron injection layer 8 is preferably a metal having a low work function. For example, an alkali metal such as sodium or cesium, an alkali earth metal such as barium or calcium, etc. can be used.

The film thickness of the electron injection layer 8 is preferably 0.1 nm to 5 nm.

Inserting an extremely thin insulating film (thickness of about 0.1 nm to 5 nm) such as LiF, _MgF2 , _Li2O , _Cs2CO3 as _an electron injection layer 8 at the interface between the cathode 9 and the electron transport layer 7 is also an effective method to improve the efficiency of the device (Appl. Phys. Lett., Vol. 70, p. 152, 1997; Japanese Patent Publication No. 10-74586; IEEE Trans. Electron. Devices, Vol. 44, p. 1245, 1997; Society for Information Display (SID) 04 Digest, p. 154). Furthermore, it is preferable to dope an organic electron transport material represented by a nitrogen-containing heterocyclic compound such as 4,7-diphenyl-1,10-phenanthroline or a metal complex such as an aluminum complex of 8-hydroxyquinoline with an alkali metal such as sodium, potassium, cesium, lithium, or cadmium (described in Japanese Patent Laid-Open No. 10-270171, Japanese Patent Laid-Open No. 2002-100478, Japanese Patent Laid-Open No. 2002-100482, etc.) because it can achieve excellent film quality with both electron injection and improved transport properties. The film thickness in this case 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 8 is formed by laminating on the light-emitting layer 5 or the hole blocking layer 6 or the electron transport layer 7 thereon by wet film forming method or vacuum evaporation method in the same manner as the light-emitting layer 5. The details in the case of the wet film forming method are the same as those in the case of the light-emitting layer 5.

<Cathode 9> Cathode 9 plays a role of injecting electrons into the layer (electron injection layer 8 or light-emitting layer 5, etc.) on the side of light-emitting layer 5. As the material of cathode 9, the material used in anode 2 can be used. However, in terms of efficient electron injection, it is preferable to use a metal with a low work function. As the material of cathode 9, for example, metals such as tin, magnesium, indium, calcium, aluminum, and silver or alloys thereof can be used. As the material of cathode 9, for example, alloy electrodes with low work functions such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy can be listed.

In terms of device stability, it is preferable to stack a metal layer having a high work function and being stable relative to the atmosphere on the cathode 9 to protect the cathode 9 made of a metal having a low work function. Examples of the stacked metal include aluminum, silver, copper, nickel, chromium, gold, and platinum.

The cathode film thickness is usually the same as that of the anode 2.

<Other constituent layers> The above description is centered on the element having the layer structure shown in FIG1 , but between the anode 2 and cathode 9 of the organic electroluminescent element of the present invention and the light-emitting layer 5 , any layers other than the layers described above may be present as long as their performance is not impaired. Any layers other than the light-emitting layer 5 may also be omitted.

For example, it is also effective to provide an electron blocking layer between the hole transport layer 4 and the light-emitting layer 5 for the same purpose as the hole blocking layer 8. The electron blocking layer has the following functions: by blocking the electrons moving from the light-emitting layer 5 from reaching the hole transport layer 4, the probability of recombination with holes in the light-emitting layer 5 is increased, and the generated excitons are confined in the light-emitting layer 5; and the holes injected from the hole transport layer 4 are efficiently transferred toward the light-emitting layer 5.

As the characteristics required for the electron blocking layer, high hole transport, large energy gap (difference between HOMO and LUMO), and high excited triplet energy level (T1) can be listed. In the case where the light-emitting layer 5 is formed by a wet film forming method, it is preferable that the electron blocking layer is also formed by a wet film forming method because it makes the device manufacturing easier. Therefore, the electron blocking layer is also preferably compatible with wet film forming. As materials used in such an electron blocking layer, copolymers of dioctylfluorene and triphenylamine represented by F8-TFB (International Publication No. 2004/084260) can be listed.

The structure may be the opposite of FIG. 1 , that is, cathode 9, electron injection layer 8, electron transport layer 7, hole blocking layer 6, luminescent layer 5, hole transport layer 4, hole injection layer 3, and anode 2 are sequentially stacked on substrate 1. The organic electroluminescent element of the present invention may also be disposed between two substrates, at least one of which has high transparency.

It is also possible to have a structure in which multiple levels of the layer structure shown in Figure 1 are stacked (a structure in which multiple light-emitting units are stacked). In this case, if, for example _{, V2O5} is used as a charge generation layer instead of the interface layer between the levels (light-emitting units) (in the case of the anode being indium tin oxide (ITO) and the cathode being Al, these two layers), the barriers between the levels are reduced, which is better from the perspective of light-emitting efficiency and driving voltage.

The present invention can be applied to any one of a single organic electroluminescent element, an element having a structure arranged in an array, and a structure in which the anode and the cathode are arranged in an X-Y matrix.

[Display device and lighting device] The display device and lighting device of the present invention use the organic electroluminescent element of the present invention. There is no particular limitation on the form or structure of the display device and lighting device of the present invention, and the organic electroluminescent element of the present invention can be used and assembled according to conventional methods. For example, the display device of the present invention can be formed by the method described in "Organic EL Display" (Ohmsha, published on August 20, 2004, written by Shizue Tokito, Chiba Ya Adachi, and Hideyuki Murata).

The following is a more specific description of the present invention by showing an embodiment. The present invention is not limited to the following embodiment, and the present invention can be implemented by any modification as long as it does not deviate from the main purpose of the present invention.

[Example 1] The following method was used to prepare an organic electroluminescent element.

For a transparent conductive film of indium-tin oxide (ITO) deposited to a thickness of 50 nm on a glass substrate, it was patterned into 2 mm wide stripes using conventional photolithography and hydrochloric acid etching to form an anode. The substrate with the ITO pattern was cleaned in the order of ultrasonic cleaning with a surfactant aqueous solution, washing with ultrapure water, ultrasonic cleaning with ultrapure water, and washing with ultrapure water, then dried with compressed air and finally cleaned with ultraviolet ozone.

As a composition for forming a hole injection layer, a composition was prepared by dissolving a hole transporting polymer compound represented by the following formula (P-1) at a concentration of 3.0 mass % and a compound represented by the following formula (HI-1) at a concentration of 0.3 mass % in ethyl benzoate.

[Chemistry 26]

The hole injection layer-forming composition was spin-coated on the substrate in the atmosphere, and dried on a hot plate at 240° C. for 30 minutes in the atmosphere to form a uniform thin film with a film thickness of 40 nm as a hole injection layer.

Next, a composition for forming a hole transport layer prepared by dissolving 3 mass % of a charge transporting polymer compound represented by the following structural formula (HT-1) in cyclohexylbenzene was spin-coated on the substrate on which the hole injection layer was formed in a nitrogen glove box, and dried at 230° C. for 30 minutes using a heating plate in the nitrogen glove box to form a uniform thin film with a film thickness of 43 nm as the hole transport layer.

[Chemistry 27]

Next, as materials for the light-emitting layer, 75 parts by mass of a polymer compound (Mw = 39000, Mw/Mn = 1.41) represented by the following structural formula (H-1), 25 parts by mass of a compound represented by the following structural formula (H-2), and 20 parts by mass of a compound represented by the following structural formula (D-1) were weighed and dissolved in cyclohexylbenzene in an amount of 6.0% by mass in total to prepare a composition for forming a light-emitting layer.

[Chemistry 28]

The composition for forming a luminescent layer was spin-coated on the substrate having the hole transport layer formed thereon in a nitrogen glove box, and dried at 120° C. for 20 minutes using a hot plate in the nitrogen glove box to form a uniform thin film with a thickness of 70 nm as a luminescent layer.

The substrate on which the light-emitting layer is formed is placed in a vacuum evaporation device, and the inside of the device is evacuated to a pressure below 2×10 ^-4 Pa.

Next, the compound represented by the following structural formula (HB-1) and 8-hydroxyquinolinium were co-deposited on the light-emitting layer at a film thickness ratio of 2:3 at a rate of 1 Å/sec by vacuum evaporation to form a hole blocking layer with a film thickness of 30 nm.

[Chemistry 29]

Next, as a mask for cathode evaporation, a 2 mm wide stripe-shaped shadow mask was placed in close contact with the substrate in a manner perpendicular to the ITO stripes of the anode, and set in another vacuum evaporation device. Aluminum was heated by a molybdenum boat to form an aluminum layer with a thickness of 80 nm at an evaporation rate of 1 Å/sec to 8.6 Å/sec to form a cathode.

Next, in a nitrogen glove box, a glass cap provided with a dehydrating sheet was placed so as to cover the evaporation part, and the periphery of the evaporation part was bonded and sealed to the glass cap using a UV curable resin.

By performing the above-described operations, an organic electroluminescent device having a light-emitting area portion with a size of 2 mm×2 mm was obtained.

[Example 2] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-2): (D-1) = 50:50:20.

[Example 3] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the composition for forming the light-emitting layer was (H-1): (H-3): (D-1) = 75:25:20. The structural formula of (H-3) is shown below.

[Chemistry 30]

[Comparative Example 1] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1):(D-1)=100:20.

[Evaluation of Element] The voltage (V) at which the organic electroluminescent elements prepared in Examples 1 to 3 and Comparative Example 1 emitted light at a brightness of 1000 cd/m ² was measured, and the difference from the voltage of Comparative Example 1 (voltage of Examples 1 to 3 and Comparative Example 1 - voltage of Comparative Example 1) was obtained as the voltage difference (V). The current luminous efficiency (cd/A) at which the organic electroluminescent elements prepared in Examples 1 to 3 and Comparative Example 1 emitted light at a brightness of 1000 cd/m ² was measured, and the relative value when the current luminous efficiency of Comparative Example 1 was set to 100 was obtained as the relative luminous efficiency. The external quantum efficiency (EQE) of the organic electroluminescent elements produced in Examples 1 to 3 and Comparative Example 1 when emitting light at a brightness of 1000 cd/m ² was obtained, and the relative value when the EQE of Comparative Example 1 was 100 was defined as the relative EQE. These evaluation results are shown in Table 1. As shown in Table 1, it can be seen that the organic electroluminescent element of the present invention has improved luminous efficiency and reduced voltage compared with the organic electroluminescent element of the comparative example.

[Table 1] Luminescent layer material composition (mass fraction) Voltage difference (V) Relative luminous efficiency Relative to EQE Embodiment 1 H-1:H-2:D-1 =75:25:20 -0.13 110 107 Embodiment 2 H-1:H-2:D-1 =50:50:20 -0.14 110 107 Embodiment 3 H-1:H-3:D-1 =75:25:20 -0.16 100 99 Comparison Example 1 H-1:D-1 =100:20 0 100 100

[Example 4] The device was prepared in the same manner as in Example 1 except that the compound represented by the following structural formula (H-4) was used instead of the compound represented by the structural formula (H-2), and the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-4): (D-1) = 75:25:20.

[Chemistry 31]

[Example 5] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-4): (D-1) = 50:50:20.

[Example 6] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-4): (D-1) = 25:75:20.

[Example 7] The device was prepared in the same manner as in Example 1 except that the compound represented by the following structural formula (H-5) was used instead of the structural formula represented by the structural formula (H-2), and the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-5): (D-1) = 75:25:20.

[Chemistry 32]

[Example 8] The device was prepared in the same manner as in Example 1 except that the compound represented by the following structural formula (H-6) was used instead of the compound represented by the structural formula (H-2), and the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-6): (D-1) = 75:25:20.

[Chemistry 33]

[Comparative Example 2] Prepare components in the same manner as in Comparative Example 1.

[Comparative Example 3] The device was prepared in the same manner as in Example 1 except that the compound represented by the following structural formula (H-7) was used instead of the compound represented by the structural formula (H-2), and the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-7): (D-1) = 75:25:20.

[Chemistry 34]

[Comparative Example 4] The device was prepared in the same manner as in Example 1 except that the compound represented by the following structural formula (D-2) was used instead of the compound represented by the structural formula (D-1), and the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-1): (H-4): (D-2) = 75:25:20.

[Chemistry 35]

[Comparative Example 5] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the light-emitting layer forming composition was (H-1): (H-5): (D-2) = 75:25:20.

[Comparative Example 6] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the light-emitting layer forming composition was set to (H-1): (H-6): (D-2) = 75:25:20.

[Comparative Example 7] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the light-emitting layer forming composition was (H-1): (H-7): (D-2) = 75:25:20.

[Evaluation of Element] The voltage (V) at which the organic electroluminescent elements prepared in Examples 4 to 8 and Comparative Examples 2 to 7 emitted light at a brightness of 1000 cd/m ² was measured, and the difference between the voltage of the element in Comparative Example 2 and the voltage of each element (voltage of Examples 4 to 8 and Comparative Examples 2 to 7 - voltage of Comparative Example 2) was determined as voltage difference (V). The external quantum efficiency (EQE) of the organic electroluminescent elements prepared in Examples 4 to 8 and Comparative Examples 2 to 7 when emitting light at a brightness of 1000 cd/m ² was determined, and the relative value of the EQE of each element when the EQE of Comparative Example 2 was set to 100 was determined as relative EQE. The organic electroluminescent elements prepared in Examples 4 to 8 and Comparative Examples 2 to 7 were driven at a constant current, and the time until the brightness dropped to 95% of the initial brightness was calculated with an initial brightness Lo = 3000 cd/m ² , and the relative value of the LT95 of each element when the LT95 of Comparative Example 2 was set to 100 was calculated as the relative driving life. These results are shown in Table 2. As shown in Table 2, it can be seen that the organic electroluminescent element of the present invention has a low voltage, a high luminous efficiency (EQE), and a long driving life.

[Table 2] Luminescent layer material composition (mass fraction) Voltage difference (V) Relative to EQE Relative drive life Embodiment 4 H-1:H-4:D-1 =75:25:20 -0.14 114 442 Embodiment 5 H-1:H-4:D-1 =50:50:20 -0.26 127 802 Embodiment 6 H-1:H-4:D-1 =25:75:20 +0.05 155 1040 Embodiment 7 H-1:H-5:D-1 =75:25:20 -0.24 110 420 Embodiment 8 H-1:H-6:D-1 =75:25:20 -0.18 132 272 Comparison Example 2 H-1:D-1 =100:20 0 100 100 Comparison Example 3 H-1:H-7:D-1 =75:25:20 -0.03 117 135 Comparison Example 4 H-1:H-4:D-2 =75:25:20 +2.83 94 0.3 Comparison Example 5 H-1:H-5:D-2 =75:25:20 +2.62 94 0.2 Comparison Example 6 H-1:H-6:D-2 =75:25:20 +9.12 twenty two 9 Comparison Example 7 H-1:H-7:D-2 =75:25:20 +6.86 27 0.01

[Example 9] The components were manufactured in the same manner as in Example 1.

[Comparative Example 8] The device was prepared in the same manner as in Example 1 except that the material composition (by mass) contained in the light-emitting layer forming composition was set to (H-1): (H-2): (D-2) = 75:25:20.

[Comparative Example 9] The device was prepared in the same manner as in Example 1 except that the polymer compound represented by the following structural formula (H-8) was used instead of the polymer compound represented by the structural formula (H-1), and the material composition (by mass) contained in the composition for forming the light-emitting layer was set to (H-8): (H-2): (D-1) = 75:25:20.

[Chemistry 36]

[Evaluation of device] The voltage (V) at which the organic electroluminescent devices manufactured in Example 9, Comparative Example 8 and Comparative Example 9 emitted light at a brightness of 1000 cd/m ² was measured, and the difference from the voltage in Comparative Example 2 (voltage in Example 9, Comparative Example 2, Comparative Example 8 and Comparative Example 9 - voltage in Comparative Example 2) was obtained as the voltage difference (V). The external quantum efficiency (EQE) of the organic electroluminescent devices manufactured in Example 9, Comparative Example 8 and Comparative Example 9 when emitting light at a brightness of 1000 cd/m ² was obtained, and the relative value when the EQE in Comparative Example 2 was set to 100 was set to the relative EQE. The organic electroluminescent elements prepared in Example 9, Comparative Example 8 and Comparative Example 9 were driven at a constant current, and the initial brightness Lo = 3000 cd/ ^m2 was converted to obtain the time until the brightness dropped to 95% of the initial brightness, which was taken as LT95 (hr). The relative value of LT95 of each element when LT95 of Comparative Example 2 was set to 100 was obtained as the relative driving life. These results are shown in Table 3. As shown in Table 3, it can be seen that the element of the present invention has a low voltage, a high luminous efficiency (EQE), and a high driving durability. On the other hand, the element of Comparative Example 9, in which the polymer compound contained in the luminescent layer does not include the structure represented by formula (2) of the present invention, has a high voltage and a low luminous efficiency.

[Table 3] Luminescent layer material composition (mass fraction) Voltage difference (V) Relative to EQE Relative drive life Embodiment 9 H-1:H-2:D-1 =75:25:20 -0.13 107 305 Comparison Example 2 H-1:D-1 =100:20 0 100 100 Comparative Example 8 H-1:H-2:D-2 =75:25:20 +3.28 85 205 Comparative Example 9 H-8:H-2:D-1 =75:25:20 +0.00 98 369

Although the present invention has been described in detail using specific aspects, it is obvious to those skilled in the art that various modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese Patent Application No. 2019-110408 filed on June 13, 2019 and is incorporated herein by reference in its entirety.

1: Substrate 2: Anode 3: Hole injection layer 4: Hole transport layer 5: Luminescent layer 6: Hole blocking layer 7: Electron transport layer 8: Electron injection layer 9: Cathode 10: Organic electroluminescent element

FIG. 1 is a cross-sectional view schematically showing an example of the structure of an organic electroluminescent element of the present invention.

1: Substrate

2: Anode

3: Hole injection layer

4: Hole transport layer

5: Luminescent layer

6: Hole blocking layer

7:Electron transmission layer

8: Electron injection layer

9: cathode

10: Organic electroluminescent element

Claims (11)

A composition for an organic electroluminescent device, comprising: a compound represented by the following formula (1); a polymer compound having a repeating unit having a structure represented by the following formula (2); a compound represented by the following formula (3), and a solvent;

In formula (1), R ¹ and R ² are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent; when there are a plurality of R ¹ and R ² , the plurality of R ¹ and R ² may be the same or different; adjacent R ¹ or R 2 bonded to the benzene ring may be any one of ² can be bonded to each other to form a ring condensed to the benzene ring; a is an integer of 0 to 4; b is an integer of 0 to 3; m is an integer of 1 to 20; n is an integer of 0 to 2; Ring A is any one of a pyridine ring, a pyrazine ring, a pyrimidine ring, an imidazole ring, an oxazole ring, a thiazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an aza-tris-benzene ring, and a carboline ring; Ring A may also have a substituent; the substituent is a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkyl group having 3 to 2 any one of a (hetero)aryloxy group having 0 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms, an arylsilyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 2 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 20 carbon atoms, or a combination thereof; adjacent substituents bonded to ring A may bond to each other to form a ring condensed to ring A; Z ¹ represents a direct bond or an m+1-valent aromatic linking group; L ¹ represents an auxiliary ligand; l is an integer of 1 to 3; when there are multiple auxiliary ligands, they may be different or the same;

In formula (2), R ³ and R ⁴ are independently any one of an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent;

In formula (3), ^X1 represents C or N; ^R5 to ^R7 are independently an alkyl group having 1 to 20 carbon atoms, a (hetero)aralkyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a (hetero)aryloxy group having 3 to 20 carbon atoms, an alkylsilanyl group having 1 to 20 carbon atoms, an arylsilanyl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, and a (hetero)aryl group having 3 to 30 carbon atoms, or a combination thereof; these groups may further have a substituent; when there are multiple ^R5 groups, the multiple ^{R5 groups} may be the same or different; the adjacent R5 groups bonded to the benzene ring may be any of: ^{wherein R6} and ^R7 are not simultaneously unsubstituted phenyl groups; and in the compound represented by the formula (3), the three partial structures of [phenyl-( ^R5 )c], ^R6 and ^R7 are not identical structures. When the partial structure has a substituent, the substituent is also included. The composition for an organic electroluminescent device as claimed in claim 1, wherein ^Z1 in the formula (1) is a direct bond. The composition for an organic electroluminescent device as claimed in claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (1-1);

In formula (1-1), three X ^2s simultaneously represent C or N; Z ² represents a direct bond or a p+1-valent aromatic linking group; Z ³ represents a direct bond or a q+1-valent aromatic linking group; p and q are integers of 1 to 10; R ¹ , R ² , a, b, n, m, ring A, L ¹ , and l have the same meanings as R ¹ , R ² , a, b, m, n, ring A, L ¹ , and l in formula (1). The composition for an organic electroluminescent device according to claim 1 or claim 2, wherein the compound represented by formula (1) is a compound represented by formula (1-2);

In formula (1-2), R ¹ , a, m, n, ring A, Z ¹ , L ¹ , and l have the same meanings as R ¹ , a, m, n, ring A, Z ¹ , L ¹ , and l in formula (1); R ¹⁵ to R ¹⁷ are substituents. The composition for an organic electroluminescent element as described in claim 1 or claim 2, wherein 1 in the formula (1) is 3. The composition for an organic electroluminescent device according to claim 1 or claim 2, wherein the polymer compound having a repeating unit having a structure represented by the formula (2) comprises a repeating unit represented by the following formula (2-1);

In formula (2-1), Ar ²¹ to Ar ²³ each independently represent a divalent (hetero)aryl group having 3 to 30 carbon atoms which may have a substituent; Ar ²⁴ and Ar ²⁵ each independently represent a (hetero)aryl group having 3 to 30 carbon atoms which may have a substituent; and r represents an integer of 0 to 2. The composition for an organic electroluminescent device according to claim 1 or claim 2, wherein the terminals of R ⁵ to R ⁷ in the compound represented by formula (3) independently contain a phenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, an indolecarbazolyl group, an indenocarbazolyl group or an indenofluorenyl group. A method for manufacturing an organic electroluminescent element, comprising the step of forming a luminescent layer by a wet film forming method using the organic electroluminescent element composition as described in any one of claim 1 to claim 7. An organic electroluminescent element having a light-emitting layer formed using the composition for an organic electroluminescent element as described in any one of claims 1 to 7. A display device having an organic electroluminescent element as described in claim 9. A lighting device having an organic electroluminescent element as described in claim 9.