TW201311612A - Organic electroluminescence element and compound used therefor - Google Patents

Abstract

An organic electroluminescence element using a monospirobifluorene compound represented by general formula in a light-emitting layer exhibits a high emission efficiency. At least one of R1 through R8 represents an electron-donating group, with the rest representing hydrogen atoms; at least one of R9 through R16 represents an electron-withdrawing group other than a triazino group, with the rest representing hydrogen atoms; and the number of symbols R1 through R16 which represent hydrogen atoms is between 11 and 14, inclusive.

Description

Organic electroluminescent element and compound used therefor

The present invention relates to an organic electroluminescence device (organic EL (Electro Luminescence) device) having high luminous efficiency and a luminescent material used therefor.

Research on improving the luminous efficiency of organic electroluminescent elements is prevailing. In particular, various studies have been made to improve luminous efficiency by newly developing an electron transport material, a hole transport material, a light-emitting material, and the like which constitute an organic electroluminescence element. Among them, studies on organic electroluminescent elements using a compound having a spirobifluorene skeleton have also been found, and several proposals have been made so far.

For example, Patent Document 1 describes a phosphorescent organic electroluminescence device in which a compound having a spirobifluorene skeleton is used for a hole shielding layer. Further, Patent Document 2 discloses an organic electroluminescence device in which a compound having a spirobifluorene skeleton bonded with two carbazole groups is used as a host material of a light-emitting layer. Further, Patent Document 3 describes an organic electroluminescence device in which a compound having a styridine skeleton substituted with a styryl group or a phenyl group is used as a host material of a light-emitting layer. Further, Patent Document 4 discloses an organic electroluminescence device having a light-emitting layer composed of only a compound having a biphenyl-substituted spirobifluorene skeleton. Further, Patent Document 5 discloses an organic electroluminescence device having a light-emitting layer composed of only benzene or a naphthalene compound substituted with 1 to 3 spirobifluorene rings. Further, Patent Document 6 describes that one of the following has been issued. In the organic electroluminescence device of the optical layer, the light-emitting layer is composed only of a benzene compound substituted with 3 to 6 spirobifluorene rings.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-528836

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2010-27681

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2001-307879

[Patent Document 4] Japanese Patent Laid-Open No. Hei 7-278537

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2002-121547

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2006-256982

As described above, various studies have been conducted on compounds having a spirobifluorene skeleton, and several proposals relating to the application of the organic electroluminescence device have been proposed. However, it has not been said that a detailed study has been completed for all compounds having a spirobifluorene skeleton. In particular, regarding the use of a luminescent material of an organic electroluminescence device having a compound of a spirobifluorene skeleton, usefulness has been confirmed only for a part of the compounds. Further, no clear relationship has been found between the chemical structure of a compound having a spirobifluorene skeleton and the usefulness of the compound as a light-emitting material, and it is difficult to predict the usefulness as a light-emitting material based on the chemical structure. Further, since the compound having a spirobifluorene skeleton is not necessarily easily synthesized, there is a case in which the provision of the compound itself is accompanied by difficulty. The inventors of the present invention have conducted research in consideration of such problems, and their purpose is to synthesize a snail which has not been developed and researched so far. A compound of a diterpene skeleton and evaluated for its usefulness as a luminescent material of an organic electroluminescence device. Further, another object of the intensive research is to find a general formula of a compound useful as a light-emitting material, and to spread the structure of an organic electroluminescence device having high luminous efficiency.

The inventors of the present invention conducted intensive studies to achieve the above object, and as a result, found that a specific compound having a spirobifluorene skeleton has an excellent property as a light-emitting material of an organic electroluminescence device. Based on this finding, the inventors of the present invention have provided the following invention as a method for solving the above problems.

[1] An organic electroluminescence device comprising: an anode, a cathode, and at least one organic layer between the anode and the cathode and including a light-emitting layer, and having the following formula in the light-emitting layer (1) the monospiral diterpene compound shown, [In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represent a hydrogen atom or an electron-donating group, and at least one represents an electron-donating group; R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently a hydrogen atom or three An electron withdrawing group other than the base, and at least one represents three An electron withdrawing group other than a group; wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ 11 to 14 of R ¹⁵ and R ¹⁶ are a hydrogen atom].

[2] The organic electroluminescence device according to [1], wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) is supplied An electron-substituted aryl group.

[3] The organic electroluminescence device according to [1], wherein at least one of R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following a structure represented by the general formula (2), [In the formula (2), R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ each independently represent a hydrogen atom or an electron-donating group, and at least one represents an electron-donating group].

[4] The organic electroluminescence device according to [1], wherein at least one of R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following a structure represented by any one of the general formulae (3) to (5), [In the above formula, R ³¹ and R ³² each independently represent a substituted or unsubstituted aryl group, and an aryl group represented by R ³¹ may be bonded to an aryl group represented by R ³² ; R ⁴¹ , R ⁴² and R ⁴³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁴¹ and R ⁴² may together form a ring structure, and R ⁴² and R ⁴³ may together form a ring. R ⁵¹ , R ⁵² and R ⁵³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁵¹ and R ⁵² may together form a ring structure, R ⁵² and R ⁵³ may together form a ring structure].

[5] The organic electroluminescence device according to [1], wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following a structure represented by any one of the general formulae (A) to (C), [In the general formula (A), Z ¹ represents a nitrogen atom, an oxygen atom, a sulfur atom or a halogen atom, and A ¹ and A ² may each independently form an aromatic ring, a heteroaromatic ring, an aliphatic ring or a non-aromatic hetero ring; In the formula (B), R ²⁰ represents a hydrogen atom, an aryl group or an atomic group necessary for forming a ring structure represented by A ⁴ , and A ³ and A ⁴ may each independently form a heteroaromatic ring or a non-aromatic heterocyclic ring. In the general formula (C), Z ¹ , Z ² , Z ³ and Z ⁴ each independently represent an oxygen atom or a sulfur atom].

[6] The organic electroluminescence device according to [1], wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following Any structure of D1~D13,

[7] The organic electroluminescence device according to any one of [1] to [6] wherein R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ^{15 of the} formula (1) At least one of R ¹⁶ has a structure represented by any one of the following general formulae (6) to (9), [In the above formula, R ⁶¹ and R ⁶² each independently represent a substituted or unsubstituted aryl group; and R ⁷¹ and R ⁷² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The substituted aryl group, R ⁷¹ and R ⁷² may together form a ring structure; R ⁸¹ , R ⁸² and R ⁸³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group. The aryl group, R ⁸¹ and R ⁸² may together form a ring structure, and R ⁸² and R ⁸³ may together form a ring structure; R ⁹¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The aryl group, Z represents the formation of three a linking group necessary for a heteroaromatic ring other than a ring].

[8] The organic electroluminescence device according to any one of [1] to [6] wherein R ⁹ , R ¹⁰ , R ¹³ , R ¹² , R ¹³ , R ¹⁴ , R ^{15 of the} formula (1) At least one of R ¹⁶ has any of the following structures,

[9] The organic electroluminescence device according to any one of [1] to [8] which has a light-emitting layer containing only the compound represented by the above formula (1).

[10] The organic electroluminescence device according to any one of [1] to [8] wherein a compound represented by the above formula (1) is used as a dopant of the light-emitting layer.

[11] The organic electroluminescence device according to any one of [1] to [10] which has only The light emitting layer serves as an organic layer.

[12] A monospirobiguanide compound represented by the following formula (1'), [In the formula (1'), R ^{1 '} , R ^{2 '} , R ^{3 '} , R ^{4 '} , R ^{5 '} , R ^{6 '} , R ^{7 '} and R ^{8 '} are each independently a hydrogen atom or an electron-donating group. And at least one represents an aryl group substituted with an electron-donating group; R ^{9 '} , R ^{10 '} , R ^{11 '} , R ^{12 '} , R ^{13 '} , R ^{14 '} , R ^{15 '} and R ^{16 '} are each independently a hydrogen atom Or three An electron withdrawing group other than the base, and at least one represents three An electron withdrawing group other than a group; wherein R ^{1 '} , R ^{2 '} , R ^{3 '} , R ^{4 '} , R ^{5 '} , R ^{6 '} , R ^{7 '} , R ^{8 '} , R ^{9 '} , R ^{10 '} , R ^{11 to 14 of} R ^' , R12 ^' , R13 ^' , R14 ^' , R15 ^' and R16 ^' are hydrogen atoms].

[13] The compound according to [12], wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following formula (2) ) the structure shown, [In the formula (2), R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ each independently represent a hydrogen atom or an electron-donating group, and at least one represents an electron-donating group].

[14] The compound according to [12], wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following formula (3) ) the structure shown in any one of ~(5), [In the above formula, R ³¹ and R ³² each independently represent a substituted or unsubstituted aryl group, and an aryl group represented by R ³¹ may be bonded to an aryl group represented by R ³² ; R ⁴¹ , R ⁴² and R ⁴³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁴¹ and R ⁴² may together form a ring structure, and R ⁴² and R ⁴³ may together form a ring. R ⁵¹ , R ⁵² and R ⁵³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁵¹ and R ⁵² may together form a ring structure, R ⁵² and R ⁵³ may together form a ring structure].

[15] The compound according to [12], wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has any one of the following structures:

[16] The compound according to any one of [12] to [15] wherein at least R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ of the formula (1) a structure having any one of the following general formulae (6) to (9),

[In the above formula, R ⁶¹ and R ⁶² each independently represent a substituted or unsubstituted aryl group; and R ⁷¹ and R ⁷² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The substituted aryl group, R ⁷¹ and R ⁷² may together form a ring structure; R ⁸¹ , R ⁸² and R ⁸³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group. The aryl group, R ⁸¹ and R ⁸² may together form a ring structure, and R ⁸² and R ⁸³ may together form a ring structure; R ⁹¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The aryl group, Z represents the formation of three a linking group necessary for a heteroaromatic ring other than a ring].

[17] The compound according to any one of [12] to [16] wherein at least R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ of the formula (1) One has any of the following structures,

[18] A luminescent material comprising the compound according to any one of [12] to [17].

The organic electroluminescence device of the present invention has characteristics such as high luminous efficiency and easy formation of a light-emitting layer of a thin film. Further, the compound of the present invention is extremely useful as a light-emitting material of such an organic electroluminescence device.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made in accordance with a representative embodiment or a specific example of the present invention, but the present invention is not limited to such an embodiment or a specific example. In addition, the numerical range represented by the "~" in this specification is a range which contains the numerical value of the before and after the [~.

[Compound represented by the formula (1)]

The organic electroluminescence device of the present invention is characterized by comprising a monospirobiguanide compound represented by the following formula (1) in the light-emitting layer. Therefore, the monospirobiguanide compound represented by the formula (1) will be described first.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ^{8 in the} formula (1) each independently represent a hydrogen atom or an electron-donating group. Wherein at least one of the points represents an electron donating group. When two or more of the two or more electron-donating groups are present, two or more electron-donating groups may be the same or different. It is preferably the same. In R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ , it is preferred that the electron-donating group is R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ^{7 .} Any one of them is more preferably any one of R ² , R ³ , R ⁶ and R ⁷ . Further, it is preferably any one or two of R ² , R ³ , R ⁶ and R ⁷ , and in the case of two, it is preferably any one of R ² and R ³ and R ⁶ and R ⁷ Any one.

The electron-donating group represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ has the property of providing electrons to the spirobifluorene ring when bonded to the spirobifluorene ring. base. The electron-donating group may be any of an aromatic group, a heteroaromatic group, and an aliphatic group, or may be a combination of two or more of these. Examples of the electron-donating group include an alkyl group (which may be linear, branched, or cyclic, preferably having a carbon number of 1 to 6, more preferably a carbon number of 1 to 3). Examples thereof include a methyl group, an ethyl group, a propyl group, a pentyl group, a hexyl group, and an isopropyl group, and an alkoxy group (which may be linear, branched, or cyclic, preferably having a carbon number of 1 to 6, more preferably The carbon number is preferably from 1 to 3, and specific examples thereof include a methoxy group, an amine group or a substituted amine group (preferably an amine group substituted with an aromatic group, and specific examples thereof include a diphenylamino group and an anilino group. , toluyl), aryl (may be a monocyclic ring or a fused ring, and may be further substituted with an aryl group, and specific examples thereof include a phenyl group, a biphenyl group, a biphenyl group), and a heterocyclic ring structure. An electron donating group (preferably an electron donating group having a heterocyclic structure containing a nitrogen atom or a sulfur atom, and specific examples thereof include a thienyl group, a benzothienyl group, A pyridyl group, a pyrrolyl group, a fluorenyl group, a carbazolyl group, and the like. The electron-donating group is preferably, for example, a σp value of -0.06 or less, more preferably -0.14 or less, still more preferably -0.28 or less.

Preferably, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ is an aryl group substituted with an electron-donating group. The aryl group described herein may be one containing one aromatic ring, or may be a structure having two or more aromatic rings fused. The carbon number of the aryl group is preferably from 6 to 22, more preferably from 6 to 18, still more preferably from 6 to 14, more preferably from 6 to 10 (i.e., phenyl, 1-naphthyl, 2-naphthyl). The best is phenyl. Further, it is preferable that the electron-donating group substituted on the aryl group has the above σp value.

More preferably, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ is a group represented by the following formula (2).

In the formula (2), R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ each independently represent a hydrogen atom or an electron-donating group. Wherein at least one of the points represents an electron donating group. The electron donating group described herein is preferably one having the above σp value. In R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ , R ²² and R ²⁴ are preferably an electron-donating group or R ²³ is an electron-donating group, and more preferably R ²³ is an electron-donating group.

Further, it is preferable that at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ has any one of the following general formulae (3) to (5). structure.

General formula (3)

In the above formula, R ³¹ and R ³² each independently represent a substituted or non-substituted aryl group, R ³¹ represented by R ³² and the aryl group represented by the aryl group may link. R ⁴¹ , R ⁴² and R ⁴³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁴¹ and R ⁴² may together form a ring structure, R ⁴² and R ⁴³ may also form a ring structure together. R ⁵¹ , R ⁵² and R ⁵³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁵¹ and R ⁵² may together form a ring structure, R ⁵² and R ⁵³ may also form a ring structure together.

The ring structure formed by R ⁴¹ and R ⁴³ , R ⁴² and R ⁴³ , R ⁵¹ and R ⁵² , and R ⁵² and R ⁵³ together may be any one of an aromatic ring, a heteroaromatic ring and an aliphatic ring, preferably an aromatic ring or A heteroaromatic ring, more preferably an aromatic ring. Specific examples of the ring structure include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring.

The aryl group described in the present specification may be one containing one aromatic ring, or may be a structure having two or more aromatic rings fused. The carbon number of the aryl group Preferably, it is 6 to 22, more preferably 6 to 18, still more preferably 6 to 14, and even more preferably 6 to 10 (i.e., phenyl, 1-naphthyl, 2-naphthyl).

The alkyl group described in the present specification may be linear, may be branched, or may be cyclic. A linear or branched alkyl group is preferred. The carbon number of the alkyl group is preferably from 1 to 20, more preferably from 1 to 12, still more preferably from 1 to 6, more preferably from 1 to 3 (i.e., methyl, ethyl, n-propyl, isopropyl). . Examples of the cyclic alkyl group include a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.

Examples of the substituent of the aryl group or the alkyl group include an alkyl group, an aryl group, an alkoxy group, and an aryloxy group. The description and preferred ranges of the alkyl group and the aryl group which may be employed as the substituent are the same as described above. Further, the alkoxy group which may be used as a substituent may be linear, may be branched, or may be cyclic. A linear or branched alkoxy group is preferred. The number of carbon atoms of the alkoxy group is preferably from 1 to 20, more preferably from 1 to 12, still more preferably from 1 to 6, more preferably from 1 to 3 (i.e., methoxy, ethoxy, n-propoxy, Isopropoxy). Examples of the cyclic alkoxy group include a cyclopentyloxy group, a cyclohexyloxy group, and a cycloheptyloxy group. Further, the aryloxy group which may be used as a substituent may be one having one aromatic ring, or may be a structure having two or more aromatic rings fused. The carbon number of the aryloxy group is preferably from 6 to 22, more preferably from 6 to 18, still more preferably from 6 to 14, more preferably from 6 to 10 (i.e., phenoxy, 1-naphthyloxy, 2-naphthalene) Oxy).

Examples of the substituent of the alkyl group and the aryl group in the general formulae (3) to (5) include a group exhibiting electron donating properties.

The electron-donating group represented by at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ may be, in addition to the above, the following formula (A) An electron donating group of the skeleton shown in any of ~(C).

In the formula (A), Z ¹ represents a nitrogen atom, an oxygen atom, a sulfur atom or a ruthenium atom. Further, A ¹ and A ² in the formula (A) may independently form an aromatic ring, a heteroaromatic ring, an aliphatic ring or a non-aromatic heterocyclic ring, or may not form such a ring. For example, when Z ¹ is a nitrogen atom, when both of A ¹ and A ² form a benzene ring, the general formula (A) represents a carbazole skeleton. Further, when a benzene ring is formed in A ¹ and A ² does not form a ring structure, the formula (A) represents an anthracene skeleton. Further, in the case where neither A ¹ nor A ² forms a ring structure, the formula (A) represents a pyrrole skeleton. As another example, when Z ¹ is a germanium atom, when both of A ¹ and A ² form a benzene ring, the general formula (A) represents a silafluorene skeleton. Further, when Z ¹ is a sulfur atom, when A ¹ forms a benzene ring and A ² does not form a ring structure, the formula (A) represents a benzothiophene skeleton.

When A ¹ and A ^{2 of the} formula (A) form a ring structure, the ring structure may also be a fused ring structure in which a plurality of rings are fused. The fused ring may be one in which the aromatic rings are fused to each other, or the heteroaromatic rings may be fused to each other, or the fatty rings may be fused to each other, and further may be an aromatic ring and a heteroaromatic ring. There is no particular limitation on the combination of different types of rings. Further, the fused rings may be the same or different from each other. For example, when Z ¹ is a sulfur atom, when A ¹ forms a ring structure in which a furan ring and a benzene ring are fused, and A ² does not form a ring structure, the formula (A) represents a benzodifuran skeleton.

The ring structure which can be formed by A ¹ and A ^{2 of the} formula (A) is preferably an aromatic ring or a heteroaromatic ring, more preferably an aromatic ring.

The aromatic ring which A ¹ and A ² can form is a benzene ring. Examples of the heteroaromatic ring which can be formed by A ¹ and A ² include a furan ring, a thiophene ring, and a pyrrole ring. Oxazole ring, different Oxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazan ring, pyridine ring, hydrazine Ring, pyrimidine ring, pyridyl ring. Examples of the aliphatic ring which can be formed by A ¹ and A ² include a cyclopentene ring, a cyclohexene ring, a cycloheptene ring, a cyclopentadiene ring, a cyclohexadiene ring, a cycloheptadiene ring, and a cycloheptane. Triene ring. Examples of the non-aromatic hetero ring which can be formed by A ¹ and A ² include a pyrroline ring, an imidazoline ring, and a pyrazoline ring. Examples of the fused ring which A ¹ and A ² may form include a naphthalene ring, an anthracene ring, a phenanthrene ring, an anthracene ring, an anthracene ring, an isoindole ring, a carbazole ring, a benzopyran ring, and a quinoline ring. Isoquinoline ring, Chlorocyclic ring, quinazoline ring, quin Porphyrin ring, hydrazine Ring, acridine ring, Ring, carbazole ring, pyridine ring, acridine ring, brown Ring, phenanthroline and the like.

In the formula (B), R ²⁰ represents a hydrogen atom, an aryl group or an atomic group necessary for forming a ring structure represented by A ⁴ . Further, A ³ and A ⁴ in the formula (B) may independently form a heteroaromatic ring or a non-aromatic heterocyclic ring, or may not form such a ring. Specific examples of the heteroaromatic ring or the non-aromatic heterocyclic ring which can be formed by A ³ and A ⁴ can be referred to the specific examples of the heteroaromatic ring or the non-aromatic heterocyclic ring which can be formed by the above A ¹ and A ² . Further, the aryl group which may be used for R ²⁰ may be one having one aromatic ring, or may be a structure having two or more aromatic rings fused. The carbon number of the aryl group is preferably from 6 to 22, more preferably from 6 to 18, still more preferably from 6 to 14, more preferably from 6 to 10 (i.e., a benzene ring or a naphthalene ring), and most preferably a phenyl group. .

As an example of the structure represented by the formula (B), for example, when R ²⁰ is a hydrogen atom and A ³ does not form a ring structure, the formula (B) represents an aniline skeleton. Further, when R ²⁰ is a benzene ring and A ³ does not form a ring structure, the formula (B) represents a diphenylamine skeleton. Further, when R ²⁰ is a group of atoms necessary for forming a piperidine ring and A ³ forms a piperidine ring, the formula (B) represents A pyridinium skeleton.

In the formula (C), Z ¹ , Z ² , Z ³ and Z ⁴ each independently represent an oxygen atom or a sulfur atom. The atoms may be the same or different, preferably the same.

Preferred specific examples of the electron-donating group represented by at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are listed below. However, the electron-donating group which can be employed in the general formula (1) is not limited to the specific examples.

R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ^{16 of the} formula (1) each independently represent a hydrogen atom or three An electron withdrawing group other than the base. Wherein at least one of the three represents An electron withdrawing group other than the base. When two or more of the electron withdrawing groups are present, two or more electron withdrawing groups may be the same or different. It is preferably the same. Among R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ , those having an electron withdrawing group are preferably R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ^{15 .} Any one of them is more preferably any one of R ¹⁰ , R ¹¹ , R ¹⁴ and R ¹⁵ . Further, it is preferably any one or two of R ¹⁰ , R ¹¹ , R ¹⁴ and R ¹⁵ , and in the case of two, it is preferably any one of R ¹⁰ and R ¹¹ and R ¹⁴ and R ¹⁵ Any one.

The electron withdrawing group represented by R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ^{16 of} the formula (1) has a self-spinning bond when bonded to a spirobifluorene ring. The ring attracts the base of the nature of the electron. The electron-withdrawing group may be any of an aromatic group, a heteroaromatic group, and an aliphatic group, or may be a combination of two or more of these. Examples of the electron-withdrawing group include a nitro group and a perfluoroalkyl group (preferably having a carbon number of 1 to 6, more preferably a carbon number of 1 to 3, and specific examples thereof include a trifluoromethyl group) and a sulfonium group. An electron withdrawing group containing a heterocyclic ring structure (preferably an electron withdrawing group having a heterocyclic ring structure containing a nitrogen atom or a sulfur atom), and specific examples thereof may be mentioned. Diazolyl, benzothiadiazolyl, tetrazolyl, thiazolyl, imidazolyl, etc., but three Except for the base, a group containing a phosphine oxide structure, a cyano group or the like. Examples of the group of electron-withdrawing groups include a group obtained by removing a cyano group from a specific example of the electron-withdrawing group described above. The electron-withdrawing group preferably has a σp value of 0.02 or more, more preferably 0.34 or more, and still more preferably 0.62 or more.

It is preferable that at least one of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ has a structure represented by any one of the following general formulae (6) to (9). .

In the above formula, R ⁶¹ and R ⁶² each independently represent a substituted or unsubstituted aryl group. R ⁷¹ and R ⁷² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁷¹ and R ⁷² may together form a ring structure. R ⁸¹ , R ⁸² and R ⁸³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁸¹ and R ⁸² may together form a ring structure, R ⁸² and R ⁸³ may also form a ring structure together. R ⁹¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and Z represents a formation of three A linking group necessary for a heteroaromatic ring other than the ring. The Z-linked chain may be a carbon atom only, or may contain only a hetero atom, or may be a mixture of a carbon atom and a hetero atom. As the hetero atom, a nitrogen atom is preferred. Further, the linking chain is preferably 2 to 4 atoms long, more preferably 2 or 3 atoms long. Examples of the element constituting the linking chain include those containing only a carbon atom, those containing only a nitrogen atom, and a combination of a carbon atom and a sulfur atom.

For the description and preferred ranges of the aryl and alkyl groups described herein, reference may be made to the description and preferred of the aryl and alkyl groups which may be employed for R ⁴¹ , R ⁴² , R ⁴³ , R ⁵¹ , R ⁵² and R ⁵³ . range. In addition, examples of the substituent of the aryl group or the alkyl group in the general formulae (6) to (9) include an alkyl group, an aryl group, an alkoxy group, and an aryloxy group.

Preferred specific examples of the electron-withdrawing group represented by at least one of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are listed below. However, the electron withdrawing group which can be used in the general formula (1) is not limited to the specific examples.

[Chemistry 20]

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ^{15 of the} formula (1) And 11 to 14 of R ¹⁶ are hydrogen atoms. In this case, it is preferred that 4 to 7 of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are a hydrogen atom, and more preferably 6 or 7 are a hydrogen atom. Further, it is preferred that 4 to 7 of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are a hydrogen atom, and more preferably 6 or 7 are a hydrogen atom. Preferred examples thereof include: 7 of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are a hydrogen atom, and R ⁹ , R ¹⁰ , R ¹¹ and R ¹² , a compound of 7 of R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ being a hydrogen atom; or 6 of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ One is a hydrogen atom, and six of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are a hydrogen atom.

Further, the compound represented by the formula (1) of the present invention is a monospirobiguanide compound. Therefore, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ^{16 are} not A group containing a spirobifluorene ring.

Among the compounds represented by the above formula (1), the compound represented by the following formula (1') is a novel compound.

General formula (1')

In the formula (1'), R ^{1 '} , R ^{2 '} , R ^{3 '} , R ^{4 '} , R ^{5 '} , R ^{6 '} , R ^{7 '} and R ^{8 '} are each independently a hydrogen atom or an electron-donating group. And at least one represents an aryl group substituted with an electron donating group. R ^{9 '} , R ^{10 '} , R ^{11 '} , R ^{12 '} , R ^{13 '} , R ^{14 '} , R ^{15 '} and R ^{16 '} are each independently a hydrogen atom or three An electron withdrawing group other than the base, and at least one represents three An electron withdrawing group other than the base. Wherein R ^{1 '} , R ^{2 '} , R ^{3 '} , R ^{4 '} , R ^{5 '} , R ^{6 '} , R ^{7 '} , R ^{8 '} , R ^{9 '} , R ^{10 '} , R ^{11 '} , R ^{12 '} , 11 to 14 of R ^{13 '} , R ^{14 '} , R ^{15 '} and R ^{16 '} are hydrogen atoms.

The description and preferred ranges of the electron-donating group, the electron-donating group-substituted aryl group, and the electron-withdrawing group in the formula (1') can be referred to the corresponding description in the above formula (1).

The molecular weight of the compound represented by the formula (1) is preferably 1,500 or less, more preferably 1200 or less, in the case where a film of an organic layer containing the compound is to be produced by a vapor deposition method, and more preferably 1200 or less. It is preferably 1,000 or less, and more preferably 800 or less. The lower limit of the molecular weight can be set, for example, to 350 or more.

Specific examples of the compound represented by the formula (1) are exemplified below, but the compound represented by the formula (1) which can be used in the present invention is not limited by the specific examples. Further, in the table, D1 to D3 represent an aryl group substituted with the above electron-donating group, A1 to A4 represent the above electron withdrawing group, and H represents a hydrogen atom.

[Synthesis of a compound represented by the formula (1)]

The synthesis method of the compound represented by the formula (1) is not particularly limited. The synthesis of the compound represented by the formula (1) can be carried out by appropriately combining known synthesis methods or conditions.

For example, as a preferred synthesis method, the synthesis shown in the following scheme can be exemplified law. Here, a synthesis method of a compound of the formula (15) in which one fluorene group substituted with an electron-donating group and an electron-withdrawing group is substituted on the other anthracene skeleton is exemplified.

In the above scheme, the dihalogenated spirobifluorene represented by the formula (11) is first reacted with boric acid represented by the formula (12). X in the formula (11) represents a halogen atom. Specific 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 preferred, and a bromine atom is more preferred. D in the formula (12) represents an electron donating group. In the reaction, the compound represented by the formula (12) is controlled only in such a manner as to react with one X of the formula (11). For example, by suppressing the amount of the compound represented by the formula (12) to a small amount, formation of a disubstituted substance can be suppressed. The compound represented by the formula (13) obtained by the reaction is further reacted with a boric acid represented by the formula (14). A in the formula (14) represents an electron withdrawing group. By this reaction, the target product represented by the formula (15) is obtained. In the reaction of the halogenated spirobifluorene with boric acid in the first step and the second step, the reaction conditions generally used can be employed.

The boric acid used in the first step and the second step of the above procedure may also be exchanged. In other words, it may be reacted with boric acid represented by the formula (14) in the first step and with boric acid represented by the formula (12) in the second step.

The synthesis method of the compound represented by the formula (1) other than the formula (15) can be synthesized according to the method of the above scheme. Further, depending on the type of the substituent to be introduced into the halogenated spirobifluorene, a reaction peculiar to the substituent may be used. For example, in the case where a diphenylphosphinyl group is to be introduced, a halogenated spirobifluorene may be reacted with diphenylphosphine chloride to first introduce a diphenylphosphino group, followed by oxidation using hydrogen peroxide or the like. The diphenylphosphino group is converted to a diphenylphosphinyl group.

For details of the reactions, reference may be made to the synthesis examples which will be described later. Further, the compound represented by the formula (1) can also be synthesized by combining other known synthesis reactions.

[Organic Electroluminescent Element]

The organic electroluminescent device of the present invention has a structure including an anode, a cathode, and an organic layer between the anode and the cathode. The organic layer may include at least a light-emitting layer, and may include only the light-emitting layer, or may have one or more organic layers in addition to the light-emitting layer. The organic electroluminescence device of the present invention contains a compound represented by the formula (1) in the light-emitting layer.

In the light-emitting layer, the compound represented by the formula (1) may be contained as a host material, and together with a doping material having another structure, constitute a light-emitting layer, and the compound represented by the formula (1) may also be used as a dopant material. Containing, and having The main material of his structure together constitutes a luminescent layer. Further, the light-emitting layer may be composed only of the compound represented by the formula (1).

The compound represented by the formula (1) has a high film forming ability, is stable in a neat film state, and can achieve excellent luminous efficiency in a pure film state. Further, the HOMO (Highest Occupied Molecular Orbital) of the compound represented by the formula (1) has a relatively preferred energy level with respect to the commonly used anode, and the compound represented by the formula (1) The LUMO (Lowest Unoccupied Molecular Orbital) has a relatively good energy level relative to the commonly used cathode. For example, the energy level diagram of the compound 1 is as shown in Fig. 5, and can be preferably combined with ITO (Indium Tin Oxide) or LiF (Lithium Fluoride) which is mostly used as an electrode. Therefore, even a single-layer type organic electroluminescence element having a simple structure in which a pure thin film layer of a compound represented by the general formula (1) is formed on the anode as a light-emitting layer and a cathode is formed thereon can be realized. Higher luminous efficiency. Therefore, when the compound represented by the formula (1) is used, there is a possibility that an organic electroluminescence device having a simple structure can be produced more easily than before, and the cost can be suppressed to be low.

The organic electroluminescence device of the present invention has a structure in which at least an anode, an organic layer, and a cathode are laminated. In the case of a single-layer type organic electroluminescence device, there is only a light-emitting layer between the anode and the cathode, but the organic electroluminescent device of the present invention also includes a plurality of organic layers. The organic layer other than the light-emitting layer is called a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron beam according to its function. For the layer or the like, a known material can be used in combination as appropriate. Specific examples of the composition including the anode and the cathode include an anode, a light-emitting layer, a cathode, an anode, a hole injection layer, a light-emitting layer, a cathode, an anode, a hole injection layer, a hole transport layer, a light-emitting layer, and a cathode. Anode\hole injection layer\light emitting layer\electron injection layer\cathode, anode\hole injection layer\hole transport layer\light emitting layer\electron injection layer\cathode, anode\hole injection layer\light emitting layer\electron transport layer \Electron injection layer\cathode, anode\hole injection layer\hole transport layer\light emitting layer\electron transport layer\electron injection layer\cathode, anode\light emitting layer\electron injection layer\cathode, anode\light emitting layer\electron injection Layer\electron transport layer\cathode, anode\hole injection layer\light emitting layer\hole blocking layer\electron injection layer\cathode. The structures of the anode/organic layer/cathode can be formed on the substrate. Furthermore, the configuration that can be employed in the present invention is not limited to these. Further, the compound represented by the formula (1) is preferably used for the light-emitting layer, but the compound represented by the formula (1) is not used as a charge transport material or the like for the organic layer other than the light-emitting layer.

When manufacturing the respective organic layers or electrodes constituting the organic electroluminescence device of the present invention, a known production method can be appropriately selected. Further, among the respective organic layers or electrodes, various materials used in the known organic electroluminescence devices can be selected and used. Further, in the organic electroluminescence device of the present invention, a known technique or various modifications which can be easily conceived by a known technique can be added as needed. Hereinafter, a representative material constituting the organic electroluminescence device will be described, but the material of the organic electroluminescence device usable in the present invention is not limited by the following description.

(substrate)

The substrate serves as a support for supporting the structure of the anode, the organic layer, and the cathode. It functions as a function of the substrate when manufacturing the structure of the anode, the organic layer, and the cathode. The substrate may be composed of a transparent material or a semi-transparent or opaque material. When the light is taken out from the anode side, it is preferred to use a transparent substrate. Examples of the material constituting the substrate include glass, quartz, metal, polycarbonate, polyester, polymethacrylate, and polyfluorene. When a flexible substrate is used, a flexible organic electroluminescent device can be produced.

(anode)

The anode has a function of injecting a hole into the organic layer. As such an anode, a material having a high work function is preferably used, and for example, a material of 4 eV or more is preferably used. Specific examples thereof include metals (for example, aluminum, gold, silver, nickel, palladium, platinum), metal oxides (for example, indium oxide, tin oxide, zinc oxide, a mixture of indium oxide and tin oxide [ITO], zinc oxide and indium oxide. A mixture [IZO (Indium Zinc Oxide)], a metal halide (for example, copper iodide), and carbon black. Further, a conductive polymer such as polyaniline, poly(3-methylthiophene) or polypyrrole may also be used. When the light is taken out on the anode side, it is preferable to use a material having a high transmittance for light emission such as ITO or IZO. The transmittance is preferably 10% or more, more preferably 50% or more, still more preferably 80% or more. Further, the thickness of the anode is usually 3 nm or more, preferably 10 nm or more. The upper limit value can be set to, for example, 1 μm or less. However, when the anode is not required to have transparency, the thickness may be thick. For example, the anode may function as the substrate. The anode can be formed, for example, by a vapor deposition method, a sputtering method, or a coating method. In the case where a conductive polymer is used for the anode, an anode may be formed on the substrate by electrolytic polymerization. Surface treatment after forming the anode To improve the hole injection function. Specific examples of the surface treatment include plasma treatment (for example, argon plasma treatment, oxygen plasma treatment), UV (UltraViolet) treatment, ozone treatment, and the like.

(hole injection layer and hole transmission layer)

The hole injection layer has a function of transmitting a hole from the anode to the side of the light-emitting layer. Since the hole injection layer is usually formed on the anode, it is preferably a layer excellent in adhesion to the anode surface. Therefore, it is preferably composed of a material having a high film forming ability. The hole transport layer has a function of transmitting a hole to the light emitting layer side. The hole transport layer contains a material having excellent hole transportability.

In the hole injection layer and the hole transport layer, a hole transport material having a high hole mobility and a small ionization energy is used. The ionization energy can be, for example, preferably selected from 4.5 to 6.0 eV. As the hole transporting material, various materials which can be used for the hole injection layer or the hole transport layer of the organic electroluminescence element can be appropriately selected and used. The hole transporting material may be a polymer material having a repeating unit or a low molecular compound.

Examples of the hole transporting material include an aromatic tertiary amine compound and a styrylamine compound. An oxadiazole derivative, an imidazole derivative, a triazole derivative, a pyrazoline derivative, a pyrazolone derivative, a phenylenediamine derivative, an arylamine derivative, an amine-substituted chalcone derivative, An azole derivative, a polyarylalkane derivative, a styryl fluorene derivative, an anthrone derivative, an anthracene derivative, an anthracene derivative, a decazane derivative, a decane-based polymer, an aniline-based copolymer, a thiophene-based polymerization And porphyrin compounds.

Preferred examples of the hole transporting material include aromatic tertiary amine compounds, and specific examples thereof include triphenylamine, trimethylamine, and N,N'-diphenyl-N,N'-(3-methylphenyl)- 1,1'-biphenyl-4,4'-diamine, N,N,N',N'-(4-methylphenyl)-1,1'-phenyl-4,4'-diamine ,N,N,N',N'-(4-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'- Dinaphthyl-1,1'-biphenyl-4,4'-diamine, N,N'-(methylphenyl)-N,N'-(4-n-butylphenyl)-phenanthrene-9 , 10-diamine, N,N bis(4-di-4-toluaminophenyl)-4-phenyl-cyclohexane, N,N'-bis(4'-diphenylamino-4-linked Phenyl)-N,N'-diphenylbenzidine, N,N'-bis(4'-diphenylamino-4-phenyl)-N,N'-diphenylbenzidine, N,N'-Bis(4'-diphenylamino-4-phenyl)-N,N'-bis(1-naphthyl)benzidine,N,N'-bis(4'-phenyl(1-naphthyl)amine4-phenyl)-N,N'-diphenylbenzidine,N,N'-bis(4'-phenyl(1-naphthyl)amino-4-phenyl)-N,N' - bis(1-naphthyl)benzidine or the like. Further, as a preferred hole transporting material, a phthalocyanine-based compound may be mentioned, and specific examples thereof include H ₂ Pc, CuPc, CoPc, NiPc, ZnPc, PdPc, FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, and Cl _{2 .} SiPc, (HO)AlPc, (HO)GaPc, VOPc, TiOPc, MoOPc, GaPc-O-GaPc [Pc represents phthalocyanine]. Further, a metal oxide such as PEDOT (Poly(3,4-ethylenedioxythiophene)) or molybdenum oxide or a known aniline derivative can be preferably used.

The hole transporting material used in the present invention may be selected from one type in one layer, or two or more types may be used in combination in one layer. Further, the hole injection layer or the hole transport layer can be formed, for example, by a vapor deposition method, a sputtering method, or a coating method. The thickness of the hole injection layer or the hole transport layer is usually 3 nm or more, preferably 10 nm or more. The upper limit value can be set, for example, to 5 μm or less.

(lighting layer)

The luminescent layer of the organic electroluminescent device of the present invention may be composed of a host material And the dopant material may also be a single material. The compound represented by the formula (1) of the present invention can be used as a host material, a dopant material, and a single material constituting the light-emitting layer.

When the light-emitting layer contains the host material and the dopant material, in order to prevent concentration quenching, the dopant material is preferably used in an amount of 10% by weight or less based on the host material, more preferably 2% by weight or less. The doping material and the host material may each be used alone or in combination of two or more. The doping can be carried out by co-evaporating the host material and the dopant material. In this case, the host material and the dopant material can also be pre-mixed and then vapor-deposited.

Examples of the host material used in the light-emitting layer include a hydroxyquinoline derivative metal complex, An oxadiazole derivative, a distyryl arene derivative, a diphenylphosphonium derivative or the like. In addition to this, it is also possible to appropriately select and use a host material as a light-emitting layer.

As the dopant material, it can be selected in consideration of the wavelength of light emission or the like. For example, a wide range of materials such as an isobenzofuran derivative, an anthracene derivative, a distyryl arene derivative, and a carbazole derivative can be used. Further, a phosphorescent material, a heat-activated retardation fluorescent material, an excitation complex type luminescent material, or the like can be appropriately selected and used.

As the phosphorescent material, various conventional metal complex compounds are exemplified. Examples of the phosphorescent material include, for example, FIrpic, FCNIr, Ir(dbfmi), FIr6, Ir(fbppz) ₂ (dfbdp), and Irr compound such as FIrN4, or [Cu(hereinafter). Dnbp)(DPEPhos)]BF ₄ or [Cu(dppb)(DPEPhos)]BF ₄ ,[Cu(μ-I)dppb] ₂ ,[Cu(μ-Cl)DPEphos] ₂ ,Cu(2-tzq)( Cu complexes such as DPEPhos), [Cu(PNP)] ₂ , compound 1001, Cu(Bpz ₄ ) (DPEPhos), Pt complexes such as FPt and Pt-4. The structures of these are shown below.

Although a representative phosphorescent material is described above, the phosphorescent material which can be used in the present invention is not limited thereto, and a known luminescent material may be used as long as the formula (A) and the formula (B) are satisfied. The main luminescent materials are described, for example, in Chapter 9 of the "Organic EL Device Physics, Materials Chemistry, and Device Applications" published by CMC.

Examples of the heat-activated delayed fluorescent material include the following PIC-TRZ and [Cu(PNP- ^t Bu)] ₂ as preferred examples.

Examples of the excitation complex type light-emitting material include m-MTDATA and PBD, PyPySPyPy and NPB, PPSPP and NPB, which are preferred examples.

(hole blocking layer)

The hole blocking layer has a function of preventing movement to the cathode side via the holes of the light emitting layer. It is preferably formed between the light-emitting layer and the organic layer on the cathode side. Examples of the organic material forming the hole blocking layer include an aluminum compound, a gallium-discriminating compound, a phenanthroline derivative, a pyrene derivative, and a hydroxyquinoline derivative metal complex. Diazole derivatives, An azole derivative. Specific examples thereof include bis(8-hydroxyquinoline)(4-phenylphenolate)aluminum, bis(2-methyl-8-hydroxyquinoline)(4-phenylphenolate)gallium, 2,9-di Methyl-4,7-diphenyl-1,10-morpholine (BCP, Bathocuproin) and the like. The hole blocking layer may be selected from a single organic material or may be used alone or in combination of two or more. Further, the hole blocking layer can be formed, for example, by a vapor deposition method, a sputtering method, or a coating method. The thickness of the hole barrier layer is usually 3 nm or more, preferably 10 nm or more. The upper limit value can be set, for example, to 5 μm or less.

(electron injection layer and electron transport layer)

The electron injecting layer has a function of transporting electrons from the cathode to the side of the light emitting layer. Since the electron injecting layer is usually formed in contact with the cathode, it is preferably a layer excellent in adhesion to the surface of the cathode. The electron transport layer has a function of transporting electrons to the light-emitting layer side. The electron transport layer contains a material having excellent electron transport properties.

In the electron injecting layer and the electron transporting layer, an electron transporting material having a high electron mobility and a large ionization energy is used. As the electron transporting material, various materials which can be used for the electron injecting layer or the electron transporting layer of the organic electroluminescent element can be appropriately selected and used. The electron transporting material may be a polymer material having a repeating unit or a low molecular compound.

Examples of the electron transporting material include an anthrone derivative, a quinodimethane derivative, a terephthalene derivative, a thiopyran dioxide derivative, and the like. An azole derivative, a thiazole derivative, Diazole derivatives, triazole derivatives, imidazole derivatives, perylene tetracarboxylic acid derivatives, quinolin A porphyrin derivative, a mercapto methane derivative, a quinone dimethane derivative, an anthrone derivative, or the like. Specific examples of the preferred electron transporting material include 2,5-bis(1-phenyl)-1,3,4- Azole, 2,5-bis(1-phenyl)-1,3,4-thiazole, 2,5-bis(1-phenyl)-1,3,4- Diazole, 2-(4'-tert-butylphenyl)-5-(4"-biphenyl) 1,3,4- Diazole, 2,5-bis(1-naphthyl)-1,3,4- Diazole, 1,4-bis[2-(5-phenyl) Diazolyl]]benzene, 1,4-bis[2-(5-phenyl) (oxadiazolyl)-4-t-butylbenzene], 2-(4'-tert-butylphenyl)-5-(4"-biphenyl)-1,3,4-thiadiazole, 2, 5-bis(1-naphthyl)-1,3,4-thiadiazole, 1,4-bis[2-(5-phenylthiadiazolyl)]benzene, 2-(4'-third Phenyl)-5-(4"-biphenyl)-1,3,4-triazole, 2,5-bis(1-naphthyl)-1,3,4-triazole, 1,4-double [2-(5-Phenyltriazolyl)]benzene, lithium 8-hydroxyquinolate, bis(8-hydroxyquinoline) zinc, bis(8-hydroxyquinoline) copper, bis(8-hydroxyquinoline) Manganese, tris(8-hydroxyquinoline)aluminum, tris(2-methyl-8-hydroxyquinoline)aluminum, tris(8-hydroxyquinoline)gallium, bis(10-hydroxybenzo[h]quinoline) Bismuth, bis(10-hydroxybenzo[h]quinoline) zinc, bis(2-methyl-8-quinoline)chlorogallium, bis(2-methyl-8-quinoline)(o-cresol) gallium , bis(2-methyl-8-quinoline) (1-naphthol) aluminum, bis(2-methyl-8-quinoline) (2-naphthol) gallium, and the like.

The electron transporting material used in the present invention may be selected from one type in one layer, or two or more types may be used in combination in one layer. Further, the electron injecting layer or the electron transporting layer can be formed, for example, by a vapor deposition method, a sputtering method, or a coating method. The thickness of the electron injecting layer or the electron transporting layer is usually 3 nm or more. Good for 10 nm or more. The upper limit value can be set, for example, to 5 μm or less.

(cathode)

The cathode has a function of injecting electrons into the organic layer. As such a cathode, a material having a low work function is preferably used, and for example, a material of 4 eV or less is preferably used. Specific examples thereof include metals (for example, tin, magnesium, indium, calcium, aluminum, and silver) and alloys (for example, aluminum-lithium alloys, magnesium-silver alloys, and magnesium-indium alloys). When the light is taken out from the cathode side, it is preferred to use a material having a high transmittance. The transmittance is preferably 10% or more, more preferably 50% or more, still more preferably 80% or more. Further, the thickness of the cathode is usually 3 nm or more, preferably 10 nm or more. The upper limit value can be set, for example, to 1 μm or less, but may be thicker when the cathode is not required to have transparency. The cathode can be formed, for example, by a vapor deposition method or a sputtering method. In order to protect the cathode, it is preferred to form a protective layer on the cathode. Such a protective layer is preferably a layer comprising a metal having a high work function and being stable, for example, a metal layer of aluminum, silver, copper, nickel, chromium, gold, platinum or the like.

The organic electroluminescent device of the present invention can be further applied to various uses. For example, an organic electroluminescence display device can be produced by using the organic electroluminescence device of the present invention. For details, refer to "Organic EL Display" (Ohm Co., Ltd.), which is a joint work of Jing Shi, Anda Chiba, and Murata. Further, the organic electroluminescence device of the present invention is particularly applicable to organic electroluminescence illumination which is in great demand.

[Examples]

The features of the present invention will be further specifically described below by way of synthesis examples, test examples, and production examples. The materials, processing contents, processing steps, and the like shown below may be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, this issue The scope of the invention is not limited by the specific examples shown below.

(Synthesis Example 1)

In the present synthesis, Compound 1 was synthesized according to the following scheme.

Under argon, 1.9 g (4.0 mmol) of compound 101, 234 mg (0.32 mmol) of Pd(dppf)Cl ₂ were added to the reaction vessel, and then 48 ml of benzene and 2 mol/L of potassium carbonate 24 ml were added. Tetrahydrofuran (THF, Tetrahydrofuran) 12 ml, and 0.87 g (3 mmol) of Compound 102 were stirred at 75 ° C for 72 hours. After stirring, an aqueous solution of ammonium chloride was added to the reaction system to stop the reaction. The mixture was extracted with toluene, and the organic layer was washed with brine, dried over magnesium sulfate, and concentrated. The obtained crude product was purified by column chromatography using hexane/chloroform solvent to afford 960 mg of Compound 103 (yield 50%).

NMR (CDCl ₃ ): δ 8.17-8.07 (m, 4H), 7.79 (d, J = 8.0, 1H), 7.68 (d, J = 8.5, 1H), 7.52-7.44 (m, 4H), 7.35-7.32 (m, 4H), 7.26-7.20 (m, 2H), 7.10-7.03 (m, 6H), 6.98 (d, J = 8.5, 2H), 6.87 (s, 1H), 6.81 (s, 1H), 6.71 (dd, J = 8.0, 7.5, 2H).

958 mg (1.5 mmol) of compound 103, 20 ml of tetrahydrofuran (THF) were added to the reaction vessel under argon and cooled to -78 °C. 2 ml (3.2 mmol) of n-butyllithium was added dropwise to the reaction system and stirred for 3 hours, then 448 μl (2.5 mmol) of diphenylphosphonium chloride was added and stirred for 1 hour, returned to room temperature and stirred overnight. . After completion of the reaction, water was added to stop the reaction, and the mixture was extracted with ethyl acetate and concentrated, and the obtained crude product was applied to the next reaction without purification.

30 ml of dichloromethane and 9 ml of hydrogen peroxide water were added to the obtained product, and the mixture was stirred at room temperature overnight. Thereafter, water was added to the reaction system to stop the reaction. After extracting with methylene chloride, the organic layer was washed with aqueous sodium hydrogen sulfate, and the organic layer was dried over magnesium sulfate. Purification by column chromatography using hexane/ethyl acetate solvent afforded 550 mg of Compound 1 (yield 48%).

NMR (CDCl ₃ ): δ 8.18 (d, J = 7.5, 1H), 8.12 (d, J = 7.5, 1H), 8.08 (d, J = 10.5, 1H), 8.04 (d, J = 7.5, 1H) , 7.70 (d, J = 8.0, 1H), 7.57-7.42 (m, 3H), 7.37 (d, J = 8.5, 2H), 7.30-7.27 (m, 3H), 7.23 (t, J = 7.5, 1H) ), 7.14 (t, J = 7.5, 1H), 7.05-6.98 (m, 7H), 6.93 (d, J = 8.5, 2H), 6.81 (s, 1H), 6.72 (d, J = 8.0, 6H) , 6.64 - 6.63 (d, J = 8.0, 1H).

(Synthesis Examples 2 to 56 and 58 to 88)

Compounds 2 to 56 and 58 to 88 can be synthesized in the same manner as in Synthesis Example 1 or Synthesis Example 57 described below.

(Synthesis Example 57)

In the present synthesis, compound 57 was synthesized according to the following scheme.

2,7-Dibromo-2',7'-dicyano-9,9'-spirobiquinone 0.52 g (0.99 mmol, compound a), (2,3,6,7-tetrahydro-1H, 5H-benzo[ij]quina To a 100 ml three-necked flask, -9-yl)boronic acid 0.62 g (2.9 mmol) was added, and to the mixture were added 10 mL of toluene, 2 mL of ethanol, and 3 ml of a 2M aqueous potassium carbonate solution. The mixture was foamed for 20 minutes using nitrogen. After foaming, tetrakis(triphenylphosphine)palladium(0) 0.090 g (0.078 mmol) was added to the mixture. The mixture was stirred at 70 ° C for 21 hours under a nitrogen stream. After stirring, the mixture was added to 200 mL of toluene and 200 mL of water and stirred. After stirring, the organic layer and the aqueous layer were separated, and the organic layer was washed with brine. After washing, magnesium sulfate was added to the organic layer to dry. After drying, the mixture was suction filtered to obtain a filtrate. The solid obtained by concentrating the obtained filtrate was washed with methanol. After washing, the solid was dissolved in chloroform, and then hexane was added for reprecipitation to obtain a solid. The obtained solid was purified by silica gel column chromatography (developing solvent: chloroform). After purification, the obtained fraction was concentrated, and solid was recovered to give a yellow powdery solid (Comp. 57).

¹ H NMR (500 MHz, CDCl ₃ ): 7.98 (d, J = 8.0 Hz, 2H), 7.83 (d, J = 8.0 Hz, 2H), 7.71 (d, J = 8.0 Hz, 2H), 7.57 (d) , J=8.0 Hz, 2H), 7.14 (s, 2H), 6.84 (s, 4H), 6.67 (s, 2H), 3.12 (d, J = 11 Hz, 8H), 2.72 (t, J = 6.4 Hz) , 8H), 1.93 (d, J = 11 Hz, 8H).

</RTI>^< RTI ID=0.0></RTI>^</RTI>^{<RTI ID} =0.0>

(Example 1)

In the present production example, an organic electroluminescence device and a pure film having the structure shown in Fig. 1 were produced using Compound 1, and the luminous efficiency was evaluated.

(1) Fabrication and evaluation of organic electroluminescent elements

Indium tin oxide (ITO) 2 was formed on the glass 1 to a thickness of about 30 to 100 nm, and the compound 1 was vacuum-deposited thereon to form a film having a thickness of 80 nm. The mean square roughness (RMS, Root Mean Square) of the film surface was 1.34 nm. Then, 0.7 nm of lithium fluoride (LiF) 4 was vacuum-deposited, and then aluminum (Al) 5 was vapor-deposited at a thickness of 90 nm to prepare an organic electroluminescence device having the layer structure shown in Fig. 1.

The current density-voltage-luminance (JVL) characteristics of the produced organic electroluminescence device were measured using a semiconductor parameter analyzer and a power meter, and the results are shown in Fig. 2. The device of this embodiment achieved 1550 mA/cm ² at a driving voltage of 15.0 V and reached 850 cd/m ² at a driving voltage of 13.0 V. Further, the results of measuring the current density-external quantum efficiency characteristics are shown in Fig. 3. The components of this embodiment achieved an external quantum efficiency of 0.47%.

(2) Production and evaluation of pure film

A pure film was produced by vapor-depositing the compound 1 on a quartz substrate, and the emission spectrum was measured. The results are shown in Fig. 4. The sharp luminescence with a peak of 432 nm was confirmed, and the luminescence quantum yield was 57%. Further, the energy level of HOMO was measured using a photoelectron spectroscopy apparatus for the pure film of Compound 1. Further, the absorption limit energy was measured using a spectrophotometer, and this was defined as an energy gap. The position of the energy gap measured only by the HOMO energy level is set to the LUMO energy level. As a result, the energy level of HOMO was determined to be 5.3 eV, and the energy level of LUMO was 2.3 eV. An energy level diagram of the organic electroluminescent device of the present embodiment is shown in FIG.

From the above, it was confirmed that the compound 1 has a good film forming ability and exhibits a high luminescence quantum yield in the state of a pure film, indicating that it is suitable for the production of a single-layer type organic electroluminescence element.

(Examples 2 to 50, 52 to 57, and 59 to 88)

The usefulness of Compounds 2 to 50, 52 to 57, and 59 to 88 was also confirmed in the same manner as in Example 1.

(Example 51)

In the present example, a toluene solution of Compound 51 was prepared and the luminescence spectrum was measured (Fig. 6). The PL (Photo Luminescence) transition attenuation was measured at 300 K using a fast camera, and a short life component of 11.55 ns and a long life component of 124.9 μs were observed (Fig. 7). That is, according to the compound 51, in addition to the observation of short-lived fluorescence, heat-activated delayed fluorescence derived from a long-lived component was observed.

[化29]

(Example 57)

Using the compound 57 synthesized in Synthesis Example 57, the luminescence spectrum of the solution was measured in the same manner as in Example 51, and as a result, luminescence at a peak of 550 nm was confirmed. Further, when the PL transition attenuation was measured, a short-lived component of 10.61 ns and a long-lived component of 434.38 μs were observed (Fig. 8). That is, according to the compound 10, in addition to the observation of short-lived fluorescence, heat-activated delayed fluorescence derived from a long-lived component was observed.

[Industrial availability]

The compound of the present invention is a compound which is useful as a light-emitting material of an organic electroluminescence device. Especially in the state of pure film, it exhibits high luminescence quantum yield and high film forming ability, so industrial application of various organic electroluminescent elements typified by single-layer type organic electroluminescent elements can be expected. . Therefore, the industrial availability of the present invention is high.

1‧‧‧glass

2‧‧‧ITO

3‧‧‧Compound 1

4‧‧‧LiF

5‧‧‧Al

Fig. 1 is a schematic cross-sectional view showing a layer structure of an organic electroluminescence device of an example.

Fig. 2 is a graph showing the current density-voltage-luminance characteristics of Example 1.

Fig. 3 is a graph showing the current density-external quantum efficiency characteristics of Example 1.

4 is an luminescence spectrum of Example 1.

Figure 5 is an energy level diagram of Embodiment 1.

Figure 6 is an luminescence spectrum of the solution of Example 51.

Fig. 7 is a graph showing the PL transition attenuation of Example 51.

Fig. 8 is a graph showing the PL transition attenuation of Example 58.

1‧‧‧glass

2‧‧‧ITO

3‧‧‧Compound 1

4‧‧‧LiF

5‧‧‧Al

Claims (18)

An organic electroluminescence device comprising an anode, a cathode, and at least one organic layer between the anode and the cathode and including a light-emitting layer, and containing the following general formula (1) in the light-emitting layer a single spirobiindole compound, [In the formula (1), R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represent a hydrogen atom or an electron-donating group, and at least one represents an electron-donating group; R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently a hydrogen atom or three An electron withdrawing group other than the base, and at least one represents three An electron withdrawing group other than a group; wherein R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ And 11 to 14 of R ¹⁶ are hydrogen atoms]. The organic electroluminescent device according to claim 1, wherein at least one of R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) is an aryl group substituted with an electron-donating group. . The organic electroluminescence device according to claim 1, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following formula ( 2) the structure shown, [In the formula (2), R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ each independently represent a hydrogen atom or an electron-donating group, and at least one represents an electron-donating group]. The organic electroluminescence device according to claim 1, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following formula ( 3) The structure shown in any of (5), [In the above formula, R ³¹ and R ³² each independently represent a substituted or unsubstituted aryl group, and an aryl group represented by R ³¹ may be bonded to an aryl group represented by R ³² ; R ⁴¹ , R ⁴² and R ⁴³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁴¹ and R ⁴² may together form a ring structure, and R ⁴² and R ⁴³ may together form a ring. R ⁵¹ , R ⁵² and R ⁵³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁵¹ and R ⁵² may together form a ring structure, R ⁵² and R ⁵³ may together form a ring structure]. The organic electroluminescence device according to claim 1, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following formula ( The structure shown in any of A)~(C), [In the general formula (A), Z ¹ represents a nitrogen atom, an oxygen atom, a sulfur atom or a halogen atom, and A ¹ and A ² may each independently form an aromatic ring, a heteroaromatic ring, an aliphatic ring or a non-aromatic hetero ring; In the formula (B), R ²⁰ represents a hydrogen atom, an aryl group or an atomic group necessary for forming a ring structure represented by A ⁴ , and A ³ and A ⁴ may each independently form a heteroaromatic ring or a non-aromatic heterocyclic ring. In the general formula (C), Z ¹ , Z ² , Z ³ and Z ⁴ each independently represent an oxygen atom or a sulfur atom]. The organic electroluminescence device according to claim 1, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following D1 to D13; Any structure, The organic electroluminescent device according to any one of claims 1 to 6, wherein at least one of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ of the formula (1) A structure having any one of the following general formulae (6) to (9), [In the above formula, R ⁶¹ and R ⁶² each independently represent a substituted or unsubstituted aryl group; and R ⁷¹ and R ⁷² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The substituted aryl group, R ⁷¹ and R ⁷² may together form a ring structure; R ⁸¹ , R ⁸² and R ⁸³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group. The aryl group, R ⁸¹ and R ⁸² may together form a ring structure, and R ⁸² and R ⁸³ may together form a ring structure; R ⁹¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The aryl group, Z represents the formation of three a linking group necessary for a heteroaromatic ring other than a ring]. The organic electroluminescent device according to any one of claims 1 to 6, wherein at least one of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ of the formula (1) Have any of the following structures, The organic electroluminescence device according to any one of claims 1 to 6, which has a light-emitting layer containing only the compound represented by the above formula (1). The organic electroluminescence device according to any one of claims 1 to 6, which uses the compound represented by the above formula (1) as a dopant of the light-emitting layer. The organic electroluminescent element according to any one of claims 1 to 6, which has only a light-emitting layer as an organic layer. A monospirobiguanide compound represented by the following formula (1'): [In the formula (1'), R ^{1 '} , R ^{2 '} , R ^{3 '} , R ^{4 '} , R ^{5 '} , R ^{6 '} , R ^{7 '} and R ^{8 '} are each independently a hydrogen atom or an electron-donating group. And at least one represents an aryl group substituted with an electron-donating group; R ^{9 '} , R ^{10 '} , R ^{11 '} , R ^{12 '} , R ^{13 '} , R ^{14 '} , R ^{15 '} and R ^{16 '} are each independently a hydrogen atom Or three An electron withdrawing group other than the base, and at least one represents three An electron withdrawing group other than a group; wherein R ^{1 '} , R ^{2 '} , R ^{3 '} , R ^{4 '} , R ^{5 '} , R ^{6 '} , R ^{7 '} , R ^{8 '} , R ^{9 '} , R ^{10 '} , R ^{11 to 14 of} R ^' , R12 ^' , R13 ^' , R14 ^' , R15 ^' and R16 ^' are hydrogen atoms]. The compound of claim 12, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following formula (2) Structure, [In the formula (2), R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ each independently represent a hydrogen atom or an electron-donating group, and at least one represents an electron-donating group]. The compound of claim 12, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has the following formula (3) to ( 5) The structure shown in any one of them, [In the above formula, R ³¹ and R ³² each independently represent a substituted or unsubstituted aryl group, and an aryl group represented by R ³¹ may be bonded to an aryl group represented by R ³² ; R ⁴¹ , R ⁴² and R ⁴³ independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁴¹ and R ⁴² may together form a ring structure, and R ⁴² and R ⁴³ may together form a ring. R ⁵¹ , R ⁵² and R ⁵³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R ⁵¹ and R ⁵² may together form a ring structure, R ⁵² and R ⁵³ may together form a ring structure]. The compound of claim 12, wherein at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ of the formula (1) has any of the following structures: The compound according to any one of claims 12 to 15, wherein at least one of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ of the formula (1) has the following a structure shown in any one of the formulas (6) to (9), [In the above formula, R ⁶¹ and R ⁶² each independently represent a substituted or unsubstituted aryl group; and R ⁷¹ and R ⁷² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The substituted aryl group, R ⁷¹ and R ⁷² may together form a ring structure; R ⁸¹ , R ⁸² and R ⁸³ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group. The aryl group, R ⁸¹ and R ⁸² may together form a ring structure, and R ⁸² and R ⁸³ may together form a ring structure; R ⁹¹ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group; The aryl group, Z represents the formation of three a linking group necessary for a heteroaromatic ring other than a ring]. The compound according to any one of claims 12 to 15, wherein at least one of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ of the formula (1) has the following a structure, A luminescent material comprising a compound according to any one of claims 12 to 17.