WO2020235562A1

WO2020235562A1 - Composition for organic electroluminescent element, organic electroluminescent element, production method therefor, and display device

Info

Publication number: WO2020235562A1
Application number: PCT/JP2020/019788
Authority: WO
Inventors: 良子梶山; 和弘長山; 飯田　宏一朗
Original assignee: 三菱ケミカル株式会社
Priority date: 2019-05-20
Filing date: 2020-05-19
Publication date: 2020-11-26
Also published as: CN113874467A; TW202106696A; KR20220010598A; JPWO2020235562A1

Abstract

The present invention relates to a composition for an organic electroluminescent element comprising: a compound represented by formula (1) wherein a triazine ring has been substituted at a specific position; and a compound represented by formula (2), whereof the maximum light-emission wavelength is a shorter wave than that of the compound represented by formula (1); and a solvent.

Description

Compositions for organic electroluminescent devices, organic electroluminescent devices and their manufacturing methods, and display devices

The present invention relates to a composition for an organic electroluminescent device that is useful for forming a light emitting layer of an organic electroluminescent device (hereinafter, may be referred to as an "organic EL device"). The present invention also relates to an organic electroluminescent device having a light emitting layer formed by using the composition for the organic electroluminescent device, a method for manufacturing the organic electroluminescent device, and a display device having the organic electroluminescent device.

Various electronic devices that use organic EL elements, such as organic EL lighting and organic EL displays, have been put into practical use. Since the applied voltage of the organic electric field light emitting element is low, the power consumption is low and the three primary colors can be emitted. Therefore, the application to small and medium-sized displays represented by mobile phones and smartphones has begun as well as large display monitors. ..
An organic electroluminescent device is manufactured by stacking a plurality of layers such as a light emitting layer, a charge injection layer, and a charge transport layer. Currently, most organic electroluminescent elements are manufactured by vapor-depositing an organic material under vacuum, but the vacuum-deposited method complicates the vapor deposition process and is inferior in productivity. It is extremely difficult to increase the size of lighting and display panels with organic electroluminescent devices manufactured by the vacuum deposition method.

In recent years, a wet film forming method (coating method) has been studied as a process for efficiently manufacturing an organic electroluminescent element that can be used for a large-scale display or lighting. Since the wet film deposition method has an advantage that a stable layer can be easily formed as compared with the vacuum film deposition method, it is expected to be applied to mass production of displays and lighting devices and to large devices.
In order to manufacture an organic electroluminescent device by a wet film formation method, all the materials used must be soluble in an organic solvent and can be used as ink. If the material used is inferior in solubility, operations such as heating for a long time are required, so that the material may deteriorate before use. Further, if the uniform state cannot be maintained for a long time in the solution state, the material is precipitated from the solution, and the film formation by an inkjet device or the like becomes impossible. The material used in the wet film forming method is required to have solubility in two meanings: that it dissolves quickly in an organic solvent and that it does not precipitate after being dissolved and maintains a uniform state.

The advantage of the wet film deposition method over the vacuum film deposition method is that more material types can be used in one layer. In the vacuum deposition method, it becomes difficult to control the vapor deposition rate to a constant level as the number of material types increases, whereas in the wet film deposition method, even if the material types increase, as long as each material is dissolved in an organic solvent, it is sufficient. An ink having a constant component ratio can be produced.
In recent years, an attempt to improve the performance of an organic electroluminescent device by using two or more types of iridium complexes in an ink to increase the luminous efficiency of the organic electroluminescent device or lower the drive voltage by utilizing this advantage has been attempted. (For example, Patent Documents 1 and 2).

On the other hand, focusing on the chemical structure of the material, attempts have been made to use an iridium complex containing phenylpyridine in which the triazine ring is substituted at a specific position as a ligand as a red light emitting material in a white light emitting element (for example, Patent Documents). 3 and 4).

International Publication No. 2015/192939 International Publication No. 2016/015815 International Publication No. 2017/154884 Japanese Patent Application Laid-Open No. 2018-83941

However, the above-mentioned prior art is not sufficient in terms of the performance of the organic electroluminescent device for display applications, and in particular, further reduction of the drive voltage, improvement of luminous efficiency, and improvement of drive life of the red device. Was sought.
The present invention provides an organic electric field light emitting element capable of manufacturing an organic electric field light emitting element by a wet film forming method, particularly for a red element, having a lower driving voltage, higher light emitting efficiency, and a longer driving life than conventional ones. Make it an issue.

The present inventors have made diligent studies in view of the above problems in order to take advantage of the wet film formation method in which more material types can be used in one layer. As a result, an iridium complex having a relatively short maximum emission wavelength is used as an assist dopant, and an iridium complex containing phenylpyridine in which the triazine ring is substituted at a specific position is used as an emission dopant in the red element to assist. The present invention has been completed by finding that the performance of an organic electroluminescent element is improved by producing an organic electroluminescent element using a composition for an organic electroluminescent element in which a dopant and a light emitting dopant are dissolved in a solvent. I came to do.
It has also been found that the performance of the organic electroluminescent device is further improved by using the iridium complex, which is a light emitting dopant, in a composition ratio larger than that of the assist dopant.

The composition for an organic electroluminescent element according to the present invention contains an iridium complex whose maximum emission wavelength is a short wave with respect to the emission dopant as an assist dopant, and uses phenylpyridine in which the triazine ring is substituted at a specific position as a ligand. The containing iridium complex is contained as a light emitting dopant. Therefore, it is possible to manufacture an organic electroluminescent device having a lower drive voltage, higher luminous efficiency, and longer drive life than conventional ones. Further, in the composition for an organic electroluminescent device according to the present invention, by making the composition ratio of the light emitting dopant larger than the composition ratio of the assist dopant, light emission from the assist dopant can be suitably suppressed, and the light emission from the assist dopant can be suppressed more vividly. It is possible to manufacture an organic electroluminescent device having a light emitting color.

That is, the gist of the present invention is as follows.
[1] A compound represented by the following formula (1), a compound represented by the following formula (2) having a shorter maximum emission wavelength than the compound represented by the above formula (1), and a solvent are used. A composition for an organic electroluminescent device.

[In the above formula, R ¹ and R ² 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, and 3 carbon atoms, respectively. ~ 20 (hetero) aryloxy groups, 1 to 20 carbon atoms alkylsilyl groups, 6 to 20 carbon atoms arylsilyl groups, 2 to 20 carbon atoms alkylcarbonyl groups, 7 to 20 carbon atoms arylcarbonyl groups, It is an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. When a plurality of R ¹ and R ² exist, they may be the same or different from each other. If R ¹ there are a plurality bonded R ¹ adjacent to each other may form a ring.
a is an integer of 0 to 4, and b is an integer of 0 to 3.
R ³ and R ⁴ are independently hydrogen atom, fluorine atom, chlorine atom, bromine atom, alkyl group having 1 to 20 carbon atoms, (hetero) aralkyl group having 7 to 40 carbon atoms, and 1 to 20 carbon atoms, respectively. Alkoxy group, (hetero) aryloxy group having 3 to 20 carbon atoms, alkylsilyl group having 1 to 20 carbon atoms, arylsilyl group having 6 to 20 carbon atoms, alkylcarbonyl group having 2 to 20 carbon atoms, 7 carbon atoms. It is an arylcarbonyl group having up to 20 carbonyl groups, an alkylamino group having 2 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 20 carbon atoms. These groups may further have substituents. When a plurality of R ³ and R ⁴ exist, they may be the same or different from each other.
L ¹ represents an organic ligand, and m is an integer of 1 to 3. ]

[In the formula, ^{R 5} is an alkyl group having 1 to 20 carbon atoms, having 7 to 40 carbon atoms (hetero) aralkyl group, an alkoxy group having 1 to 20 carbon atoms, having 3 to 20 carbon atoms (hetero) aryloxy Group, alkylsilyl group with 1 to 20 carbon atoms, arylsilyl group with 6 to 20 carbon atoms, alkylcarbonyl group with 2 to 20 carbon atoms, arylcarbonyl group with 7 to 20 carbon atoms, alkylamino with 1 to 20 carbon atoms A group, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. If R ⁵ is plurally present, they may be the same or different.
c is an integer from 0 to 4.
Ring A is any of pyridine ring, pyrazine ring, pyrimidine ring, imidazole ring, oxazole ring, thiazole ring, quinoline ring, isoquinoline ring, quinazoline ring, quinoxaline ring, azatriphenylene ring, carboline ring, benzothiazole ring, and benzoxazole ring. Is it?
Ring A may have a substituent, which 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, and carbon. An alkoxy group having 1 to 20 carbon atoms, a (hetero) aryloxy group having 3 to 20 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms, an arylsilyl group having 6 to 20 carbon atoms, and 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, or a (hetero) aryl group having 3 to 20 carbon atoms. Further, adjacent substituents bonded to the ring A may be bonded to each other to further form a ring. When there are a plurality of rings A, they may be the same or different.
L ² represents an organic ligand, and n is an integer of 1 to 3. ]

[2] The organic electroluminescent device according to the above [1], wherein the composition ratio of the compound represented by the formula (1) is equal to or greater than the composition ratio of the compound represented by the formula (2) in terms of parts by mass. Composition for.
[3] The composition for an organic electric field light emitting element according to the above [1] or [2], wherein the compound represented by the formula (1) is a compound represented by the following formula (1-1).

[In the above ^{^{formulas, R 1, R 2, a}} , b, L 1, m , the ^R 1 in ^the formula ^{(1), R 2, a} , b, a ^L 1, m and respectively the same.
R ⁶ and R ⁷ are independently alkyl groups having 1 to 20 carbon atoms, (hetero) aralkyl groups having 7 to 40 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, and (heterogeneous) having 3 to 20 carbon atoms. ) Aryloxy group, alkylsilyl group with 1 to 20 carbon atoms, arylsilyl group with 6 to 20 carbon atoms, alkylcarbonyl group with 2 to 20 carbon atoms, arylcarbonyl group with 7 to 20 carbon atoms, 1 to 20 carbon atoms Alkylamino group, arylamino group having 6 to 20 carbon atoms, or (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. When a plurality of R ⁶ and R ⁷ exist, they may be the same or different from each other.
d and e are independently integers from 0 to 5. ]

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

[In the above ^{^{formulas, R 2 ~ R 4, b}} , L 1, m is, ^R 2 ^~ ^R 4 in the formula ^(1), b, is ^L 1, m and respectively the same.
R ¹⁴ to R ¹⁶ are substituents, and when a plurality of R ¹⁴ to R ¹⁶ are present, they may be the same or different from each other.
i is an integer from 0 to 4. ]

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

[In the above ^{^{^{formulas, R 2, R 6, R}}} 7, b, d, e, L 1, m is, ^R 2 in the formula ^{^{(1-1), R 6, R}} 7, b, d, e, L It is synonymous with ¹ and m, respectively.
R ¹⁴ to R ¹⁶ are substituents, and when a plurality of R ¹⁴ to R ¹⁶ are present, they may be the same or different from each other.
i is an integer from 0 to 4. ]

[6] For the organic electroluminescent device according to any one of the above [1] to [5], wherein the compound represented by the formula (2) is a compound represented by the following formula (2-1). Composition.

[In the above formula, Ring ^{A, L} 2, n, Ring A in the formula (2) ^{is L} 2, n and respectively the same.
R ⁸ has 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, and 1 carbon atom. Alkylsilyl group of ~ 20, arylsilyl group of 6-20 carbons, alkylcarbonyl group of 2-20 carbons, arylcarbonyl group of 7-20 carbons, alkylamino group of 1-20 carbons, 6 carbons It is an arylamino group of up to 20 or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. If R ⁸ is plurally present, they may be the same or different.
f is an integer from 0 to 5. ]

[7] The m in the formula (1) is less than 3, and L ¹ has at least one structure selected from the group consisting of the following formulas (3), (4), and (5). The composition for an organic electroluminescent device according to any one of [1] to [6].

[In the above formulas (3) to (5), R ⁹ and R ¹⁰ are synonymous with R ¹ in the above formula (1), and when a plurality of R ⁹ and R ¹⁰ exist, they are the same. May be different.
R ¹¹ to R ¹³ are independently substituted with an alkyl group having 1 to 20 carbon atoms which may be substituted with a hydrogen atom and a fluorine atom, a phenyl group which may be substituted with an alkyl group having 1 to 20 carbon atoms, or It is a halogen atom.
g is an integer from 0 to 4. h is an integer from 0 to 4.
Ring B is a pyridine ring, a pyrimidine ring, an imidazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an azatriphenylene ring, a carboline ring, a benzothiazole ring, or a benzoxazole ring. Ring B may further have a substituent. ]

[8] a in the formula (1) is 1, or, no ring a is an integer of 2 or more in the formula (1), and adjacent R ¹ are bonded to each other, wherein [1 ] To [7]. The composition for an organic electroluminescent device according to any one of.
[9] A method for producing an organic electroluminescent device, which comprises a step of forming a light emitting layer by a wet film forming method using the organic electroluminescent device composition according to any one of the above [1] to [8].
[10] An organic electroluminescent device having a light emitting layer formed by using the organic electroluminescent device composition according to any one of the above [1] to [8].
[11] A display device having the organic electroluminescent device according to the above [10].

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to manufacture an organic electroluminescent device by a wet film formation method, particularly for a red device, and it is possible to provide an organic electroluminescent device having a lower driving voltage, higher luminous efficiency, and a longer driving life than conventional devices. it can.

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

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.
In the present specification, the (hetero) aralkyl group, the (hetero) aryloxy group, and the (hetero) aryl group are an aralkyl group that may contain a heteroatom and an aryloxy group that may contain a heteroatom, respectively. Represents an aryl group, which may contain a heteroatom. "May contain heteroatoms" means that one or more carbon atoms forming an aryl skeleton in the main skeleton of an aryl group, an aralkyl group or an aryloxy group are substituted with heteroatoms. Indicates that you are. Examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, a silicon atom and the like, and among them, a nitrogen atom is preferable from the viewpoint of durability.

[Light emitting dopant]
The composition for an organic electroluminescent device according to the present embodiment contains a compound represented by the following formula (1), and such a compound mainly functions as a light emitting dopant. The compound represented by the formula (1) may contain only one type or a plurality of types. Further, the compound serving as a light emitting dopant may contain a compound serving as a light emitting dopant other than the compound represented by the formula (1), but in that case, the formula ( The total content of the compounds represented by 1) is preferably 50% by mass or more, more preferably 100% by mass. That is, it is more preferable that only the compound represented by the formula (1) is used.

In the above formula (1), R ¹ and R ² 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, and carbon. A (hetero) aryloxy group having 3 to 20 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, and an arylcarbonyl group having 7 to 20 carbon atoms. A group, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. When a plurality of R ¹ and R ² exist, they may be the same or different from each other. If R ¹ there are a plurality bonded R ¹ adjacent to each other may form a ring.
a is an integer of 0 to 4, and b is an integer of 0 to 3.

R ³ and R ⁴ are independently hydrogen atom, fluorine atom, chlorine atom, bromine atom, alkyl group having 1 to 20 carbon atoms, (hetero) aralkyl group having 7 to 40 carbon atoms, and 1 to 20 carbon atoms, respectively. Alkoxy group, (hetero) aryloxy group having 3 to 20 carbon atoms, alkylsilyl group having 1 to 20 carbon atoms, arylsilyl group having 6 to 20 carbon atoms, alkylcarbonyl group having 2 to 20 carbon atoms, 7 carbon atoms. It is an arylcarbonyl group having up to 20 carbonyl groups, an alkylamino group having 2 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 20 carbon atoms. These groups may further have substituents. When a plurality of R ³ and R ⁴ exist, they may be the same or different from each other.
L ¹ represents an organic ligand, and m is an integer of 1 to 3.

R ¹ to R ⁴ are independent of each other, and from the viewpoint of durability, 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 carbon. More preferably, it is a (hetero) aryl group having 3 to 30 carbon atoms or a (hetero) aryl group having 3 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms, a (hetero) aralkyl group having 7 to 40 carbon atoms, or the like. It is more preferably an (hetero) aryl group having 3 to 20 carbon atoms, and even more preferably an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 40 carbon atoms or an aryl group having 6 to 20 carbon atoms. preferable.
The substituents that R ¹ to R ⁴ may further have are preferably substituents selected from the substituent group Z described later.
when a is 2 or more, two adjacent R ¹ may be bonded to each other to form a ring.

R ¹ is more present, as the adjacent R ¹ are bonded to each other to form a ring, for example, fluorene, naphthalene, dibenzothiophene, and a dibenzofuran. From the viewpoint of stability, fluorene is particularly preferable.
It is preferred from the viewpoint of long-wavelength emission wavelengths can R ¹ adjacent one in which binding to the each other to form a ring.

Further, it is preferable the emission wavelength R ¹ adjacent from the viewpoint of not longer wavelength not intended to form a ring not bind to each other. That, a is 1 in formula (1), or, preferably has no ring a is 2 or more, and adjacent R ¹ are bonded to each other.

a is preferably 0 from the viewpoint of easy production, preferably 1 or 2 from the viewpoint of enhancing durability and solubility, and further preferably 1. b is preferably 0 from the viewpoint of easy production, and is preferably 1 from the viewpoint of enhancing solubility.
Since there are many structures having a high electron acceptability including a triazine ring and LUMO is more stabilized, m is preferably 2 or 3, and more preferably 3.

L ¹ is an organic ligand and is not particularly limited, but is preferably a monovalent bidentate ligand, and is more preferably selected from the following chemical formulas. The broken line in the chemical formula represents a coordination bond. When two organic ligands L ¹ is present, the organic ligand L ¹ may have a different structure from each other. Also, when m is 3, L ¹ does not exist.
When m in the formula (1) is less than 3, it is preferable that L ¹ has at least one structure selected from the group consisting of the following formulas (3), (4), and (5).

In the above formulas (3), (4) and (5), R ⁹ and R ¹⁰ are synonymous with R ¹ in the above formula (1). That is, it is selected from the same group as the substituent selected as R ¹ , and the preferred example is also the same, and may further have a substituent. When a plurality of R ⁹ and R ¹⁰ exist, they may be the same or different from each other.
R ¹¹ to R ¹³ are independently substituted with an alkyl group having 1 to 20 carbon atoms which may be substituted with a hydrogen atom and a fluorine atom, a phenyl group which may be substituted with an alkyl group having 1 to 20 carbon atoms, or It is a halogen atom.
g is an integer from 0 to 4. h is an integer from 0 to 4.
Ring B is a pyridine ring, a pyrimidine ring, an imidazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an azatriphenylene ring, a carboline ring, a benzothiazole ring, or a benzoxazole ring. Ring B may further have a substituent.

The substituents that R ⁹ , R ¹⁰ and Ring B may further have are preferably substituents selected from the Substituent Group Z described later.
Further preferable R ⁹ and R ¹⁰ are independently alkyl groups having 1 to 20 carbon atoms or aryl groups having 6 to 30 carbon atoms which may be substituted with alkyl groups having 1 to 20 carbon atoms. Here, the aryl group having 6 to 30 carbon atoms is a group in which a plurality of monocyclic, bicyclic condensed rings, tricyclic condensed rings, monocyclic, dicyclic fused rings, or tricyclic condensed rings are linked.

g and h are preferably 0 from the viewpoint of easy production, preferably 1 or 2 from the viewpoint of enhancing solubility, and even more preferably 1.
R ¹¹ to R ¹³ are independently substituted with an alkyl group having 1 to 20 carbon atoms which may be substituted with a hydrogen atom and a fluorine atom, and a phenyl group or a halogen which may be substituted with an alkyl group having 1 to 20 carbon atoms, respectively. Representing an atom, more preferably R ¹¹ and R ¹³ are methyl or t-butyl groups, and R ¹² is a hydrogen atom, an alkyl or phenyl group having 1 to 20 carbon atoms.

From the viewpoint of durability, the ring B is preferably a pyridine ring, a pyrimidine ring, or an imidazole ring, and more preferably a pyridine ring.
The hydrogen atom on the ring B has an alkyl group having 1 to 20 carbon atoms, a (hetero) aralkyl group having 7 to 40 carbon atoms, or a (hetero) aralkyl group having 3 to 20 carbon atoms (from the viewpoint of durability and enhanced solubility. It is preferably substituted with a hetero) aryl group.
Further, the hydrogen atom on the ring B is preferably not substituted from the viewpoint of easy production.
Further, since the hydrogen atom on the ring B tends to generate excitons when used as an organic electroluminescent element, a phenyl group or a naphthyl which may have a substituent may be provided from the viewpoint of increasing the luminous efficiency. It is preferably substituted with a group. The substituent that the phenyl group or the naphthyl group may have is preferably a substituent selected from the Substituent Group Z described later.

Further, the ring B may be a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an azatriphenylene ring, or a carboline ring from the viewpoint of increasing the luminous efficiency because excitons are easily generated on the assist dopant. preferable. Of these, a quinoline ring, an isoquinoline ring, and a quinazoline ring are more preferable in terms of durability and red light emission.
A more preferable substituent of the ring B is an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms which may be substituted with an alkyl group having 1 to 20 carbon atoms. Here, the aryl group having 6 to 20 carbon atoms is a group in which a plurality of monocyclic, bicyclic condensed rings, tricyclic condensed rings, monocyclic, dicyclic fused rings, or tricyclic condensed rings are linked.

As the compound represented by the formula (1), which is a light emitting dopant contained in the composition for an organic electroluminescent device according to the present embodiment, R ³ and R ⁴ are phenyl groups which may have a substituent. A compound, that is, a compound represented by the following formula (1-1) is preferable.

[In the above ^formulas, ^{R 1, R 2, a,} b, L 1, m is an ^{^{R 1, R 2, a,}} b, L 1, m and same meanings in the formula (1).
R ⁶ and R ⁷ are independently alkyl groups having 1 to 20 carbon atoms, (hetero) aralkyl groups having 7 to 40 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, and (heterogeneous) having 3 to 20 carbon atoms. ) Aryloxy group, alkylsilyl group with 1 to 20 carbon atoms, arylsilyl group with 6 to 20 carbon atoms, alkylcarbonyl group with 2 to 20 carbon atoms, arylcarbonyl group with 7 to 20 carbon atoms, 1 to 20 carbon atoms Alkylamino group, arylamino group having 6 to 20 carbon atoms, or (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. When a plurality of R ⁶ and R ⁷ exist, they may be the same or different from each other.
d and e are independently integers from 0 to 5. ]

From the viewpoint of durability, R ⁶ and R ⁷ have 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 an arylamino group having 3 to 30 carbon atoms. It is 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. It is more preferable that it is an alkyl group having 1 to 20 carbon atoms or an aralkyl group having 7 to 40 carbon atoms.
The substituents that R ⁶ and R ⁷ may further have are preferably substituents selected from the substituent group Z described later.

D and e are preferably 0 from the viewpoint of easy production, preferably 1 or 2 from the viewpoint of enhancing durability and solubility, and further preferably 1. b is preferably 0 from the viewpoint of easy production, and is preferably 1 from the viewpoint of enhancing solubility.

Emitting dopant of the formula contained in the composition for organic electroluminescence element of the present embodiment (1) is, a is equal to or greater than 2, the structure is that each other R ¹ adjacent to each to form a fluorene ring bonded preferable. Among them, the compound represented by the formula (1-2) is preferable.

[In the above ^{^{formulas, R 2 ~ R 4, b}} , L 1, m is an ^R 2 ^~ R 4 in the formula ^{(1), b, L 1} , m and respectively the same.
R ¹⁴ to R ¹⁶ are substituents, and when a plurality of R ¹⁴ to R ¹⁶ are present, they may be the same or different from each other.
i is an integer from 0 to 4. ]

R ¹⁴ is a substituent that substitutes for R ¹ when R ¹ is a phenyl group, and is preferably a substituent selected from the substituent group Z described later. More preferably, it is an aromatic hydrocarbon group having 6 to 30 carbon atoms which may be substituted with an alkyl group having 1 to 20 carbon atoms and an alkyl group having 1 to 20 carbon atoms. Here, the aromatic hydrocarbon group having 6 to 30 carbon atoms is a monocyclic, 2 to 4 ring fused ring, or a group in which a plurality of monocyclic or 2 to 4 ring fused rings are linked. An alkyl group having 1 to 20 carbon atoms is more preferable, and an alkyl group having 1 to 8 carbon atoms is even more preferable.
R ^15, ^{R 16} is a substituent in which a part or ^{R 1} in ^{R 1} is substituted for ^{R 1} when was a methyl group, preferably each independently, an alkyl group having 1 to 20 carbon atoms, carbon atoms It may be substituted with an alkyl group of 1 to 20 or an aromatic hydrocarbon group having 6 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms. It is an aromatic hydrocarbon group having 6 to 30 carbon atoms. Here, the aromatic hydrocarbon group having 6 to 30 carbon atoms is a monocyclic, 2 to 4 ring fused ring, or a group in which a plurality of monocyclic or 2 to 4 ring fused rings are linked. More preferably, it is an alkyl group having 1 to 20 carbon atoms, or an aromatic hydrocarbon group having 6 or 12 carbon atoms which may be substituted with an alkyl group having 1 to 20 carbon atoms, and more preferably. It is an aromatic hydrocarbon group having 6 carbon atoms which may be substituted with an alkyl group of 1 to 8 or an alkyl group having 1 to 8 carbon atoms. Here, the aromatic hydrocarbon structure having 6 carbon atoms has a benzene structure, and the aromatic hydrocarbon structure having 12 carbon atoms has a biphenyl structure.

Specific examples of preferable alkyl groups in R ¹⁴ to R ¹⁶ include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, isopropyl group and isobutyl. Examples thereof include a group, an isopentyl group, a t-butyl group, a cyclohexyl group, and a 2-ethylhexyl group.
Specific examples of the preferred aromatic hydrocarbon groups in R ¹⁴ to R ¹⁶ include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, and a benzpyrene ring having one free atomic value. , Chrysene ring, triphenylene ring, fluorantene ring, biphenyl group, terphenyl group and the like.
Specific examples of the preferred alkoxy group in R ¹⁵ and R ¹⁶ include a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a hexyloxy group, a cyclohexyloxy group, an octadecyloxy group and the like.

The compound serving as the light emitting dopant represented by the formula (1-1) contained in the composition for an organic electroluminescent device according to the present embodiment is more preferably the compound represented by the formula (1-3).

[In the above ^{^{^{formulas, R 2, R 6, R}}} 7, b, d, e, L 1, m ^{^{^{is, R 2, R 6, R}}} 7 in formula (1-1), b, d, e, L 1 , M are synonymous with each other.
R ¹⁴ to R ¹⁶ are substituents, and when a plurality of R ¹⁴ to R ¹⁶ are present, they may be the same or different from each other.
i is an integer from 0 to 4. ]

Substituents represented by R ¹⁴ ~ ^{R 16} are each a substituent represented by ^R 14 ^{~ R 16} in the formula (1-2) synonymous, and preferred ranges are also the same.

Hereinafter, preferred specific examples of the compound represented by the formula (1), which is a light emitting dopant contained in the composition for an organic electroluminescent device according to the present embodiment other than those shown in the examples, will be shown. It is not limited to.

[Assist Dopant]
The composition for an organic electroluminescent device according to the present embodiment contains a compound represented by the following formula (2), and such a compound mainly functions as an assist dopant. The compound represented by the formula (2) has a shorter maximum emission wavelength than the compound represented by the formula (1) which is the above-mentioned light emitting dopant. Therefore, when the assist dopant represented by the formula (2) is in the excited state, energy transfer to the light emitting dopant represented by the formula (1) having a smaller excitation energy occurs, so that the light emitting dopant is in the excited state. After that, light emission from the light emitting dopant is observed.
The compound represented by the formula (2) may contain only one kind or a plurality of kinds. Further, the compound serving as an assist dopant may contain a compound serving as an assist dopant other than the compound represented by the formula (2), but in that case, the formula ( The total content of the compounds represented by 2) is preferably 50% by mass or more, more preferably 100% by mass. That is, it is more preferable that only the compound represented by the formula (2) is used.

Further, it is preferable that the composition ratio of the compound represented by the formula (1) is equal to or higher than the composition ratio of the compound represented by the formula (2) in terms of parts by mass. As a result, it is possible to suppress the direct emission from the assist dopant represented by the formula (2), and the assist dopant represented by the formula (2) to the light emitting dopant represented by the formula (1) with high efficiency. Energy is transferred to. Therefore, light emission of the light emitting dopant can be obtained with high efficiency.

In the above formula, ^{R 5} is an alkyl group having 1 to 20 carbon atoms, (hetero) aralkyl groups having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, having 3 to 20 carbon atoms (hetero) aryloxy group , Alkylsilyl group with 1 to 20 carbon atoms, arylsilyl group with 6 to 20 carbon atoms, alkylcarbonyl group with 2 to 20 carbon atoms, arylcarbonyl group with 7 to 20 carbon atoms, alkylamino group with 1 to 20 carbon atoms , An arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. If R ⁵ is plurally present, they may be the same or different.
c is an integer from 0 to 4.
Ring A is any of pyridine ring, pyrazine ring, pyrimidine ring, imidazole ring, oxazole ring, thiazole ring, quinoline ring, isoquinoline ring, quinazoline ring, quinoxaline ring, azatriphenylene ring, carboline ring, benzothiazole ring, and benzoxazole ring. Is it?

Ring A may have a substituent.
Such substituents include a fluorine atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 20 carbon atoms, a (hetero) arylyl group having 7 to 40 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an alkoxy group having 3 to 20 carbon atoms. A (hetero) aryloxy group, an alkylsilyl group having 1 to 20 carbon atoms, an arylsilyl group having 6 to 20 carbon atoms in an aryl group, an alkylcarbonyl group having 2 to 20 carbon atoms, and 7 carbon atoms. It is an arylcarbonyl group having up to 20 carbon atoms, an alkylamino group having 2 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 20 carbon atoms. Further, adjacent substituents bonded to the ring A may be bonded to each other to further form a ring. When there are a plurality of rings A, they may be the same or different.
L ² represents an organic ligand, and n is an integer of 1 to 3.

The substituent that R ⁵ may further have is preferably a substituent selected from the Substituent Group Z described later.
From the viewpoint of durability, R ⁵ has 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) having 3 to 30 carbon atoms. ) Aryl group is more preferable, and 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 is further preferable. R ⁵ is a phenyl group which may have a substituent from the viewpoint of durability and solubility, and is preferably bonded to the m-position of ring A and the p-position of iridium. That is, it is preferable to contain a compound represented by the following formula (2-1). The substituent that may be possessed is preferably a substituent selected from the Substituent Group Z described later.

[In the above formula, Ring ^{A, L} 2, n are each a ring ^{A, L} 2, n in the formula (2) interchangeably.
R ⁸ has 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, and 1 carbon atom. Alkylsilyl group of ~ 20, arylsilyl group of 6-20 carbons, alkylcarbonyl group of 2-20 carbons, arylcarbonyl group of 7-20 carbons, alkylamino group of 1-20 carbons, 6 carbons It is an arylamino group of up to 20 or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. If R ⁸ is plurally present, they may be the same or different.
f is an integer from 0 to 5. ]

The substituent that R ⁸ may further have is preferably a substituent selected from the Substituent Group Z described later.
f is preferably 0 from the viewpoint of easy production, preferably 1 or 2 from the viewpoint of durability and enhancement of solubility, and further preferably 1.
From the viewpoint of durability, the ring A is preferably a pyridine ring, a pyrimidine ring, or an imidazole ring, and more preferably a pyridine ring.

The hydrogen atom on the ring A has an alkyl group having 1 to 20 carbon atoms, a (hetero) aralkyl group having 7 to 40 carbon atoms, and a (hetero) having 3 to 20 carbon atoms from the viewpoint of durability and enhanced solubility. ) It is preferably substituted with an aryl group. Further, the hydrogen atom on the ring A is preferably not substituted from the viewpoint of easy production. The hydrogen atom on the ring A is a phenyl group or a naphthyl group which may have a substituent from the viewpoint of improving the luminous efficiency because excitons are easily generated when it is used as an organic electroluminescent element. It is preferably substituted.

It is preferable that the ring A is a quinoline ring, an isoquinolin ring, a quinazoline ring, a quinoxalin ring, an azatriphenylene ring, or a carboline ring because excitons are easily generated on the assist dopant and the light emission efficiency is enhanced. Of these, a quinoline ring, an isoquinoline ring, and a quinazoline ring are preferable in terms of durability.
L ² is an organic ligand and is not particularly limited, but is preferably a monovalent bidentate ligand, and a more preferable example is the same as that shown as a preferable example of L ¹ . When two organic ligands L ² are present, the organic ligands L ² may have different structures from each other. Further, when n is 3, L ² does not exist.

Hereinafter, preferred specific examples of the compound represented by the formula (2), which is an assist dopant contained in the composition for an organic electroluminescent device according to the present embodiment other than those shown in the examples, will be shown. It is not limited to.

[Substituent group Z]
Substituents include alkyl groups, aralkyl groups, heteroaralkyl groups, alkoxy groups, aryloxy groups, heteroaryloxy groups, alkylsilyl groups, arylsilyl groups, alkylcarbonyl groups, arylcarbonyl groups, alkylamino groups and arylamino groups. , Aryl group, or heteroaryl group can be used.
Preferably, an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 40 carbon atoms, a heteroaralkyl 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, etc. Heteroaryloxy group with 3 to 20 carbon atoms, alkylsilyl group with 1 to 20 carbon atoms, arylsilyl group with 6 to 20 carbon atoms, alkylcarbonyl group with 2 to 20 carbon atoms, arylcarbonyl group with 7 to 20 carbon atoms , An alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a heteroaryl group having 3 to 30 carbon atoms, more specifically described later. It is the substituent described in [Specific example of substituent].
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. Is.

[Specific example of substituent]
Specific examples of the substituents in each of the above-mentioned compound structures and the substituents in the substituent group Z are as follows.
The alkyl group having 1 to 20 carbon atoms may be a linear, branched or cyclic alkyl group. More specifically, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, isopropyl group, isobutyl group, isopentyl group, t-butyl group. , Cyclohexyl group and the like. Of these, a linear alkyl group having 1 to 8 carbon atoms such as a methyl group, an ethyl group, an n-butyl group, an n-hexyl group and an n-octyl group is preferable.

The (hetero) aralkyl group having 7 to 40 carbon atoms is a group in which a part of hydrogen atoms constituting a linear alkyl group, a branched alkyl group, or a cyclic alkyl group is substituted with an aryl group or a heteroaryl group. Refers to. More specifically, 2-phenyl-1-ethyl group, cumyl group, 5-phenyl-1-pentyl group, 6-phenyl-1-hexyl group, 7-phenyl-1-heptyl group, tetrahydronaphthyl group and the like Can be mentioned. Of these, 5-phenyl-1-pentyl group, 6-phenyl-1-hexyl group and 7-phenyl-1-heptyl group are preferable.

Specific examples of the alkoxy group having 1 to 20 carbon atoms include a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a hexyloxy group, a cyclohexyloxy group, an octadecyloxy group and the like. Of these, a hexyloxy group is preferable.

Specific examples of the (hetero) aryloxy group having 3 to 20 carbon atoms include a phenoxy group and a 4-methylphenyloxy group. Of these, a phenoxy group is preferable.

Specific examples of the alkylsilyl group having 1 to 20 carbon atoms include a trimethylsilyl group, a triethylsilyl group, a triisopropylsilyl group, a dimethylphenyl group, a t-butyldimethylsilyl group, a t-butyldiphenylsilyl group and the like. .. Of these, a triisopropyl group, a t-butyldimethylsilyl group and a t-butyldiphenylsilyl group are preferable.

Specific examples of the arylsilyl group having 6 to 20 carbon atoms include a diphenylpyridylsilyl group and a triphenylsilyl group. Of these, a triphenylsilyl group is preferable.

Specific examples of the alkylcarbonyl group having 2 to 20 carbon atoms include an acetyl group, a propionyl group, a pivaloyl group, a caproyl group, a decanoyl group, a cyclohexylcarbonyl group and the like. Of these, an acetyl group and a pivaloyl group are preferable.

Specific examples of the arylcarbonyl group having 7 to 20 carbon atoms include a benzoyl group, a naphthoyl group, an antryl group and the like. Of these, a benzoyl group is preferable.

Specific examples of the alkylamino group having 1 to 20 carbon atoms include a methylamino group, a dimethylamino group, a diethylamino group, an ethylmethylamino group, a dihexylamino group, a dioctylamino group, a dicyclohexylamino group and the like. Of these, a dimethylamino group and a dicyclohexylamino group are preferable.

Specific examples of the arylamino group having 6 to 20 carbon atoms include a phenylamino group, a diphenylamino group, a di (4-tolyl) amino group, a di (2,6-dimethylphenyl) amino group and the like. Of these, a diphenylamino group and a di (4-tolyl) amino group are preferable.

The (hetero) aryl group having 3 to 30 carbon atoms is a linked aromatic hydrocarbon in which an aromatic hydrocarbon group, an aromatic heterocyclic group, and a plurality of aromatic hydrocarbons having one free atomic value are linked. It means a group, a linked aromatic heterocyclic group in which a plurality of aromatic heterocyclic groups are linked, or a group in which at least one or more aromatic hydrocarbons and aromatic heterocycles are arbitrarily linked.
Specific examples include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysen ring, a triphenylene ring, a fluorantene ring, and a furan ring, which have one free valence. Benzofuran ring, dibenzofuran ring, thiophene ring, benzothiophene ring, dibenzothiophene ring, pyrrol ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrrolomidazole ring, pyrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole Ring, thienothiophene ring, flopilol ring, flofuran ring, thienoflan ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, Examples include groups such as a cinnoline ring, a quinoxaline ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, and an azulene ring. Examples of the linked aromatic hydrocarbon group in which a plurality of aromatic hydrocarbons are linked include a biphenyl group and a terphenyl group.

Among the (hetero) aryl groups, a benzene ring, a naphthalene ring, a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, a pyridine ring, a pyrimidine ring, and a triazine ring having one free valence are preferable from the viewpoint of durability. Among them, an aryl group having 6 to 18 carbon atoms such as a benzene ring, a naphthalene ring or a phenanthrene ring, which has one free valence and may be substituted with an alkyl group having 1 to 8 carbon atoms, or 1 A pyridine ring having 1 free valence and may be substituted with an alkyl group having 1 to 4 carbon atoms is more preferable, and an alkyl group having 1 free valence and 1 to 8 carbon atoms. It is more preferably an aryl group having 6 to 18 carbon atoms, such as a benzene ring, a naphthalene ring or a phenanthrene ring which may be substituted with.

When the group in the compound has a plurality of substituents, the combination of these substituents includes, for example, a combination of an aryl group and an alkyl group, a combination of an aryl group and an aralkyl group, or an aryl group and an alkyl group. Combinations with aralkyl groups can be used, but are not limited thereto. As the combination of the aryl group and the aralkyl group, for example, a combination of a benzene, a biphenyl group, a terphenyl group, a 5-phenyl-1-pentyl group, and a 6-phenyl-1-hexyl group can be used.

[Maximum emission wavelength]
The method for measuring the maximum emission wavelength of the compound in the present embodiment is shown below.
The maximum emission wavelength of the compound can be determined from the photoluminescence spectrum of a solution in which the material is dissolved in an organic solvent, or the photoluminescence spectrum of a thin film of the material alone.
In the case of photoluminescence of a solution, a spectrophotometer (organic EL quantum yield measurement manufactured by Hamamatsu Photonics Co., Ltd.) is used for a solution in which a compound is dissolved in 2-methyl tetrahydrofuran at a concentration of 1 × 10 ^-4 mol / L or less at room temperature. The phosphorescence spectrum is measured with the apparatus C9920-02). The wavelength indicating the maximum value of the obtained phosphorescence spectral intensity is defined as the maximum emission wavelength.
In the case of thin film photoluminescence, a thin film is prepared by vacuum vapor deposition or solution coating of a material, photoluminescence is measured with the above spectrophotometer, and the wavelength indicating the maximum value of the obtained emission spectral intensity is set to the maximum emission. Let the wavelength be.
It is necessary to obtain and compare the maximum emission wavelengths of the compound used for the emission dopant and the compound used for the assist dopant by the same method.

The compound represented by the formula (2) as an assist dopant contained in the composition for an organic electroluminescent device according to the present embodiment has a maximum emission wavelength as compared with the compound represented by the formula (1) as a light emitting dopant. Is a short wave.
The maximum emission wavelength of the compound serving as the emission dopant is preferably 580 nm or more, more preferably 590 nm or more, further preferably 600 nm or more, preferably 700 nm or less, and more preferably 680 nm or less. When the maximum emission wavelength is in this range, it tends to be possible to express a preferable color of a red light emitting material suitable as an organic electroluminescent element.
It is preferable that the maximum emission wavelength of the compound serving as an assist dopant and the maximum emission wavelength of the compound serving as a light emitting dopant are separated by 10 nm or more because efficient energy transfer can be performed.

The compound represented by the formula (1) is preferably contained in the same amount as or more than the compound represented by the formula (2). That is, it is preferable that the composition ratio of the compound represented by the formula (1) in terms of parts by mass is equal to or higher than the composition ratio of the compound represented by the formula (2). The compound represented by the formula (1) is more preferably contained 1 to 3 times as much as the compound represented by the formula (2) in terms of parts by mass. From the viewpoint of luminous efficiency and long life of the device, the content is particularly preferably 1 to 2 times. It is more preferably contained twice or more from the viewpoint of obtaining more vivid light emission, and further preferably less than twice from the viewpoint of reducing the driving voltage of the element. As a result, the energy from the assist dopant is more efficiently transferred to the light emitting dopant, so that high luminous efficiency can be obtained and the life of the device is expected to be extended.

[Method for synthesizing iridium complex compound]
The compound represented by the formula (2) and the compound represented by the formula (1), which are the assist dopant and the light emitting dopant contained in the composition for the organic electroluminescent device according to the present embodiment, are both iridium complex compounds. The method for synthesizing the iridium complex compound is shown below.
The ligand of the iridium complex compound can be synthesized by a combination of known methods and the like. Ligand synthesis is performed by Suzuki-Miyaura coupling reaction between arylboronic acids and halogenated heteroaryls, Friedlayer cyclization reaction with 2-formyl or acylaniline, or acyl-aminopyridines at ortho positions with each other. It can be synthesized by a known reaction such as (Chem. Rev. 2009, 109, 2652, or Organic Reactions, 1982, 28 (2), 37-201).

The iridium complex compound can be synthesized by a combination of known methods using the above-mentioned ligand and iridium chloride n hydrate as raw materials. This will be described below.
As a method for synthesizing the iridium complex compound, for the sake of clarity, a method via a chlorine-bridged iridium binuclear complex as shown in the following formula [A] using a phenylpyridine ligand as an example (MG Colombo). , TC Brunold, T. Riedener, HU GudelInorg. Chem., 1994, 33, 545-550), further chlorine cross-linking with acetylacetonate from a dinuclear complex as shown in the following formula [B]. Method for obtaining the desired product after exchanging and converting to a mononuclear complex (S. Lamansky, P. Djurovich, D. Murphy, F. Abdel-Razzaq, R. Kwong, IT syba, M. Borz, B. Mui, R. Bau, M. Thompson, Inorg. Chem., 2001, 40, 1704-1711) and the like can be exemplified, but the present invention is not limited thereto.

For example, the typical reaction conditions represented by the following formula [A] are as follows. In the present specification, Et in the chemical formula means an ethyl group, and Tf means a trifluoromethylsulfonyl group.
As a first step, a chlorine-crosslinked iridium binuclear complex is synthesized by a reaction of 2 equivalents of the first ligand and 1 equivalent of iridium chloride n hydrate. As the solvent, a mixed solvent of 2-ethoxyethanol and water is usually used, but a solvent-free solvent or another solvent may be used. The reaction can be promoted by using an excessive amount of the ligand or by using an additive such as a base. Other crosslinkable anionic ligands such as bromine can be used instead of chlorine.

The reaction temperature is not particularly limited, but usually 0 ° C. or higher is preferable, and 50 ° C. or higher is more preferable. Further, 250 ° C. or lower is preferable, and 150 ° C. or lower is more preferable. When the reaction temperature is within this range, only the desired reaction proceeds without accompanying by-products or decomposition reactions, and high selectivity tends to be obtained.

In the second step, a halogen ion scavenger such as silver trifluoromethanesulfonate is added and brought into contact with the second ligand to obtain the desired complex. Although ethoxyethanol or diglyme is usually used as the solvent, no solvent or other solvent can be used depending on the type of ligand, and a plurality of solvents can be mixed and used. It is not always necessary because the reaction may proceed without the addition of a halogen ion scavenger, but the scavenger is used to increase the reaction yield and selectively synthesize facial isomers having a higher quantum yield. Is advantageous. The reaction temperature is not particularly limited, but is usually carried out in the range of 0 ° C. to 250 ° C.

The typical reaction conditions represented by the following formula [B] will be described.
The first-stage dinuclear complex can be synthesized in the same manner as in the formula [A].
In the second step, one equivalent or more of a 1,3-dione compound such as acetylacetone and a basic compound capable of extracting active hydrogen of the 1,3-dione compound such as sodium carbonate are added to the dinuclear complex. By reacting in an equivalent amount or more, it is converted into a mononuclear complex in which the 1,3-dionat ligand is coordinated. Usually, a solvent such as ethoxyethanol or dichloromethane that can dissolve the dinuclear complex of the raw material is used, but if the ligand is liquid, it can be carried out without a solvent. The reaction temperature is not particularly limited, but is usually carried out in the range of 0 ° C. to 200 ° C.

The third step is to react one or more equivalents of the second ligand. The type and amount of the solvent are not particularly limited, and may be solvent-free as long as the second ligand is liquid at the reaction temperature. The reaction temperature is also not particularly limited, but since the reactivity is slightly poor, the reaction is often carried out at a relatively high temperature of 100 ° C to 300 ° C. Therefore, a solvent having a high boiling point such as glycerin is preferably used.
After the final reaction, purification is performed to remove unreacted raw materials, reaction by-products and solvents. Purification operations in ordinary synthetic organic chemistry can be applied, but purification is mainly performed by normal phase silica gel column chromatography as described in the above non-patent documents. A single or mixed solution of hexane, heptane, dichloromethane, chloroform, ethyl acetate, toluene, methyl ethyl ketone, and methanol can be used as the developing solution. Purification may be performed multiple times under different conditions. Other chromatography techniques, such as reverse phase silica gel chromatography, size exclusion chromatography, paper chromatography, and purification operations such as liquid separation washing, reprecipitation, recrystallization, powder suspension washing, vacuum drying, etc., as required. Can be applied.

[Solvent, composition ratio]
The composition for an organic electroluminescent device according to this embodiment contains a solvent.
The composition for an organic electroluminescent device is usually used for forming a layer or a film by a wet film forming method, and is particularly preferably used for forming a light emitting layer of an organic electroluminescent device.
The content of the light emitting dopant in the composition for an organic electroluminescent device is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 20% by mass or less, preferably 10% by mass or less. is there. By setting the content of the light emitting dopant in this range, when the composition is used for an organic electroluminescent device application, the excitation energy is transferred to an adjacent layer, for example, a hole transport layer or a hole blocking layer. In addition, the emission efficiency can be improved because the extinction is less likely to occur due to the interaction between excitons. The content of the luminescent dopant is the total content of the compounds represented by the formula (1).

The content of the assist dopant in the composition for an organic electroluminescent device is usually 0.005% by mass or more, preferably 0.05% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less. is there. By setting the content of the assist dopant in this range, when the composition is used for an organic electroluminescent device application, it is efficient from an adjacent layer, for example, a hole transport layer or a hole blocking layer to a light emitting layer. Holes and electrons are injected, and the drive voltage can be reduced. The content of the assist dopant is the total content of the compounds represented by the formula (2).

The composition for an organic electroluminescent device may contain only one kind of compound serving as an assist dopant represented by the formula (2), or may contain two or more kinds in combination. However, when two or more kinds are included, the maximum emission wavelength of all the assist dopant compounds is shorter than the maximum emission wavelength of the emission dopant compound represented by the formula (1). Further, when two or more kinds of compounds serving as light emitting dopants represented by the formula (1) are contained, the maximum emitting wavelengths of all the assist dopant compounds are higher than the maximum light emitting wavelengths of all the light emitting dopant compounds. Is a short wave.

In the composition for an organic electroluminescent device, the composition ratio (mass%) of the compound represented by the formula (1) serving as a light emitting dopant is the composition ratio (mass%) of the compound represented by the formula (2) serving as an assist dopant. ) Is the same as or larger than that. By increasing the composition ratio of the compound serving as the light emitting dopant, the width of the light emitting spectrum becomes narrower and vivid light emission can be obtained when the organic electroluminescent device is used, which is suitable for display device applications. When two or more kinds of compounds serving as assist dopants are included, the total composition ratio (mass%) of the compounds serving as light emitting dopants is larger than the total composition ratios (mass%) of all the compounds serving as assist dopants. Larger is preferred.

It is more preferable that the compound serving as the light emitting dopant has 1 to 3 times the mass of the compound serving as the assist dopant. As a result, the energy from the assist dopant is transferred to the light emitting dopant more efficiently, so that higher luminous efficiency can be obtained. It is particularly preferable to have 1 to 2 times. From the viewpoint of obtaining more vivid light emission, the composition ratio (mass%) of the compound serving as the light emitting dopant is more preferably twice or more larger than the composition ratio (mass%) of the compound serving as the assist dopant. On the other hand, from the viewpoint of reducing the driving voltage of the device, the composition ratio (mass%) of the compound serving as the light emitting dopant is preferably less than twice the composition ratio (mass%) of the compound serving as the assist dopant.

The solvent contained in the composition for an organic electroluminescent device is a volatile liquid component used for forming a layer containing an assist dopant and a light emitting dopant by wet film formation.

The solvent is not particularly limited as long as it is a solvent in which a compound serving as an assist dopant as a solute and a compound serving as a light emitting dopant are dissolved well. Further, it is preferably a solvent that dissolves a charge transporting compound described later.
Preferred solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, bicyclohexane; aromatic hydrocarbons such as toluene, xylene, mesitylene, phenylcyclohexane, tetralin; chlorobenzene, dichlorobenzene, trichlorobenzene and the like. Halogenized aromatic hydrocarbons such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, etc. Aromatic ethers such as 2,4-dimethylanisole and diphenyl ether; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate; cyclohexanone, cycloocta Aromatic ketones such as non- and fencon; Aromatic alcohols such as cyclohexanol and cyclooctanol; Aromatic ketones such as methyl ethyl ketone and dibutyl ketone; Aromatic alcohols such as butanol and hexanol; Ethylene glycol dimethyl ether and ethylene Examples thereof include aliphatic ethers such as glycol diethyl ether and propylene glycol-1-monomethyl ether acetate (PGMEA). Of these, alcans and aromatic hydrocarbons are more preferable, and phenylcyclohexane is even more preferable because it has a preferable viscosity and boiling point in the wet film forming process.

One of these solvents may be used alone, or two or more of these solvents may be used 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, and particularly preferably 200 ° C. or higher. Within this range, it is possible to prevent the film formation stability from being lowered due to solvent evaporation from the composition for the organic electroluminescent device during wet film formation. The boiling point is usually 270 ° C. or lower, preferably 250 ° C. or lower, and more preferably 240 ° C. or lower.

The content of the solvent 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 parts by mass with respect to 100 parts by mass of the composition for an organic electroluminescent device. It is .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.
When the light emitting layer of the organic electroluminescent device is formed by the composition for an organic electroluminescent device, the thickness is usually about 3 to 200 nm, but the viscosity of the composition is increased by setting the solvent content to the above lower limit or more. It is possible to prevent the film formation workability from being lowered due to being too high. On the other hand, when the thickness is not more than the above upper limit, the thickness of the film obtained by removing the solvent after film formation is obtained to be a certain level or more, and the film forming property is improved.

[Charge transporting compound]
The composition for an organic electroluminescent device according to the present embodiment preferably further contains a charge transporting compound.
As the charge transporting compound, a compound conventionally used as a material for an organic electroluminescent device can be used. For example, triarylamine, biscarbazole, triaryltriazine, triarylpyrimidine and its derivatives, naphthalene, perylene, pyrene, anthracene, chrysene, naphthalene, phenanthrene, coronene, fluoranthene, benzo substituted with arylamino or carbazolyl groups. Examples thereof include condensed aromatic ring compounds such as phenanthrene, fluorene and acetnaphthofluoranthene.

Further, the charge transporting compound may be a polymer, and the polymer charge transporting compound includes poly (9,9-dioctylfluorene-2,7-diyl) and poly [(9,9-dioctylfluorene). -2,7-diyl) -co- (4,4'-(N- (4-sec-butylphenyl)) diphenylamine)], poly [(9,9-dioctylfluorene-2,7-diyl) -co -(1,4-Benzo-2 {2,1'-3} -triazole)] and other polyfluorene-based materials, poly [2-methoxy-5- (2-hetylhexyloxy) -1,4-phenylene vinylene ] And other polyphenylene vinylene-based materials.
One of these charge transporting compounds may be used alone, or two or more of these may be used in any combination and ratio.

[Organic electroluminescent device]
The organic electroluminescent device according to the present embodiment includes a layer formed by using the above composition for an organic electroluminescent device, preferably by a wet film forming method.
The organic electroluminescent device preferably has at least an anode, a cathode, and at least one organic layer between the anode and the cathode on the substrate, and at least one of the organic layers relates to the present embodiment. This is a layer formed by using a composition for an organic electroluminescent device. It is more preferable that such a layer is formed by a wet film forming method. Further, although the organic layer includes a light emitting layer, it is more preferable that the light emitting layer is a layer formed by using the composition for an organic electroluminescent device according to the present embodiment.

In the present specification, the wet film forming method is a film forming method, that is, as a coating method, for example, a spin coating method, a dip coating method, a die coating method, a bar coating method, a blade coating method, a roll coating method, a spray coating method, and the like. We adopt methods such as capillary coating method, inkjet method, nozzle printing method, screen printing method, gravure printing method, flexographic printing method, etc., and dry the film formed by these methods to form a film. Refers to the method of doing.

FIG. 1 is a schematic cross-sectional view showing a structural example suitable for the organic electroluminescent device 10 of the present invention. In FIG. 1, reference numeral 1 is a substrate, reference numeral 2 is an anode, reference numeral 3 is a hole injection layer, reference numeral 4 is a hole transport layer, reference numeral 5 is a light emitting layer, reference numeral 6 is a hole blocking layer, and reference numeral 7 is an electron transport layer. , Reference numeral 8 represents an electron injection layer, and reference numeral 9 represents a cathode.
As the material applied to these structures, known materials can be applied, and there is no particular limitation, but typical materials and manufacturing methods for each layer are described below as examples. In the following, when citations such as gazettes and treatises are cited, the relevant contents can be appropriately applied and applied within the scope of common sense of those skilled in the art.

<Board 1>
The substrate 1 serves as a support for an organic electroluminescent element, and usually a quartz or glass plate, a metal plate, a metal foil, or a synthetic resin, that is, a plastic film or sheet is used. Of these, a glass plate or a transparent synthetic resin film such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. The substrate 1 is preferably made of a material having a high gas barrier property because the organic electroluminescent element is unlikely to be deteriorated by the outside air. In particular, when a material having a low gas barrier property such as a synthetic resin substrate is used, it is preferable to provide a dense silicon oxide film or the like on at least one surface of the substrate 1 to improve the gas barrier property.

<Anode 2>
The anode 2 has a function of injecting holes into the layer on the light emitting layer side. The anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum; a metal oxide such as an oxide of indium and / or tin; a metal halide such as copper iodide; carbon black or poly (3). -Methylthiophene), polypyrrole, polyaniline and other conductive polymers.

The anode 2 is usually formed by a dry method such as a sputtering method or a vacuum vapor deposition method. When the anode 2 is formed by using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, conductive polymer fine powder, etc., it is dispersed in an appropriate binder resin solution. It can also be formed by coating it on the substrate 1. In the case of a conductive polymer, the anode 2 can be formed by directly forming a thin film on the substrate by electrolytic polymerization or by applying the conductive polymer on the substrate (Appl. Phys. Lett., Volume 60, p. 2711, 1992).

The anode 2 usually has a single-layer structure, but may have a laminated structure as appropriate. When the anode 2 has a laminated structure, different conductive materials may be laminated on the first-layer anode.
The thickness of the anode 2 may be determined according to the required transparency, material, and the like. When particularly high transparency is required, a thickness having a visible light transmittance of 60% or more is preferable, and a thickness having a visible light transmittance of 80% or more is more preferable. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

When transparency is not required, the thickness of the anode 2 may be any thickness depending on the required strength and the like. In this case, the anode 2 may have the same thickness as the substrate 1.
When the next layer is formed on the surface of the anode 2 after it is formed, impurities on the anode are removed by treating with ultraviolet rays + ozone, oxygen plasma, argon plasma, etc. before the film formation. At the same time, it is preferable to adjust the ionization potential to improve the hole injection property.

<Hole injection layer 3>
The layer having a function of transporting holes from the anode 2 side to the light emitting layer 5 side is usually called a hole injection transport layer or a hole transport layer. When there are two or more layers having a function of transporting holes from the anode 2 side to the light emitting layer 5, the layer closer to the anode 2 side may be referred to as the hole injection layer 3.
Hereinafter, the hole injection layer 3 will be described, but the hole injection transport layer or the hole transport layer when the layer responsible for the hole transport function is one layer will also be described as the hole injection layer 3. .. That is, the hole transport layer 4, which will be described later, is different from the hole transport layer when the layer responsible for transporting holes is one layer, and is on the light emitting layer 5 side when such layers are two or more layers. The name of the closer layer, which is an arbitrary layer.
The hole injection layer 3 is preferably used because it enhances the function of transporting holes from the anode 2 to the light emitting layer 5. When the hole injection layer 3 is used, the hole injection layer 3 is usually formed on the anode 2.

The film thickness of the hole injection layer 3 is usually 1 nm or more, preferably 5 nm or more, and usually 1000 nm or less, preferably 500 nm or less.
The hole injection layer 3 may be formed by either a vacuum vapor deposition method or a wet film deposition method. In terms of excellent film forming property, it is preferably formed by a wet film forming method.
The hole injection layer 3 preferably contains a hole transporting compound, and more preferably contains a hole transporting compound and an electron accepting compound. Further, the hole injection layer 3 preferably contains a cation radical compound, and particularly preferably contains a cation radical compound and a hole transporting compound.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound that becomes the hole injection layer 3.
In the case of the wet film forming method, a solvent is usually further contained. It is preferable that the composition for forming a hole injection layer has high hole transportability and can efficiently transport the injected holes. For this reason, it is preferable that the hole mobility is high and impurities that serve as traps are unlikely to be generated during production or use. Further, it is preferable 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, that is, when the layer having a function of transporting holes from the anode 2 side to the light emitting layer 5 side is one layer of the hole injection layer 3, the light emitting layer It is preferable that the light emitted from No. 5 is not extinguished, or that the light emitting layer 5 and the light emitting layer 5 are formed with an exciplex so as not to reduce the luminous efficiency.

As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole-transporting compounds include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, compounds in which a tertiary amine is linked with a fluorene group, and hydrazone. Examples thereof include system compounds, silazane compounds, and quinacridone compounds.

Among the above-mentioned exemplified compounds, an aromatic amine compound is preferable, and an aromatic tertiary amine compound is particularly preferable from the viewpoint of amorphousness and visible light transmission. The aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and also includes a compound having a group derived from an aromatic tertiary amine.
The type of the aromatic tertiary amine compound is not particularly limited, but a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerized compound in which repeating units are continuous) is easy to obtain uniform light emission due to the surface smoothing effect. It is preferable to use. Preferred examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

In formula (I), Ar ¹ and Ar ² are independently monovalent aromatic groups which may have a substituent or monovalent complex aromatic groups which may have a substituent. Represents. Ar ³ to Ar ⁵ each independently represent a divalent aromatic group which may have a substituent or a divalent heteroaromatic group which may have a substituent. Q represents a linking group selected from the following linking group group. Further, of Ar ¹ to Ar ⁵ , two groups bonded to the same N atom may be bonded to each other to form a ring.
The linking groups are shown below.

(In the above formulas, Ar 6 ^~ Ar ¹⁶ are each independently, .R ^a represents an heteroaromatic group optionally having an optionally substituted aromatic group or a substituent and R ^b each independently represents a hydrogen atom or any substituent.)

The aromatic groups and heteroaromatic groups of Ar ¹ to Ar ¹⁶ include a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, and a pyridine ring in terms of solubility, heat resistance, and hole injection transportability of the polymer compound. Derived groups are preferable, and groups derived from benzene rings and naphthalene rings are more preferable.
Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (I) include those described in International Publication No. 2005/089024.

(Electron accepting compound)
Since the hole injection layer 3 can improve the conductivity of the hole injection layer 3 by oxidizing the hole transporting compound, it is preferable that the hole injection layer 3 contains an electron accepting compound.
As the electron-accepting compound, a compound having an oxidizing power and an ability to accept one electron from the hole-transporting compound described above is preferable. Specifically, a compound having an electron affinity of 4 eV or more is more preferable, and a compound having an electron affinity of 5 eV or more is further preferable.

Examples of such an electron-accepting compound include a triarylboron compound, a metal halide, a Lewis acid, an organic acid, an onium salt, a salt of an arylamine and a metal halide, and a salt of an arylamine and a Lewis acid. Examples thereof include one or more compounds selected from the group consisting of two or more compounds. Specifically, onium salts substituted with organic groups such as 4-isopropyl-4'-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium tetrafluoroborate (International Publication No. 2005/089024); chloride. High valence inorganic compounds such as iron (III) (Japanese Patent Laid-Open No. 11-251667), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; tris (pentafluorophenyl) borane (Japanese Patent Laid-Open No. 20033-) Aromatic boron compounds such as (No. 31365); fullerene derivatives, iodine and the like can be mentioned.

(Cation radical compound)
As the cation radical compound, an ionic compound composed of a cation radical, which is a chemical species obtained by removing one electron from a hole transporting compound, and a counter anion is preferable. When the cation radical is derived from a hole-transporting polymer compound, the cation radical has a structure in which one electron is removed from the repeating unit of the polymer compound.

The cation radical is preferably a chemical species obtained by removing one electron from the above-mentioned compound as a hole-transporting compound in terms of amorphousness, visible light transmittance, heat resistance, solubility and the like. ..
The cationic radical compound can be produced by mixing the hole transporting compound and the electron accepting compound described above. By mixing the above-mentioned hole-transporting compound and electron-accepting compound, electron transfer occurs from the hole-transporting compound to the electron-accepting compound, and the hole-transporting compound consists of a cation radical and a counter anion. A cationic radical compound is produced.

Examples of the cationic radical compound include poly (3,4-ethylenedioxythiophene) (PEDOT / PSS) (Adv. Matter., 2000, Vol. 12, p. 481) doped with poly (4-styrene sulfonic acid) and emeraldine. Cationic radical compounds derived from polymer compounds such as hydrochloride (J. Phys. Chem., 1990, Vol. 94, p. 7716) are also produced by oxidative polymerization (dehydropolymerization).
The oxidative polymerization referred to here is to chemically or electrochemically oxidize a monomer in an acidic solution using peroxodisulfate or the like. In the case of this oxidative polymerization (dehydrogenation), a cation radical obtained by removing one electron from a repeating unit of a polymer, which is polymerized by oxidizing a monomer and has an anion derived from an acidic solution as a counter anion, is generated. Generate.

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

The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but it is preferably low from the viewpoint of film thickness uniformity, and hole injection A higher layer is preferable from the viewpoint that defects are less likely to occur in the layer 3. The concentration of the hole transporting compound in the composition for forming a hole injection layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and further. It is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.

Examples of the solvent include ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, amide-based solvents and the like.
Examples of the ether-based solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and anisole. , Fenetol, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole and other aromatic ethers.

Examples of the ester-based 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, methylnaphthalene and the like.

Examples of the amide solvent include N, N-dimethylformamide, N, N-dimethylacetamide and the like.
In addition to these, dimethyl sulfoxide and the like can also be used.

The formation of the hole injection layer 3 by the wet film formation method is usually performed on a layer corresponding to the lower layer of the hole injection layer 3, usually on the anode 2, after preparing the composition for forming the hole injection layer. It is carried out by coating and forming a film and drying. In the hole injection layer 3, the coating film is usually dried by heating, vacuum drying, or the like after the film formation.

(Formation of hole injection layer 3 by vacuum deposition method)
When the hole injection layer 3 is formed by the vacuum vapor deposition method, usually one or more of the constituent materials of the hole injection layer 3, that is, the hole transporting compound, the electron accepting compound, and the like described above are used. Put it in the crucible installed in the vacuum container. At this time, when two or more kinds of materials are used, each is usually put in a separate crucible. After that, the inside of the vacuum vessel is evacuated to about 10 ^-4 Pa with a vacuum pump, and then the crucible is heated to evaporate the material in the crucible while controlling the amount of evaporation. When two or more kinds of materials are used, each crucible is usually heated and evaporated while controlling the amount of evaporation independently. By such an operation, the hole injection layer 3 is formed on the anode 2 on the substrate placed facing the crucible. When two or more kinds of materials are used, they can be put into a crucible as a mixture, heated and evaporated to form the hole injection layer 3.

The degree of vacuum during vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 ^-6 Torr (0.13 × 10 ^-4 Pa) or more, 9.0 × 10 ^-6 Torr ( It is 12.0 × 10 ^-4 Pa) or less. The vapor deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / sec or more and 5.0 Å / sec or less. The film formation temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher and 50 ° C. or lower.

<Hole transport layer 4>
The hole transport layer 4 is a layer that has a function of transporting holes from the anode 2 side to the light emitting layer 5. Although the hole transport layer 4 is not an essential layer in the organic electroluminescent device according to the present embodiment, it is preferable to provide the hole transport layer 4 from the viewpoint of enhancing 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 there is a hole injection layer 3, the hole transport layer 4 is formed between the hole injection layer 3 and the light emitting layer 5.

The film 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 either a vacuum vapor deposition method or a wet film deposition method. From the viewpoint of excellent film forming property, it is preferable to form by a wet film forming method.

The hole transport layer 4 usually contains a hole transport compound that becomes the hole transport layer 4. Examples of the hole-transporting compound contained in the hole-transporting layer 4 include two or more tertiary compounds represented by 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl. Aromatic diamine containing amine and having two or more fused aromatic rings replaced with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), 4,4', 4''-tris (1-naphthylphenylamino) tri Aromatic amine compounds having a starburst structure such as phenylamine (J. Lumin., 72-74, pp. 985, 1997), aromatic amine compounds consisting of triphenylamine tetramers (Chem. Commun., 2175, 1996), 2,2', 7,7'-tetrax- (diphenylamino) -9,9'-spirobifluorene and other spiro compounds (Synth. Metals, 91, 209, 1997). , 4,4'-N, N'-dicarbazolebiphenyl and other carbazole derivatives and the like. Polyvinylcarbazole, polyvinyltriphenylamine (Japanese Patent Laid-Open No. 7-53953), polyarylene ether sulfone containing tetraphenylbenzidine (Polym. Adv. Tech., Vol. 7, p. 33, 1996) and the like are also preferable. Can be used.

(Formation of hole transport layer 4 by wet film formation method)
When the hole transport layer 4 is formed by the wet film forming method, usually, in the same manner as when the hole injection layer 3 is formed by the wet film forming method, instead of the hole injection layer forming composition. It is formed using a composition for forming a hole transport layer.
When the hole transport layer 4 is formed by the wet film formation method, the hole transport layer forming composition usually further contains a solvent. As the solvent used in the hole transport layer forming composition, the same solvent as the solvent used in the hole injection layer forming composition described above can be used.

The concentration of the hole-transporting compound in the composition for forming the hole-transporting layer can be in the same range as the concentration of the hole-transporting compound in the composition for forming the hole-injecting layer.
The hole transport layer 4 can be formed by the wet film formation method in the same manner as the hole injection layer 3 film formation method described above.

(Formation of hole transport layer 4 by vacuum deposition method)
When the hole transport layer 4 is formed by the vacuum vapor deposition method, holes are usually used instead of the constituent materials of the hole injection layer 3 in the same manner as when the hole injection layer 3 is formed by the vacuum vapor deposition method. It can be formed using the constituent materials of the transport layer 4. The film formation conditions such as the degree of vacuum, the vapor deposition rate, and the temperature at the time of vapor deposition can be the same as those at the time of vacuum vapor deposition of the hole injection layer 3.

<Light emitting layer 5>
The light emitting layer 5 is a layer having a function of emitting light by being excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 when an electric field is applied between the pair of electrodes. ..
The light emitting layer 5 is a layer formed between the anode 2 and the cathode 9. The light emitting layer 5 is formed between the hole injection layer 3 and the cathode 9 when the hole injection layer 3 is above the anode 2, and is positive when the hole transport layer 4 is above the anode 2. It 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, but a thick film thickness is preferable from the viewpoint that defects are unlikely to occur in the film, and a thin film thickness is preferable from the viewpoint that a low driving voltage is likely to occur. .. The film thickness of the light emitting layer 5 is preferably 3 nm or more, more preferably 5 nm or more, and usually 200 nm or less, further preferably 100 nm or less.
The light emitting layer 5 is preferably formed using the composition for an organic electroluminescent device according to the present embodiment, and more preferably formed by a wet coating method.
In addition to the light emitting layer formed by the wet coating method using the composition for an organic electroluminescent device according to the present embodiment, the organic electroluminescent device may contain other light emitting materials and charge transporting materials. The luminescent material and the charge transporting material of the above will be described in detail.

(Luminescent material)
The light emitting material is not particularly limited as long as it emits light at a desired light emitting wavelength and the effect of the present invention is not impaired, and a known light emitting material can be applied. The light emitting material may be either a fluorescent light emitting material or a phosphorescent light emitting material, but a material having good luminous efficiency is preferable, and a phosphorescent light emitting material is preferable from the viewpoint of internal quantum efficiency.

Examples of the fluorescent light emitting material include the following materials.
Examples of the fluorescent light emitting material (blue fluorescent light emitting material) that gives blue light emission include naphthalene, perylene, pyrene, anthracene, coumarin, chrysene, p-bis (2-phenylethenyl) benzene, and derivatives thereof.
The fluorescent light-emitting material giving green luminescence (green fluorescent material), for example, quinacridone derivatives, coumarin _derivatives, aluminum complexes such as _{_{Al (C 9 H 6 NO)}} 3 and the like.

Examples of the fluorescent light emitting material (yellow fluorescent light emitting material) that gives yellow light emission include rubrene, a perimidone derivative, and the like.
Examples of the fluorescent light emitting material (red fluorescent light emitting material) that gives red light emission include DCM (4- (dimethyanomethylene) -2-methyl-6- (p-dimethylaminostylyl) -4H-pyran) compounds, benzopyran derivatives, and rhodamine derivatives. , Benzothioxanthene derivatives, azabenzothioxanthene and the like.

As the phosphorescent material, for example, from the 7th to 11th groups of the long periodic table (hereinafter, unless otherwise specified, the term "periodic table" refers to the long periodic table). Examples thereof include an organic metal complex containing a selected metal. The metal selected from Groups 7 to 11 of the periodic table is preferably ruthenium, rhodium, palladium, silver, renium, osmium, iridium, platinum, gold and the like.

As the ligand of the organic metal complex, a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or a (hetero) arylpyrazole ligand is linked to a pyridine, pyrazole, phenanthroline or the like is preferable. In particular, a phenylpyridine ligand and a phenylpyrazole ligand are preferable. Here, the (hetero) aryl group represents at least one of an aryl group and a heteroaryl group.

Specific preferred phosphorescent materials include tris (2-phenylpyridine) iridium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, bis (2-phenylpyridine) platinum, and tris (2). -Finylpyridine complexes such as osmium and tris (2-phenylpyridine) renium and porphyrin complexes such as octaethyl platinum porphyrin, octaphenyl platinum porphyrin, octaethyl palladium porphyrin and octaphenyl palladium porphyrin can be mentioned.

Polymer-based luminescent materials include poly (9,9-dioctylfluorene-2,7-diyl) and poly [(9,9-dioctylfluorene-2,7-diyl) -co- (4,4'-). (N- (4-sec-butylphenyl)) diphenylamine)], poly [(9,9-dioctylfluorene-2,7-diyl) -co- (1,4-benzo-2 {2,1'-3) } -Triazole)] and other polyfluorene-based materials, and poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene] and other polyphenylene vinylene-based materials can be mentioned.

(Charge transport material)
The charge transporting material is a material having positive charge (hole) or negative charge (electron) transportability, and is not particularly limited as long as the effects of the present invention are not impaired, and known materials can be applied.
As the charge transporting material, a compound or the like conventionally used for the light emitting layer 5 of the organic electroluminescent device can be used, and a compound used as a host material for the light emitting layer 5 is particularly preferable.

Specific examples of the charge transporting material include aromatic amine compounds, phthalocyanine compounds, porphyrin compounds, oligothiophene compounds, polythiophene compounds, benzylphenyl compounds, and compounds in which a tertiary amine is linked with a fluorene group. , Hydrazone-based compounds, silazane-based compounds, silanamine-based compounds, phosphamine-based compounds, quinacridone-based compounds, and other compounds exemplified as hole-transporting compounds in the hole injection layer 3, as well as anthracene-based compounds and pyrene-based compounds. , Carbazole-based compounds, pyridine-based compounds, phenanthroline-based compounds, oxadiazole-based compounds, silol-based compounds and other electron-transporting compounds.

As the charge transporting material, two or more fused aromatic rings containing two or more tertiary amines represented by 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl are used. Aromatic amines having a starburst structure such as aromatic diamines substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), 4,4', 4''-tris (1-naphthylphenylamino) triphenylamines, etc. Aromatic amine compounds consisting of tetramers of triphenylamines (Chem. Commun., 2175, 1996), 2,2 series compounds (J. Lumin., 72-74, pp. 985, 1997). Fluorene compounds such as', 7,7'-tetrax- (diphenylamino) -9,9'-spirobifluorene (Synth. Metals, Vol. 91, p. 209, 1997), 4, 4'-N, N Compounds exemplified as the hole-transporting compound of the hole-transporting layer 4 such as a carbazole-based compound such as ′ -dicarbazolebiphenyl can also be preferably used. In addition, 2- (4-biphenylyl) -5- (p-talshalbutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 2,5-bis (1-naphthyl) -1,3 , 4-Oxadiazole (BND) and other oxadiazole compounds, 2,5-bis (6'-(2', 2''-bipyridyl))-1,1-dimethyl-3,4-diphenylsilol Examples thereof include silol compounds such as (PyPySPyPy), phenanthroline compounds such as vasophenanthroline (BPhen) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP, vasocproin).

(Formation of light emitting layer 5 by wet film formation method)
The organic electroluminescent device preferably has a light emitting layer formed by a wet film forming method using the composition for an organic electroluminescent device according to the present embodiment.
As the light emitting layer 5, a light emitting layer may be provided in addition to the light emitting layer formed by using the composition for an organic electroluminescent device according to the present embodiment. The method for forming these light emitting layers may be a vacuum vapor deposition method or a wet film forming method, but the wet film forming method is preferable because of its excellent film forming property.

When the light emitting layer 5 is formed by the wet film forming method, usually, in the same manner as when the hole injection layer 3 is formed by the wet film forming method, light emission is performed instead of the composition for forming the hole injection layer. The material to be layer 5 is formed by using a light emitting layer forming composition prepared by mixing with a soluble solvent (solvent for light emitting layer).
Examples of the solvent include ether-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, amide-based solvents, alcan-based solvents, halogenated aromatic hydrocarbon-based solvents, etc., which were mentioned for the formation of the hole injection layer 3. Examples thereof include an aliphatic alcohol solvent, an alicyclic alcohol solvent, an aliphatic ketone solvent and an alicyclic ketone solvent. The solvent used is as exemplified as the solvent of the iridium complex compound-containing composition in the present embodiment. Specific examples of the solvent are given below, but the present invention is not limited thereto as long as the effect of the present invention is not impaired.

For example, aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetol, 2 -Aromatic ether solvents such as methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, diphenyl ether; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic ester solvents such as ethyl, propyl benzoate, n-butyl benzoate; toluene, xylene, mesitylene, cyclohexylbenzene, tetralin, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, 1,4 -Aromatic hydrocarbon solvents such as diisopropylbenzene and methylnaphthalene; amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide; alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin and bicyclohexane Solvents: Halogenized aromatic hydrocarbon solvents such as chlorobenzene, dichlorobenzene and trichlorobenzene; aliphatic alcohol solvents such as butanol and hexanol; alicyclic alcohol solvents such as cyclohexanol and cyclooctanol; methyl ethyl ketone and dibutyl ketone Such as aliphatic ketone solvent; cyclohexanone, cyclooctanone, alicyclic ketone solvent such as fencon and the like can be mentioned. Of these, alkane-based solvents and aromatic hydrocarbon-based solvents are particularly preferable.

In order to obtain a more uniform film, it is preferable that the solvent evaporates at an appropriate rate from the liquid film immediately after the film formation. Therefore, as described above, 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, more preferably 230 ° C. or lower. Is.
The amount of the solvent used is arbitrary as long as the effect of the present invention is not significantly impaired, but the total content in the light emitting layer forming composition, that is, the iridium complex compound-containing composition is low in viscosity, so that the film forming operation can be performed. A large amount is preferable from the viewpoint of easy execution, and a low value is preferable from the viewpoint of easy formation of a thick film. As described above, the content of the solvent is preferably 1% by mass or more, more preferably 10% by mass or more, particularly preferably 50% by mass or more, and preferably 99.99% by mass or less in the iridium complex compound-containing composition. , More preferably 99.9% by mass or less, and particularly preferably 99% by mass or less.

As a method for removing the solvent after the wet film formation, heating or depressurization can be used. As the heating means used in the heating method, a clean oven and a hot plate are preferable because heat is evenly applied to the entire film.
The heating temperature in the heating step is arbitrary as long as the effect of the present invention is not significantly impaired, but a high temperature is preferable from the viewpoint of shortening the drying time, and a low temperature is preferable from the viewpoint of less damage to the material. The upper limit of the heating temperature is usually 250 ° C. or lower, preferably 200 ° C. or lower, and more preferably 150 ° C. or lower. The lower limit of the heating temperature is usually 30 ° C. or higher, preferably 50 ° C. or higher, and more preferably 80 ° C. or higher. By setting the temperature to the above upper limit or less, the temperature becomes lower than the heat resistance of the normally used charge transporting material or phosphorescent material, and decomposition and crystallization can be suppressed. By setting the heating temperature to the above lower limit or higher, it is possible to avoid a long time in removing the solvent. The heating time in the heating step is appropriately determined by the boiling point and 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 light emitting layer 5 by vacuum vapor deposition method)
When the light emitting layer 5 is formed by the vacuum vapor deposition method, usually, one or more of the constituent materials of the light emitting layer 5, that is, the above-mentioned light emitting material, charge transporting compound, etc., are installed in a crucible. Put in. At this time, when two or more kinds of materials are used, each is usually put in a separate crucible. Then, after exhausting the inside of the vacuum vessel to about 10 ^-4 Pa with a vacuum pump, the pit is heated to evaporate while controlling the amount of evaporation of the material in the pit. When two or more kinds of materials are used, each crucible is usually heated and evaporated while controlling the amount of evaporation independently. By such an operation, the light emitting layer 5 is formed on the hole injection layer 3 or the hole transport layer 4 placed facing the crucible. When two or more kinds of materials are used, they can be put into a crucible as a mixture and heated and evaporated to form a light emitting layer 5.

The degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 ^-6 Torr (0.13 × 10 ^-4 Pa) or more, 9.0 × 10 ^-6 Torr ( It is 12.0 × 10 ^-4 Pa) or less. The vapor deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / sec or more and 5.0 Å / sec or less. The film formation temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher and 50 ° C. or lower.

<Hole blocking layer 6>
A 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 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.
The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have. The physical properties required for the material constituting the hole blocking layer 6 are high electron mobility and low hole mobility, an energy gap, that is, a large difference between HOMO and LUMO, and an excited triplet level (T1). ) Is high.

Examples of the material of the hole blocking layer 6 satisfying such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum and bis (2-methyl-8-quinolinolato) (triphenylsilanorat) aluminum. Mixed ligand complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinolato) aluminum dinuclear metal complexes and other metal complexes, distyrylbiphenyl derivatives, etc. (Japanese Patent Laid-Open No. 11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole and other triazole derivatives (Japanese Patent Laid-Open No. 11-242996) Japanese Patent Application Laid-Open No. 7-41759), phenanthroline derivatives such as bassokproin (Japanese Patent Laid-Open No. 10-79297), and the like can be mentioned. A compound having at least one pyridine ring substituted at the 2, 4 and 6 positions described in WO 2005/022962 is also preferable as a material for the hole blocking layer 6.

The method for forming the hole blocking layer 6 is not limited, and the hole blocking layer 6 can be formed in the same manner as the method for forming the light emitting layer 5 described above.
The film thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

<Electron transport layer 7>
The electron transport layer 7 is provided between the light emitting layer 5 or the hole element layer 6 and the electron injection layer 8 for the purpose of further improving the current efficiency of the device.
The electron transport layer 7 is formed of a compound capable of efficiently transporting electrons injected from the cathode 9 in the direction of the light emitting layer 5 between the electrodes to which an electric field is applied. As the electron-transporting compound used in the electron-transporting layer 7, the electron-injecting efficiency from the cathode 9 or the electron-injecting layer 8 is high, and the injected electrons can be efficiently transported with high electron mobility. It needs to be a compound.

Examples of the electron-transporting compound satisfying such conditions include a metal complex such as an aluminum complex of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), and a metal complex of 10-hydroxybenzo [h] quinoline. , Oxaziazole derivative, distyrylbiphenyl derivative, silol derivative, 3-hydroxyflavon metal complex, 5-hydroxyflavon metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948). ), Kinoxalin compound (Japanese Patent Laid-Open No. 6-207169), phenanthroline derivative (Japanese Patent Application Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, Examples thereof include n-type hydride amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenium.

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 vapor deposition method in the same manner as the light emitting layer 5. Usually, the vacuum deposition method is often used.

<Electron injection layer 8>
The electron injection layer 8 plays a role of efficiently injecting the electrons injected from the cathode 9 into the electron transport layer 7 or the light emitting layer 5.
In order to efficiently perform electron injection, it is preferable to use a metal having a low work function as the material for forming the electron injection layer 8. As an example, alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the like are used.

The film thickness of the electron injection layer 8 is preferably 0.1 to 5 nm.
An ultra-thin insulating film having a film thickness of about 0.1 to 5 nm, such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO _3, etc., is inserted as an electron injection layer 8 at the interface between the cathode 9 and the electron transport layer 7. This is also an effective method for improving the efficiency of the device (Appl. Phys. Lett., Vol. 70, p. 152, 1997; Japanese Patent Application Laid-Open No. 10-74586; IEEE Trans. Electron. Devices, 44. Volume, p. 1245, 1997; SID 04 Digest, 2004, p. 154).

Further, an organic electron transport material typified by a nitrogen-containing heterocyclic compound such as basophenanthroline or a metal complex such as an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, or rubidium (). (Described in Japanese Patent Application Laid-Open No. 10-270171, Japanese Patent Application Laid-Open No. 2002-100478, Japanese Patent Application Laid-Open No. 2002-1000482, etc.) It is preferable because it enables this. In this case, the film thickness 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 on the light emitting layer 5 by a wet film forming method or a vacuum vapor deposition 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 in the case of the light emitting layer 5 described above.

<Cathode 9>
The cathode 9 plays a role of injecting electrons into a layer on the light emitting layer 5 side such as the electron injection layer 8 or the light emitting layer 5. As the material of the cathode 9, the material used for the above-mentioned indium 2 can be used, but in order to efficiently inject electrons, it is preferable to use a metal having a low work function, for example, tin and magnesium. , Indium, calcium, aluminum, silver and other metals or alloys thereof are used. Examples of the material of the cathode 9 include alloy electrodes having a low work function such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

From the viewpoint of device stability, it is preferable to laminate a metal layer having a high work function and stable to the atmosphere on the cathode 9 to protect the cathode 9 made of a metal having a low work function. Examples of the metal to be laminated include metals such as aluminum, silver, copper, nickel, chromium, gold, and platinum.
The film thickness of the cathode is usually the same as that of the anode 2.

<Other constituent layers>
Although the elements having the layer structure shown in FIG. 1 have been mainly described above, the above is described between the anode 2 and the cathode 9 and the light emitting layer 5 in the organic electroluminescent device according to the present embodiment as long as the performance is not impaired. In addition to the layers described in the description, any layer may be provided, or any layer other than the light emitting layer 5 may be omitted.

For example, it is also effective to provide an electron blocking layer between the hole transporting layer 4 and the light emitting layer 5 for the same purpose as the hole blocking layer 8. The electron blocking layer prevents electrons moving from the light emitting layer 5 from reaching the hole transporting layer 4, thereby increasing the recombination probability with holes in the light emitting layer 5 and producing excitons. It has a role of confining the holes in the light emitting layer 5 and a role of efficiently transporting the holes injected from the hole transport layer 4 in the direction of the light emitting layer 5.

The characteristics required for the electron blocking layer include high hole transportability, a large energy gap, that is, a large difference between HOMO and LUMO, and a high excited triplet level (T1).
When the light emitting layer 5 is formed by the wet film forming method, it is preferable that the electron blocking layer is also formed by the wet film forming method because the device can be easily manufactured.
Therefore, it is preferable that the electron blocking layer also has wet film formation compatibility, and the material used for such an electron blocking layer is a copolymer of dioctylfluorene and triphenylamine represented by F8-TFB (international). Publication No. 2004/084260) and the like.

The structure opposite to that of FIG. 1, that is, the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, the hole transport layer 4, the hole injection layer 3, and the anode on the substrate 1. It is also possible to stack in the order of 2. It is also possible to provide the organic electroluminescent device according to the present embodiment between two substrates, one of which is highly transparent.
It is also possible to have a structure in which a plurality of layers shown in FIG. 1 are stacked, that is, a structure in which a plurality of light emitting units are stacked. In that case, if V ₂ O ₅ or the like is used as the charge generation layer instead of the interface layer between the stages, that is, between the light emitting units, the barrier between the stages is reduced, which is more preferable from the viewpoint of luminous efficiency and driving voltage. The interface layer means, for example, two layers when the anode is ITO and the cathode is Al.
The present invention can be applied to any of a single element, an element having an array-arranged structure, and a structure in which an anode and a cathode are arranged in an XY matrix.

[Display device]
The display device and the lighting device according to the present embodiment have the above-mentioned organic electroluminescent element. The type and structure of the display device are not particularly limited, and can be assembled according to a conventional method using the organic electroluminescent device according to the present embodiment.
For example, the display device according to this embodiment can be used by the method described in "Organic EL Display" (Ohmsha, published on August 20, 2004, by Shizushi Tokito, Chihaya Adachi, Hideyuki Murata). Can be formed.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples, and the present invention can be arbitrarily modified and implemented without departing from the gist thereof.

[Example 1]
An organic electroluminescent device was manufactured by the following method.
A transparent conductive film of indium tin oxide (ITO) deposited on a glass substrate to a thickness of 50 nm (manufactured by Sanyo Vacuum Co., Ltd., sputter-deposited product) is 2 mm using ordinary photolithography technology and hydrochloric acid etching. The width stripes were patterned to form an anode. The substrate on which the ITO pattern is formed is washed in the order of ultrasonic cleaning with an aqueous surfactant solution, water washing with ultrapure water, ultrasonic cleaning with ultrapure water, and water washing with ultrapure water, and then dried with compressed air. Finally, UV ozone cleaning was performed.

As the composition for forming the hole injection layer, 3.0% by mass of the hole-transporting polymer compound having a repeating structure represented by the following formula (P-1) and the composition represented by the following formula (HI-1). A composition was prepared in which 0.6% by mass of an oxidizing agent was dissolved in ethyl benzoate.
This solution was spin-coated on the substrate in the atmosphere and dried at an atmospheric hot plate at 240 ° C. for 30 minutes to form a uniform thin film having a film thickness of 40 nm to form a hole injection layer.

Next, 100 parts by mass of the charge-transporting polymer compound having a structure represented by the following formula (HT-1) was dissolved in cyclohexylbenzene to prepare a 3.0% by mass solution.
This solution was spin-coated in a nitrogen glove box on a substrate coated with the hole injection layer and dried on a hot plate in the nitrogen glove box at 230 ° C. for 30 minutes to form a uniform thin film having a film thickness of 40 nm. It was formed and used as a hole transport layer.

Subsequently, as the material of the light emitting layer, the compound represented by the following formula (H-1) is 60 parts by mass, the compound represented by the following formula (H-2) is 40 parts by mass, and the following formula (D-1) is used. Weigh 15 parts by mass of the compound that becomes the red light emitting dopant and 15 parts by mass of the compound that becomes the assist dopant represented by the following formula (D-2), dissolve it in cyclohexylbenzene, and 7.8% by mass. The solution was prepared.

This solution was spin-coated in a nitrogen glove box on a substrate coated with the hole transport layer and dried on a hot plate in the nitrogen glove box at 120 ° C. for 20 minutes to form a uniform thin film having a film thickness of 80 nm. It was formed and used as a light emitting layer. The compound represented by the formula (D-1) is a dopant having a wavelength of 613 nm, and the compound represented by the formula (D-2) is a dopant having a wavelength of 555 nm as the maximum emission wavelength.

The substrate on which the light emitting layer was formed was installed in a vacuum vapor deposition apparatus, and the inside of the apparatus was exhausted until it became 2 × 10 ^-4 Pa or less.
Next, the compound represented by the following formula (HB-1) and 8-hydroxyquinolinola tritium were placed on the light emitting layer at a rate of 1 Å / sec by vacuum deposition so as to have a film thickness ratio of 2: 3. A hole blocking layer having a film thickness of 30 nm was formed by co-depositing with.

Subsequently, a striped shadow mask having a width of 2 mm was brought into close contact with the substrate so as to be orthogonal to the ITO stripe of the anode as a mask for cathode vapor deposition, and installed in another vacuum vapor deposition apparatus. Then, aluminum was heated by a molybdenum boat to form an aluminum layer having a film thickness of 80 nm at a vapor deposition rate of 1 to 8.6 Å / sec to form a cathode.
As described above, an organic electroluminescent device having a light emitting area portion having a size of 2 mm × 2 mm was obtained.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-1) was observed.

[Example 2]
The electroluminescent layer composition was set to (H-1) :( H-2) :( D-1) :( D-3) = 60: 40: 15: 15 by the mass ratio of the compounds represented by each formula. Except for this, an organic electroluminescent device was produced in the same manner as in Example 1.
The structural formula of the compound represented by the formula (D-3) is shown below. The compound represented by the formula (D-3) is a dopant having a wavelength of 560 nm as the maximum emission wavelength.

[Example 3]
The electroluminescent layer composition was set to (H-1) :( H-2) :( D-1) :( D-4) = 60: 40: 15: 15 by the mass ratio of the compounds represented by each formula. Except for this, an organic electroluminescent device was produced in the same manner as in Example 1.
The structural formula of the compound represented by the formula (D-4) is shown below. The compound represented by the formula (D-4) is a dopant having a wavelength of 558 nm as the maximum emission wavelength.

[Comparative Example 1]
A compound represented by the formula (D-5) is used as the red electroluminescent dopant, and the light emitting layer composition is determined by the mass ratio of the compounds represented by each formula (H-1) :( H-2) :( D-. 5): An organic electroluminescent device was produced in the same manner as in Example 1 except that (D-2) = 60:40:15:15.
The structural formula of the compound represented by the formula (D-5) is shown below.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-5) was observed.

[Comparative Example 2]
A compound represented by the formula (D-5) is used as the red electroluminescent dopant, and the light emitting layer composition is determined by the mass ratio of the compounds represented by each formula (H-1) :( H-2) :( D-. An organic electroluminescent device was produced in the same manner as in Example 1 except that (5): (D-3) = 60:40:15:15.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-5) was observed.

[Comparative Example 3]
A compound represented by the formula (D-5) is used as the red electroluminescent dopant, and the light emitting layer composition is determined by the mass ratio of the compounds represented by each formula (H-1) :( H-2) :( D-. An organic electroluminescent device was produced in the same manner as in Example 1 except that (5): (D-4) = 60:40:15:15.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-5) was observed.

[Evaluation of element]
The current luminous efficiency (cd / A) and the external quantum efficiency EQE (%) when the organic electroluminescent devices of Examples 1 to 3 and Comparative Examples 1 to 3 were made to emit light at a brightness of 1000 cd / m ² were obtained. It was measured. The ratios of the current luminous efficiencies of Example n (n are 1 to 3) are calculated when the current luminous efficiency of Comparative Example n (n is 1 to 3) is 1, and the relative luminous efficiencies are shown in Table 1. did. Further, the value of ΔEQE = EQE (Example n) -EQE (Comparative Example n) obtained by subtracting the EQE of Comparative Example n (n is 1 to 3) from the EQE of Example n (n is 1 to 3) is obtained. It is also described in Table 1 below.
As shown in the results of Table 1, an organic electroluminescent device using the compound represented by the formula (D-1) according to the present embodiment as a light emitting dopant as a light emitting layer material is represented by the formula (D-5). It was found that the efficiency was improved regardless of the structure of the compound serving as the assist dopant as compared with the organic electroluminescent device using the compound.

[Comparative Example 4]
The light emitting layer composition is calculated by the mass ratio of the compounds represented by each formula, without using the compound represented by the formula (D-2) that serves as an assist punt, (H-1) :( H-2) :. An organic electroluminescent device was produced in the same manner as in Example 1 except that (D-1) = 60:40:15.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-1) was observed.

[Comparative Example 5]
The light emitting layer composition is represented by each formula by using the compound represented by the formula (D-5) as the red light emitting dopant and without using the compound represented by the formula (D-2) which is an assist punt. An organic electroluminescent device was produced in the same manner as in Example 1 except that the mass ratio of the compounds was (H-1) :( H-2) :( D-5) = 60: 40: 15.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-5) was observed.

[Evaluation of element]
The external quantum efficiency EQE of the obtained organic electroluminescent devices of Example 1, Comparative Example 1, Comparative Example 4 and Comparative Example 5 was measured when light was emitted at a brightness of 1000 cd / m ² . Changes in the EQE of an organic electroluminescent device (Example 1 or Comparative Example 1) containing a compound as an assist dopant with respect to the EQE of an organic electroluminescent device (Comparative Example 4 or Comparative Example 5) containing no compound serving as an assist dopant. The width is defined as ΔEEQU, and is described in Table 2 or Table 3 below.
As shown in the results of Tables 2 and 3, the organic electroluminescent device (Example 1) in which the compound represented by the formula (D-1) according to the present embodiment is used as the light emitting dopant as the light emitting layer material is represented by the formula. It can be seen that the range of change in the external quantum efficiency when the compound serving as the assist dopant is added is large as compared with the organic electroluminescent device (Comparative Example 1) using the compound represented by (D-5).

[Example 4]
A compound represented by the formula (D-6) is used as the red electroluminescent dopant, and the light emitting layer composition is determined by the mass ratio of the compounds represented by each formula (H-1) :( H-2) :( D-. 6): An organic electroluminescent device was produced in the same manner as in Example 1 except that (D-2) = 60: 40: 15: 15. The compound represented by the formula (D-6) is a dopant having a wavelength of 627 nm as the maximum emission wavelength.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-6) was observed.

[Example 5]
The electroluminescent layer composition was set to (H-1) :( H-2) :( D-6) :( D-7) = 60: 40: 15: 15 by the mass ratio of the compounds represented by each formula. Except for this, an organic electroluminescent device was produced in the same manner as in Example 1. The compound represented by the formula (D-7) is a dopant having a wavelength of 605 nm as the maximum emission wavelength.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-6) was observed.

[Comparative Example 6]
Except that the mass ratio of the compounds represented by each formula was set to (H-1) :( H-2) :( D-6) = 60: 40: 15, the light emitting layer composition was the same as that of Example 1. An organic electroluminescent device was produced in the same manner.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-6) was observed.

[Comparative Example 7]
The electroluminescent layer composition was set to (H-1) :( H-2) :( D-5) :( D-7) = 60: 40: 15: 15 by the mass ratio of the compounds represented by each formula. Except for this, an organic electroluminescent device was produced in the same manner as in Example 1.
When a voltage was applied to the obtained organic electroluminescent device, red light emission derived from the compound represented by the formula (D-5) was observed.

[Evaluation of element]
The external quantum efficiency EQE of the obtained organic electroluminescent devices of Example 4, Example 5, Comparative Example 6 and Comparative Example 7 when they were made to emit light at a brightness of 1000 cd / m ² was measured, and the EQE of Comparative Example 6 was measured. The difference between the above is described as ΔEQE. Further, the organic electroluminescent element was driven with a current density of 60 mA / cm ^2, the LT80 was measured for a time when the relative emission luminance became 80%, and the relative life when the LT80 of Comparative Example 6 was set to 100 was described. It is shown in Table 4 below.
As shown in the results of Table 4, the organic electroluminescent device used in the light emitting layer in combination with the compound represented by the formula (D-6) according to the present embodiment as the light emitting dopant and the compound serving as the assist dopant is efficient. It can be seen that the device has a high drive life and a long drive life. Among them, it can be seen that an organic electroluminescent device using a compound represented by the formula (D-7) as a compound serving as an assist dopant has higher luminous efficiency and a longer drive life.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on May 20, 2019 (Japanese Patent Application No. 2019-094708), the contents of which are incorporated herein by reference.

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

Claims

An organic electroluminescence containing a compound represented by the following formula (1), a compound represented by the following formula (2) having a shorter maximum emission wavelength than the compound represented by the above formula (1), and a solvent. Composition for light emitting element.

[In the above formula, R 1 and R 2 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, and 3 carbon atoms, respectively. ~ 20 (hetero) aryloxy groups, 1 to 20 carbon atoms alkylsilyl groups, 6 to 20 carbon atoms arylsilyl groups, 2 to 20 carbon atoms alkylcarbonyl groups, 7 to 20 carbon atoms arylcarbonyl groups, It is an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. When a plurality of R 1 and R 2 exist, they may be the same or different from each other. If R 1 there are a plurality bonded R 1 adjacent to each other may form a ring.
a is an integer of 0 to 4, and b is an integer of 0 to 3.
R 3 and R 4 are independently hydrogen atom, fluorine atom, chlorine atom, bromine atom, alkyl group having 1 to 20 carbon atoms, (hetero) aralkyl group having 7 to 40 carbon atoms, and 1 to 20 carbon atoms, respectively. Alkoxy group, (hetero) aryloxy group having 3 to 20 carbon atoms, alkylsilyl group having 1 to 20 carbon atoms, arylsilyl group having 6 to 20 carbon atoms, alkylcarbonyl group having 2 to 20 carbon atoms, 7 carbon atoms. It is an arylcarbonyl group having up to 20 carbonyl groups, an alkylamino group having 2 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 20 carbon atoms. These groups may further have substituents. When a plurality of R 3 and R 4 exist, they may be the same or different from each other.
L 1 represents an organic ligand, and m is an integer of 1 to 3. ]

[In the formula, R 5 is an alkyl group having 1 to 20 carbon atoms, having 7 to 40 carbon atoms (hetero) aralkyl group, an alkoxy group having 1 to 20 carbon atoms, having 3 to 20 carbon atoms (hetero) aryloxy Group, alkylsilyl group with 1 to 20 carbon atoms, arylsilyl group with 6 to 20 carbon atoms, alkylcarbonyl group with 2 to 20 carbon atoms, arylcarbonyl group with 7 to 20 carbon atoms, alkylamino with 1 to 20 carbon atoms A group, an arylamino group having 6 to 20 carbon atoms, or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. If R 5 is plurally present, they may be the same or different.
c is an integer from 0 to 4.
Ring A is any of pyridine ring, pyrazine ring, pyrimidine ring, imidazole ring, oxazole ring, thiazole ring, quinoline ring, isoquinoline ring, quinazoline ring, quinoxaline ring, azatriphenylene ring, carboline ring, benzothiazole ring, and benzoxazole ring. Is it?
Ring A may have a substituent, which 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, and carbon. An alkoxy group having 1 to 20 carbon atoms, a (hetero) aryloxy group having 3 to 20 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms, an arylsilyl group having 6 to 20 carbon atoms, and 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, or a (hetero) aryl group having 3 to 20 carbon atoms. Further, adjacent substituents bonded to the ring A may be bonded to each other to further form a ring. When there are a plurality of rings A, they may be the same or different.
L 2 represents an organic ligand, and n is an integer of 1 to 3. ]
The composition for an organic electroluminescent device according to claim 1, wherein the composition ratio of the compound represented by the formula (1) is equal to or greater than the composition ratio of the compound represented by the formula (2) in terms of parts by mass.
The composition for an organic electroluminescent device according to claim 1 or 2, wherein the compound represented by the formula (1) is a compound represented by the following formula (1-1).

[In the above formulas, R 1, R 2, a , b, L 1, m , the R 1 in the formula (1), R 2, a , b, a L 1, m and respectively the same.
R 6 and R 7 are independently alkyl groups having 1 to 20 carbon atoms, (hetero) aralkyl groups having 7 to 40 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, and (heterogeneous) having 3 to 20 carbon atoms. ) Aryloxy group, alkylsilyl group with 1 to 20 carbon atoms, arylsilyl group with 6 to 20 carbon atoms, alkylcarbonyl group with 2 to 20 carbon atoms, arylcarbonyl group with 7 to 20 carbon atoms, 1 to 20 carbon atoms Alkylamino group, arylamino group having 6 to 20 carbon atoms, or (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. When a plurality of R 6 and R 7 exist, they may be the same or different from each other.
d and e are independently integers from 0 to 5. ]
The composition for an organic electroluminescent device according to claim 1 or 2, wherein the compound represented by the formula (1) is a compound represented by the following formula (1-2).

[In the above formulas, R 2 ~ R 4, b , L 1, m is, R 2 ~ R 4 in the formula (1), b, is L 1, m and respectively the same.
R 14 to R 16 are substituents, and when a plurality of R 14 to R 16 are present, they may be the same or different from each other.
i is an integer from 0 to 4. ]
The composition for an organic electroluminescent device according to claim 3, wherein the compound represented by the formula (1-1) is a compound represented by the following formula (1-3).

[In the above formulas, R 2, R 6, R 7, b, d, e, L 1, m is, R 2 in the formula (1-1), R 6, R 7, b, d, e, L It is synonymous with 1 and m, respectively.
R 14 to R 16 are substituents, and when a plurality of R 14 to R 16 are present, they may be the same or different from each other.
i is an integer from 0 to 4. ]
The composition for an organic electroluminescent device according to any one of claims 1 to 5, wherein the compound represented by the formula (2) is a compound represented by the following formula (2-1).

[In the above formula, Ring A, L 2, n, Ring A in the formula (2) is L 2, n and respectively the same.
R 8 has 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, and 1 carbon atom. Alkylsilyl group of ~ 20, arylsilyl group of 6-20 carbons, alkylcarbonyl group of 2-20 carbons, arylcarbonyl group of 7-20 carbons, alkylamino group of 1-20 carbons, 6 carbons It is an arylamino group of up to 20 or a (hetero) aryl group having 3 to 30 carbon atoms. These groups may further have substituents. If R 8 is plurally present, they may be the same or different.
f is an integer from 0 to 5. ]
Claims 1 to 1, wherein m in the formula (1) is less than 3, and L 1 has at least one structure selected from the group consisting of the following formulas (3), (4), and (5). 6. The composition for an organic electroluminescent device according to any one of 6.

[In the above formulas (3) to (5), R 9 and R 10 are synonymous with R 1 in the above formula (1), and when a plurality of R 9 and R 10 exist, they are the same. May be different.
R 11 to R 13 are independently substituted with an alkyl group having 1 to 20 carbon atoms which may be substituted with a hydrogen atom and a fluorine atom, a phenyl group which may be substituted with an alkyl group having 1 to 20 carbon atoms, or It is a halogen atom.
g is an integer from 0 to 4. h is an integer from 0 to 4.
Ring B is a pyridine ring, a pyrimidine ring, an imidazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, an azatriphenylene ring, a carboline ring, a benzothiazole ring, or a benzoxazole ring. Ring B may further have a substituent. ]
Wherein a a is 1 of Formula (1) or the formula (1) a does not have a ring integer of 2 or more, and R 1 the adjacent coupled together in, according to claim 1 to 7 The composition for an organic electroluminescent device according to any one of the above.
A method for manufacturing an organic electroluminescent device, which comprises a step of forming a light emitting layer by a wet film forming method using the organic electroluminescent device composition according to any one of claims 1 to 8.
An organic electroluminescent device having a light emitting layer formed by using the organic electroluminescent device composition according to any one of claims 1 to 8.
A display device having the organic electroluminescent element according to claim 10.