JP6367189B2 - Luminescent materials, organic light emitting devices and compounds - Google Patents

Description

  The present invention relates to a compound useful as a light emitting material and an organic light emitting device using the compound.

  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 efforts have been made to increase the light emission efficiency by newly developing and combining electron transport materials, hole transport materials, light emitting materials, and the like constituting the organic electroluminescence element. Among them, research on organic electroluminescent devices using compounds having a structure in which a phenylene group is bonded to a fused heteroaromatic ring can also be seen.

For example, Patent Document 1 describes an example in which a compound represented by the following general formula is used as a host material in a light emitting layer existing between a pair of electrodes constituting an organic electroluminescence element. R ^{1 to} R ⁵ in the following general formula are a hydrogen atom, an alkyl group or an aryl group, α is an arylene group, Ar ¹ is an aryl group, A is a diarylaminoaryl group, a substituted carbazol-3-yl Group or a carbazol-9-ylaryl group. However, Patent Document 1 does not describe an example showing the usefulness of the compound represented by the following general formula as a light-emitting material, and Ar ¹ and A in the following general formula are bonded to each other. There is also no description of compounds that form cyclic structures.

Patent Document 2 describes an example in which a compound represented by the following general formula is used as a light emitting material in a light emitting layer existing between a pair of electrodes constituting an organic electroluminescent element. R ^{1 to} R ¹² in the following general formula are hydrogen atom, halogen atom, lower alkyl group, alkoxy group, acyl group, nitro group, cyano group, amino group, dialkylamino group, diarylamino group, vinyl group, aryl group or It is a heteroaryl group, and Ar ^{1 to} Ar ⁴ are defined to represent an aryl group or a heteroaryl group. However, the invention described in Patent Document 2 is an invention related to a symmetric compound in which a common diarylphenyl group is substituted at the 2-position and 3-position of the quinoxaline ring, and the utility of other compounds is not described. Absent.

Patent Document 3 describes an example in which a compound represented by the following general formula is used as a hole transport material in a hole transport layer existing between a pair of electrodes constituting an organic electroluminescence element. ing. R ¹ , R ² , R ^{4 to} R ⁷ in the following general formula are a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group or a heteroaryl group, and R ³ is a hydrogen atom, a halogen atom, an alkyl group, An alkoxy group, R ⁸ and R ⁹ are a halogen atom, an alkyl group, an alkoxy group, an aryl group, Ar is an aryl group, A and B are heteroaryl groups having a C═N bond, and X ¹ and X ² are carbon atoms or nitrogen atoms, m and n are 0 or 1, and p and q are defined to represent any integer of 0 to 4. However, the invention described in Patent Document 3 is an invention relating to a compound in which a diarylamino group is bonded to the 2-position of the carbazole ring, and the utility of other compounds is not described. Also, no examples showing the usefulness of the compounds represented by the following general formulas as light emitting materials are described.

WO 2007/108403 WO2004 / 094389 WO2012 / 085576

  Thus, some studies have been made so far in which an organic electroluminescent device uses a compound having a structure in which a phenylene group is bonded to a fused heteroaromatic ring. However, many of them have been developed for applications other than light-emitting materials, and those that have been examined for usefulness as light-emitting materials are limited. And what examined the usefulness as a luminescent material has the structure of a compound special like the compound described in patent document 2, for example, and is quite limited. As a result of investigations by the present inventors, it has been found that the compound described in Patent Document 2 has room for improvement in light emission quantum efficiency as a light emitting material. On the other hand, when the diversion of the compound of Patent Document 3 that has not been shown to be useful as a luminescent material was examined as a luminescent material, it was confirmed that a sufficient luminescence quantum yield could not be increased. Among compounds having a structure in which a phenylene group is bonded to a fused heteroaromatic ring, there are many compounds that have not been synthesized so far. For this reason, it has been difficult to find a similar compound that is highly useful as a light-emitting material, even with reference to the results of conventional studies.

  Under these circumstances, the present inventors have further investigated the usefulness of a compound having a structure in which a phenylene group is bonded to a fused heteroaromatic ring as a luminescent material, and found a compound having excellent luminescent properties. The research was repeated aiming at. And the general formula of the compound useful as a luminescent material was derived, and the earnest examination was advanced for the purpose of generalizing the structure of the organic light emitting element with high luminous efficiency.

  As a result of intensive studies, the present inventors have found that a compound having a specific structure has excellent properties as a light emitting material. In addition, it has been found that such a group of compounds is useful as a delayed fluorescent material, and it has been clarified that an organic light-emitting device having high 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.

［一般式（１）において、Ａ¹〜Ａ⁷のうちの１〜４つはＮを表し、残りは各々独立にＣ−Ｒを表す。Ｒは水素原子または非芳香族基を表す。Ａｒ¹〜Ａｒ³は各々独立に置換もしくは無置換のアリーレン基を表す。Ｚは単結合または連結基を表す。］
［２］ 前記一般式（１）で表される化合物が下記一般式（２）で表される構造を有することを特徴とする［１］に記載の発光材料。

［一般式（２）において、Ａ¹〜Ａ⁷のうちの１〜４つはＮを表し、残りは各々独立にＣ−Ｒを表す。Ｒは水素原子または非芳香族基を表す。Ａｒ¹は置換もしくは無置換のアリーレン基を表す。Ｒ¹¹〜Ｒ¹⁴およびＲ¹⁷〜Ｒ²⁰は各々独立に水素原子または置換基を表す。Ｒ¹¹とＲ¹²、Ｒ¹²とＲ¹³、Ｒ¹³とＲ¹⁴、Ｒ¹⁷とＲ¹⁸、Ｒ¹⁸とＲ¹⁹、Ｒ¹⁹とＲ²⁰は互いに結合して環状構造を形成していてもよい。Ｚ¹は単結合または連結鎖長原子数が１または２の連結基を表す。］
［３］ 前記一般式（１）で表される化合物が下記一般式（３）で表される構造を有することを特徴とする［１］に記載の発光材料。

［一般式（３）において、Ａ¹〜Ａ⁷のうちの２〜４つはＮを表し、残りはＣ−Ｒを表す。Ｒは水素原子または非芳香族基を表す。Ａｒ¹は置換もしくは無置換のアリーレン基を表す。Ｙは置換もしくは無置換のカルバゾール−９−イル基、置換もしくは無置換の１０Ｈ−フェノキサジン−１０−イル基、置換もしくは無置換の１０Ｈ−フェノチアジン−１０−イル基、または置換もしくは無置換の１０Ｈ−フェナジン−５−イル基を表す。］
［４］ 前記一般式（３）のＹが下記一般式（４）〜（７）のいずれかで表される基であることを特徴とする［３］に記載の発光材料。

［一般式（４）〜（７）において、Ｒ²¹〜Ｒ²⁴、Ｒ²⁷〜Ｒ³⁸、Ｒ⁴¹〜Ｒ⁴⁸、Ｒ⁵¹〜Ｒ⁵⁸、Ｒ⁶¹〜Ｒ⁶⁵は、各々独立に水素原子または置換基を表す。Ｒ²¹とＲ²²、Ｒ²²とＲ²³、Ｒ²³とＲ²⁴、Ｒ²⁷とＲ²⁸、Ｒ²⁸とＲ²⁹、Ｒ²⁹とＲ³⁰、Ｒ³¹とＲ³²、Ｒ³²とＲ³³、Ｒ³³とＲ³⁴、Ｒ³⁵とＲ³⁶、Ｒ³⁶とＲ³⁷、Ｒ³⁷とＲ³⁸、Ｒ⁴¹とＲ⁴²、Ｒ⁴²とＲ⁴³、Ｒ⁴³とＲ⁴⁴、Ｒ⁴⁵とＲ⁴⁶、Ｒ⁴⁶とＲ⁴⁷、Ｒ⁴⁷とＲ⁴⁸、Ｒ⁵¹とＲ⁵²、Ｒ⁵²とＲ⁵³、Ｒ⁵³とＲ⁵⁴、Ｒ⁵⁵とＲ⁵⁶、Ｒ⁵⁶とＲ⁵⁷、Ｒ⁵⁷とＲ⁵⁸、Ｒ⁶¹とＲ⁶²、Ｒ⁶²とＲ⁶³、Ｒ⁶³とＲ⁶⁴、Ｒ⁶⁴とＲ⁶⁵、Ｒ⁵⁴とＲ⁶¹、Ｒ⁵⁵とＲ⁶⁵は互いに結合して環状構造を形成していてもよい。］
［５］ 前記一般式（３）のＹが下記一般式（８）で表される基であることを特徴とする［３］に記載の発光材料。

［一般式（８）において、Ｒ^21'〜Ｒ^24'およびＲ^27'〜Ｒ³⁰は、各々独立に水素原子または置換基を表すが、Ｒ^23'とＲ^28'の少なくとも一方は置換基である。Ｒ^21'とＲ^22'、Ｒ^22'とＲ^23'、Ｒ^23'とＲ^24'、Ｒ^27'とＲ^28'、Ｒ^28'とＲ^29'、Ｒ^29'とＲ^30'は互いに結合して環状構造を形成していてもよい。］
［６］ 一般式（８）において、Ｒ^23'とＲ^28'の少なくとも一方は置換もしくは無置換のジアリールアミノ基、または置換もしくは無置換のカルバゾール−９−イル基であることを特徴とする［５］に記載の発光材料。
［７］ 前記一般式（３）のＹが前記一般式（５）で表される基であることを特徴とする［４］に記載の発光材料。
［８］ 前記一般式（１）で表される化合物からなる遅延蛍光体。
［９］ ［１］〜［７］のいずれか１項に記載の発光材料を含むことを特徴とする有機発光素子。
［１０］ 遅延蛍光を放射することを特徴とする［９］に記載の有機発光素子。
［１１］ 有機エレクトロルミネッセンス素子であることを特徴とする［９］または［１０］に記載の有機発光素子。
［１２］ 前記一般式（２）で表される化合物。
[1] A light emitting material comprising a compound represented by the following general formula (1).

[In the general formula (1), one 1-4 of A ¹ to A ⁷ represents N, represents a C-R each independently rest. R represents a hydrogen atom or a non-aromatic group. Ar ^{1 to} Ar ³ each independently represents a substituted or unsubstituted arylene group. Z represents a single bond or a linking group. ]
[2] The light-emitting material according to [1], wherein the compound represented by the general formula (1) has a structure represented by the following general formula (2).

[In General formula (2), 1-4 of A < ¹ > -A < ⁷ > represent N, and the remainder each independently represents CR. R represents a hydrogen atom or a non-aromatic group. Ar ¹ represents a substituted or unsubstituted arylene group. R ^{11 to} R ¹⁴ and R ^{17 to} R ²⁰ each independently represent a hydrogen atom or a substituent. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , and R ¹⁹ and R ²⁰ may be bonded to each other to form a cyclic structure. Z ¹ represents a single bond or a linking group having 1 or 2 linking chain long atoms. ]
[3] The light-emitting material according to [1], wherein the compound represented by the general formula (1) has a structure represented by the following general formula (3).

[In General formula (3), 2-4 of A < ¹ > -A < ⁷ > represents N, and the remainder represents CR. R represents a hydrogen atom or a non-aromatic group. Ar ¹ represents a substituted or unsubstituted arylene group. Y represents a substituted or unsubstituted carbazol-9-yl group, a substituted or unsubstituted 10H-phenoxazin-10-yl group, a substituted or unsubstituted 10H-phenothiazin-10-yl group, or a substituted or unsubstituted 10H -Represents a phenazin-5-yl group. ]
[4] The luminescent material according to [3], wherein Y in the general formula (3) is a group represented by any one of the following general formulas (4) to (7).

[In the general formulas (4) to (7), 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 are each independently a hydrogen atom or a substituent. Represents a group. 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 , and R ⁵⁵ and R ⁶⁵ may be bonded to each other to form a cyclic structure. ]
[5] The luminescent material according to [3], wherein Y in the general formula (3) is a group represented by the following general formula (8).

[In General Formula (8), R ^{21 ′ to} R ^{24 ′} and R ^{27 ′ to} R ³⁰ each independently represent a hydrogen atom or a substituent, but at least one of R ^{23 ′} and R ^{28 ′} is a substituent. is there. 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' are bonded to each other Thus, a ring structure may be formed. ]
[6] In general formula (8), at least one of R ^{23 ′} and R ^{28 ′} is a substituted or unsubstituted diarylamino group, or a substituted or unsubstituted carbazol-9-yl group [ 5].
[7] The luminescent material according to [4], wherein Y in the general formula (3) is a group represented by the general formula (5).
[8] A delayed phosphor comprising the compound represented by the general formula (1).
[9] An organic light emitting device comprising the light emitting material according to any one of [1] to [7].
[10] The organic light-emitting device according to [9], which emits delayed fluorescence.
[11] The organic light-emitting device according to [9] or [10], which is an organic electroluminescence device.
[12] A compound represented by the general formula (2).

  The compound represented by the general formula (1) is useful as a light emitting material. In addition, the compound represented by the general formula (1) includes those that emit delayed fluorescence. An organic light emitting device using the compound of the present invention as a light emitting material 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 Compound 1 of Example 1. 2 is a transient attenuation curve of the organic photoluminescence element of Example 1. FIG. 2 is an absorption / emission spectrum of Compound 2 of Example 2. 6 is a transient attenuation curve of the organic photoluminescence device of Example 2. 2 is an absorption / emission spectrum of Compound 3 of Example 3. 6 is a transient attenuation curve of the organic photoluminescence device of Example 3. 6 is an emission spectrum of the organic electroluminescence device of Example 4. 5 is a current density-voltage characteristic of the organic electroluminescence element of Example 4. It is the current density-external quantum efficiency characteristic of the organic electroluminescent element of Example 4. 6 is an emission spectrum of the organic electroluminescence element of Example 5. 10 is a current density-voltage characteristic of the organic electroluminescence element of Example 5. It is the current density-external quantum efficiency characteristic of the organic electroluminescent element 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 luminescent material of the present invention is characterized by comprising a compound represented by the following general formula (1).

In General formula (1), 1-4 of A < ¹ > -A < ⁷ > represent N, and the remainder each independently represents CR. The number of N in A ^{1 to} A ⁷ is more preferably 1 to 3, and even more preferably 2. When ^{one of} A ^{1 to} A ⁷ is N, any of A ^{1 to} A ⁷ may be N, but preferably one of A ^{1 to} A ³ is N It is. When 2 to 4 of A ^{1 to} A ⁷ are N, 2 to 4 N may be present in only one of the two rings, or N is present in both rings. May be. When two of A ^{1 to} A ⁷ are N, for example, A ¹ and A ² , A ¹ and A ³ , A ² and A ³ , A ⁴ and A ⁶ , A ⁴ and A ⁷ , A ¹ And A ⁴ , A ¹ and A ⁷ , A ² and A ⁴ , A ² and A ⁷ , A ² and A ⁵ , and A ² and A ⁶ . When three of A ^{1 to} A ⁷ are N, for example, A ¹ and A ² and A ³ , A ⁴ and A ⁵ and A ⁷ , A ⁴ and A ⁶ and A ⁷ , A ¹ and A ³ And A ⁴ , A ¹ and A ³ and A ⁵ , A ¹ and A ³ and A ⁶ , A ¹ and A ³ and A ⁷ , A ¹ and A ² and A ⁴ , A ¹ and A ² and A ⁵ , A A combination of ¹ and A ² and A ⁶ , A ¹ , A ² and A ⁷ can be mentioned. When four of A ^{1 to} A ⁷ are N, for example, A ¹ and A ³ and A ⁴ and A ⁵ , A ¹ and A ³ and A ⁴ and A ⁶ , A ¹ and A ³ and A ⁴ And A ⁷ , A ¹ and A ³ and A ⁵ and A ⁶ , A ¹ and A ³ and A ⁵ and A ⁷ , A ¹ and A ³ and A ⁶ and A ⁷ , A ¹ and A ² and A ⁴ and A ⁵ , A ¹ and A ² and A ⁴ and A ⁶ , A ¹ and A ² and A ⁴ and A ⁷ , A ¹ and A ² and A ⁵ and A ⁶ , A ¹ and A ² , A ⁵ and A ⁷ , and a combination of a ¹ and a ² and a ⁶ and a ^7. Combinations other than these specific combinations may be employed. A preferred combination is a combination in which at least A ¹ and A ³ are N.

Of A ^{1 to} A ⁷ , those other than N each independently represent C—R. R represents a hydrogen atom or a non-aromatic group. That is, A ^{1 to} A ⁷ other than N are C—H or a group in which a non-aromatic group R is bonded to a carbon atom. The non-aromatic ring group here means a group having no aromatic ring or heteroaromatic ring. Examples of the non-aromatic group which R can take include a hydroxy group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylthio group having 1 to 20 carbon atoms, and 2 to 10 carbon atoms. Alkenyl group, alkynyl group having 2 to 10 carbon atoms, haloalkyl group having 1 to 10 carbon atoms, trialkylsilyl group having 3 to 20 carbon atoms, trialkylsilylalkyl group having 4 to 20 carbon atoms, 5 to 20 carbon atoms And a trialkylsilylalkynyl group having 5 to 20 carbon atoms. Among these specific examples, those that can be substituted with a substituent may be further substituted. More preferred substituents are a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms and an alkoxy group having 1 to 20 carbon atoms. Further preferred substituents are a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms and a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms.

  The alkyl group may be linear, branched, or cyclic, and more preferably has 1 to 6 carbon atoms. Specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, and tert-butyl. Group, pentyl group, hexyl group and isopropyl group. The alkoxy group may be linear, branched or cyclic, and more preferably has 1 to 6 carbon atoms. Specific examples thereof include methoxy group, ethoxy group, propoxy group, butoxy group, tert-butoxy group. A group, a pentyloxy group, a hexyloxy group, and an isopropyloxy group.

Ar ^{1 to} Ar ³ in the general formula (1) each independently represent a substituted or unsubstituted arylene group. The arylene group that Ar ^{1 to} Ar ³ can take may be a monocyclic arylene group or a condensed ring arylene group. Specific examples include 1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group, 1,2-naphthylene group, 1,3-naphthylene group, 1,4-naphthylene group, 1,5- A naphthylene group and a 1,8-naphthylene group can be mentioned.

Ar ¹ is preferably a 1,3-phenylene group, a 1,4-phenylene group, a 1,3-naphthylene group or a 1,4-naphthylene group, more preferably a 1,4-phenylene group or a 1,4-naphthylene group. . The arylene group that Ar ¹ may take may have a substituent. In this case, examples of the substituent include a hydroxy group, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and an alkoxy group having 1 to 20 carbon atoms. , An alkylthio group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, a heteroaryl group having 3 to 40 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, and 1 carbon atom -10 haloalkyl group, C3-C20 trialkylsilyl group, C4-C20 trialkylsilylalkyl group, C5-C20 trialkylsilylalkenyl group, C5-C20 trialkylsilyl An alkynyl group etc. are mentioned. Among these specific examples, those that can be substituted with a substituent may be further substituted. More preferred substituents are substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, substituted or unsubstituted aryl groups having 6 to 40 carbon atoms, and substituted groups having 3 to 40 carbon atoms. Or it is an unsubstituted heteroaryl group. Further preferred substituents are substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, substituted or unsubstituted alkoxy groups having 1 to 10 carbon atoms, substituted or unsubstituted aryl groups having 6 to 15 carbon atoms, carbon numbers 3 to 12 substituted or unsubstituted heteroaryl groups.

Ar ² and Ar ³ are preferably a 1,2-phenylene group or a 1,2-naphthylene group, and more preferably a 1,2-phenylene group. The arylene group that Ar ² and Ar ³ can have may have a substituent. In this case, examples of the substituent include a hydroxy group, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, and a carbon number. 1-20 alkoxy group, C1-C20 alkylthio group, C1-C20 alkyl-substituted amino group, C12-C40 aryl-substituted amino group, C2-C20 acyl group, C6-C6 ˜40 aryl group, C 3-40 heteroaryl group, C 12-40 substituted or unsubstituted carbazolyl group, C 2-10 alkenyl group, C 2-10 alkynyl group, carbon number 2-10 alkoxycarbonyl group, C1-C10 alkylsulfonyl group, C1-C10 haloalkyl group, amide group, C2-C10 alkylamide group, carbon number Examples include 3 to 20 trialkylsilyl groups, 4 to 20 carbon trialkylsilylalkyl groups, 5 to 20 carbon trialkylsilylalkenyl groups, 5 to 20 carbon trialkylsilylalkynyl groups, and nitro groups. It is done. 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 C3-C40 substituted or unsubstituted heteroaryl group, C1-C10 substituted or unsubstituted dialkylamino group, C12-C40 substituted or unsubstituted diarylamino group, C12-C40 A substituted or unsubstituted carbazolyl group; 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 1 to 10 carbon atoms. Or an unsubstituted dialkylamino group, a substituted or unsubstituted diarylamino group having 12 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 15 carbon atoms, and a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms It is a group.

  The aryl group described as the substituent may be a single ring or a condensed ring, and specific examples thereof include a phenyl group and a naphthyl group. The heteroaryl group may be a single ring or a condensed ring, and specific examples thereof include a pyridyl group, a pyridazyl group, a pyrimidyl group, a triazyl group, a triazolyl group, and a benzotriazolyl group. These heteroaryl groups may be a group bonded through a hetero atom or a group bonded through a carbon atom constituting a heteroaryl ring.

In the general formula (1), Z represents a single bond or a linking group. Z is is for connecting the Ar ² and Ar ^3, by bonding atoms and Z other than bonded atoms to the nitrogen atom of the formula among the ring-constituting atoms of Ar ² and Ar ³ (1) Preferably it is. Specifically, it is preferable that Z is bonded to the α-position atom or β-position atom of Ar ² and Ar ³ bonded to the nitrogen atom, and the α-position atom and Z are bonded. Is more preferable. Z is preferably a single bond or a linking group. In the case of a linking group, the number of linking chain long atoms is preferably 1 or 2, and more preferably 1. Examples of the linking group having a linking chain length atom number of 1 include —O—, —S—, —C (R ¹ ) (R ² ) —, and —N (R ³ ) —. In addition, as a linking group having 2 linking chain long atoms, —C (R ⁴ ) (R ⁵ ) —C (R ⁶ ) (R ⁷ ) —, —C (R ⁸ ) = C (R ⁹ ) — Can be mentioned. Here, R ^{1 to} R ⁹ each independently represents a hydrogen atom or a substituent. For specific examples and preferred ranges of the substituent, the specific examples and preferred ranges exemplified as the substituent of the arylene group that Ar ² and Ar ³ can take can be referred to. R ¹ and R ² , R ⁴ and R ⁵ , R ⁶ and R ⁷ , R ⁸ and R ⁹ may be the same or different from each other. Examples of the case where they are the same include a case where both are methyl groups and a case where they are ethyl groups.

The compound represented by the general formula (1) preferably has a structure represented by the following general formula (2).

For the definitions and preferred ranges of A ^{1 to} A ⁷ and Ar ^{1 in} the general formula (2), the corresponding description in the general formula (1) can be referred to. Further, the definition and preferable range of Z ¹ in formula (2), can be referred to the Z in the general formula (1). R ^{11 to} R ¹⁴ and R ^{17 to} R ²⁰ in the general formula (2) each independently represent a hydrogen atom or a substituent. Specific examples and preferred ranges of the substituents that can be taken by R ^{11 to} R ¹⁴ and R ^{17 to} R ²⁰ include the specific examples exemplified as the substituent of the arylene group that Ar ² and Ar ³ can take in the general formula (1) Reference can be made to preferred ranges.

R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , and R ¹⁹ and R ²⁰ may be bonded to each other to form a cyclic structure. 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 compound represented by the general formula (1) preferably has a structure represented by the following general formula (3).

For the definitions and preferred ranges of A ^{1 to} A ⁷ and Ar ^{1 in} the general formula (3), the corresponding description in the general formula (1) can be referred to. Y in the general formula (3) is a substituted or unsubstituted carbazol-9-yl group, a substituted or unsubstituted 10H-phenoxazin-10-yl group, a substituted or unsubstituted 10H-phenothiazin-10-yl group, or It represents a substituted or unsubstituted 10H-phenazin-5-yl group.

Specifically, Y in the general formula (3) is preferably a group represented by any one of the following general formulas (4) to (7).

In the general formulas (4) to (7), R ^{21 to} R ²⁴ , R ^{27 to} R ³⁸ , R ^{41 to} R ⁴⁸ , R ^{51 to} R ⁵⁸ , and R ^{61 to} R ⁶⁵ are each independently a hydrogen atom or a substituent. Represents. For the explanation and preferred ranges of the substituents herein, the specific examples and preferred ranges exemplified as the substituents of the arylene group that can be taken by Ar ² and Ar ³ in the general formula (1) can be referred to. R ^{21 to} R ²⁴ , R ^{27 to} R ³⁸ , R ^{41 to} R ⁴⁸ , R ^{51 to} R ⁵⁸ , and R ^{61 to} R ⁶⁵ are each independently any of the above general formulas (4) to (7). It is also preferable that it is a group represented. The number of substituents in the general formulas (4) to (7) is not particularly limited. Moreover, all may be unsubstituted (namely, a hydrogen atom). Furthermore, when there are two or more substituents in each of the general formulas (4) to (7), these substituents may be the same or different. When a substituent exists in the general formulas (4) to (7), the substituent is preferably any of R ^{22 to} R ²⁴ and R ^{27 to} R ²⁹ if the substituent is the general formula (4). , R ²³ and R ²⁸ are particularly preferable. In the general formula (5), any one of R ^{32 to} R ³⁷ is preferable, and in the general formula (6), R ⁴² to Any one of R ⁴⁷ is preferable, and in the case of the general formula (7), any of R ⁵² , R ⁵³ , R ⁵⁶ , R ⁵⁷ , and R ^{62 to} R ⁶⁴ is preferable.

In the general formulas (4) to (7), 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 are bonded together to form a cyclic structure. It may be. 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).

Y in the general formula (2) is preferably a group represented by the following general formula (8).

In the general formula (8), R ^{21 ′ to} R ^{24 ′} and R ^{27 ′ to} R ³⁰ each independently represent a hydrogen atom or a substituent, but at least one of R ^{23 ′} and R ^{28 ′} is a substituent. . That is, R ^{23 ′} is a substituent, R ^{28 ′} is a substituent, or both R ^{23 ′} and R ^{28 ′} are substituents. For example, among R ^{21 ′ to} R ^{24 ′} and R ^{27 ′ to} R ³⁰ , when only R ^{23 ′} is a substituent, only R ^{28 ′} is a substituent, or R ^{23 ′} and R ^{28 The} case where only both are substituents can be mentioned. When at least one of R ^{23 ′} and R ^{28 ′} is a substituent, the emission quantum efficiency tends to be higher than when substituted at other positions. In particular, this tendency is remarkable when at least one of R ^{23 ′} and R ^{28 ′} is a substituted or unsubstituted diarylamino group or a substituted or unsubstituted carbazol-9-yl group.

R ^{21 ′ to} R ^{24 ′} , R ^{27 ′ to} R ³⁰ , description of the substituents that can be taken by the diarylamino group and carbazol-9-yl group, and preferred ranges thereof, Ar ² and Ar in the general formula (1) Specific examples and preferred ranges exemplified as the substituent for the arylene group ³ can be referred to. In the general formula (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 ′} may be bonded to each other to form a cyclic structure. For the explanation and preferred range of the cyclic structure, the corresponding description in the general formula (2) can be referred to.

  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.

By applying the present invention, it is also conceivable to use a compound containing a plurality of structures represented by the general formula (1) in the molecule as a light emitting 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 light emitting material. Specifically, a monomer containing a polymerizable functional group in any of R, Ar ^{1 to} Ar ³ , and Z of C—R that can be taken by A ^{1 to} A ⁷ in the general formula (1) is prepared. It can be considered that a polymer having a repeating unit is obtained by polymerizing alone or copolymerized with other monomers, and the polymer is used as a light emitting material. Alternatively, it is also conceivable that dimers and trimers are obtained by reacting compounds having a structure represented by the general formula (1) and used as a luminescent material.

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} CR R, Ar ^{1 to} Ar ³ , and Z that can be taken by A ^{1 to} A ^{7 in} the structure of the general formula (1) constituting Q. Any one of R, Ar ¹ , R ^{11 to} R ¹⁴ , R ^{17 to} R ²⁰ , and Z ¹ of C—R that A ^{1 to} A ⁷ of the structure of the general formula (2) can take, the structure of the general formula (3) Any ^one of R, Ar ¹ and Y of C—R which can be taken by A ^{1 to} A ⁷ in any one of formulas (4), R ^{21 to} R ²⁴ and R ^{27 to} R ^{30 in} the structure of the general formula (4) Any one of R ^{31 to} R ^{38 in} the structure of the general formula (5), any of R ^{41 to} R ^{48 in} the structure of the general formula (6), R ^{51 to} R ⁵⁸ , R in the structure of the general formula (7) either ^{61 ~R 65,} R ²¹ of the structure of the general formula (8) ^{'~R 24',} can be coupled to any of the R ^{27 '~R 30'.} 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).

A polymer having a repeating unit containing these formulas (11) to (14) is a compound of R, Ar ^{1 to} Ar ³ , Z of C—R that A ^{1 to} A ⁷ of the structure of the general formula (1) can take. It can be synthesized by introducing a hydroxy group into any of them, reacting the following compound as a linker 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 (2)]
Of the compounds represented by the general formula (1), the compound represented by the general formula (2) is a novel compound.
The compound represented by the general formula (2) can be synthesized by combining known reactions. For example, it can be synthesized by reacting according to the following scheme.

Regarding the explanation of A ^{1 to} A ⁷ , Ar ¹ , R ^{11 to} R ¹⁴ , R ^{17 to} R ²⁰ , and Z ^{1 in} the above reaction formula, the corresponding description in the general formula (2) 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 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 (2) can also be synthesized by combining other known synthesis reactions.

[Organic light emitting device]
The compound represented by the general formula (1) of the present invention is useful as a light emitting material of an organic light emitting device. For this reason, the compound represented by General formula (1) of this invention can be effectively used as a luminescent material for the light emitting layer of an organic light emitting element. The compound represented by the general formula (1) includes a delayed fluorescent material (delayed phosphor) that emits delayed fluorescence. That is, the present invention relates to a delayed phosphor having a structure represented by the general formula (1), an invention using a compound represented by the general formula (1) as a delayed phosphor, and a general formula (1). An invention of a method for emitting delayed fluorescence using the represented compound is also provided. An organic light emitting device using such a compound as a light emitting material emits delayed fluorescence and has a feature of high luminous efficiency. The principle will be described below by taking an organic electroluminescence element as an example.

  In an organic electroluminescence element, carriers are injected into a light emitting material from both positive and negative electrodes to generate an excited light emitting material and emit light. In general, in the case of a carrier injection type organic electroluminescence element, 25% of the generated excitons are excited to the excited singlet state, and the remaining 75% are excited to the excited triplet state. Therefore, the use efficiency of energy is higher when phosphorescence, which is light emission from an excited triplet state, is used. However, since the excited triplet state has a long lifetime, energy saturation occurs due to saturation of the excited state and interaction with excitons in the excited triplet state, and in general, the quantum yield of phosphorescence is often not high. On the other hand, the delayed fluorescent material transitions to the excited triplet state due to intersystem crossing, etc., and then crosses back to the excited singlet state due to triplet-triplet annihilation or absorption of thermal energy, and emits fluorescence. To do. In the organic electroluminescence device, it is considered that a thermally activated delayed fluorescent material by absorption of thermal energy is particularly useful. When a delayed fluorescent material is used for the organic electroluminescence element, excitons in the excited singlet state emit fluorescence as usual. On the other hand, excitons in the excited triplet state absorb heat generated by the device and cross between the excited singlets to emit fluorescence. At this time, since the light is emitted from the excited singlet, the light is emitted at the same wavelength as the fluorescence, but the light lifetime (luminescence lifetime) generated by the reverse intersystem crossing from the excited triplet state to the excited singlet state is normal. Since the fluorescence becomes longer than the fluorescence and phosphorescence, it is observed as fluorescence delayed from these. This can be defined as delayed fluorescence. If such a heat-activated exciton transfer mechanism is used, the ratio of the compound in an excited singlet state, which normally generated only 25%, is increased to 25% or more by absorbing thermal energy after carrier injection. It can be raised. If a compound that emits strong fluorescence and delayed fluorescence even at a low temperature of less than 100 ° C is used, the heat of the device will sufficiently cause intersystem crossing from the excited triplet state to the excited singlet state and emit delayed fluorescence. Efficiency can be improved dramatically.

By using the compound represented by the general formula (1) of the present invention as a light-emitting material of a light-emitting layer, excellent organic light-emitting devices such as an organic photoluminescence device (organic PL device) and an organic electroluminescence device (organic EL device) Can be provided. At this time, the compound represented by the general formula (1) of the present invention may have a function of assisting light emission of another light emitting material included in the light emitting layer as a so-called assist dopant. That is, the compound represented by the general formula (1) of the present invention contained in the light emitting layer includes the lowest excitation singlet energy level of the host material contained in the light emitting layer and the lowest excitation of other light emitting materials contained in the light emitting layer. It may have the lowest excited singlet energy level between singlet energy levels.
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.

(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.

(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 each of the anode and the cathode, and the light emitting material may be used alone for the light emitting layer. , Preferably including a luminescent material and a host material. As a luminescent material, the 1 type (s) or 2 or more types chosen from the compound group of this invention represented by General formula (1) can be used. In order for the organic electroluminescent device and the organic photoluminescent device of the present invention to exhibit high luminous efficiency, it is important to confine singlet excitons and triplet excitons generated in the light emitting material in the light emitting material. Therefore, it is preferable to use a host material in addition to the light emitting material in the light emitting layer. As the host material, an organic compound having at least one of excited singlet energy and excited triplet energy higher than that of the light emitting material of the present invention can be used. As a result, singlet excitons and triplet excitons generated in the light emitting material of the present invention can be confined in the molecules of the light emitting material of the present invention, and the light emission efficiency can be sufficiently extracted. However, even if singlet excitons and triplet excitons cannot be sufficiently confined, there are cases where high luminous efficiency can be obtained, so that host materials that can achieve high luminous efficiency are particularly limited. And can be used in the present invention. In the organic light emitting device or organic electroluminescent device of the present invention, light emission is generated from the light emitting material of the present invention contained in the light emitting layer. This emission includes both fluorescence and delayed fluorescence. However, light emission from the host material may be partly or partly emitted.
When the host material is used, the amount of the compound of the present invention, which is a light emitting material, is preferably 0.1% by weight or more, more preferably 1% by weight or more, and 50% or more. It is preferably no greater than wt%, more preferably no greater than 20 wt%, and even more preferably no greater than 10 wt%.
The host material in the light-emitting layer is preferably an organic compound that has a hole transporting ability and an electron transporting ability, prevents the emission of longer wavelengths, and has a high glass transition temperature.

(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, preferred compounds that can also be used as a host material for 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. In addition, 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, with respect to phosphorescence, in ordinary organic compounds such as the compounds of the present invention, the excited triplet energy is unstable and is converted into heat and the like, and the lifetime is short and it is immediately deactivated. 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 with greatly improved light emission efficiency can be obtained by containing the compound represented by the general formula (1) in the light emitting layer. 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 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. Note that the evaluation of the light emission characteristics is as follows: source meter (manufactured by Keithley: 2400 series), semiconductor parameter analyzer (manufactured by Agilent Technologies: E5273A), optical power meter measuring device (manufactured by Newport: 1930C), optical spectrometer (Ocean Optics Co., Ltd .: USB2000), spectroradiometer (Topcon Co., Ltd .: SR-3), and streak camera (Hamamatsu Photonics Co., Ltd. model C4334) were used.

Synthesis Example 1 Synthesis of Compound 1

  To a two-necked flask purged with nitrogen, 2- (4-bromophenyl) quinoxaline (1.14 g, 4.00 mmol), phenoxazine (0.81 g, 4.40 mmol), potassium carbonate (1.82 g, 13.2 mmol). ), 40 ml of toluene was added, and the mixture was stirred at room temperature for 10 minutes. Thereto was added a mixed solution of palladium (II) acetate (29.6 mg, 0.13 mmol), tri-tert-butylphosphine (98.0 mg, 0.48 mmol) and 40 ml of toluene, and the mixture was heated and refluxed for 24 hours. After cooling to room temperature, chloroform and brine were added, and the organic layer was separated and extracted. Anhydrous magnesium sulfate was added for dehydration, and the solvent was distilled off under reduced pressure. The target product (2- (4-N-phenoxazylphenoxy) quinoxaline) was isolated and purified by silica gel column chromatography using a mixed solvent of chloroform: hexane = 1: 1 (yield: 1.44 g, yield) : 92.9%).

Synthesis Example 2 Synthesis of Compound 2

  To a nitrogen-substituted two-necked flask, 2- (4-bromophenyl) quinoxaline (1.36 g, 4.78 mmol), 3-diphenylaminocarbazole (1.76 g, 5.26 mmol), potassium carbonate (2.18 g, 15.8 mmol) and 30 ml of toluene were added and stirred at room temperature for 10 minutes. Thereto was added a mixed solution of palladium (II) acetate (36.0 mg, 0.16 mmol), tri-tert-butylphosphine (117 mg, 0.58 mmol) and 30 ml of toluene, and the mixture was heated and refluxed for 24 hours. After cooling to room temperature, chloroform and brine were added, and the organic layer was separated and extracted. Anhydrous magnesium sulfate was added for dehydration, and the solvent was distilled off under reduced pressure. The desired product 2- {4-N- (3-diphenylaminocarbazolyl) phenyl} quinoxaline was isolated and purified by silica gel column chromatography using chloroform (yield: 1.57 g, yield: 61.1%). ).

Synthesis Example 3 Synthesis of Compound 3

  To a nitrogen-substituted two-necked flask, 2- (4-bromophenyl) quinoxaline (1.29 g, 4.54 mmol), 3,6-di (diphenylamino) carbazole (3.42 g, 6.81 mmol), potassium carbonate (2.82 g, 20.4 mmol) and 45 ml of toluene were added and stirred at room temperature for 10 minutes. Thereto was added a mixed solution of palladium (II) acetate (45.0 mg, 0.20 mmol), tri-tert-butylphosphine (152 mg, 0.75 mmol) and 45 ml of toluene, and the mixture was heated and refluxed for 24 hours. After cooling to room temperature, chloroform and brine were added, and the organic layer was separated and extracted. Anhydrous magnesium sulfate was added for dehydration, and the solvent was distilled off under reduced pressure. The desired product 2- [4-N- {3,6-bis (diphenylamino) carbazolyl} phenyl] quinoxaline was isolated and purified by silica gel column chromatography using chloroform (yield: 1.28 g, yield: 40). 0.0%).

Example 1 Production and Evaluation of Organic Photoluminescence Device Using Compound 1 A toluene solution (concentration 10 ⁻⁵ mol / L) of Compound 1 was prepared in a glove box under an Ar atmosphere. The results of measuring the absorption spectrum of the prepared toluene solution and the emission spectrum by 410 nm excitation light are shown in FIG. Further, FIG. 3 shows a transient decay curve in which delayed fluorescence was observed at a peak wavelength of 559 nm for a toluene solution bubbled with nitrogen. This transient decay curve shows the result of measuring the luminescence lifetime obtained by measuring the process in which the emission intensity is deactivated by applying excitation light to the compound. In the case of normal single component light emission (fluorescence or phosphorescence), the light emission intensity decays in a single exponential manner. This means that if the vertical axis of the graph is semi-log, it will decay linearly. In the transient decay curve of Compound 1 shown in FIG. 3, such a linear component (fluorescence) is observed at the beginning of observation, but a component deviating from linearity appears after several μsec. This is light emission of the delay component, and the signal added to the initial component becomes a loose curve with a tail on the long time side. By measuring the luminescence lifetime in this way, it was confirmed that Compound 1 is a luminescent material containing a delay component in addition to the fluorescent component. The photoluminescence quantum efficiency was 12.6% for the toluene solution without bubbling and 29.3% for the toluene solution bubbling with nitrogen.

Example 2 Production and Evaluation of Organic Photoluminescence Element Using Compound 2 A toluene solution of Compound 2 (concentration 10 ⁻⁵ mol / L) was prepared in a glove box under an Ar atmosphere. FIG. 4 shows the results of measuring the absorption spectrum of the prepared toluene solution and the emission spectrum by the excitation light at 382 nm. FIG. 5 shows a transient decay curve in which delayed fluorescence was observed at a peak wavelength of 533 nm for the toluene solution before and after nitrogen bubbling. The photoluminescence quantum efficiency was 20.6% with a toluene solution without bubbling and 53.5% with a toluene solution bubbling with nitrogen.

Example 3 Production and Evaluation of Organic Photoluminescence Device Using Compound 3 A toluene solution of Compound 3 (concentration 10 ⁻⁵ mol / L) was prepared in a glove box under an Ar atmosphere. FIG. 6 shows the results of measuring the absorption spectrum of the prepared toluene solution and the emission spectrum by 400 nm excitation light. In addition, FIG. 7 shows a transient decay curve in which delayed fluorescence was observed at a peak wavelength of 548 nm for the toluene solution before and after nitrogen bubbling. The photoluminescence quantum efficiency was 23.2% with a toluene solution without bubbling and 55.4% with a toluene solution bubbling with nitrogen.

(Example 4) Production and evaluation of organic electroluminescence element using compound 1 Each thin film was formed by vacuum deposition 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 5.0 × 10 ⁻⁴ Pa. First, α-NPD was formed on ITO to a thickness of 30 nm, and then mCP was formed to a thickness of 10 nm. Next, Compound 1 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 1 was 6.0% by weight. Next, TPBi is formed to a thickness of 65 nm, further lithium fluoride (LiF) is vacuum-deposited to a thickness of 0.5 nm, and then aluminum (Al) is evaporated to a thickness of 100 nm to form a cathode. A luminescence element was obtained.
Using the manufactured organic electroluminescence element, a semiconductor parameter analyzer (manufactured by Agilent Technologies: E5273A), an optical power meter measurement device (manufactured by Newport: 1930C), and an optical spectrometer (manufactured by Ocean Optics: USB2000) As a result, emission of 563 nm was observed as shown in FIG. The current density-voltage characteristic is shown in FIG. 9, and the current density-external quantum efficiency characteristic is shown in FIG. The organic electroluminescence device using Compound 1 as the light emitting material achieved an external quantum efficiency of 8.6%.

(Example 5) Production and evaluation of organic electroluminescence device using compound 3 Each thin film was formed by vacuum deposition 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 5.0 × 10 ⁻⁴ Pa. First, α-NPD was formed on ITO to a thickness of 30 nm, and then mCP was formed to a thickness of 10 nm. Next, Compound 3 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 3 was 6.0% by weight. Next, TPBi is formed to a thickness of 65 nm, further lithium fluoride (LiF) is vacuum-deposited to a thickness of 0.5 nm, and then aluminum (Al) is evaporated to a thickness of 100 nm to form a cathode. A luminescence element was obtained.
Using the manufactured organic electroluminescence element, a semiconductor parameter analyzer (manufactured by Agilent Technologies: E5273A), an optical power meter measurement device (manufactured by Newport: 1930C), and an optical spectrometer (manufactured by Ocean Optics: USB2000) As a result, emission of 562 nm was observed as shown in FIG. The current density-voltage characteristics are shown in FIG. 12, and the current density-external quantum efficiency characteristics are shown in FIG. The organic electroluminescence device using Compound 1 as the light emitting material achieved an external quantum efficiency of 12.8%. Assuming that an ideal organic electroluminescence device balanced using a fluorescent material having a light emission quantum efficiency of 100% is prototyped, if the light extraction efficiency is 20 to 30%, the external quantum efficiency of fluorescent light emission is 5 -7.5%. This value is generally regarded as a theoretical limit value of the external quantum efficiency of an organic electroluminescence device using a fluorescent material. As is clear from FIG. 13, the organic electroluminescence device of the present invention using Compound 1 is extremely excellent in that high external quantum efficiency exceeding the theoretical limit value is realized.

Comparative Example 1 Evaluation Using Comparative Compound A toluene solution (concentration 10 ⁻⁵ mol / L) was prepared using the following comparative compound instead of the compound 1 of Example 1. Transient decay curves were measured for the toluene solution without nitrogen bubbling and the toluene solution with nitrogen bubbling, but no clear delayed fluorescence was observed due to nitrogen bubbling. For this reason, it was confirmed that the comparative compound is not a delayed phosphor.

  The compound of the present invention is useful as a light emitting material. For this reason, the compound of this invention is effectively used as a luminescent material for organic light emitting elements, such as an organic electroluminescent element. Since the compounds of the present invention include those that emit delayed fluorescence, it is also possible to provide an organic light-emitting device 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 (11)

A light emitting material comprising a compound represented by the following general formula (2).

[In General Formula (2), A ¹ and A ³ of A ^{1 to} A ⁷ represent N, or A ¹ , A ³ , A ⁴ and A ⁷ represent N, and the rest each independently represents C— R is represented. R represents a hydrogen atom or a non-aromatic group. Ar ¹ represents a substituted or unsubstituted arylene group. R ^{11 to} R ¹⁴ and R ^{17 to} R ²⁰ each independently represent a hydrogen atom or a substituent. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , and R ¹⁹ and R ²⁰ may be bonded to each other to form a cyclic structure. Z ¹ represents a single bond or a linking group having 1 or 2 linking chain long atoms. ] The luminescent material according to claim 1, wherein the compound represented by the general formula (2) has a structure represented by the following general formula (3).

[In General Formula (3), A ¹ and A ³ out of A ^{1 to} A ⁷ represent N, or A ¹ , A ³ , A ⁴ and A ⁷ represent N, and the rest represent C—R. . R represents a hydrogen atom or a non-aromatic group. Ar ¹ represents a substituted or unsubstituted arylene group. Y represents a substituted or unsubstituted carbazol-9-yl group, a substituted or unsubstituted 10H-phenoxazin-10-yl group, a substituted or unsubstituted 10H-phenothiazin-10-yl group, or a substituted or unsubstituted 10H -Represents a phenazin-5-yl group. ] The luminescent material according to claim 2 , wherein Y in the general formula (3) is a group represented by any one of the following general formulas (4) to (7).

[In the general formulas (4) to (7), 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 are each independently a hydrogen atom or a substituent. Represents a group. 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 , and R ⁵⁵ and R ⁶⁵ may be bonded to each other to form a cyclic structure. ] The luminescent material according to claim 2 , wherein Y in the general formula (3) is a group represented by the following general formula (8).

[In General Formula (8), R ^{21 ′ to} R ^{24 ′} and R ^{27 ′ to} R ³⁰ each independently represent a hydrogen atom or a substituent, but at least one of R ^{23 ′} and R ^{28 ′} is a substituent. is there. 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' are bonded to each other Thus, a ring structure may be formed. ] In the general formula (8), in claim 4, wherein at least one of R ^{23 'and} R ^28' is a substituted or unsubstituted diarylamino group or a substituted or unsubstituted carbazol-9-yl group, The luminescent material as described. The luminescent material according to claim 3 , wherein Y in the general formula (3) is a group represented by the general formula (5). A delayed phosphor comprising a compound represented by the following general formula (2).

[In General Formula (2), A ¹ and A ³ of A ^{1 to} A ⁷ represent N, or A ¹ , A ³ , A ⁴ and A ⁷ represent N, and the rest each independently represents C— R is represented. R represents a hydrogen atom or a non-aromatic group. Ar ¹ represents a substituted or unsubstituted arylene group. R ^{11 to} R ¹⁴ and R ^{17 to} R ²⁰ each independently represent a hydrogen atom or a substituent. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , and R ¹⁹ and R ²⁰ may be bonded to each other to form a cyclic structure. Z ¹ represents a single bond or a linking group having 1 or 2 linking chain long atoms. ] The organic light emitting device which comprises a luminescent material according to any one of claims 1-6. The organic light emitting device according to claim 8 , which emits delayed fluorescence. The organic light emitting device according to claim 8 or claim 9, characterized in that an organic electroluminescence element. A compound represented by the following general formula (2).

[In General Formula (2), A ¹ and A ³ of A ^{1 to} A ⁷ represent N, or A ¹ , A ³ , A ⁴ and A ⁷ represent N, and the rest each independently represents C— R is represented. R represents a hydrogen atom or a non-aromatic group. Ar ¹ represents a substituted or unsubstituted arylene group. R ^{11 to} R ¹⁴ and R ^{17 to} R ²⁰ each independently represent a hydrogen atom or a substituent. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , and R ¹⁹ and R ²⁰ may be bonded to each other to form a cyclic structure. Z ¹ represents a single bond or a linking group having 1 or 2 linking chain long atoms. ]

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