JP6580392B2 - Compound, mixture, light emitting layer, organic light emitting device and assist dopant - Google Patents

Description

  The present invention relates to a compound useful as an assist dopant, a mixture using the compound, a light emitting layer, and an organic light emitting device.

Researches for increasing the light emission efficiency of organic light emitting devices such as organic electroluminescence devices (organic EL devices) are being actively conducted. In particular, various studies have been made to increase the light emission efficiency by devising materials used for the light emitting layer. Among them, research on organic light-emitting devices using delayed phosphors as the material of the light-emitting layer can also be found.
The delayed phosphor is an organic material that can cross back from the excited triplet state to the excited singlet state when transitioning to the excited triplet state, and emits fluorescence when returning from the excited singlet state to the ground state. A compound. The lifetime of light generated by the reverse intersystem crossing from the excited triplet state to the excited singlet state is longer than normal fluorescence (immediate fluorescence) or phosphorescence, and thus is observed as fluorescence delayed from these.
Here, the formation probability of singlet excitons and triplet excitons formed by current excitation of the light emitting layer is statistically 25% for singlet excitons and 75% for triplet excitons. For this reason, in general, organic light-emitting devices that utilize singlet exciton fluorescence radiation are said to have a limit in improving luminous efficiency because triplet exciton energy, which accounts for 75% of the total, is not effectively used for light emission. ing. On the other hand, in the delayed phosphor, triplet excitons transition to the excited singlet state through the intersystem crossing, so that in principle 100% exciton energy can be used for fluorescence emission. For this reason, the organic electroluminescence element using the delayed phosphor as the material of the light emitting layer can obtain much higher light emission efficiency than that using a normal fluorescent material. From these points, research on the assumption that the delayed phosphor is used as a light-emitting material has been actively conducted, and recently, proposals regarding an organic electroluminescence device using the delayed phosphor as a host have also been found.
For example, Patent Document 1 describes that a delayed phosphor is used as a host of a light emitting layer. As a specific example of the delayed phosphor, a carbazole structure is included in an aromatic six-membered ring containing nitrogen such as a pyrimidine ring or a pyrazine ring. And compounds having a structure in which 10H-9,9-dimethylacridine structures are linked are described.

International Publication No. 2012/133188 Pamphlet

As described above, the use of a delayed phosphor as a host material is described in Patent Document 1. However, the delayed phosphor specifically described in Patent Document 1 is only a limited compound as described above, and the same document confirms the usefulness of the other delayed phosphor as a host material. It has not been.
That is, in the host (delayed phosphor) specifically described in Patent Document 1, a carbazole structure or a 10H-9,9-dimethylacridine structure is linked to an aromatic six-membered ring containing nitrogen such as a pyrimidine ring. This is only a compound having a structure. For example, the literature does not describe an example in which a compound having a structure in which a substituted amino group or a heterocyclic ring having a nitrogen atom is bonded to a benzene ring substituted with a cyano group is used as a host. Further, Patent Document 1 does not describe any use of the delayed phosphor as an assist dopant for the light emitting layer.
Under such circumstances, the present inventors have intensively studied for the purpose of developing a delayed phosphor useful as a host or assist dopant.

  The inventors of the present invention combined various delayed phosphors with a light emitting material and evaluated the performance as a host. Among the delayed phosphors, in particular, a benzene ring substituted with a cyano group has a substituted amino group or a binding site. It has been found that a compound having a structure in which a heterocyclic ring having a nitrogen atom is bonded is highly useful as a host. Furthermore, the present inventors have evaluated the light emission characteristics by doping a normal host with various delayed phosphors and light emitting materials. As a result, the benzene ring substituted with the cyano group has a substituted amino group or a nitrogen atom. It has been found that a compound substituted with a heterocyclic ring is extremely useful as an assist dopant for promoting light emission of a light emitting material. In addition, it has been clarified that by using such a compound as a material for the light emitting layer, an organic light emitting element having high light emission efficiency can be provided at low cost. Based on these findings, the present inventors have provided the following present invention as means for solving the above problems.

[1] A compound represented by the following general formula (1).
[In General Formula (1), R ^{1 to} R ⁵ each independently represent a hydrogen atom or a substituent other than a cyano group, and at least one of R ^{1 to} R ⁵ is each independently the following General Formula (2) or It is group represented by following General formula (3). ]
[In General formula (2), R < ¹¹ > -R < ²⁰ > represents a hydrogen atom or a substituent each independently. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁴ and R ¹⁵ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , R ¹⁹ And R ²⁰ may be bonded to each other to form a cyclic structure. ]
[In the general formula (3) represents a hydrogen atom or a substituent each independently R ⁷¹ to R ⁷⁹ is. R ⁷¹ and R ⁷² , R ⁷² and R ⁷³ , R ⁷³ and R ⁷⁴ , R ⁷⁴ and R ⁷⁵ , R ⁷⁶ and R ⁷⁷ , R ⁷⁷ and R ⁷⁸ , R ⁷⁸ and R ⁷⁹ are bonded to each other to form a cyclic structure. You may do it. ]
[2] The compound according to [1], wherein the group represented by the general formula (2) is a group represented by any one of the following general formulas (4) to (8).
[In the general formulas (4) to (8), R ^{21 to} R ²⁴ , R ^{27 to} R ³⁸ , R ^{41 to} R ⁴⁸ , R ^{51 to} R ⁵⁸ , R ^{61 to} R ⁶⁵ , R ^{81 to} R ⁹⁰ are Independently represents a hydrogen atom or a substituent. R ²¹ and R ²² , R ²² and R ²³ , R ²³ and R ²⁴ , R ²⁷ and R ²⁸ , R ²⁸ and R ²⁹ , R ²⁹ and R ³⁰ , R ³¹ and R ³² , R ³² and R ³³ , R ³³ And R ³⁴ , R ³⁵ and R ³⁶ , R ³⁶ and R ³⁷ , R ³⁷ and R ³⁸ , R ⁴¹ and R ⁴² , R ⁴² and R ⁴³ , R ⁴³ and R ⁴⁴ , R ⁴⁵ and R ⁴⁶ , R ⁴⁶ and R ⁴⁷ , R ⁴⁷ and R ⁴⁸ , R ⁵¹ and R ⁵² , R ⁵² and R ⁵³ , R ⁵³ and R ⁵⁴ , R ⁵⁵ and R ⁵⁶ , R ⁵⁶ and R ⁵⁷ , R ⁵⁷ and R ⁵⁸ , R ⁶¹ and R ⁶² , R ⁶² and R ^63, R ⁶³ and R ^64, R ⁶⁴ and R ^65, R ⁵⁴ and R ^61, R ⁵⁵ and R ^65, R ⁸¹ and R ^82, R ⁸² and R ^83, R ⁸³ and R ^84, R ⁸⁵ And R ⁸⁶ , R ⁸⁶ and R ⁸⁷ , R ⁸⁷ and R ⁸⁸ , and R ⁸⁹ and R ⁹⁰ may be bonded to each other to form a cyclic structure. ]
[3] The compound according to [1] or [2], wherein R ^{3 in the} general formula (1) is a group represented by the general formula (2).
[4] At least one of R ¹ , R ² , R ⁴ , and R ^{5 in} the general formula (1) is independently an alkyl group having 1 to 3 carbon atoms, [3] Compound.
[5] The compound according to [1] or [2], wherein R ¹ and R ^{5 in} the general formula (1) are groups represented by the general formula (2).
[6] The compound according to any one of [1] to [5], wherein the group represented by the general formula (2) is a group represented by the general formula (8). .
[7] The compound according to [6], wherein R ⁸⁹ and R ^{90 in} the general formula (8) are both substituted or unsubstituted aryl groups.

[8] A mixture comprising a material composed of the compound represented by the general formula (1) and a luminescent material doped in the material.

[9] A light emitting layer comprising a material composed of the compound represented by the general formula (1) and a light emitting material doped in the material.
[10] The compound represented by the general formula (1) is an organic compound having the highest lowest excited singlet energy level among the organic compounds contained in the light emitting layer. Light emitting layer.
[11] The light-emitting layer according to [9] or [10], wherein the compound represented by the general formula (1) is a delayed phosphor.
[12] The compound represented by the general formula (1) is characterized in that the energy difference ΔE _st between the lowest excited singlet state and the lowest excited triplet state of 77K is 0.3 eV or less [11] ] The light emitting layer of description.
[13] The light emitting layer according to [9], further comprising a host.
[14] The host, the compound represented by the general formula (1), and the light emitting material satisfy the following formula (A), and the compound represented by the general formula (1) is a delayed phosphor. The light emitting layer according to [13], which is characterized.
Formula (A) E _S1 (A)> E _S1 (B)> E _S1 (C)
[In the above formula, E _S1 (A) represents the lowest excited singlet energy level of the host, E _S1 (B) represents the lowest excited singlet energy level of the compound represented by the general formula (1), E _S1 (C) represents the lowest excited singlet energy level of the light emitting material. ]
[15] The compound represented by the general formula (1) is characterized in that the energy difference ΔE _st between the lowest excited singlet state and the lowest excited triplet state of 77K is 0.3 eV or less [14] ] The light emitting layer of description.

[16] An organic light-emitting device comprising the light-emitting layer according to any one of [9] to [15].
[17] The organic light-emitting device according to [16], which is an organic electroluminescence device.

[18] An assist dopant comprising a compound represented by the following general formula (1).
[In General Formula (1), R ^{1 to} R ⁵ each independently represent a hydrogen atom or a substituent other than a cyano group, and at least one of R ^{1 to} R ⁵ is each independently the following General Formula (2) or It is group represented by following General formula (3). ]
[In General formula (2), R < ¹¹ > -R < ²⁰ > represents a hydrogen atom or a substituent each independently. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁴ and R ¹⁵ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , R ¹⁹ And R ²⁰ may be bonded to each other to form a cyclic structure. ]
[In the general formula (3) represents a hydrogen atom or a substituent each independently R ⁷¹ to R ⁷⁹ is. R ⁷¹ and R ⁷² , R ⁷² and R ⁷³ , R ⁷³ and R ⁷⁴ , R ⁷⁴ and R ⁷⁵ , R ⁷⁶ and R ⁷⁷ , R ⁷⁷ and R ⁷⁸ , R ⁷⁸ and R ⁷⁹ are bonded to each other to form a cyclic structure. You may do it. ]
[19] A luminescent material comprising the compound represented by the general formula (1).
[20] The luminescent material according to [19], wherein the group represented by the general formula (2) is a group represented by the general formula (8).
[21] The luminescent material according to [20], wherein R ⁸⁹ and R ^{90 in} the general formula (8) are both substituted or unsubstituted aryl groups.
[22] The luminescent material according to [20] or [21], wherein R ¹ and R ^{5 in} the general formula (1) are groups represented by the general formula (8).

  The compounds of the present invention are useful as host and assist dopants. An organic light emitting device using the compound of the present invention as a host or assist dopant can realize high luminous efficiency.

It is a schematic sectional drawing which shows the layer structural example of an organic electroluminescent element. 2 is an absorption emission spectrum of a toluene solution of Compound 1 of Test Example 1. 2 is a transient decay curve of a toluene solution of Compound 1 of Test Example 1. 2 is a transient decay curve of a thin film of Compound 1 of Test Example 1. 2 shows an immediate emission spectrum and a delayed emission spectrum of a thin film of Compound 1 of Test Example 1. 2 is an absorption emission spectrum of a toluene solution of Compound 2 of Test Example 2. 3 is a transient decay curve of a toluene solution of Compound 2 of Test Example 2. 3 is a transient decay curve of a thin film of Compound 2 of Test Example 2. 2 shows an immediate emission spectrum and a delayed emission spectrum of a thin film of Compound 2 of Test Example 2. 2 is an absorption emission spectrum of a toluene solution of Compound 3 of Test Example 3. 4 is a transient decay curve of a toluene solution of Compound 3 of Test Example 3. 4 is a transient decay curve of a thin film of Compound 3 of Test Example 3. 2 shows an immediate emission spectrum and a delayed emission spectrum of a thin film of Compound 3 of Test Example 3. 4 is an absorption emission spectrum of a toluene solution of Compound 4 of Test Example 4. 6 is a transient decay curve of a toluene solution of Compound 4 of Test Example 4. 6 is a transient decay curve of a thin film of Compound 4 of Test Example 4. 2 shows an immediate emission spectrum and a delayed emission spectrum of a thin film of Compound 4 of Test Example 4. 6 is an absorption emission spectrum of a toluene solution of Compound 5 of Test Example 5. 6 is a transient decay curve of a toluene solution of Compound 5 of Test Example 5. 2 is an absorption emission spectrum of a toluene solution of Compound 6 of Test Example 6. 7 is a transient decay curve of a toluene solution of Compound 6 of Test Example 6. 7 is a transient decay curve of a neat thin film of Compound 6 of Test Example 6. 2 shows an immediate emission spectrum and a delayed emission spectrum of a neat thin film of Compound 6 of Test Example 6. 7 is an absorption emission spectrum of a doped thin film of Compound 6 of Test Example 6. 6 is a transient decay curve of a doped thin film of Compound 6 of Test Example 6. 7 shows an immediate emission spectrum and a delayed emission spectrum of a doped thin film of Compound 6 of Test Example 6. 2 is a transient decay curve of the organic electroluminescence device of the compound 2 of Example 1. It is the immediate fluorescence spectrum and delayed fluorescence spectrum of the organic electroluminescent element of the compound 2 of Example 1. It is the immediate fluorescence spectrum and delayed fluorescence spectrum of the thin film of the compound 2 of Example 1. 2 is an emission spectrum of an organic electroluminescence element of the compound 6 of Example 2. 2 is an emission spectrum of an organic electroluminescence element of the compound 6 of Example 3. 2 is an emission spectrum of an organic electroluminescence element of the compound 6 of Example 4. 2 is an emission spectrum of an organic electroluminescence element of the compound 6 of Example 5. 6 is a graph showing voltage-current density characteristics of an organic electroluminescence element of the compound 6 of Example 5.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. In addition, the isotope species of the hydrogen atom present in the molecule of the compound used in the present invention is not particularly limited. For example, all the hydrogen atoms in the molecule may be ¹ H, or a part or all of them are ² H. (Deuterium D) may be used.

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

In General Formula (1), R ^{1 to} R ⁵ each independently represent a hydrogen atom or a substituent other than a cyano group, and at least one of R ^{1 to} R ⁵ is each independently the following General Formula (2) or It is group represented by General formula (3).
The group represented by the general formula (2) or (3) may be only one of R ^{1 to} R ⁵ , or 2 to 5, but one or two It is preferable that
When the group represented by the general formula (2) or (3) is only one of R ^{1 to} R ⁵ , R ² or R ³ is represented by the general formula (2) or (3). It is preferably a group, and R ³ is preferably a group represented by the general formula (2) or (3).
When two of R ^{1 to} R ⁵ are groups represented by the general formula (2) or (3), R ¹ or R ² and R ⁴ or R ⁵ are represented by the general formula (2) or (3 ), And R ¹ and R ⁵ are more preferably groups represented by the general formula (2) or (3). When three of R ^{1 to} R ⁵ are groups represented by the general formula (2) or (3), R ¹ , R ³ and R ⁵ are represented by the general formula (2) or (3). It is preferable that it is group represented. Further, when four of R ^{1 to} R ⁵ are groups represented by the general formula (2) or (3), R ¹ , R ² , R ⁴ , R ⁵ are represented by the general formula (2) or ( The group represented by 3) is preferable.

In the general formulas (2) and (3), R ^{11 to} R ²⁰ and R ^{71 to} R ⁷⁹ each independently represent a hydrogen atom or a substituent. The number of substituents is not particularly limited, and all of R ^{11 to} R ²⁰ and R ^{71 to} R ⁷⁹ may be unsubstituted (that is, a hydrogen atom). When two or more of R ^{11 to} R ²⁰ are substituents and two or more of R ^{71 to} R ⁷⁹ are substituents, the plurality of substituents may be the same or different from each other. May be. When a substituent is present in the general formula (3), the substituent is preferably any one of R ^{72 to} R ⁷⁴ , R ⁷⁷ and R ⁷⁸ .
Examples of the substituent that R ^{11 to} R ²⁰ and R ^{71 to} R ⁷⁹ can take include, for example, a hydroxy group, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and 1 to 1 carbon atoms. 20 alkylthio groups, alkyl substituted amino groups having 1 to 20 carbon atoms, acyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 40 carbon atoms, heteroaryl groups having 3 to 40 carbon atoms, and 2 to 10 carbon atoms Alkenyl group, C2-C10 alkynyl group, C2-C10 alkoxycarbonyl group, C1-C10 alkylsulfonyl group, C1-C10 haloalkyl group, amide group, C2-C10 Alkylamide group, trialkylsilyl group having 3 to 20 carbon atoms, trialkylsilylalkyl group having 4 to 20 carbon atoms, trialkylsilylalkenyl group having 5 to 20 carbon atoms, and 5 to 2 carbon atoms It includes trialkylsilyl alkynyl group and a nitro group of. Among these specific examples, those that can be substituted with a substituent may be further substituted. More preferred substituents are a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, carbon A substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms and a dialkyl-substituted amino group having 1 to 20 carbon atoms. More preferable substituents are a fluorine atom, a chlorine atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, and a substituted group having 6 to 15 carbon atoms. Or it is an unsubstituted aryl group, a C3-C12 substituted or unsubstituted heteroaryl group.

R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁴ and R ¹⁵ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , R ¹⁹ And R ²⁰ , R ⁷¹ and R ⁷² , R ⁷² and R ⁷³ , R ⁷³ and R ⁷⁴ , R ⁷⁴ and R ⁷⁵ , R ⁷⁶ and R ⁷⁷ , R ⁷⁷ and R ⁷⁸ , R ⁷⁸ and R ⁷⁹ are bonded to each other. An annular structure may be formed. The cyclic structure may be an aromatic ring or an alicyclic ring, may contain a hetero atom, and the cyclic structure may be a condensed ring of two or more rings. The hetero atom here is preferably selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom. Examples of cyclic structures formed include benzene ring, naphthalene ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, pyrrole ring, imidazole ring, pyrazole ring, triazole ring, imidazoline ring, oxazole ring, isoxazole ring, thiazole And a ring, an isothiazole ring, a cyclohexadiene ring, a cyclohexene ring, a cyclopentaene ring, a cycloheptatriene ring, a cycloheptadiene ring, and a cycloheptaene ring.

The group represented by the general formula (2) is preferably a group represented by any one of the following general formulas (4) to (8), and is preferably a group represented by the general formula (8). More preferred.

In the general formulas (4) to (8), R ^{21 to} R ²⁴ , R ^{27 to} R ³⁸ , R ^{41 to} R ⁴⁸ , R ^{51 to} R ⁵⁸ , R ^{61 to} R ⁶⁵ , R ^{81 to} R ⁹⁰ are each independently Represents a hydrogen atom or a substituent. For the explanation and preferred range of the substituents mentioned here, the explanation and preferred range of the substituents which can be taken by the above R ^{11 to} R ²⁰ can be referred to. The number of substituents in general formulas (4) to (8) is not particularly limited. R ^{21 to} R ²⁴ , R ^{27 to} R ³⁸ , R ^{41 to} R ⁴⁸ , R ^{51 to} R ⁵⁸ , R ^{61 to} R ⁶⁵ , R ^{81 to} R ⁹⁰ and the above R ^{71 to} R ⁷⁹ are each independently A group represented by any one of formulas (3) to (8) is also preferred. It is also preferred that all are unsubstituted (ie hydrogen atoms). Moreover, when there are two or more substituents in each of the general formulas (4) to (8), these substituents may be the same or different.
Moreover, when a substituent exists in General formula (4)-(8), if the substituent is General formula (4), it shall be either R < ²² > -R < ²⁴ >, R < ²⁷ > -R < ²⁹ >. Is more preferable, and at least one of R ²³ and R ²⁸ is more preferable. In the general formula (5), any one of R ^{32 to} R ³⁷ is preferable, and in the general formula (6), R It is preferably any one of ^{42 to} R ⁴⁷ , and if it is general formula (7), it is preferably any of R ⁵² , R ⁵³ , R ⁵⁶ , R ⁵⁷ , R ^{62 to} R ^64. preferably if 8) R ⁸² ~R ^87, is either R ^89, R ^90, it is preferably R ⁸⁹ and R ^90. The substituent represented by R ⁸⁹ and R ⁹⁰ is preferably a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, and more preferably a substituted or unsubstituted phenyl group. The substituents represented by R ⁸⁹ and R ⁹⁰ are preferably the same.

In the general formulas (4) to (8), R ²¹ and R ²² , R ²² and R ²³ , R ²³ and R ²⁴ , R ²⁷ and R ²⁸ , R ²⁸ and R ²⁹ , R ²⁹ and R ³⁰ , R ³¹ and R ³² , R ³² and R ³³ , R ³³ and R ³⁴ , R ³⁵ and R ³⁶ , R ³⁶ and R ³⁷ , R ³⁷ and R ³⁸ , R ⁴¹ and R ⁴² , R ⁴² and R ⁴³ , R ⁴³ and R ⁴⁴ R ⁴⁵ and R ⁴⁶ , R ⁴⁶ and R ⁴⁷ , R ⁴⁷ and R ⁴⁸ , R ⁵¹ and R ⁵² , R ⁵² and R ⁵³ , R ⁵³ and R ⁵⁴ , R ⁵⁵ and R ⁵⁶ , R ⁵⁶ and R ⁵⁷ , R ⁵⁷ and R ⁵⁸ , R ⁶¹ and R ⁶² , R ⁶² and R ⁶³ , R ⁶³ and R ⁶⁴ , R ⁶⁴ and R ⁶⁵ , R ⁵⁴ and R ⁶¹ , R ⁵⁵ and R ⁶⁵ , R ⁸¹ and R ⁸² , R ⁸² R ⁸³ , R ⁸³ and R ⁸⁴ , R ⁸⁵ and R ⁸⁶ , R ⁸⁶ and R ⁸⁷ , R ⁸⁷ and R ⁸⁸ , and R ⁸⁹ and R ⁹⁰ may be bonded to each other to form a cyclic structure. For the explanation and preferred examples of the cyclic structure, reference can be made to the explanation and preferred examples of the cyclic structure formed by combining R ¹¹ and R ¹² in the general formula (2).

  It is preferable that all the groups represented by the general formula (2) present in the general formula (1) are groups represented by any one of the general formulas (4) to (8). For example, the group which all is represented by General formula (8) can be illustrated preferably.

R ^{1 to} R ⁵ other than the group represented by formula (2) or (3) are each independently a hydrogen atom or a substituent other than a cyano group. The number of substituents taken by R ^{1 to} R ⁵ other than the group represented by the general formula (2) or (3) is not particularly limited, and all the groups other than the group represented by the general formula (2) or (3) are used. It may be unsubstituted (that is, a hydrogen atom). When two or more of R ^{1 to} R ⁵ take a substituent other than the group represented by the general formula (2) or (3), the plurality of substituents may be the same as or different from each other.
For the explanation and preferred ranges of the substituents that R ^{1 to} R ⁵ can take, reference can be made to the explanations and preferred ranges of the substituents that can be taken by the above R ^{11 to} R ²⁰ excluding the cyano group. Among these, when R ³ is a group represented by the general formula (2) or a group represented by (3), at least one of R ¹ , R ² , R ⁴ and R ⁵ has 1 to 20 carbon atoms. It is preferable that R ¹ , R ² , R ⁴ , and R ⁵ are all alkyl groups having 1 to 20 carbon atoms. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms.

  Below, the specific example of a compound represented by General formula (1) is illustrated. However, the compound represented by the general formula (1) that can be used in the present invention should not be limitedly interpreted by these specific examples.

The molecular weight of the compound represented by the general formula (1) is, for example, 1500 or less when the organic layer containing the compound represented by the general formula (1) is intended to be formed by vapor deposition. Preferably, it is preferably 1200 or less, more preferably 1000 or less, and even more preferably 800 or less. The lower limit of the molecular weight is the molecular weight of the minimum compound represented by the general formula (1).
The compound represented by the general formula (1) may be formed by a coating method regardless of the molecular weight. If a coating method is used, a film can be formed even with a compound having a relatively large molecular weight.
The compound represented by the general formula (1) is useful as a host and assist dopant in the light emitting layer. In addition, by applying the present invention, a compound containing a plurality of structures represented by the general formula (1) in the molecule may be used as a host or assist dopant. In addition, the compound represented by General formula (1) can also be used as a luminescent material.

For example, it is conceivable to use a polymer obtained by previously polymerizing a polymerizable group in the structure represented by the general formula (1) and polymerizing the polymerizable group as a host and an assist dopant. . Specifically, by preparing a monomer containing a polymerizable functional group in any of R ^{1 to} R ^{5 in} the general formula (1) and polymerizing this alone or copolymerizing with other monomers, It is conceivable to obtain a polymer having a repeating unit and use the polymer as a host and an assist dopant. Alternatively, it is conceivable that dimers and trimers are obtained by reacting compounds having a structure represented by the general formula (1) and used as a host and assist dopant.
Examples of the polymer having a repeating unit containing a structure represented by the general formula (1) include a polymer containing a structure represented by the following general formula (9) or (10).

In General Formula (9) or (10), Q represents a group including the structure represented by General Formula (1), and L ¹ and L ² represent a linking group. Carbon number of a coupling group becomes like this. Preferably it is 0-20, More preferably, it is 1-15, More preferably, it is 2-10. And preferably has a structure represented by - linking group -X ¹¹ -L ^11. Here, X ¹¹ represents an oxygen atom or a sulfur atom, and is preferably an oxygen atom. L ¹¹ represents a linking group, preferably a substituted or unsubstituted alkylene group, or a substituted or unsubstituted arylene group, and a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, or a substituted or unsubstituted group A phenylene group is more preferable.
In general formula (9) or (10), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ and R ¹⁰⁴ each independently represent a substituent. Preferably, it is a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, or a halogen atom, more preferably an unsubstituted alkyl group having 1 to 3 carbon atoms. An unsubstituted alkoxy group having 1 to 3 carbon atoms, a fluorine atom, and a chlorine atom, and more preferably an unsubstituted alkyl group having 1 to 3 carbon atoms and an unsubstituted alkoxy group having 1 to 3 carbon atoms.
The linking group represented by L ¹ and L ² is any ^one of R ^{1 to} R ^{5 in} the structure of the general formula (1) constituting Q, any one of R ^{11 to} R ^{20 in} the general formula (2), Any one of R ^{71 to} R ^{78 having} the structure of the formula (3), any of R ^{21 to} R ²⁴ and R ^{27 to} R ³⁰ having the structure of the general formula (4), and R ³¹ to having the structure having the general formula (5) one of R ^38, either R ⁴¹ to R ⁴⁸ of the structure of the general formula (6), one of the general R ⁵¹ to R ⁵⁸ of the structure of formula (7), R ⁶¹ to R ^65, the general formula (8 ) Can be bonded to any one of R ^{81 to} R ⁹⁰ . Two or more linking groups may be linked to one Q to form a crosslinked structure or a network structure.

Specific examples of the structure of the repeating unit include structures represented by the following formulas (11) to (14).

In the polymer having a repeating unit containing these formulas (11) to (14), a hydroxy group is introduced into any ^one of R ^{1 to} R ^{5 in} the structure of the general formula (1), and this is used as a linker. It can be synthesized by reacting a compound to introduce a polymerizable group and polymerizing the polymerizable group.

  The polymer containing the structure represented by the general formula (1) in the molecule may be a polymer composed only of repeating units having the structure represented by the general formula (1), or other structures may be used. It may be a polymer containing repeating units. The repeating unit having a structure represented by the general formula (1) contained in the polymer may be a single type or two or more types. Examples of the repeating unit not having the structure represented by the general formula (1) include those derived from monomers used in ordinary copolymerization. Examples thereof include a repeating unit derived from a monomer having an ethylenically unsaturated bond such as ethylene and styrene.

[Synthesis Method of Compound Represented by General Formula (1)]
The compound represented by the general formula (1) can be synthesized by combining known reactions. For example, a compound in which R ³ in the general formula (1) is a group represented by the general formula (2) can be synthesized by reacting the following two compounds.

For the explanation of R ¹ , R ² , R ⁴ , R ⁵ , R ^{11 to} R ^{20 in} the above reaction formula, the corresponding description in the general formula (1) can be referred to. X represents a halogen atom, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom, a bromine atom, and an iodine atom are preferable.
The above reaction is an application of a known coupling reaction, and known reaction conditions can be appropriately selected and used. The details of the above reaction can be referred to the synthesis examples described below. The compound represented by the general formula (1) can also be synthesized by combining other known synthesis reactions.

[blend]
The compound represented by the general formula (1) of the present invention can constitute a mixture in which a material made of the compound is doped with a light emitting material. Such a mixture can be suitably used as a material for a light emitting layer of an organic light emitting device, for example.
In the mixture, one type of the compound represented by the general formula (1) may be used alone, or two or more types may be used in combination.
The light emitting material may be any of a red light emitting material, a green light emitting material, and a blue light emitting material, and may be a mixture of two or three color light emitting materials. Further, each of the red light emitting material, the green light emitting material, and the blue light emitting material may be composed of one kind of organic compound, or may be a combination of two or more kinds of organic compounds.
The content of the compound represented by the general formula (1) in the mixture is larger than the content of the light emitting material. For a preferable range of these contents, the description of the contents of the compound represented by the general formula (1) and the light emitting material in the following light emitting layer can be referred to.
The mixture may contain an organic compound other than the compound represented by the general formula (1) and the light emitting material.
Specific examples of the light emitting material, specific examples of the organic compound that can be used other than the compound represented by the general formula (1) and the light emitting material, specific examples of the light emitting material and other organic compounds used in the following light emitting layer Can be referred to.

[Organic light emitting device]
The compound represented by the general formula (1) of the present invention is useful as a host and assist dopant in an organic light-emitting device. Therefore, the compound represented by the general formula (1) of the present invention can be effectively used as a host or assist dopant in the light emitting layer of the organic light emitting device, thereby realizing an organic light emitting device with high light emission efficiency. be able to.
Here, in the present invention, the “host” is an organic compound contained in the light emitting layer together with the light emitting material, and is an organic compound having the highest lowest excited singlet energy level among the organic compounds contained in the light emitting layer. Say. The “assist dopant” means that the light emitting material including at least the assist dopant, the host, and the light emitting material has higher luminous efficiency than the light emitting layer having the same composition except that the assist dopant is not included. An organic compound. In addition, the compound represented by General formula (1) can also be used as a luminescent material.
Hereinafter, an organic light-emitting device (organic light-emitting device of the present invention) containing a compound represented by the general formula (1) and a light-emitting material in a light-emitting layer will be specifically described.

The organic light-emitting device of the present invention may be an organic photoluminescence device (organic PL device) or an organic electroluminescence device (organic EL device).
The organic photoluminescence element has a structure in which at least a light emitting layer is formed on a substrate. The organic electroluminescence element has a structure in which an organic layer is formed at least between an anode, a cathode, and an anode and a cathode. The organic layer includes at least a light emitting layer, and may consist of only the light emitting layer, or may have one or more organic layers in addition to the light emitting layer. Examples of such other organic layers include a hole transport layer, a hole injection layer, an electron blocking layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an exciton blocking layer. The hole transport layer may be a hole injection / transport layer having a hole injection function, and the electron transport layer may be an electron injection / transport layer having an electron injection function. A specific example of the structure of an organic electroluminescence element is shown in FIG. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer, 6 is an electron transport layer, and 7 is a cathode.
Below, each member and each layer of an organic electroluminescent element are demonstrated. In addition, description of a board | substrate and a light emitting layer corresponds also to the board | substrate and light emitting layer of an organic photo-luminescence element.

[Light emitting layer]
The light emitting layer is a layer that emits light after excitons are generated by recombination of holes and electrons injected from the anode and the cathode, respectively.
In the organic light emitting device of the present invention, the light emitting layer contains the compound represented by the general formula (1) and a light emitting material. The compound represented by the general formula (1) may be used as a host or an assist dopant.
(System using a compound represented by the general formula (1) as a host)
The light emitting layer using the compound represented by the general formula (1) as a host is formed by doping a host composed of the compound represented by the general formula (1) with a light emitting material, and represented by the general formula (1). The compound to be formed is configured such that the lowest excited singlet energy level is the highest among the organic compounds constituting the light emitting layer. Thereby, the excited singlet energy generated by the compound represented by the general formula (1) by recombination of holes and electrons easily moves to the light emitting material and is confined in the light emitting material. It is estimated that it contributes effectively. As a result, high luminous efficiency can be obtained.

The compound represented by the general formula (1) used as a host is preferably a delayed phosphor. Thereby, luminous efficiency can be made higher. Here, in the present specification, the term “delayed phosphor” refers to a state in which, after transitioning to the excited triplet state, the excited singlet state can cross between the reverse terms, and the excited singlet state returns to the ground state. An organic compound that emits fluorescence. Note that the lifetime of light generated by reverse intersystem crossing from the excited triplet state to the excited singlet state is longer than normal fluorescence (immediate fluorescence) or phosphorescence, and thus is observed as fluorescence delayed from these. When the compound represented by the general formula (1) is a delayed phosphor, it is presumed that high luminous efficiency is obtained for the following reason.
That is, when holes and electrons recombine on the host molecules in the light-emitting layer, the host is excited from the ground state to the excited singlet state and excited triplet state, but when the host is a delayed phosphor, the excited triplet A host molecule excited to a state transitions to an excited singlet state through reverse intersystem crossing. For this reason, in addition to the excited singlet energy directly generated by recombination of holes and electrons, the excited triplet energy can also be used as excited singlet energy through reverse intersystem crossing. Since both excited singlet energies move to the light emitting material to cause the light emitting material to emit light, it is estimated that high light emission efficiency can be obtained.

  The content of the compound represented by the general formula (1) and the light emitting material contained in the light emitting layer is not particularly limited, but the content of the compound represented by the general formula (1) as a host is more than the content of the light emitting material. Is also preferably large. Specifically, when the total mass of the content of the compound represented by the general formula (1) and the content of the light emitting material is 100% by mass, the content of the compound represented by the general formula (1) is: The content is preferably 50% by mass or more and 99.9% by mass or less, and the content of the light emitting material is more preferably 0.1% by mass or more and 50% by mass or less.

(System using a compound represented by the general formula (1) as an assist dopant)
The light emitting layer using the compound represented by the general formula (1) as an assist dopant is configured by doping a host with an assist dopant made of the compound represented by the general formula (1) and a light emitting material. Here, the host is an organic compound other than the compound represented by the general formula (1) and the light emitting material, and is the organic compound having the highest lowest excited singlet energy level among the organic compounds contained in the light emitting layer. .

In the system using the compound represented by the general formula (1) as an assist dopant, the compound represented by the general formula (1) is a delayed phosphor, and the host material and the compound represented by the general formula (1) It is preferable that the light emitting material satisfies the following formula (A).
Formula (A) E _S1 (A)> E _S1 (B)> E _S1 (C)
In the above formula, E _S1 (A) represents the lowest excited singlet energy level of the host, and E _S1 (B) represents the lowest excited singlet energy level of the compound represented by the general formula (1) which is an assist dopant. E _S1 (C) represents the lowest excited singlet energy level of the luminescent material.
Thereby, the compound represented by General formula (1) can be effectively functioned as an assist dopant, and luminous efficiency can be further increased. This is presumably due to the following reasons.
That is, when excitation energy is generated by recombination of holes and electrons in the light emitting layer, each compound contained in the light emitting layer is excited from the ground state to the excited singlet state and the excited triplet state. At this time, when the compound represented by the general formula (1) which is the host and the assist dopant and the light emitting material satisfy the formula (A), the excited singlet of the compound represented by the host and the general formula (1). The energy easily moves to the light emitting material, and the light emitting material in the ground state transitions to the excited singlet state. The light emitting material that has been in an excited singlet state emits fluorescence (radiation deactivation) when it subsequently returns to the ground state.
Here, in the compound represented by the general formula (1), which is a delayed phosphor, a molecule excited to an excited triplet state transitions to an excited singlet state through reverse intersystem crossing. For this reason, in addition to the excited singlet energy directly generated by recombination of holes and electrons, the excited triplet energy can also be used as excited singlet energy through reverse intersystem crossing. Since both of these excited singlet energies and the excited singlet energy generated by the host move to the light emitting material and contribute to light emission of the light emitting material, it is presumed that higher luminous efficiency can be obtained.

In the system using the compound represented by the general formula (1) as an assist dopant, the host and the compound represented by the general formula (1) preferably further satisfy the following formula (B). Thereby, much higher luminous efficiency can be realized.
Formula (B) E _T1 (A)> E _T1 (B)
In the above formula, E _T1 (A) represents the lowest excited triplet energy level at 77 K of the host, and E _T1 (B) represents the lowest excited triplet at 77 K of the compound represented by the general formula (1) which is an assist dopant. It represents the term energy level. The relationship between the lowest excited triplet energy level E _T1 (B) at 77K of the compound represented by the general formula (1) and the lowest excited triplet energy level E _T1 (C) at 77K of the light emitting material is not particularly limited. However, E _T1 (B)> E _T1 (C) may be selected.
When the host and the compound represented by the general formula (1) satisfy the formula (B), the excited triplet energy generated by the host easily moves to the compound represented by the general formula (1), The compound is excited to the excited triplet state. As described above, in the compound represented by the general formula (1), which is a delayed phosphor, the molecule excited to the excited triplet state transitions to the excited singlet state through the intersystem crossing, and as a result The excited triplet energy generated by the host is also presumed to contribute effectively to the light emission of the light emitting material as excited singlet energy. Thereby, higher luminous efficiency can be obtained.

  The content of the host, the compound represented by the general formula (1) and the light emitting material are not particularly limited, but the content of the compound represented by the general formula (1) is more than the content of the host. Small is preferable. Thereby, higher luminous efficiency can be obtained. Specifically, when the total weight of the content W1 of the host, the content W2 of the compound represented by the general formula (1), and the content W3 of the light emitting material is 100% by weight, the content W1 of the host is 15 The content W2 of the compound represented by the general formula (1) is preferably 5.0% by weight or more and 50% by weight or less, preferably the light emitting material. The content W3 of is preferably 0.5% by weight or more and 5.0% by weight or less.

As described above, it is preferable that the compound represented by the general formula (1) is a delayed phosphor in both cases where it is used as a host and when it is used as an assist dopant. This delayed phosphor is preferably a thermally activated delayed phosphor that reversely crosses from the excited singlet state to the excited triplet state by absorption of thermal energy. Thermally activated delayed phosphor absorbs the heat generated by the device and crosses the reverse triplet from the excited triplet state to the excited singlet relatively easily and efficiently contributes to the emission of the excited triplet energy. Can do.
The compound represented by the general formula (1) which is a delayed phosphor has a difference ΔE _st of 0 between the energy level E _s1 in the lowest excited singlet state and the energy level E _{T1 in} the lowest excited triplet state of 77K. 0.3 eV or less is preferable, 0.2 eV or less is more preferable, 0.1 eV or less is further preferable, and 0.08 eV or less is even more preferable. In the delayed phosphor having the energy difference ΔE _st in the above range, the reverse intersystem crossing from the excited triplet state to the excited singlet state occurs relatively easily, and the excited triplet energy can efficiently contribute to light emission. .

  As the light emitting material used in the system using the compound represented by the general formula (1) as a host and the system using the compound represented by the general formula (1) as an assist dopant, a known light emitting material can be used, and at least A luminescent material that can emit fluorescence is preferable, and delayed fluorescence or phosphorescence may be emitted together with fluorescence. For example, the following compounds can be preferably used.

  The host used in the system using the compound represented by the general formula (1) as assist dopan is not particularly limited except that the lowest excited singlet energy level is the highest among the organic compounds contained in the light emitting layer. A host generally used in the light emitting layer can be used. Among these, an organic compound that has a hole transporting ability and an electron transporting ability, prevents emission of longer wavelengths, and has a high glass transition temperature is preferable.

  In the organic electroluminescence device of the present invention, light emission is mainly caused by the light emitting material, but it may be partly or partly emitted from the compound or host represented by the general formula (1). Further, this light emission is at least fluorescent light emission, and may include delayed fluorescent light emission or phosphorescent light emission.

(Other organic compounds)
In a system using the compound represented by the general formula (1) as a host, the light emitting layer may be composed of only the compound represented by the general formula (1) and a light emitting material, or may contain other organic compounds. May be.
In the system using the compound represented by the general formula (1) as an assist dopant, the light emitting layer may be composed only of the compound represented by the general formula (1), a light emitting material, and a host. An organic compound may be included. Examples of other organic compounds include organic compounds having a hole transport ability, organic compounds having an electron transport ability, and the like. As the organic compound having a hole transport ability and the organic compound having an electron transport ability, the following hole transport material and electron transport material can be referred to.

[substrate]
The organic electroluminescence device of the present invention is preferably supported on a substrate. The substrate is not particularly limited and may be any substrate conventionally used for organic electroluminescence elements. For example, a substrate made of glass, transparent plastic, quartz, silicon, or the like can be used.

[anode]
As the anode in the organic electroluminescence element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by vapor deposition or sputtering of these electrode materials, and a pattern of a desired shape may be formed by photolithography, or when pattern accuracy is not so high (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. Or when using the material which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

[cathode]
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic electroluminescence element is transparent or translucent, the emission luminance is advantageously improved.
In addition, by using the conductive transparent material mentioned in the description of the anode as a cathode, a transparent or semi-transparent cathode can be produced. By applying this, an element in which both the anode and the cathode are transparent is used. Can be produced.

[Injection layer]
The injection layer is a layer provided between the electrode and the organic layer for lowering the driving voltage and improving the luminance of light emission. There are a hole injection layer and an electron injection layer, and between the anode and the light emitting layer or the hole transport layer. Further, it may be present between the cathode and the light emitting layer or the electron transport layer. The injection layer can be provided as necessary.

[Blocking layer]
The blocking layer is a layer that can prevent diffusion of charges (electrons or holes) and / or excitons existing in the light emitting layer to the outside of the light emitting layer. The electron blocking layer can be disposed between the light emitting layer and the hole transport layer and blocks electrons from passing through the light emitting layer toward the hole transport layer. Similarly, a hole blocking layer can be disposed between the light emitting layer and the electron transporting layer to prevent holes from passing through the light emitting layer toward the electron transporting layer. The blocking layer can also be used to block excitons from diffusing outside the light emitting layer. That is, each of the electron blocking layer and the hole blocking layer can also function as an exciton blocking layer. The term “electron blocking layer” or “exciton blocking layer” as used herein is used in the sense of including a layer having the functions of an electron blocking layer and an exciton blocking layer in one layer.

[Hole blocking layer]
The hole blocking layer has a function of an electron transport layer in a broad sense. The hole blocking layer has a role of blocking holes from reaching the electron transport layer while transporting electrons, thereby improving the recombination probability of electrons and holes in the light emitting layer. As the material for the hole blocking layer, the material for the electron transport layer described later can be used as necessary.

Electron blocking layer]
The electron blocking layer has a function of transporting holes in a broad sense. The electron blocking layer has a role to block electrons from reaching the hole transport layer while transporting holes, thereby improving the probability of recombination of electrons and holes in the light emitting layer. .

[Exciton blocking layer]
The exciton blocking layer is a layer for preventing excitons generated by recombination of holes and electrons in the light emitting layer from diffusing into the charge transport layer. It becomes possible to efficiently confine in the light emitting layer, and the light emission efficiency of the device can be improved. The exciton blocking layer can be inserted on either the anode side or the cathode side adjacent to the light emitting layer, or both can be inserted simultaneously. That is, when the exciton blocking layer is provided on the anode side, the layer can be inserted adjacent to the light emitting layer between the hole transport layer and the light emitting layer, and when inserted on the cathode side, the light emitting layer and the cathode Between the luminescent layer and the light-emitting layer. Further, a hole injection layer, an electron blocking layer, or the like can be provided between the anode and the exciton blocking layer adjacent to the anode side of the light emitting layer, and the excitation adjacent to the cathode and the cathode side of the light emitting layer can be provided. Between the child blocking layer, an electron injection layer, an electron transport layer, a hole blocking layer, and the like can be provided. When the blocking layer is disposed, at least one of the excited singlet energy and the excited triplet energy of the material used as the blocking layer is preferably higher than the excited singlet energy and the excited triplet energy of the light emitting material.

[Hole transport layer]
The hole transport layer is made of a hole transport material having a function of transporting holes, and the hole transport layer can be provided as a single layer or a plurality of layers.
The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. Known hole transport materials that can be used include, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indolocarbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, Examples include amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. An aromatic tertiary amine compound and an styrylamine compound are preferably used, and an aromatic tertiary amine compound is more preferably used.

[Electron transport layer]
The electron transport layer is made of a material having a function of transporting electrons, and the electron transport layer can be provided as a single layer or a plurality of layers.
The electron transport material (which may also serve as a hole blocking material) may have a function of transmitting electrons injected from the cathode to the light emitting layer. Examples of the electron transport layer that can be used include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide oxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  When producing an organic electroluminescent element, you may use not only the compound represented by General formula (1) for a light emitting layer but layers other than a light emitting layer. In that case, the compound represented by General formula (1) used for a light emitting layer and the compound represented by General formula (1) used for layers other than a light emitting layer may be same or different. For example, the compound represented by the general formula (1) may be used for the injection layer, blocking layer, hole blocking layer, electron blocking layer, exciton blocking layer, hole transporting layer, electron transporting layer, and the like. . The method for forming these layers is not particularly limited, and the layer may be formed by either a dry process or a wet process.

Below, the preferable material which can be used for an organic electroluminescent element is illustrated concretely. However, the material that can be used in the present invention is not limited to the following exemplary compounds. Moreover, even if it is a compound illustrated as a material which has a specific function, it can also be diverted as a material which has another function. In the structural formulas of the following exemplary compounds, R and R _{2 to} R ₇ each independently represent a hydrogen atom or a substituent. n represents an integer of 3 to 5.

  First, in the system using the compound represented by the general formula (1) as an assist dopant, preferred compounds that can be used as a host of the light emitting layer are listed.

  Next, examples of preferable compounds that can be used as the hole injection material will be given.

  Next, examples of preferred compounds that can be used as a hole transport material are listed.

  Next, examples of preferable compounds that can be used as an electron blocking material are given.

  Next, preferred compound examples that can be used as a hole blocking material are listed.

  Next, examples of preferable compounds that can be used as an electron transporting material will be given.

  Next, examples of preferable compounds that can be used as the electron injection material are given.

  Furthermore, preferable compound examples are given as materials that can be added. For example, adding as a stabilizing material can be considered.

The organic electroluminescence device produced by the above-described method emits light by applying an electric field between the anode and the cathode of the obtained device. At this time, if the light is emitted by excited singlet energy, light having a wavelength corresponding to the energy level is confirmed as fluorescence emission and delayed fluorescence emission. Further, in the case of light emission by excited triplet energy, a wavelength corresponding to the energy level is confirmed as phosphorescence. Since normal fluorescence has a shorter fluorescence lifetime than delayed fluorescence, the emission lifetime can be distinguished from fluorescence and delayed fluorescence.
On the other hand, in the case of phosphorescence, in ordinary organic compounds, the excited triplet energy is unstable and converted to heat, etc., and the lifetime is short and it is deactivated immediately. In order to measure the excited triplet energy of a normal organic compound, it can be measured by observing light emission under extremely low temperature conditions.

  The organic electroluminescence element of the present invention can be applied to any of a single element, an element having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix. According to the present invention, an organic light emitting device having greatly improved light emission efficiency can be obtained by incorporating the compound represented by the general formula (1) into the light emitting layer as a host or assist dopant. The organic light emitting device such as the organic electroluminescence device of the present invention can be further applied to various uses. For example, it is possible to produce an organic electroluminescence display device using the organic electroluminescence element of the present invention. For details, see “Organic EL Display” (Ohm Co., Ltd.) written by Shizushi Tokito, Chiba Adachi and Hideyuki Murata. ) Can be referred to. In particular, the organic electroluminescence device of the present invention can be applied to organic electroluminescence illumination and backlights that are in great demand.

  The features of the present invention will be described more specifically with reference to synthesis examples, test examples and examples. The following materials, processing details, processing procedures, and the like can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. In addition, the evaluation of the light emission characteristics was performed using a high performance ultraviolet visible near infrared spectrophotometer (Perkin Elmer: Lambda 950), a fluorescence spectrophotometer (Horiba, Ltd .: FluoroMax-4), an absolute PL quantum yield measuring device (Hamamatsu). Photonics: C11347), source meter (Ceethley: 2400 series), semiconductor parameter analyzer (Agilent Technology: E5273A), optical power meter measuring device (Newport: 1930C), optical spectrometer ( The measurement was performed using a spectroradiometer (manufactured by Topcon Co., Ltd .: SR-3) and a streak camera (C4334 manufactured by Hamamatsu Photonics Co., Ltd.).

The lowest excited singlet energy level E _S1 and the lowest excited triplet energy level E _T1 of the compounds used in the examples were determined by the following procedure. The energy difference ΔE _st between the lowest excited singlet state and the lowest excited triplet state of 77K was obtained by calculating the difference between E _S1 and E _T1 .
(1) Lowest excited singlet energy level E _S1
The sample to be measured was deposited on a Si substrate to prepare a sample, and the fluorescence spectrum of this sample was measured at room temperature (300K). In the fluorescence spectrum, the vertical axis represents light emission and the horizontal axis represents wavelength. A tangent line was drawn with respect to the fall of the emission spectrum on the short wave side, and a wavelength value λ edge [nm] at the intersection of the tangent line and the horizontal axis was obtained. A value obtained by converting this wavelength value into an energy value by the following conversion formula was defined as E _S1 .
Conversion formula: E _S1 [eV] = 1239.85 / λedge
For the measurement of the emission spectrum, a nitrogen laser (Lasertechnik Berlin, MNL200) was used as an excitation light source, and a streak camera (Hamamatsu Photonics, C4334) was used as a detector.

(2) Lowest excited triplet energy level E _T1
The same sample as the singlet energy E _S1 was cooled to 77 [K], the sample for phosphorescence measurement was irradiated with excitation light (337 nm), and the phosphorescence intensity was measured using a streak camera. A tangent line was drawn with respect to the rising edge of the phosphorescence spectrum on the short wavelength side, and a wavelength value λ edge [nm] at the intersection of the tangent line and the horizontal axis was obtained. A value obtained by converting this wavelength value into an energy value by the following conversion formula was defined as _ET1 .
Conversion formula: E _T1 [eV] = 1239.85 / λedge
The tangent to the short wavelength rising edge of the phosphorescence spectrum was drawn as follows. When moving on the spectrum curve from the short wavelength side of the phosphorescence spectrum to the maximum value on the shortest wavelength side among the maximum values of the spectrum, tangents at each point on the curve are considered toward the long wavelength side. The slope of this tangent line increases as the curve rises (that is, as the vertical axis increases). The tangent drawn at the point where the value of the slope takes the maximum value was taken as the tangent to the rising edge of the phosphorescence spectrum on the short wavelength side.
In addition, the maximum point having a peak intensity of 10% or less of the maximum peak intensity of the spectrum is not included in the above-mentioned maximum value on the shortest wavelength side, and has the maximum slope value closest to the maximum value on the shortest wavelength side. The tangent drawn at the point where the value was taken was taken as the tangent to the rising edge of the phosphorescence spectrum on the short wavelength side.

Synthesis Example 1 Synthesis of Compound 1
4-bromobenzonitrile (0.5 g, 2.75 mmol), 9,9-diphenylacridine (0.99 g, 3.0 mmol), tris (dibenzylideneacetone) dipalladium (0.76 g, 0.825 mmol), tri -Tert-butylphosphonium tetrafluoroborate (0.96 g, 3.3 mmol) and sodium tert-butoxide (0.53 g, 5.5 mmol) were added to a 100 ml container, and nitrogen substitution was performed three times. Thereafter, 30 ml of toluene was added, and the mixture was heated and stirred at 110 ° C. for 24 hours. The reaction mixture was cooled to room temperature, diluted with toluene, filtered through celite, and concentrated. This concentrate was purified by silica gel chromatography using a mixed solvent of dichloromethane: hexane = 2: 3 as a developing solvent, and 4- (10H-9,9-diphenylacridin-10-yl) benzonitrile as a white powder was obtained. The yield was 0.987 g, and the yield was 83%.

Synthesis Example 2 Synthesis of Compound 2
3- (10H-9, which is a white powder by performing the same operation as in Synthesis Example 1 except that 4-bromobenzonitrile was changed to 3-bromobenzonitrile (0.5 g, 2.75 mmol). 9-Diphenylacridin-10-yl) benzonitrile was obtained in a yield of 0.861 g and a yield of 72%.

Synthesis Example 3 Synthesis of Compound 3
The white powder 2- (10H-9, 9-Diphenylacridin-10-yl) benzonitrile was obtained in a yield of 1.022 g and a yield of 86%.

(Synthesis Example 4) Synthesis of Compound 4
4-Bromobenzonitrile was changed to 4-bromo-3-methylbenzonitrile (0.5 g, 2.55 mmol), and the amount of 9,9-diphenylacridine used was changed from 0.99 g (3.0 mmol) to 0.93 g. 3-methyl-4- (10H-9,9-diphenylacridin-10-yl) benzonitrile, which is a white powder, by performing the same operation as in Synthesis Example 1 except that it was changed to (2.8 mmol). Was obtained in a yield of 0.89 g and a yield of 78%.

Synthesis Example 5 Synthesis of Compound 5
4-iodo-2,3,5,6-tetramethylbenzonitrile (2 g, 7.0 mmol), methyl 2- (phenylamino) benzoate (1.9 g, 8.4 mmol), copper powder (0.94 g, 7 mmol), copper iodide (1.3 g, 7 mmol), and potassium carbonate (1.06 g, 7.7 mmol) were added to a 100 ml three-necked flask, and nitrogen substitution was performed three times. Thereafter, the mixture was heated and stirred at 190 ° C. for 24 hours without a solvent. The reaction mixture was cooled to room temperature, diluted with dichloromethane, filtered through celite, and concentrated. The concentrate was purified by silica gel chromatography using a mixed solvent of dichloromethane: hexane = 1: 4 as a developing solvent, and N- (4-cyano-2,3,5,6-tetramethylphenyl) as a yellow powder. A yield of 1.978 g of methyl N-phenylanthranilate was obtained in a yield of 73%.

The inside of a 100 ml two-necked flask containing methyl N- (4-cyano-2,3,5,6-tetramethylphenyl) -N-phenylanthranilate (1.0 g, 2.6 mmol) was purged with nitrogen, and 30 ml of tetrahydrofuran. In addition, it was dissolved. To this solution, 3.4 ml of 1.6M phenyllithium was added dropwise at -78 ° C. The mixture was gradually returned to room temperature over 2 hours and further stirred for 2 hours. Then, water was added to this reaction solution, the organic layer was extracted with ethyl acetate, and the concentrate was obtained by concentrating this organic layer. The inside of a 100 ml two-necked flask containing 1.564 g of this concentrate was purged with nitrogen, and 40 ml of dichloromethane was added and dissolved. Methanesulfonic acid (0.36 g, 3.7 mmol) was added dropwise to this solution, and the mixture was heated and stirred at 40 ° C. for 3 hours. The reaction solution was washed with aqueous sodium hydrogen carbonate, and the organic layer was extracted with dichloromethane and concentrated. This concentrate was purified by silica gel chromatography using a mixed solvent of dichloromethane: hexane = 1: 4 as a developing solvent, and 2,3,5,6-tetramethyl-4- (10H-9,9) as a white powder. -Diphenylacridin-10-yl) benzonitrile was obtained in a yield of 0.731 g and a yield of 57%.

Synthesis Example 6 Synthesis of Compound 6
2,6-difluorobenzonitrile (0.2 g, 1.44 mmol), 9,9-diphenylacridine (0.99 g, 3.0 mmol), potassium carbonate (0.5 g, 3.6 mmol) were added to a 100 ml container. 3 times with nitrogen substitution. Thereafter, 25 ml of dimethylformamide was added, and the mixture was heated and stirred at 153 ° C. for 3 days. The reaction solution was cooled to room temperature, washed with water, extracted with dichloromethane, and concentrated. This concentrate was purified by silica gel chromatography using a mixed solvent of dichloromethane: hexane = 1: 4 as a developing solvent, and 2,5-bis (10H-9,9-diphenylacridin-10-yl) as a white powder Benzonitrile was obtained in a yield of 0.413 g and a yield of 38%.
Table 1 shows the characteristic values of the compounds 1 to 6 synthesized as described above.
Note that HOMO is a value determined by measurement by atmospheric photoelectron spectroscopy, and LUMO is a value determined by using the energy gap obtained by the absorption spectrum edge.

Test Example 1 Preparation and Evaluation of Compound 1 Solution and Thin Film A toluene solution of Compound 1 (concentration 10 ⁻⁴ to 10 ⁻⁵ mol / L) was prepared in a glove box under an Ar atmosphere.
Further, a thin film of Compound 1 having a thickness of 100 nm was formed on a quartz substrate by a vacuum deposition method at a degree of vacuum of 5 × 10 ⁻⁴ Pa or less.
FIG. 2 shows the result of measuring the absorption emission spectrum of the toluene solution of Compound 1 with 353 nm excitation light.
The photoluminescence quantum efficiency was 24% for the toluene solution before bubbling with nitrogen and 29% for the toluene solution bubbled with nitrogen.
The results of measuring the transient decay curve for the toluene solution of Compound 1 are shown in FIG. In addition, FIG. 4 shows a transient attenuation curve of the thin film of Compound 1 measured at 300K and 5K with 337 nm excitation light. From FIG. 4, it was confirmed that the delayed fluorescence component was a thermally activated delayed fluorescence with an increase in temperature. Moreover, the photoluminescence quantum efficiency of the thin film of Compound 1 was 12.2%.
FIG. 5 shows the immediate emission spectrum (Prompt) and delayed emission spectrum (Delay) of the thin film of Compound 1 measured at each temperature of 300K and 5K. Here, when fitting a transient decay curve with a quadratic function, a fast component is an immediate emission spectrum (Prompt), and a slow component is a delayed emission spectrum (Delay). In FIG. 5, the immediate emission spectrum at 300K corresponds to the fluorescence spectrum, and the delayed emission spectrum at 300K corresponds to the delayed fluorescence spectrum. The immediate emission spectrum at 5K corresponds to the fluorescence spectrum, and the delayed emission spectrum corresponds to the phosphorescence spectrum.

(Test Example 2) Preparation and Evaluation of Compound 2 Solution and Thin Film A toluene solution of Compound 2 and a thin film of Compound 2 were prepared under the same conditions as Test Example 1 except that Compound 2 was used instead of Compound 1. did.
FIG. 6 shows the result of measuring the absorption emission spectrum of the toluene solution of Compound 2 with excitation light at 340 nm.
The photoluminescence quantum efficiency was 4% with the toluene solution before bubbling with nitrogen, and 10% with the toluene solution bubbled with nitrogen.
The result of measuring the transient decay curve for the toluene solution of Compound 2 is shown in FIG. In addition, FIG. 8 shows a transient decay curve by 337 nm excitation light measured at 300K, 200K, 100K, and 5K for the thin film of Compound 2. From FIG. 8, it was confirmed that the delayed fluorescence component is a thermally activated delayed fluorescence that increases with increasing temperature. Further, the photoluminescence quantum efficiency of the thin film of Compound 2 was 9.8%.
FIG. 9 shows the immediate emission spectrum (Prompt) and delayed emission spectrum (Delay) of the thin film of Compound 2 measured at temperatures of 300K and 5K. In FIG. 9, the immediate emission spectrum at 300K corresponds to the fluorescence spectrum, and the delayed emission spectrum at 300K corresponds to the delayed fluorescence spectrum. The immediate emission spectrum at 5K corresponds to the fluorescence spectrum, and the delayed emission spectrum corresponds to the phosphorescence spectrum.

Test Example 3 Preparation and Evaluation of Compound 3 Solution and Thin Film A compound 3 toluene solution and a compound 3 thin film were prepared under the same conditions as in Test Example 1, except that compound 3 was used instead of compound 1. did.
FIG. 10 shows the result of measuring the absorption emission spectrum of the compound 3 in toluene solution using 340 nm excitation light.
The photoluminescence quantum efficiency was 5.5% with the toluene solution before bubbling with nitrogen and 33% with the toluene solution bubbled with nitrogen.
The results of measuring the transient decay curve for the toluene solution of Compound 3 are shown in FIG. In addition, FIG. 12 shows a transient decay curve by 337 nm excitation light measured at 300K, 200K, 100K, and 5K for the compound 3 thin film. From FIG. 12, it was confirmed that it was a thermally activated delayed fluorescence in which the delayed fluorescence component increased with increasing temperature. Moreover, the photoluminescence quantum efficiency of the thin film of Compound 3 was 27%.
FIG. 13 shows the immediate emission spectrum (Prompt) and delayed emission spectrum (Delay) of the thin film of Compound 3 measured at 5K. In FIG. 13, the immediate emission spectrum corresponds to the fluorescence spectrum, and the delayed emission spectrum corresponds to the phosphorescence spectrum. The energy level E _{s1 in} the lowest excited singlet state of Compound 3 is 3.18 eV, the energy level E _T1 in the lowest excited triplet state is 3.07 eV, and the difference ΔE _st is 0.11 eV. It was.

Test Example 4 Preparation and Evaluation of Compound 4 Solution and Thin Film A compound 4 toluene solution and a compound 4 thin film were prepared under the same conditions as in Test Example 1, except that compound 4 was used instead of compound 1. did.
FIG. 14 shows the result of measuring the absorption emission spectrum of the toluene solution of compound 4 by excitation light at 340 nm.
The photoluminescence quantum efficiency was 4% with the toluene solution before bubbling with nitrogen and 7% with the toluene solution bubbled with nitrogen.
The result of measuring the transient decay curve for the toluene solution of Compound 4 is shown in FIG. In addition, FIG. 16 shows a transient attenuation curve by 337 nm excitation light measured at each temperature of 300K, 200K, 100K, and 5K for the thin film of Compound 4. From FIG. 16, it was confirmed that the delayed fluorescence component is a thermally activated delayed fluorescence with an increase in temperature. Further, the photoluminescence quantum efficiency of the thin film of Compound 4 was 6.1%.
FIG. 17 shows the immediate emission spectrum (Prompt) and delayed emission spectrum (Delay) of the thin film of Compound 4 measured at 5K. In FIG. 17, the immediate emission spectrum corresponds to the fluorescence spectrum, and the delayed emission spectrum corresponds to the phosphorescence spectrum. The difference ΔE _st between the energy level E _s1 in the lowest excited singlet state and the energy level E _{T1 in} the lowest excited triplet state of Compound 4 was 0.18 eV.

(Test Example 5) Preparation and Evaluation of Compound 5 Solution A toluene solution of Compound 5 was prepared under the same conditions as in Test Example 1 except that Compound 5 was used instead of Compound 1.
FIG. 18 shows the result of measuring the absorption emission spectrum of the toluene solution of compound 5 with 322 nm excitation light.
The photoluminescence quantum efficiency was 1% with the toluene solution before bubbling with nitrogen, and 2% with the toluene solution bubbled with nitrogen.
The result of measuring the transient decay curve for the toluene solution of compound 5 is shown in FIG. Referring to FIG. 19, the emission lifetime was longer after nitrogen bubbling than before nitrogen bubbling, and the characteristics of delayed fluorescence in which emission intensity increased under conditions of low oxygen concentration could be observed.

(Test Example 6) Preparation and Evaluation of Compound 6 Solution and Thin Film A toluene solution and a thin film of Compound 6 were prepared under the same conditions as in Test Example 1, except that Compound 6 was used instead of Compound 1.
FIG. 20 shows the result of measuring the absorption emission spectrum of the toluene solution of compound 6 by excitation light at 360 nm.
The photoluminescence quantum efficiency was 6.7% with a toluene solution bubbled with air and 64% with a toluene solution bubbled with nitrogen.
The results of measuring the transient decay curve for the toluene solution of Compound 6 are shown in FIG. In addition, FIG. 22 shows transient attenuation curves for the thin film of Compound 6 measured at 300K, 200K, 100K, and 8K using 337 nm excitation light. From FIG. 22, it was confirmed that the delayed fluorescence component is a thermally activated type in which the delayed fluorescence component increases as the temperature rises. Further, the photoluminescence quantum efficiency of the thin film of Compound 6 was 67.2%.
FIG. 23 shows the immediate emission spectrum (Prompt) and delayed emission spectrum (Delay) measured at 5K for the compound 6 thin film (neat thin film). In FIG. 23, the immediate emission spectrum corresponds to the fluorescence spectrum, and the delayed emission spectrum corresponds to the phosphorescence spectrum. The difference ΔE _st between the energy level E _s1 in the lowest excited singlet state and the energy level E _{T1 in} the lowest excited triplet state of Compound 6 was 0.04 eV.
A thin film (dope thin film) of Compound 6 containing 6.0% by weight of Compound 6 and DPEPO was also formed and measured. FIG. 24 shows an absorption emission spectrum, FIG. 25 shows a transient decay curve by 330 nm excitation light measured at 300K, 200K, 100K, and 5K temperatures, and FIG. 26 shows an immediate emission spectrum (Prompt) and delay measured at 5K. An emission spectrum (Delay) is shown.

(Example 1) Production and evaluation of organic electroluminescence device using compound 2 as a host Each thin film was vacuum-deposited on a glass substrate on which an anode made of indium tin oxide (ITO) having a thickness of 100 nm was formed. And a degree of vacuum of 5 × 10 ⁻⁴ Pa. First, α-NPD was formed to a thickness of 35 nm on ITO, and mCP was formed to a thickness of 10 nm thereon. Next, Compound 2 and TBPe were co-evaporated from different vapor deposition sources to form a layer having a thickness of 15 nm as a light emitting layer. At this time, the concentration of TBPe was 1.0% by weight. Next, DPEPO was formed to a thickness of 10 nm, and TPBi was formed thereon to a thickness of 30 nm. Further, lithium fluoride (LiF) was vacuum-deposited at 0.8 nm, and then aluminum (Al) was evaporated at a thickness of 100 nm to form a cathode, thereby obtaining an organic electroluminescence device.
FIG. 27 shows a transient decay curve of the manufactured organic electroluminescence device, and FIG. 28 shows an immediate emission spectrum (Prompt) and a delayed emission spectrum (Delay). The external quantum efficiency of the organic electroluminescence device using Compound 2 as a host was 2.8%.
For comparison, a thin film of Compound 2 doped with 1% by weight of TBPe was formed on a quartz substrate, and this thin film was subjected to an immediate emission spectrum (Prompt) and a delayed emission spectrum (Delay) in the same manner as in the above organic electroluminescence device. ) Was measured. The result is shown in FIG. The thin film of Compound 2 had a photoluminescence quantum efficiency (total emission quantum yield) of 72.2%.

(Example 2) Preparation and evaluation of organic electroluminescence device using compound 6 as host On each glass substrate on which an anode made of indium tin oxide (ITO) having a thickness of 100 nm was formed, each thin film was vacuum deposited. And a degree of vacuum of 5 × 10 ⁻⁴ Pa. First, α-NPD was formed to a thickness of 35 nm on ITO, and mCP was formed to a thickness of 10 nm thereon. Next, Compound 6 and TBPe were co-evaporated from different vapor deposition sources to form a layer having a thickness of 15 nm as a light emitting layer. At this time, the concentration of TBPe was 1.0% by weight. Next, DPEPO was formed to a thickness of 10 nm, and TPBi was formed thereon to a thickness of 30 nm. Further, lithium fluoride (LiF) was vacuum-deposited at 0.8 nm, and then aluminum (Al) was evaporated at a thickness of 100 nm to form a cathode, thereby obtaining an organic electroluminescence device.
FIG. 30 shows an emission spectrum of an organic electroluminescence device using Compound 6 as a host. The external quantum efficiency was 5.3%.

(Example 3) Preparation and evaluation of organic electroluminescence device using compound 6 as assist dopant Each thin film was vacuum-deposited on a glass substrate on which an anode made of indium tin oxide (ITO) having a thickness of 100 nm was formed. In this way, the layers were laminated at a degree of vacuum of 5 × 10 ⁻⁴ Pa. First, α-NPD was formed to a thickness of 35 nm on ITO, and mCP was formed to a thickness of 10 nm thereon. Next, TBPe, Compound 6, and DPEPO were co-evaporated from different evaporation sources to form a layer having a thickness of 15 nm to form a light emitting layer. At this time, the concentration of TBPe was 1.0 wt%, and the concentration of compound 6 was 6.0 wt%, 10.0 wt%, and 15.0 wt%. Next, DPEPO was formed to a thickness of 8 nm, and TPBi was formed thereon to a thickness of 37 nm. Further, lithium fluoride (LiF) was vacuum-deposited at 0.8 nm, and then aluminum (Al) was evaporated at a thickness of 100 nm to form a cathode, thereby obtaining an organic electroluminescence device.
The emission spectrum of each organic electroluminescence device using Compound 6 as a host is shown in FIG. The external quantum efficiency is 6.01% for an organic electroluminescence device having a concentration of compound 6 in the light emitting layer of 6.0% by weight, and 8.8 for an organic electroluminescence device having a concentration of compound 6 in the light emitting layer of 10.0% by weight. The organic electroluminescence device having 43% and the concentration of Compound 6 in the light emitting layer being 15.0% by weight was 13.1%. The chromaticity (x, y) of CIE was (0.13 to 0.14, 0.19).

(Example 4) Production and evaluation of organic electroluminescence device using compound 6 as light emitting material Each thin film was vacuum-deposited on a glass substrate on which an anode made of indium tin oxide (ITO) having a thickness of 100 nm was formed. In this way, the layers were stacked at a vacuum degree of 5 × 10 ⁻⁴ Pa. First, α-NPD was formed to a thickness of 35 nm on ITO, and mCP was formed to a thickness of 10 nm thereon. Next, Compound 6 and DPEPO were co-evaporated from different vapor deposition sources to form a layer having a thickness of 15 nm as a light emitting layer. At this time, the concentration of Compound 6 was 6.0% by weight. Next, DPEPO was formed to a thickness of 8 nm, and TPBi was formed thereon to a thickness of 37 nm. Further, lithium fluoride (LiF) was vacuum-deposited at 0.8 nm, and then aluminum (Al) was evaporated at a thickness of 100 nm to form a cathode, thereby obtaining an organic electroluminescence device.
The emission spectrum of each organic electroluminescence device using Compound 6 as the light emitting material is shown in FIG. The external quantum efficiency was 16%. The chromaticity (x, y) of CIE was (0.16, 0.16).

(Example 5) Preparation and evaluation of organic electroluminescence device using compound 6 as light emitting material Each thin film was vacuum-deposited on a glass substrate on which an anode made of indium tin oxide (ITO) having a thickness of 100 nm was formed. In this way, the layers were laminated at a degree of vacuum of 5 × 10 ⁻⁴ Pa. First, α-NPD was formed to a thickness of 30 nm on ITO, and mCP was formed to a thickness of 10 nm thereon. Next, Compound 6 was formed in a heat of 15 nm to form a light emitting layer. Next, DPEPO was formed to a thickness of 8 nm, and TPBi was formed thereon to a thickness of 37 nm. Further, lithium fluoride (LiF) was vacuum-deposited at 0.8 nm, and then aluminum (Al) was evaporated at a thickness of 100 nm to form a cathode, thereby obtaining an organic electroluminescence device.
FIG. 33 shows an emission spectrum of each organic electroluminescence element using Compound 6 as a light emitting material, and FIG. 34 shows a graph of voltage-current density characteristics. The external quantum efficiency was 8%. The CIE chromaticity (x, y) was (0.17, 0.24).

  The compounds of the present invention are useful as host and assist dopants. For this reason, the compound of this invention is effectively used as a host and assist dopant for organic light emitting elements, such as an organic electroluminescent element, By this, it is also possible to provide an organic light emitting element with high luminous efficiency. For this reason, this invention has high industrial applicability.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Cathode

Claims (14)

A compound represented by the following general formula (1) (excluding a compound represented by the following general formula (A)).
[In General Formula (1), R ^{1 to} R ⁵ each independently represents a hydrogen atom or a substituent other than a cyano group, and at least two of R ^{1 to} R ⁵ are each independently represented by the following General Formula (8): It is a group represented. ]
[In the general formula (8), R ⁸¹ ~R ⁹⁰ each independently represent a hydrogen atom or a substituent. ^R81 and ^R82 , ^R82 and ^R83 , ^R83 and ^R84 , ^R85 and ^R86 , ^R86 and ^R87 , ^R87 and ^R88 , ^R89 and ^R90 are bonded to each other to form a cyclic structure. You may do it. ]
Formula (A)

[In General Formula (A), Ar ^{1 to} Ar ³ each independently represents a substituted or unsubstituted aryl group, and at least one of Ar ^{1 to} Ar ³ is independently at least one electron withdrawing group. A carbazol-3-yl group substituted at the N-position with a group containing a phenyl group substituted with ] 2. The compound according to claim 1, wherein R ¹ and R ^{5 in} the general formula (1) are groups represented by the general formula (8). The compound according to claim 1 or 2, wherein R ⁸⁹ and R ^{90 in} the general formula (8) are both substituted or unsubstituted aryl groups. A compound represented by the following general formula (1) (provided that the following general formula (excluding the compound represented by A)) and material consisting of a mixture characterized in that it comprises a light-emitting material doped in the material.
[In General Formula (1), R ^{1 to} R ⁵ each independently represents a hydrogen atom or a substituent other than a cyano group , and at least two of R ^{1 to} R ⁵ are each independently represented by the following General Formula (8): It is a group represented. ]
[In the general formula (8), R ⁸¹ ~R ⁹⁰ each independently represent a hydrogen atom or a substituent. R ⁸¹ and R ^82, R ⁸² and R ^83, R ⁸³ and R ^84, R ⁸⁵ and R ^86, R ⁸⁶ and R ^87, R ⁸⁷ and R ^88, R ⁸⁹ and R ⁹⁰ may form a ring structure by bonding with each other You may do it. ]
[In General Formula (A), Ar ^{1 to} Ar ³ each independently represents a substituted or unsubstituted aryl group, and at least one of Ar ^{1 to} Ar ³ is independently at least one electron withdrawing group. A carbazol-3-yl group substituted at the N-position with a group containing a phenyl group substituted with ] A compound represented by the following general formula (1) (provided that the following general formula (excluding the compound represented by A)) and material consisting of a light-emitting layer which comprises a luminescent material doped into the material.
[In General Formula (1), R ^{1 to} R ⁵ each independently represents a hydrogen atom or a substituent other than a cyano group , and at least two of R ^{1 to} R ⁵ are each independently represented by the following General Formula (8): It is a group represented. ]
[In the general formula (8), R ⁸¹ ~R ⁹⁰ each independently represent a hydrogen atom or a substituent. R ⁸¹ and R ^82, R ⁸² and R ^83, R ⁸³ and R ^84, R ⁸⁵ and R ^86, R ⁸⁶ and R ^87, R ⁸⁷ and R ^88, R ⁸⁹ and R ⁹⁰ may form a ring structure by bonding with each other You may do it. ]
[In General Formula (A), Ar ^{1 to} Ar ³ each independently represents a substituted or unsubstituted aryl group, and at least one of Ar ^{1 to} Ar ³ is independently at least one electron withdrawing group. A carbazol-3-yl group substituted at the N-position with a group containing a phenyl group substituted with ]   The light emitting layer according to claim 5, wherein the compound represented by the general formula (1) is an organic compound having the highest lowest excited singlet energy level among the organic compounds contained in the light emitting layer. .   The light emitting layer according to claim 5 or 6, wherein the compound represented by the general formula (1) is a delayed phosphor. The compound represented by the general formula (1) has an energy difference ΔE _st between the lowest excited singlet state and the lowest excited triplet state of 77 K of 0.3 eV or less. Light emitting layer.   The light emitting layer according to claim 5, further comprising a host. The host, the compound represented by the general formula (1), and the light emitting material satisfy the following formula (A), and the compound represented by the general formula (1) is a delayed phosphor. The light emitting layer according to claim 9.
Formula (A) E _S1 (A)> E _S1 (B)> E _S1 (C)
[In the above formula, E _S1 (A) represents the lowest excited singlet energy level of the host, E _S1 (B) represents the lowest excited singlet energy level of the compound represented by the general formula (1), E _S1 (C) represents the lowest excited singlet energy level of the light emitting material. ] The compound represented by the general formula (1) has an energy difference ΔE _st between the lowest excited singlet state and the lowest excited triplet state of 77K of 0.3 eV or less. Light emitting layer.   An organic light-emitting device comprising the light-emitting layer according to claim 5.   The organic light-emitting device according to claim 12, wherein the organic light-emitting device is an organic electroluminescence device. An assist dopant comprising a compound represented by the following general formula (1) (excluding a compound represented by the following general formula (A)).
[In General Formula (1), R ^{1 to} R ⁵ each independently represents a hydrogen atom or a substituent other than a cyano group, and at least two of R ^{1 to} R ⁵ are each independently represented by the following General Formula (8): It is a group represented. ]
[In the general formula (8), R ⁸¹ ~R ⁹⁰ each independently represent a hydrogen atom or a substituent. ^R81 and ^R82 , ^R82 and ^R83 , ^R83 and ^R84 , ^R85 and ^R86 , ^R86 and ^R87 , ^R87 and ^R88 , ^R89 and ^R90 are bonded to each other to form a cyclic structure. You may do it. ]
[In General Formula (A), Ar ^{1 to} Ar ³ each independently represents a substituted or unsubstituted aryl group, and at least one of Ar ^{1 to} Ar ³ is independently at least one electron withdrawing group. A carbazol-3-yl group substituted at the N-position with a group containing a phenyl group substituted with ]