Photoelectric conversion element, hole transport promoting material, and compound

Abstract

The present invention provides: a photoelectric conversion element in which the hole transport ability can be improved; a hole transport promoting material; and a compound.　Provided is a photoelectric conversion element that includes a first electrode, a second electrode, and a light-receiving layer and an organic layer, which are disposed between the first electrode and the second electrode. The organic layer includes a hole transport layer and a hole transport promoting layer that contains an imide compound represented by formula (1), or alternatively, the organic layer includes a layer that is obtained by mixing a hole transport material and an imide compound represented by formula (1). (In formula (1), ring A represents an optionally substituted aromatic hydrocarbon ring (which may be a monocyclic ring, a fused ring, or a linked ring including a plurality of rings) having 6 to 20 carbon atoms; ring B represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms; R1 represents a specific group; and Ar1 represents a specific group.)

Description

Photoelectric conversion element, hole transport promoting material, and compound

[0001] The present invention relates to a photoelectric conversion element, a hole transport promoting material, and a compound.

[0002] Currently, active efforts are being made to create new, highly functional devices using organic materials. Research and development is particularly active on organic electronic devices, such as photoelectric conversion devices and organic electroluminescence (EL) devices, with advances being made in material and device design aimed at improving device performance. For example, in photoelectric conversion devices used for video recording, a problem exists in that slow transport of carriers (electrons and holes) generated in the light-receiving layer to the electrode can cause image retention. In organic EL devices, slow transport of carriers from the electrode to the light-emitting layer can increase the driving voltage. Therefore, highly efficient carrier movement within the device is required to achieve high device performance.

[0003] For example, it has been disclosed that a compound having an imide structure is used in the electron transport layer of an organic thin-film solar cell (see Patent Document 1). However, further improvements in performance are required in the field of organic electronic devices, and therefore further improvements are necessary.

[0004] WO2021 / 168358A1

[0005] An object of the present invention is to provide a photoelectric conversion element capable of improving the hole transport capability, and a hole transport promoting material and compound capable of improving the hole transport capability.

[0006] As a result of intensive investigations aimed at solving the above-mentioned problems, the present inventors have found that it is possible to improve the hole transport ability in a photoelectric conversion element that includes a hole transport promoting layer containing a compound having the specific structure shown below, or that includes a layer obtained by mixing a hole transport material with the compound, and have thus completed the present invention.

[0007] That is, the present invention includes the following aspects: [1] A photoelectric conversion element including a first electrode, a second electrode, and an electron-receiving layer and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer includes a hole-transporting layer and a hole-transport promoting layer containing a compound represented by the following formula (1), or includes a layer formed by mixing a hole-transporting material and a compound represented by the following formula (1): (In formula (1), ring A represents an aromatic hydrocarbon ring having 6 to 20 carbon atoms which may be substituted (which may be a single ring, a fused ring, or a linked ring containing a plurality of rings); ring B represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms; R １ each independently represents a hydroxy group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group consisting of two or more of the above groups or atoms; n represents 0, 1, 2, 3, or 4; provided that when ring B is an imidazole ring, n represents 0, 1, or 2; Ar １represents an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), or an optionally substituted heteroaromatic group having 2 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings); examples of substituents that may be substituted on the aromatic hydrocarbon ring, the aromatic hydrocarbon group, or the heteroaromatic group include a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), or a group comprising a combination of two or more of the above groups or atoms. [2] The photoelectric conversion element according to [1], wherein the light-receiving layer is a layer containing at least two kinds of organic components. [3] The photoelectric conversion element according to [1] or [2], wherein the organic layer includes the hole transport layer and the hole transport promoting layer containing the imide compound represented by formula (1), and the hole transport promoting layer is adjacent to the hole transport layer. [4] The photoelectric conversion element according to [1] or [2], wherein the organic layer includes the layer formed by mixing the hole transport material and the imide compound represented by formula (1). [5] The photoelectric conversion element according to [1] or [2], wherein R in formula (1) １ [6] The photoelectric conversion element according to any one of [1] to [4], wherein n in formula (1) is 1 or 2. [7] The photoelectric conversion element according to any one of [1] to [6], wherein ring A in formula (1) is a benzene ring or a naphthalene ring. [8] The photoelectric conversion element according to any one of [1] to [6], wherein Ar in formula (1) is １is an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted pyridyl group, an optionally substituted pyrazyl group, an optionally substituted pyrimidyl group, an optionally substituted triazyl group, an optionally substituted quinolyl group, an optionally substituted isoquinolyl group, an optionally substituted quinoxalyl group, or an optionally substituted quinazolinyl group. [9] The photoelectric conversion element according to any one of [1] to [7], １ is a phenyl group, a cyanophenyl group, a dicyanophenyl group, a naphthyl group, a cyanonaphthyl group, a dicyanonaphthyl group, a pyridyl group, a cyanopyridyl group, a dicyanopyridyl group, a pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a pyrazyl group, a cyanopyrazyl group, a dicyanopyrazyl group, a quinolyl group, a cyanoquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a quinazolinyl group, or a cyanoquinazolinyl group.

[10] A hole transport promoting material represented by the following formula (1a): (In formula (1a), ring C represents an aromatic hydrocarbon ring having 6 to 20 carbon atoms which may be substituted (which may be a single ring, a fused ring, or a linked ring containing multiple rings); ring D represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms; R ２ each independently represents a hydroxy group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group comprising a combination of two or more of the above groups or atoms; m represents 0, 1, 2, 3, or 4; provided that when ring D is an imidazole ring, m represents 0, 1, or 2; Ar ２represents an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), or an optionally substituted heteroaromatic group having 2 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings); examples of substituents that may be substituted on the aromatic hydrocarbon ring, the aromatic hydrocarbon group, or the heteroaromatic group include a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), or a group comprising a combination of two or more of the above groups or atoms.

[11] R in the formula (1a) ２

[12] The hole transport promoting material according to

[10] or

[11] , wherein m in formula (1a) is 1 or 2.

[13] The hole transport promoting material according to any one of

[10] to

[12] , wherein ring C in formula (1a) is a benzene ring or a naphthalene ring.

[14] The hole transport promoting material according to

[10] or

[11] , wherein Ar in formula (1a) is 1 or 2. ２ is an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted pyridyl group, an optionally substituted pyrazyl group, an optionally substituted pyrimidyl group, an optionally substituted triazyl group, an optionally substituted quinolyl group, an optionally substituted isoquinolyl group, an optionally substituted quinoxalyl group, or an optionally substituted quinazolinyl group.

[15] The hole transport promoting material according to any one of

[10] to

[13] , ２is a phenyl group, a cyanophenyl group, a dicyanophenyl group, a naphthyl group, a cyanonaphthyl group, a dicyanonaphthyl group, a pyridyl group, a cyanopyridyl group, a dicyanopyridyl group, a pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a pyrazyl group, a cyanopyrazyl group, a dicyanopyrazyl group, a quinolyl group, a cyanoquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a quinazolinyl group, or a cyanoquinazolinyl group.

[16] An imide compound represented by formula (1b): (In formula (1b), p represents 0, 1, or 2; q represents 1, 2, 3, 4, or 5; X １ is a nitrogen atom or C—R ６ represents; X ２ is a nitrogen atom or C—R ７ represents; Ar ３ represents a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings); R ３ represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may be a group consisting of two or more of the above groups or atoms in combination; R ４ , R ５ , R ６ , and R ７ each independently represents a hydrogen atom or a cyano group; ４ , R ５ , R ６ , and R ７ At least two of the Ar groups in the formula (1b) are cyano groups. ３ is a phenyl group, a naphthyl group, an anthryl group, a phenanthrenyl group, a triphenylenyl group, a pyridyl group, a pyrazyl group, or a pyrimidyl group.

[18] An imide compound represented by formula (1c): (In formula (1c), k represents 0, 1, 2, 3, 4, or 5; ring E represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms; r represents 1, 2, 3, or 4; provided that when ring E is an imidazole ring, r represents 1 or 2; R ８ each independently represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may be a group consisting of two or more of the above groups or atoms in combination; Ar ４ represents a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 18 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings); R ９ each independently represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may be a group in which two or more of the above groups or atoms are combined.)

[19] R in the formula (1c) ９

[20] The imide compound according to

[18] , wherein at least one of Ar in the formula (1c) is a cyano group. ４ is a phenyl group, a naphthyl group, an anthryl group, a phenanthrenyl group, a triphenylenyl group, a pyridyl group, a pyrazyl group, or a pyrimidyl group.

[21] The imide compound according to any one of

[18] to

[20] , wherein ring E in formula (1c) is an imidazole ring, a benzimidazole ring, or an imidazopyrazine ring.

[0008] According to the present invention, it is possible to provide a photoelectric conversion element capable of improving the hole transport ability, and a hole transport promoting material and compound capable of improving the hole transport ability.

[0009] 1 is a schematic cross-sectional view showing an example of a layered structure of a photoelectric conversion element according to the present invention.

[0010] (Photoelectric conversion element) The present invention is directed to a photoelectric conversion element, and provides a photoelectric conversion element that can improve the hole transport capability by including a hole transport promoting layer containing a compound having the following specific structure or by including a layer formed by mixing a hole transport material with the compound. The photoelectric conversion element of the present invention is an element that converts light energy into electric energy or an electric signal, and includes an image sensor, a photosensor, a solar cell, etc.

[0011] The photoelectric conversion element of the present invention includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode. The organic layer includes a hole transport layer and a hole transport promoting layer containing an imide compound represented by the following formula (1) (hereinafter, sometimes simply referred to as “imide compound (1)”), or includes a layer formed by mixing a hole transport material with the imide compound (1).

[0012] A detailed description of the imide compound (1) will be given later. Here, the hole transport layer has a role of transporting holes and contains a hole transport material. The hole transport promoting layer is disposed between the first electrode and the hole transport layer, has a role of facilitating the exchange of holes between the hole transport layer and the electrode, and contains a hole transport promoting material. In the present invention, the imide compound (1) is used as the hole transport promoting material.

[0013] The photoelectric conversion element of the present invention includes a first electrode, a second electrode, and an organic layer and a light-receiving layer disposed between the first electrode and the second electrode. The element configuration of the photoelectric conversion element will be described below.

[0014] <Configuration of Photoelectric Conversion Element> The photoelectric conversion element according to the present invention includes a first electrode, a second electrode, and an organic layer disposed between the first and second electrodes, the organic layer including a hole transport region. The hole transport region refers to the region between the first electrode and the light-receiving layer, and includes, for example, a hole transport layer and a hole transport promoting layer. In the present invention, the imide compound (1) can be used as the hole transport promoting material contained in the hole transport promoting layer (or the hole transport promoting material contained in a layer mixed with the hole transport material). The hole transport region is preferably adjacent to the first electrode. The photoelectric conversion element may include other layers. Examples of other layers include layers commonly used in photoelectric conversion elements. Examples include, but are not limited to, a light-receiving layer, an electron transport layer, a hole blocking layer, an electron blocking layer, and a buffer layer.

[0015] The photoelectric conversion element according to the present invention may have, for example, a first electrode, a hole transport promoting layer, a hole transport layer, and a second electrode laminated in this order, or a first electrode, a layer formed by mixing a hole transport material forming the hole transport layer with the imide compound (1), and a second electrode laminated in this order. The photoelectric conversion element may also have, for example, the first electrode, the hole transport promoting layer, and the hole transport layer laminated adjacently in this order, or another layer such as a buffer layer may be interposed between the first electrode and the hole transport promoting layer or between the hole transport promoting layer and the hole transport layer.

[0016] In one embodiment, the photoelectric conversion element of the present invention comprises a first electrode, a hole transport promotion layer, a hole transport layer, a light-receiving layer, and a second electrode stacked in this order. In another embodiment, the photoelectric conversion element of the present invention comprises a first electrode, a hole transport promotion layer, a hole transport layer, a light-receiving layer, an electron transport layer, and a second electrode stacked in this order. The layers may be stacked adjacent to each other, or other layers may be interposed between any of the layers.

[0017] The photoelectric conversion element may receive light from either the first electrode side or the second electrode side, and either the first electrode or the second electrode may be a transparent electrode. For example, the photoelectric conversion element may have a structure in which a transparent electrode (second electrode), an electron transport layer, a light-receiving layer, a hole transport layer, a hole transport promotion layer, and a metal electrode (first electrode) are stacked in this order, or a structure in which a transparent electrode (first electrode), a hole transport promotion layer, a hole transport layer, a light-receiving layer, an electron transport layer, and a metal electrode (second electrode) are stacked in this order. Furthermore, both the first electrode and the second electrode may be transparent electrodes.

[0018] Next, the imide compound (1) contained in the organic layer as a hole transport promoting material in the photoelectric conversion element of the present invention will be described.

[0019] <Imide Compound (1)> The organic layer in the photoelectric conversion element of the present invention contains the following imide compound (1).

[0020]

[0021] (In formula (1), ring A represents an aromatic hydrocarbon ring having 6 to 20 carbon atoms which may be substituted (which may be a single ring, a fused ring, or a linked ring containing a plurality of rings); ring B represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms; R １ each independently represents a hydroxy group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group consisting of two or more of the above groups or atoms; n represents 0, 1, 2, 3, or 4; provided that when ring B is an imidazole ring, n represents 0, 1, or 2; Ar １represents an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), or an optionally substituted heteroaromatic group having 2 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings); examples of substituents that may be substituted on the aromatic hydrocarbon ring, the aromatic hydrocarbon group, or the heteroaromatic group include a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a monocyclic ring, a fused ring, or a linked ring containing multiple rings), or a group consisting of a combination of two or more of the above groups or atoms.

[0022] In this specification, Ar １ represents an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a fused ring, or a linked ring containing multiple rings), or an optionally substituted heteroaromatic hydrocarbon group having 2 to 20 carbon atoms (which may be a single ring, a fused ring, or a linked ring containing multiple rings).

[0023] Ar １ Examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms in Ar (which may be a single ring, a condensed ring, or a linked ring containing multiple rings) include a phenyl group, a naphthyl group, an anthryl group, a phenanthrenyl group, a pyrenyl group, a perylenyl group, a triphenylenyl group, a tetracenyl group, a chrysenyl group, a fluorenyl group, a 9,9-dimethylfluorenyl group, a 9,9-diphenylfluorenyl group, a spirobifluorenyl group, a biphenylyl group, a terphenyl group, a naphthylphenyl group, a phenylnaphthyl group, a binaphthyl group, an anthrylphenyl group, and a phenylanthryl group. １Examples of the heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings) in the formula (I) include a pyridyl group, a pyrimidyl group, a pyrazyl group, a triazyl group, a quinolyl group, an isoquinolyl group, a quinoxalyl group, a quinazolinyl group, a pyridopyrimidinyl group, a benzoquinolyl group, a benzoisoquinolyl group, a phenanthrolyl group, a phenanthridyl group, an acridyl group, a phenazinyl group, a phenoxazinyl group, a phenothiazinyl group, a benzoquinoxalyl group, a hexaazatriphenylenyl group, a thienyl group, a furyl group, a benzothienyl group, a benzofuryl group, an isobenzofuryl group, a dibenzo ... Examples of such groups include a benzothiophenyl group, a dibenzofuranyl group, a benzoxazolyl group, a pyrrole group, an indole group, an isoindole group, an indolizinyl group, a purine group, an imidazolyl group, a carbazolyl group, a thiazolyl group, a thiadiazolyl group, a triazole group, a bipyridyl group, a phenylpyridyl group, a diphenylpyrimidyl group, a terpyridyl group, a diphenylpyrimidyl group, a dipyridylpyrimidyl group, a phenylpyrazyl group, a pyridylpyrazyl group, a diphenyltriazyl group, a dipyridyltriazyl group, a phenylquinolyl group, a pyridylquinolyl group, a phenylisoquinolyl group, and a pyridylisoquinolyl group. １ is preferably a phenyl group, a naphthyl group, a pyridyl group, a pyrazyl group, a pyrimidyl group, a triazyl group, a quinolyl group, an isoquinolyl group, a quinoxalyl group, or a quinazolinyl group, and more preferably a phenyl group, a pyridyl group, a pyrazyl group, or a quinolyl group in terms of excellent device characteristics. Furthermore, these groups may be substituted with a substituent described later, and it is more preferable that the substituent is a cyano group.

[0024] In this specification, R １represents a hydroxy group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group consisting of a combination of two or more of the above groups or atoms.

[0025] R １Specific examples of the alkyl group include, but are not limited to, a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a perfluoroheptyl group, a perfluorooctyl group, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclo hexyl group, adamantyl group, tert-butyl group, isopropyl group, phenyl group, cyanophenyl group, dicyanophenyl group, tricyanophenyl group, methylphenyl group, dimethylphenyl group, trimethylphenyl group, fluorophenyl group, difluorophenyl group, trifluorophenyl group, perfluorophenyl group, biphenyl group, pyridylphenyl group, bispyridylphenyl group, trifluoromethylphenyl group, bistrifluoromethylphenyl group, naphthyl group, cyanonaphthyl group, dicyanonaphthyl group, phenylnaphthyl group, pyridylnaphthyl group, anthryl group, phenanthrenyl group, pyrenyl group, perylenyl group, triphenylenyl group, tetracenyl group, chrysenyl group, fluorenyl group, 9,9-dimethylfluorenyl group, 9,9-diphenylfluorenyl group, spirobifluorenyl group, biphenylyl group, terphenyl group, naphthylphenyl group, phenylnaphthyl group, binaphthyl group, anthrylphenyl group, phenylanthryl group, naphthylanthryl group, pyridyl group, cyanopyridyl group, dicyanopyridyl group, tricyanopyridyl group, methylpyridyl group, dimethylpyridyl group, trimethylpyridyl group , a fluoropyridyl group, a difluoropyridyl group, a trifluoropyridyl group, a tetrafluoropyridyl group, a phenylpyridyl group, a diphenylpyridyl group, a bipyridyl group, a terpyridyl group, a trifluoromethylpyridyl group, a bistrifluoromethylpyridyl group, a pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a tricyanopyrimidyl group, a methylpyrimidyl group, a dimethylpyrimidyl group, a trimethylpyrimidyl group, a fluoropyrimidyl group, a difluoropyrimidyl group, a trifluoropyrimidyl group, a tetrafluoropyrimidyl group, a phenylpyrimidyl group,Diphenylpyrimidyl group, pyridylpyrimidyl group, bispyridylpyrimidyl group, trifluoromethylpyrimidyl group, bistrifluoromethylpyrimidyl group, pyrazyl group, cyanopyrazyl group, dicyanopyrazyl group, tricyanopyrazyl group, methylpyrazyl group, dimethylpyrazyl group, trimethylpyrazyl group, fluoropyrazyl group, difluoropyrazyl group, trifluoropyrazyl group, tetrafluoropyrazyl group, phenylpyrazyl group, pyridylpyrazyl group, trifluoromethylpyrazyl group, bistrifluoromethylpyrazyl group, triazyl group, cyanotriazyl group group, dicyanotriazyl group, methyltriazyl group, dimethyltriazyl group, fluorotriazyl group, difluorotriazyl group, phenyltriazyl group, diphenyltriazyl group, pyridyltriazyl group, bispyridyltriazyl group, trifluoromethyltriazyl group, bistrifluoromethyltriazyl group, quinolyl group, cyanoquinolyl group, dicyanoquinolyl group, phenylquinolyl group, pyridylquinolyl group, isoquinolyl group, cyanoisoquinolyl group, dicyanoisoquinolyl group, phenylisoquinolyl group, pyridylisoquinolyl group, quinoxalyl group, cyano Quinoxalyl group, dicyanoquinoxalyl group, phenylquinoxalyl group, pyridylquinoxalyl group, quinazolinyl group, cyanoquinazolinyl group, dicyanoquinazolinyl group, phenylquinazolinyl group, pyridylquinazolinyl group, pyridopyrimidinyl group, cyanopyridopyrimidinyl group, dicyanopyridopyrimidinyl group, benzoquinolyl group, cyanobenzoquinolyl group, dicyanobenzoquinolyl group, benzoisoquinolyl group, cyanobenzoisoquinolyl group, dicyanobenzoisoquinolyl group, phenanthrolyl group, cyanophenanthrolyl group, dicyanophenanthrolyl group , phenanthridyl group, cyanophenanthridyl group, dicyanophenanthridyl group, acridyl group, cyanoacridyl group, dicyanoacridyl group, phenazinyl group, cyanophenazinyl group, dicyanophenazinyl group, phenoxazinyl group, cyanophenoxazinyl group, phenothiazinyl group, cyanophenothiazinyl group, benzoquinoxalyl group, cyanobenzoquinoxalyl group, hexaazatriphenylenyl group, pentacyanohexaazatriphenyl group, thienyl group, cyanothienyl group, dicyanothienyl group, furyl group, cyanofuryl group, dicyanofuryl group,Benzothienyl group, cyanobenzothienyl group, dicyanobenzothienyl group, benzofuryl group, cyanobenzofuryl group, dicyanobenzofuryl group, isobenzofuryl group, cyanoisobenzofuryl group, dicyanoisobenzofuryl group, dibenzothiophenyl group, cyanodibenzothiophenyl group, dicyanodibenzothiophenyl group, dibenzofuranyl group, cyanodibenzofuranyl group, dicyanodibenzofuranyl group, benzoxazoleyl group, cyanobenzoxazoleyl group, dicyanobenzoxazole Examples of such groups include an aryl group, a pyrrolyl group, a cyanopyrrolyl group, an indolyl group, a dicyanoindolyl group, an isoindoleyl group, a cyanoisoindolyl group, a dicyanoisoindolyl group, an indolizinyl group, a cyanoindolizinyl group, a purine group, a cyanopurine group, an imidazolyl group, a cyanoimidazolyl group, a dicyanoimidazolyl group, a carbazolyl group, a cyanocarbazolyl group, a dicyanocarbazolyl group, a thiazolyl group, a thiadiazolyl group, and a triazolyl group. Among these, a cyano group, a fluorine atom, a trifluoromethyl group, a pyridyl group, a cyanopyridyl group, a dicyanopyridyl group, a phenyl group, a cyanophenyl group, a dicyanophenyl group, a pyrazyl group, a cyanopyrazyl group, a dicyanopyrazyl group, a pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a quinolyl group, a cyanoquinolyl group, a dicyanoquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a quinazolinyl group, a cyanoquinazolinyl group, a quinoxalyl group, or a cyanoquinoxalyl group is preferred in terms of excellent device performance. １ More preferably, has at least one cyano group.

[0026] In this specification, ring A in formula (1) represents an optionally substituted aromatic hydrocarbon ring having 6 to 20 carbon atoms (which may be a single ring, a fused ring, or a linked ring containing multiple rings). Examples of the aromatic hydrocarbon ring having 6 to 20 carbon atoms (which may be a single ring, a fused ring, or a linked ring containing multiple rings) include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a perylene ring, a triphenylene ring, a tetracene ring, a chrysene ring, a fluorene ring, a 9,9-dimethylfluorene ring, a 9,9-diphenylfluorene ring, a spirobifluorene ring, a biphenyl ring, and a terphenyl ring. Ring A is preferably a benzene ring, a naphthalene ring, or a perylene ring in terms of ease of synthesis, and is preferably a benzene ring or a naphthalene ring in terms of excellent device performance.

[0027] Ring B in formula (1) represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms. Specific examples of ring B include the following (B-1) to (B-15) as preferred examples. Ring B is preferably an imidazole ring (B-1), a benzimidazole ring (B-2), or an imidazopyrazine ring (B-9) in terms of ease of synthesis, and more preferably (B-1) in terms of excellent device performance.

[0028]

[0029] Aromatic hydrocarbon ring in ring A, Ar １ and the aromatic hydrocarbon group in Ar １ The heteroaromatic group in the formula (I) may have a substituent. The substituent here is a hydroxy group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group consisting of a combination of two or more of the above groups or atoms.

[0030] Specific examples of these substituents include, but are not limited to, a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a phenyl group, a cyanophenyl group, a dicyanophenyl group, a tricyanophenyl group, a fluorophenyl group, a difluorophenyl group, a trifluorophenyl group, a perfluorophenyl group, a biphenyl group, a pyridylphenyl group, a bispyridylphenyl group, a naphthyl group, a cyanonaphthyl group, a dicyanonaphthyl group, a phenylnaphthyl group, a pyridylnaphthyl group, an anthryl group, Phenanthrenyl group, pyrenyl group, perylenyl group, triphenylenyl group, tetracenyl group, chrysenyl group, fluorenyl group, 9,9-diphenylfluorenyl group, spirobifluorenyl group, biphenylyl group, terphenyl group, naphthylphenyl group, phenylnaphthyl group, binaphthyl group, anthrylphenyl group, phenylanthryl group, naphthylanthryl group, pyridyl group, cyanopyridyl group, dicyanopyridyl group, tricyanopyridyl group, fluoropyridyl group, difluoropyridyl group, trifluoropyridyl group, tetrafluoropyridyl group, phenylpyridyl group, a pyridyl group, a diphenylpyridyl group, a bipyridyl group, a terpyridyl group, a pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a tricyanopyrimidyl group, a fluoropyrimidyl group, a difluoropyrimidyl group, a trifluoropyrimidyl group, a tetrafluoropyrimidyl group, a phenylpyrimidyl group, a diphenylpyrimidyl group, a pyridylpyrimidyl group, a bispyridylpyrimidyl group, a pyrazyl group, a cyanopyradyl group, a dicyanopyrazyl group, a tricyanopyradyl group, a fluoropyradyl group, a difluoropyradyl group, a trifluoropyradyl group, a tetrafluoropyradyl group, a phenylpyrazyl group, a pyridylpyrazyl group, a triazyl group, a cyanotriazyl group, a dicyanotriazyl group, a fluorotriazyl group, a difluorotriazyl group, a phenyltriazyl group, a diphenyltriazyl group, a pyridyltriazyl group, a bispyridyltriazyl group, a quinolyl group, a cyanoquinolyl group, a dicyanoquinolyl group, a phenylquinolyl group, a pyridylquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a dicyanoisoquinolyl group, a phenylisoquinolyl group, a pyridylisoquinolyl group, a quinoxalyl group, a cyanoquinoxalyl group, a dicyanoquinoxalyl group,Phenylquinoxalyl group, pyridylquinoxalyl group, quinazolinyl group, cyanoquinazolinyl group, dicyanoquinazolinyl group, phenylquinazolinyl group, pyridylquinazolinyl group, pyridopyrimidinyl group, cyanopyridopyrimidinyl group, dicyanopyridopyrimidinyl group, benzoquinolyl group, cyanobenzoquinolyl group, dicyanobenzoquinolyl group, benzoisoquinolyl group, cyanobenzoisoquinolyl group, dicyanobenzoisoquinolyl group, phenanthrolyl group, cyanophenanthrolyl group, dicyanophenanthrolyl group, phenanthridyl group, cyanophenanthridyl group a dicyanophenanthridyl group, an acridyl group, a cyanoacridyl group, a dicyanoacridyl group, a phenazinyl group, a cyanophenazinyl group, a dicyanophenazinyl group, a phenoxazinyl group, a cyanophenoxazinyl group, a phenothiazinyl group, a cyanophenothiazinyl group, a benzoquinoxalyl group, a cyanobenzoquinoxalyl group, a hexaazatriphenylenyl group, a pentacyanohexaazatriphenyl group, a thienyl group, a cyanothienyl group, a dicyanothienyl group, a furyl group, a cyanofuryl group, a dicyanofuryl group, a benzothienyl group, a cyanobenzothienyl group, a diphenyl group, a ... Cyanobenzothienyl group, benzofuryl group, cyanobenzofuryl group, dicyanobenzofuryl group, isobenzofuryl group, cyanoisobenzofuryl group, dicyanoisobenzofuryl group, dibenzothiophenyl group, cyanodibenzothiophenyl group, dicyanodibenzothiophenyl group, dibenzofuranyl group, cyanodibenzofuranyl group, dicyanodibenzofuranyl group, benzoxazole group, cyanobenzoxazole group, dicyanobenzoxazole group, pyrrolyl group, cyanopyrrolyl group, indolyl group, dicyanoindolyl group, isoi an indolyl group, a cyanoisoindolyl group, a dicyanoisoindolyl group, an indolizinyl group, a cyanoindolizinyl group, a purine group, a cyanopurine group, an imidazolyl group, a cyanoimidazolyl group, a dicyanoimidazolyl group, a carbazolyl group, a cyanocarbazolyl group, a dicyanocarbazolyl group, a thiazolyl group, a thiadiazolyl group, a triazolyl group, a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a perfluoroheptyl group,Examples of such alkyl groups include a perfluorooctyl group, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a tert-butyl group, an isopropyl group, a 9,9-dimethylfluorenyl group, a methylphenyl group, a dimethylphenyl group, a trimethylphenyl group, a trifluoromethylphenyl group, a bistrifluoromethylphenyl group, a methylpyridyl group, a dimethylpyridyl group, a trimethylpyridyl group, a trifluoromethylpyridyl group, a bistrifluoromethylpyridyl group, a methylpyrimidyl group, a dimethylpyrimidyl group, a trimethylpyrimidyl group, a trifluoromethylpyrimidyl group, a bistrifluoromethylpyrimidyl group, a methylpyrazyl group, a dimethylpyrazyl group, a trimethylpyrazyl group, a trifluoromethylpyrazyl group, a bistrifluoromethylpyrazyl group, a methyltriazyl group, a dimethyltriazyl group, a trifluoromethyltriazyl group, and a bistrifluoromethyltriazyl group. Among these, a phenyl group, a naphthyl group, a pyridyl group, a pyrazyl group, a pyrimidyl group, a cyano group, a cyanophenyl group, a dicyanophenyl group, a cyanopyridyl group, or a dicyanopyridyl group is preferred in terms of excellent device performance, and a cyano group is more preferred in terms of ease of synthesis.

[0031] n represents 0, 1, 2, 3, or 4. However, when ring B is an imidazole ring, n represents 0, 1, or 2. In terms of excellent device performance, n is preferably 1, 2, 3, or 4, and in terms of ease of synthesis, n is more preferably 1 or 2.

[0032] Specific preferred examples of the imide compound (1) are shown below, but the compound of the present invention is not limited to these. Examples of the imide compound (1) include compounds represented by the following formulas (C-1) to (C-416). Among them, the compounds represented by formulas (C-1) to (C-140) are more preferred, and the compounds represented by formulas (C-2), (C-6), (C-10), (C-52), (C-72) and (C-82) are even more preferred.

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] A more preferred embodiment of the imide compound represented by the above formula (1) includes a compound represented by the following formula (X-1). In formula (X-1), ring G represents a benzene ring or a naphthalene ring. Ring H is selected from the group consisting of the following (H-1), (H-2), and (H-3). f is 1 or 2. ３ represents an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a fused ring, or a linked ring containing multiple rings) which may be substituted with a cyano group, or a heteroaromatic hydrocarbon group having 2 to 20 carbon atoms (which may be a single ring, a fused ring, or a linked ring containing multiple rings) which may be substituted with a cyano group.

[0074] The imide compound represented by formula (X-1) has an extended conjugated structure in which the conjugated system is expanded, and is expected to have a strong interaction with the HOMO orbital of a hole transport material. Furthermore, it has excellent thermal stability as a deposition material. Therefore, when combined with a hole transport material in a photoelectric conversion element, it is particularly likely to promote hole transport ability.

[0075] In the above formula (X-1), Ar ３ is preferably a phenyl group, a pyridyl group, a pyrazyl group or a quinolyl group, and these groups may be substituted with a cyano group. ３ When the group is one of these, the LUMO level can be appropriately adjusted, and the interaction with the adjacent layer can be optimized. Furthermore, the compound is easy to synthesize and has excellent thermal stability as a deposition material.

[0076] (Hole Transport Promoting Material) The present invention also relates to a hole transport promoting material represented by the following formula (1a) (hereinafter, sometimes simply referred to as "hole transport promoting material (1a)").

[0077] Ar in formula (1a) ２ represents an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an optionally substituted heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings). ２ Specific and preferred examples of the ring Ar in formula (1) １ Similar examples include:

[0078] R ２R each independently represents a hydroxy group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), an aromatic heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group consisting of a combination of two or more of the above groups or atoms. ２ Specific and preferred examples of the ring R １ Similar examples include:

[0079] Ring C represents an optionally substituted aromatic hydrocarbon ring having 6 to 20 carbon atoms (which may be a single ring, a fused ring, or a linked ring containing multiple rings). Specific and preferred examples of Ring C include the same examples as those of Ring A in Formula (1).

[0080] Ring D represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms. Specific and preferred examples of Ring D include the same examples as those of Ring B in Formula (1).

[0081] m represents 0, 1, 2, 3, or 4; provided that when ring C is an imidazole ring, m represents 0, 1, or 2; m is preferably 1, 2, 3, or 4 in terms of excellent device performance, and more preferably 2 in terms of ease of synthesis.

[0082] Aromatic hydrocarbon ring in ring C, Ar ２ aromatic hydrocarbon group in Ar ２ The heteroaromatic group in formula (1) may have a substituent. Examples of the substituent include the same substituents as those in formula (1).

[0083] Preferred specific examples of compound (1a) include the compounds represented by the formulae (C-1) to (C-392). Among these, the compounds represented by formulae (C-1) to (C-140) are more preferred, and the compounds represented by formulae (C-2), (C-52), (C-72) and (C-82) are even more preferred.

[0084] (Imide Compound) Next, the imide compound of the present invention represented by the following formula (1b) (hereinafter, sometimes simply referred to as "imide compound (1b)") will be described.

[0085] <Imide compound represented by formula (1b)>

[0086] In formula (1b), R ３ represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may also be a group consisting of a combination of two or more of the above groups or atoms. ３Specific examples of the aryl group include, but are not limited to, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a phenyl group, a cyanophenyl group, a dicyanophenyl group, a tricyanophenyl group, a fluorophenyl group, a difluorophenyl group, a trifluorophenyl group, a perfluorophenyl group, a biphenyl group, a pyridylphenyl group, a bispyridylphenyl group, a naphthyl group, a cyanonaphthyl group, a dicyanonaphthyl group, a phenylnaphthyl group, a pyridylnaphthyl group, an anthryl group, a phenanthrenyl group, a pyrenyl group, a perylenyl group, a triphenyl group, a phenyl ... phenylenyl group, tetracenyl group, chrysenyl group, fluorenyl group, 9,9-diphenylfluorenyl group, spirobifluorenyl group, biphenylyl group, terphenyl group, naphthylphenyl group, phenylnaphthyl group, binaphthyl group, anthrylphenyl group, phenylanthryl group, naphthylanthryl group, pyridyl group, cyanopyridyl group, dicyanopyridyl group, tricyanopyridyl group, fluoropyridyl group, difluoropyridyl group, trifluoropyridyl group, tetrafluoropyridyl group, phenylpyridyl group, diphenylpyridyl group, bipyrid ... Pyridyl group, pyrimidyl group, cyanopyrimidyl group, dicyanopyrimidyl group, tricyanopyrimidyl group, fluoropyrimidyl group, difluoropyrimidyl group, trifluoropyrimidyl group, tetrafluoropyrimidyl group, phenylpyrimidyl group, diphenylpyrimidyl group, pyridylpyrimidyl group, bispyridylpyrimidyl group, pyrazyl group, cyanopyradyl group, dicyanopyrazyl group, tricyanopyradyl group, fluoropyradyl group, difluoropyradyl group, trifluoropyradyl group, tetrafluoropyradyl group, phenylpyradyl group, pyridylpyradyl group, triazinyl group, a quinolyl group, a cyanotriazyl group, a dicyanotriazyl group, a fluorotriazyl group, a difluorotriazyl group, a phenyltriazyl group, a diphenyltriazyl group, a pyridyltriazyl group, a bispyridyltriazyl group, a quinolyl group, a cyanoquinolyl group, a dicyanoquinolyl group, a phenylquinolyl group, a pyridylquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a dicyanoisoquinolyl group, a phenylisoquinolyl group, a pyridylisoquinolyl group, a quinoxalyl group, a cyanoquinoxalyl group, a dicyanoquinoxalyl group, a phenylquinoxalyl group, a pyridylquinoxalyl group,Quinazolinyl group, cyanoquinazolinyl group, dicyanoquinazolinyl group, phenylquinazolinyl group, pyridylquinazolinyl group, pyridopyrimidinyl group, cyanopyridopyrimidinyl group, dicyanopyridopyrimidinyl group, benzoquinolyl group, cyanobenzoquinolyl group, dicyanobenzoquinolyl group, benzoisoquinolyl group, cyanobenzoisoquinolyl group, dicyanobenzoisoquinolyl group, phenanthrolyl group, cyanophenanthrolyl group, dicyanophenanthrolyl group, phenanthridyl group, cyanophenanthridyl group a dicyanophenanthridyl group, an acridyl group, a cyanoacridyl group, a dicyanoacridyl group, a phenazinyl group, a cyanophenazinyl group, a dicyanophenazinyl group, a phenoxazinyl group, a cyanophenoxazinyl group, a phenothiazinyl group, a cyanophenothiazinyl group, a benzoquinoxalyl group, a cyanobenzoquinoxalyl group, a hexaazatriphenylenyl group, a pentacyanohexaazatriphenyl group, a thienyl group, a cyanothienyl group, a dicyanothienyl group, a furyl group, a cyanofuryl group, a dicyanofuryl group group, benzothienyl group, cyanobenzothienyl group, dicyanobenzothienyl group, benzofuryl group, cyanobenzofuryl group, dicyanobenzofuryl group, isobenzofuryl group, cyanoisobenzofuryl group, dicyanoisobenzofuryl group, dibenzothiophenyl group, cyanodibenzothiophenyl group, dicyanodibenzothiophenyl group, dibenzofuranyl group, cyanodibenzofuranyl group, dicyanodibenzofuranyl group, benzoxazole group, cyanobenzoxazole group, dicyanobenzoxazole a cyano group, a fluorine atom, a pyridyl group, a cyanopyrrolyl group, a phenyl group, a cyanophenyl group, a pyrazolyl group, a cyanopyrrolyl group, a dicyanophenyl group, a pyrazolyl group, a cyanopyrrolyl group, a dicyanoisoindolyl group, a dicyanoisoindolyl group, a indolizinyl group, a cyanoindolizinyl group, a purine group, a cyanopurine group, an imidazolyl group, a cyanoimidazolyl group, a dicyanoimidazolyl group, a carbazolyl group, a cyanocarbazolyl group, a dicyanocarbazolyl group, a thiazolyl group, a thiadiazolyl group, a triazolyl group, and the like. Among these, a cyano group, a fluorine atom, a pyridyl group, a cyanopyridyl group, a dicyanopyridyl group, a phenyl group, a cyanophenyl group, a dicyanophenyl group, a pyrazyl group, a cyanopyrazyl group, a dicyanopyrazyl group,A pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a quinolyl group, a cyanoquinolyl group, a dicyanoquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a quinazolinyl group, a cyanoquinazolinyl group, a quinoxalyl group, or a cyanoquinoxalyl group is preferred, and a cyano group is more preferred in terms of excellent device performance.

[0087] In formula (1b), R ４ , R ５ , R ６ , and R ７ each independently represents a hydrogen atom or a cyano group. ４ , R ５ , R ６ , and R ７ At least two of these are cyano groups.

[0088] p represents 0, 1, or 2. In terms of ease of synthesis, p is preferably 0 or 1, and in terms of excellent device performance, p is more preferably 1.

[0089] q represents 1, 2, 3, 4 or 5; q is preferably 0, 1 or 2 in terms of ease of synthesis, and more preferably 1 in terms of excellent device performance.

[0090] Ar ３ represents a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings). ３Examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings) in the formula (1) include a phenyl group, a naphthyl group, an anthryl group, a phenanthrenyl group, a pyrenyl group, a perylenyl group, a triphenylenyl group, a tetracenyl group, a chrysenyl group, a fluorenyl group, a 9,9-dimethylfluorenyl group, a 9,9-diphenylfluorenyl group, a spirobifluorenyl group, a biphenylyl group, a terphenyl group, a naphthylphenyl group, a phenylnaphthyl group, a binaphthyl group, an anthrylphenyl group, a phenylanthryl group, a naphthylanthryl group, a pyridyl group, a pyrazyl group, and a pyrimidyl group. In view of excellent device performance, a phenyl group or a naphthyl group is preferred.

[0091] X １ is a nitrogen atom or C—R ６ represents X ２ is a nitrogen atom or C—R ７ Among these, R ６ and R ７ represents the above-mentioned group.

[0092] Preferred specific examples of compound (1b) include compounds represented by the formulae (C-1) to (C-140) in which n is an even number in C-n (n is 1 to 140), and compounds represented by the formulae (C-323) to (C-392). Among these, compounds represented by the formulae (C-1) to (C-140) in which n is an even number in C-n (n is 1 to 140) are more preferred, and compounds represented by (C-52) and (C-82) are even more preferred.

[0093] <Imide Compound Represented by Formula (1c)> Next, the imide compound used in the present invention, represented by the following formula (1c) (hereinafter, sometimes simply referred to as "imide compound (1c)"), will be described.

[0094] In formula (1c), R ８R each independently represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may also be a group consisting of a combination of two or more of the above groups or atoms. ８ Specific and preferred examples of R in formula (1b) are ３ Similar examples include:

[0095] R ９ R each independently represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxy group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may also be a group consisting of a combination of two or more of the above groups or atoms. ９ Specific and preferred examples of R in formula (1b) are ４ Similar examples include:

[0096] Ar ４ represents a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 18 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings). ４ Specific and preferred examples of Ar in formula (1b) are ３ Similar examples include:

[0097] Ring E represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms. Specific and preferred examples of Ring E include the same examples as those of Ring B in Formula (1).

[0098] r represents 1, 2, 3, or 4. However, when ring E is an imidazole ring, r represents 1 or 2. In terms of excellent device performance, r is preferably 1 or 2, and in terms of ease of synthesis, r is more preferably 2.

[0099] k represents 0, 1, 2, 3, 4, or 5. In terms of ease of synthesis, k is preferably 0, 1, or 2, and in terms of excellent device performance, k is more preferably 1.

[0100] Preferred specific examples of compound (1c) include compounds represented by the formulas (C-1) to (C-140) in which n is an odd number in C-n (n represents 1 to 140), and compounds represented by the formulas (C-141) to (C-322). Among these, (C-1), (C-5), (C-9), (C-51), (C-55), (C-59), (C-81), (C-85) and (C-89) are preferred, and compounds represented by (C-1), (C-51) and (C-81) are more preferred.

[0101] [Production Method] The imide compound represented by formula (1) can be synthesized by known methods or a combination thereof. For example, the imide compound (1) can be synthesized by the method shown in steps 1 to 4 below.

[0102]

[0103] In the formula, n, ring A, ring B, R １ and Ar １ has the same meaning as defined above. Ring F represents a vinylene group or a divalent aromatic group having 4 to 19 carbon atoms.

[0104] Step 1 is a method of reacting tetracarboxylic anhydride (2) with an amine compound (F-1) to obtain a monoimide compound (3). For example, the target product can be obtained according to the reaction conditions disclosed in the literature (WO2021 / 168358A1, Chem. Eur. J. 2006, 12, 6592, J. Phys. Chem. C, 2008, 112, 1721.) or the methods disclosed in Synthesis Reference Examples 1 to 4.

[0105] The tetracarboxylic acid anhydride (2) used in step 1 can be synthesized, for example, according to the method disclosed in Angew. Chem. Int. Ed. 2017, 56, 13031. Alternatively, a commercially available product may be used.

[0106] The amine compound (F-1) used in step 1 can be synthesized, for example, according to the method disclosed in Synlett 2008, 15, 2287. Alternatively, a commercially available product may be used.

[0107] The equivalent amount of the amine compound (F-1) used in step 1 is preferably in the range of 0.3 to 1.5 equivalents, more preferably in the range of 0.5 to 1.1 equivalents, relative to the tetracarboxylic acid anhydride (2), in terms of a good yield of the monoimide compound (3).

[0108] Step 1 may be carried out in a solvent. The solvent is not particularly limited as long as it does not inhibit the reaction, and examples thereof include haloalkanes such as dichloromethane, chloroform, tetrachloromethane, dichloroethane, and tetrachloroethane; ethers such as diisopropyl ether, dibutyl ether, cyclopentyl methyl ether (CPME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4-dioxane, and dimethoxyethane; aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, and tetralin; heteroaromatic compounds such as imidazole, pyridine, pyrazine, and quinoline; and solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and 4-fluoroethylene carbonate. Examples of suitable solvents include carbonates; esters such as ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, and γ-lactone; amides such as N,N-dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); ureas such as N,N,N',N'-tetramethylurea (TMU) and N,N'-dimethylpropyleneurea (DMPU); sulfoxides such as dimethyl sulfoxide (DMSO); and alcohols such as methanol, ethanol, isopropyl alcohol, butanol, octanol, benzyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, and 2,2,2-trifluoroethanol. These may be used alone or in combination in any ratio. There are no particular limitations on the amount of solvent used. Among these, DMF, DMAc, pyridine, and mixed solvents thereof are preferred in terms of good reaction yield.

[0109] The reaction in step 1 can be promoted by carrying out the reaction in the presence of a condensing agent. Examples of the condensing agent include solid acids such as alumina and silica gel; metal chlorides such as titanium tetrachloride, tin tetrachloride, and antimony pentachloride; organic bases such as triethylamine, pyridine, 4-dimethylaminopyridine, diazabicycloundecene, tetramethylethylenediamine, and 1,4-diazabicyclo[2.2.2]octane; and carbodiimides such as 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, N,N'-carbonyldiimidazole, and 1,1'-carbonyldi(1,2,4-triazole). An organic base or a condensing agent is preferred in terms of a good reaction yield, and triethylamine, pyridine or EDC is more preferred in terms of a good purity of the monoimide compound (3) obtained.

[0110] Step 1 can be carried out at a temperature appropriately selected from −80° C. to 300° C., and is preferably carried out at a temperature appropriately selected from 20° C. to 250° C. in terms of a good reaction yield, and more preferably at a temperature appropriately selected from 50° C. to 200° C.

[0111] The monoimide compound (3) can be obtained by carrying out a conventional treatment after the completion of step 1. If necessary, it may be purified using a general means used by those skilled in the art for purifying organic compounds, such as washing, precipitation, filtration, dialysis, recrystallization, column chromatography, preparative HPLC, or Soxhlet extraction. Alternatively, the monoimide compound (3) may be subjected to step 2 without purification.

[0112] Step 2 is a method of reacting a monoimide compound (3) with a diamine compound (F-2) to obtain an imide compound (1) (hereinafter, sometimes simply referred to as "imide compound (1)") contained in the photoelectric conversion element of the present invention. For example, the target product can be obtained by following the reaction conditions disclosed in the literature (WO2021 / 168358A1, J. Org. Chem. 2009, 74, 8914.) or the methods disclosed in Synthesis Examples C-2, 52, 72 and 82.

[0113] The diamine compound (F-2) used in step 2 can be synthesized, for example, according to the method disclosed in Chem. Eur. J. 2015, 21, 17314. Alternatively, a commercially available product may be used.

[0114] The equivalent amount of the amine compound (F-2) used in step 2 is preferably in the range of 0.5 to 1.5 equivalents, more preferably in the range of 0.8 to 1.2 equivalents, relative to the monoimide compound (3) in terms of a good yield of the imide compound (1).

[0115] Step 2 may be carried out in a solvent. The solvent is not particularly limited as long as it does not inhibit the reaction, and examples thereof include haloalkanes such as dichloromethane, chloroform, tetrachloromethane, dichloroethane, and tetrachloroethane; ethers such as diisopropyl ether, dibutyl ether, cyclopentyl methyl ether (CPME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4-dioxane, and dimethoxyethane; aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, and tetralin; heteroaromatic compounds such as imidazole, pyridine, pyrazine, and quinoline; and solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and 4-fluoroethylene carbonate. Examples of suitable solvents include carbonates; esters such as ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, and γ-lactone; amides such as N,N-dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); ureas such as N,N,N',N'-tetramethylurea (TMU) and N,N'-dimethylpropyleneurea (DMPU); sulfoxides such as dimethyl sulfoxide (DMSO); and alcohols such as methanol, ethanol, isopropyl alcohol, butanol, octanol, benzyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, and 2,2,2-trifluoroethanol. These may be used alone or in combination in any ratio. There are no particular limitations on the amount of solvent used. Among these, DMF, DMAc, pyridine, xylene, and mixed solvents thereof are preferred in terms of good reaction yield.

[0116] The reaction in step 2 can be promoted by carrying out the reaction in the presence of a condensing agent. Examples of the condensing agent include solid acids such as alumina and silica gel; metal chlorides such as titanium tetrachloride, tin tetrachloride, and antimony pentachloride; organic bases such as triethylamine, pyridine, 4-dimethylaminopyridine, diazabicycloundecene, tetramethylethylenediamine, and 1,4-diazabicyclo[2.2.2]octane; and carbodiimides such as 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, N,N'-carbonyldiimidazole, and 1,1'-carbonyldi(1,2,4-triazole). Organic bases are preferred in terms of high reaction yield, and triethylamine or pyridine are more preferred in terms of high purity of the resulting imide compound (1).

[0117] Step 2 can be carried out at a temperature appropriately selected from −80° C. to 300° C., and is preferably carried out at a temperature appropriately selected from 20° C. to 250° C. in terms of a good reaction yield, and more preferably at a temperature appropriately selected from 50° C. to 200° C.

[0118] The imide compound (1) can be obtained by carrying out a conventional treatment after completion of step 2. If necessary, it may be purified appropriately using a general means used by those skilled in the art for purifying organic compounds, such as washing, precipitation, filtration, dialysis, recrystallization, column chromatography, preparative HPLC, or Soxhlet extraction.

[0119] Step 3 is a method of reacting tetracarboxylic acid anhydride (2) with diamine compound (F-2) to obtain fused-ring imidazole compound (4). For example, the target compound can be obtained according to the reaction conditions disclosed in the literature (WO2021 / 168358A1, J. Org. Chem. 2009, 74, 8914.) or the methods disclosed in Synthesis Reference Examples 1 to 4.

[0120] The equivalent amount of the diamine compound (F-2) used in step 3 is preferably in the range of 0.5 to 1.5 equivalents, more preferably in the range of 0.8 to 1.2 equivalents, relative to the tetracarboxylic acid anhydride (2), in terms of a good yield of the fused-ring imidazole compound (4).

[0121] Step 3 may be carried out in a solvent. The solvent is not particularly limited as long as it does not inhibit the reaction, and examples thereof include the same solvents as those exemplified in Step 2. These may be used alone or in a mixture at any ratio. There is no particular limit to the amount of solvent used. Among these, DMF, DMAc, pyridine, xylene, and mixed solvents thereof are preferably used in terms of good reaction yield.

[0122] The reaction can be promoted by carrying out Step 3 in the presence of a condensing agent. Examples of the condensing agent include the same condensing agents as those exemplified in Step 2. An organic base is preferred in terms of high reaction yield, and triethylamine or pyridine is more preferred in terms of high purity of the resulting fused-ring imidazole compound (4).

[0123] Step 3 can be carried out at a temperature appropriately selected from −80° C. to 300° C., and is preferably carried out at a temperature appropriately selected from 20° C. to 250° C. in terms of a good reaction yield, and more preferably at a temperature appropriately selected from 50° C. to 200° C.

[0124] Fused ring imidazole compound (4) can be obtained by carrying out a conventional treatment after completion of step 3. If necessary, it may be purified using a general means used by those skilled in the art for purifying organic compounds, such as washing, precipitation, filtration, dialysis, recrystallization, column chromatography, preparative HPLC, or Soxhlet extraction. Fused ring imidazole compound (4) may also be subjected to step 4 without purification.

[0125] Step 4 is a method of reacting a fused ring imidazole compound (4) with an amine compound (F-1) to obtain an imide compound (1). For example, the target compound can be obtained by following the reaction conditions disclosed in the literature (WO2021 / 168358A1, Chem. Eur. J. 2006, 12, 6592, J. Phys. Chem. C, 2008, 112, 1721.) or the methods disclosed in Synthesis Examples C-2, 52, 72 and 82.

[0126] The equivalent amount of the amine compound (F-1) used in step 4 is preferably in the range of 0.3 to 1.5 equivalents, more preferably in the range of 0.5 to 1.0 equivalents, relative to the fused-ring imidazole compound (4), in terms of a good yield of the imide compound (1).

[0127] Step 4 may be carried out in a solvent. The solvent is not particularly limited as long as it does not inhibit the reaction, and examples thereof include the same solvents as those exemplified in Step 1. These may be used alone or in a mixture at any ratio. There is no particular limit to the amount of solvent used. Among these, DMF, DMAc, pyridine, xylene, and mixed solvents thereof are preferably used in terms of good reaction yield.

[0128] The reaction can be accelerated by carrying out Step 4 in the presence of a condensing agent. Examples of the condensing agent include the same condensing agents as those exemplified in Step 1. An organic base or a condensing agent is preferred in terms of high reaction yield, and triethylamine, pyridine, or EDC is more preferred in terms of high purity of the resulting imide compound (1).

[0129] Step 4 can be carried out at a temperature appropriately selected from −80° C. to 300° C., and is preferably carried out at a temperature appropriately selected from 20° C. to 250° C. in terms of a good reaction yield, and more preferably at a temperature appropriately selected from 50° C. to 200° C.

[0130] The imide compound (1) can be obtained by carrying out a conventional treatment after the completion of step 4. If necessary, the compound may be purified by a general means used by those skilled in the art for purifying organic compounds, such as washing, precipitation, filtration, dialysis, recrystallization, column chromatography, preparative HPLC, or Soxhlet extraction.

[0131] The hole transport promoting material of the present invention represented by formula (1a) (hereinafter, sometimes simply referred to as "hole transport promoting material (1a)") can be produced using tetracarboxylic acid anhydride (2a), amine compound (F-1a), and diamine compound (F-2a) represented by the following formulas, according to the reaction conditions disclosed in the literature (WO2021 / 168358A1, Chem. Eur. J. 2006, 12, 6592, J. Phys. Chem. C, 2008, 112, 1721, J. Org. Chem. 2009, 74, 8914.), the methods disclosed in Synthesis Examples and Reference Examples C-2, 52, 72, and 82, and the methods described in Steps 1 to 4 above. (In the formula, (1a), (2a), (F-1a) and (F-2a) have the same meanings as above.)

[0132] The imide compound of the present invention represented by formula (1b) (hereinafter, sometimes simply referred to as "imide compound (1b)") can be produced using tetracarboxylic acid anhydride (2b), amine compound (F-1b), and diamine compound (F-2b) represented by the following formulas according to the reaction conditions disclosed in the literature (WO2021 / 168358A1, Chem. Eur. J. 2006, 12, 6592, J. Phys. Chem. C, 2008, 112, 1721, J. Org. Chem. 2009, 74, 8914.), the methods disclosed in Synthesis Examples and Reference Examples C-2, 52, 72, and 82, and the methods described in Steps 1 to 4 above. (In the formula, (1b), (2b), (F-1b) and (F-2b) have the same meanings as above.)

[0133] The imide compound of the present invention represented by formula (1c) (hereinafter, sometimes simply referred to as "imide compound (1c)") can be produced using tetracarboxylic acid anhydride (2c), amine compound (F-1c), and diamine compound (F-2c) represented by the following formulas according to the reaction conditions disclosed in the literature (WO2021 / 168358A1, Chem. Eur. J. 2006, 12, 6592, J. Phys. Chem. C, 2008, 112, 1721, J. Org. Chem. 2009, 74, 8914.), the methods disclosed in Synthesis Examples and Reference Examples C-2, 52, 72, and 82, and the methods described in Steps 1 to 4 above. (In the formula, (1c), (2c), (F-1c) and (F-2c) have the same meanings as above.)

[0134] <<Action and Effect of Imide Compound (1)>> The imide compound (1) has a so-called "conjugated extended imide structure," which includes imide rings on either side of an aromatic hydrocarbon ring represented by ring A and an imidazole ring (or a fused imidazole ring) represented by ring B. This structure is expected to provide a strong interaction with the HOMO orbital of a hole transport material. When the hole transport promotion layer contains a compound represented by formula (1) or includes a layer comprising a mixture of a hole transport material and imide compound (1), it is expected that the interaction with the HOMO orbital of an adjacent hole transport layer will be enhanced, thereby facilitating carrier exchange between the hole transport layer and the hole transport promotion layer. Thus, the compound represented by formula (1) has an extremely deep LUMO level, and is therefore expected to facilitate smooth hole exchange between the hole transport layer and the electrode.

[0135] As described above, the present inventors have found that imide compound (1) can be effectively used as a hole transport promoting material that facilitates the exchange of holes between a hole transport layer and an electrode. They have confirmed that the hole transport ability of a photoelectric conversion element is enhanced when imide compound (1) (hole transport promoting material) is combined with a hole transport material. That is, they have discovered that the energy barrier required to extract carriers generated in a light-receiving layer to the electrode side in a photoelectric conversion element can be reduced by imide compound (1), which is a hole transport promoting material of the present invention.

[0136] <Embodiments> Examples of the laminate structure of the photoelectric conversion element of the present invention include the following structures (i) and (ii): (i): first electrode / hole transport promoting layer / hole transport layer / light receiving layer / second electrode (ii): first electrode / hole transport promoting layer / hole transport layer / light receiving layer / electron transport layer / second electrode

[0137] Hereinafter, the photoelectric conversion element according to the present invention will be described in more detail by taking the above configuration (ii) as an example and referring to Fig. 1. Fig. 1 is a schematic cross-sectional view showing an example of the layered configuration of the photoelectric conversion element according to the present invention.

[0138] <<First Embodiment>> A photoelectric conversion element according to a first embodiment is an organic imaging element or photosensor having the layered structure shown in Fig. 1. The photoelectric conversion element 1 includes a first electrode 11 (first electrode), a hole transport promotion layer 12, a hole transport layer 13, a light-receiving layer 14, an electron transport layer 15, and a second electrode 16 (second electrode), in this order. However, some of these layers may be omitted, or other layers may be added.

[0139] In the photoelectric conversion element 1 shown in FIG. 1 , light is incident from above the transparent first electrode 11 and is received by the light-receiving layer 14. For convenience, FIG. 1 illustrates light as being incident from the side of the light-receiving layer 14. Furthermore, a voltage is applied to the photoelectric conversion element 1 so that, of the charges (holes and electrons) generated by photoelectric conversion in the light-receiving layer 14, the holes are moved to the first electrode 11 and the electrons are moved to the second electrode 16. That is, the first electrode 11 serves as a hole-collecting electrode, and the second electrode 16 serves as an electron-collecting electrode. Note that the substrate provided on the top surface of the first electrode 11 is omitted in FIG. 1 . The substrate here is not particularly limited, and examples include a glass plate, a quartz plate, and a plastic plate. Furthermore, in a configuration in which light is incident from the substrate side, the substrate is transparent to the wavelength of light. Each of the above layers will be described below.

[0140] [First Electrode 11] A first electrode 11 or a second electrode 16 is provided on a substrate. In the case of a photoelectric conversion element configured so that light passes through the first electrode 11 and enters the light-receiving layer 14, the first electrode is formed of a transparent material that transmits or substantially transmits the light. Here, "transmits light" means that the average transmittance (of visible light) is 80% or more, and "substantially transmits light" means that the average transmittance is 50% or more. In other words, in this specification, "transparent" means that the average transmittance is 50% or more.

[0141] The transparent material used for the first electrode 11 or the second electrode 16 is not particularly limited, but examples thereof include indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, aluminum-doped tin oxide, magnesium-indium oxide, nickel-tungsten oxide, other metal oxides, metal nitrides such as gallium nitride, metal selenides such as zinc selenide, and metal sulfides such as zinc sulfide.

[0142] In the case of a photoelectric conversion element configured so that light enters the light-receiving layer 14 only from the second electrode 16 side, the transmittance characteristics of the first electrode 11 are not important. Therefore, examples of materials that can be used for the first electrode in this case include gold, iridium, molybdenum, palladium, and platinum.

[0143] [Hole Transport Promotion Layer 12] The hole transport promotion layer 12 is provided between the first electrode 11 and the hole transport layer 13 described below. The hole transport promotion layer 12 is provided to promote hole transport from the hole transport layer 13 to the first electrode 11. The hole transport promotion layer 12 contains the imide compound (1) described above. The hole transport promotion layer 12 may also contain a compound other than the imide compound (1). Examples of compounds that can be contained in the hole transport promotion layer 12 include conventionally known hole transport materials, such as the compounds used in the hole transport layer 13 described below.

[0144] [Hole Transport Layer 13] The hole transport layer 13 is provided between the hole transport promotion layer 12 and the light-receiving layer 14. The hole transport layer 13 has a role of transporting holes generated in the light-receiving layer 14 from the light-receiving layer 14 to the first electrode 11, and a role of blocking electrons generated in the light-receiving layer 14 from moving toward the first electrode 11. Depending on the application, the hole transport layer 13 may also have a role of blocking electron injection from the first electrode 11.

[0145] The hole transport layer 13 may have a single layer structure made of one or more materials, or may have a laminate structure made of multiple layers of the same or different compositions. The hole transport material that can be contained in the hole transport layer 13 may be a known hole transport material. Examples of known hole transport materials include aromatic tertiary amine compounds, naphthalene compounds, anthracene compounds, tetracene compounds, pentacene compounds, phenanthrene compounds, pyrene compounds, perylene compounds, fluorene compounds, carbazole compounds, indole compounds, pyrrole compounds, picene compounds, thiophene compounds, benzotrifuran compounds, benzotrithiophene compounds, naphthodithiophene compounds, naphthothienothiophene compounds, benzodifuran compounds, benzodithiophene compounds, benzothiophene compounds, naphthobisbenzothiophene compounds, chrysenodithiophene compounds, benzothienobenzothiophene compounds, and indolocarbazole compounds. Among these, fluorene compounds, naphthodithiophene compounds, naphthothienothiophene compounds, benzodifuran compounds, benzothiophene compounds, naphthobisbenzothiophene compounds, chrysenodithiophene compounds, benzothienobenzothiophene compounds, indolocarbazole compounds, and the like are preferred, and fluorene compounds, chrysenodithiophene compounds, benzothienobenzothiophene compounds, and indolocarbazole compounds are particularly preferred.

[0146] [Light-receiving layer 14] The light-receiving layer 14 is provided between the hole-transporting layer 13 and the electron-transporting layer 15 described below. Examples of materials for the light-receiving layer 14 include materials having a photoelectric conversion function.

[0147] The absorption layer 14 may have a single layer structure made of one or more materials, or a laminate structure made of multiple layers of the same or different compositions. In particular, in order to increase the photoelectric conversion efficiency, the absorption layer 14 is preferably made of a layer containing at least two materials (organic components).

[0148] Examples of materials (organic components) used in the light-receiving layer 14, which has a single-layer structure made of one material, include (i) coumarin and its derivatives, quinacridone and its derivatives, and phthalocyanine and its derivatives. Examples of materials (organic components) used in the light-receiving layer 14, which has a single-layer structure made of two materials, include the aforementioned combinations of (i) coumarin and its derivatives, quinacridone and its derivatives, and phthalocyanine and its derivatives with (ii) fullerene and its derivatives and other acceptor materials. The light-receiving layer 4 made of these materials may be formed by vapor deposition of a premixed powder, or by co-evaporation in any ratio. Examples of materials (organic components) used in the light-receiving layer 14, which has a single-layer structure made of three materials, include the aforementioned combinations of (i) coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives with (ii) fullerene and its derivatives and other acceptor materials, and (iii) hole-transport materials. The light-receiving layer 14 made of these materials may be formed by depositing a mixture of powders in advance, or by co-depositing the materials in any ratio.

[0149] (i) Specific examples of coumarin derivatives include coumarin 6 and coumarin 30. Specific examples of quinacridone derivatives include N,N-dimethylquinacridone. Specific examples of phthalocyanine derivatives include boron subphthalocyanine chloride and boron subnaphthalocyanine chloride (SubNC). (ii) Specific examples of fullerenes and their derivatives include

[60] fullerene,

[70] fullerene, and [6,6]-phenyl-C61-methyl butyrate (

[60] PCBM). (iii) Preferred compounds and specific examples of hole transport materials include the same compounds as those used in the hole transport layer 13 described above.

[0150] Furthermore, the material having a photoelectric conversion function is not limited to being contained only in the light-receiving layer 14. For example, the material having a photoelectric conversion function may be contained in a layer adjacent to the light-receiving layer 14 (hole transport layer 13 or electron transport layer 15).

[0151] [Electron Transport Layer 15] The electron transport layer 15 is provided between the light-receiving layer 14 and the second electrode 16 described below. The electron transport layer 15 has a role of transporting electrons generated in the light-receiving layer 14 to the second electrode 16 and a role of blocking the movement of holes from the second electrode 16, to which the electrons have been transported, to the light-receiving layer 14. Depending on the application, the electron transport layer 15 may also have a role of blocking hole injection from the second electrode 16.

[0152] The electron transport material that can be contained in the electron transport layer 15 may be a known electron transport material. Examples of the electron transport material include fullerene, fullerene derivatives, triazine derivatives, bis(8-hydroxyquinolinato)manganese, tris(8-hydroxyquinolinato)aluminum, tris(2-methyl-8-hydroxyquinolinato)aluminum, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), and Bp hen(4,7-diphenyl-1,10-phenanthroline), BAlq (bis(2-methyl-8-quinolinolato)-4-(phenylphenolato)aluminum), 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-methylpyrimidine, N,N'-diphenyl-1,4,5,8-naphthalenetetracarboxylic acid diimide, and N,N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide.

[0153] The electron transport layer 15 may have a single layer structure made of one or more materials, or may have a laminate structure made of multiple layers of the same or different compositions.

[0154] [Second Electrode 16] A second electrode 16 is provided on the electron transport layer 15. Examples of materials for the second electrode 16 include indium-tin oxide (ITO), indium-zinc oxide (IZO), sodium, a sodium-potassium alloy, magnesium, lithium, a magnesium / copper mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, and aluminum / aluminum oxide (Al ２ O ３ ) mixture, indium, lithium / aluminum mixture, gold, platinum, rare earth metals, molybdenum oxide, etc. The first electrode 11 and the second electrode 16 may be the same or different.

[0155] [Method of Forming Each Layer] Each layer except for the first electrode 11 and the second electrode 16 described above can be formed by thinning the material of each layer (together with a material such as a binder resin and a solvent, if necessary) by a known method such as vacuum deposition, spin coating, casting, LB (Langmuir-Blodgett) method, etc. There are no particular restrictions on the film thickness of each layer formed in this manner and it can be selected appropriately depending on the situation, but it is usually in the range of 5 nm to 5 μm.

[0156] The first electrode 11 and the second electrode 16 can be formed by thinning an electrode material by a method such as vapor deposition or sputtering. A pattern may be formed through a mask of a desired shape during vapor deposition or sputtering, or a pattern of a desired shape may be formed by photolithography after forming a thin film by vapor deposition or sputtering.

[0157] The film thickness of the first electrode 11 and the second electrode 16 is preferably 1 μm or less, and more preferably 10 nm or more and 200 nm or less.

[0158] The materials constituting the first electrode 11 and the second electrode 16 may be interchanged as necessary (also called an inverted structure). In such a structure, a photoelectric conversion element is formed in which light passes through the second electrode 16 and enters the light-receiving layer 14.

[0159] An imaging element including the photoelectric conversion element of this embodiment can be applied to, for example, an imaging element of a digital camera or a digital video camera, and an imaging element built into a mobile phone, etc. An optical sensor can be applied to, for example, a television remote control, an air conditioner switch, an automatic door opener, etc.

[0160] <<Second Embodiment>> A photoelectric conversion element according to a second embodiment of the present invention is a solar cell having the layered structure shown in Fig. 1. In the solar cell 1, a hole transport promotion layer 12 and a hole transport layer 13 are provided between a first electrode 11 and a light-receiving layer 14, and an electron transport layer 15 is provided between a second electrode 16 and the light-receiving layer 14. However, some of these layers may be omitted, or other layers may be added.

[0161] [First Electrode 11] The first electrode 11 is made of, for example, a transparent material, and the transparent material can be the transparent material in the first embodiment. The first electrode 11 may be formed on any substrate (for example, a transparent substrate such as glass, plastic, or polymer film).

[0162] [Hole Transport Promotion Layer 12] The material of the hole transport promotion layer 12 is the same as the material (imide compound (1)) of the hole transport promotion layer 12 in the first embodiment. The material of the hole transport promotion layer 12 may contain a conventionally known hole transport material in addition to the material in the first embodiment.

[0163] [Hole Transport Layer 13] The material of the hole transport layer 13 is the same as the material of the hole transport layer 13 in the first embodiment. The material of the hole transport layer 13 may contain a conventionally known hole transport material in addition to the hole transport material in the first embodiment.

[0164] [Light-Receiving Layer 14] The light-receiving layer 14 may be made of an electron-donating material and an electron-accepting material. This may be a planar bond type in which the electron-donating material and the electron-accepting material are bonded together at their respective planes, or a bulk heterobond type in which the electron-donating material and the electron-accepting material are mixed and formed into a film. The electron-donating material is not particularly limited, but an organic semiconductor is preferred. Examples of electron-donating materials include polymeric compounds and copolymers thereof, such as polythiophene derivatives, polyfluorene derivatives, and polyphenylene vinylene derivatives, as well as low-molecular-weight compounds, such as phthalocyanine derivatives and their metal complexes, porphyrin derivatives and their metal complexes, acene derivatives such as pentacene, and diamine derivatives. The electron-donating material may be an inorganic semiconductor in addition to an organic semiconductor, provided that the effects of the present invention are not impaired. The electron-accepting material is not particularly limited, but an organic semiconductor is preferred. Examples of electron-accepting materials include fullerene derivatives, perylene derivatives, and naphthalene derivatives.

[0165] [Electron Transport Layer 15] The electron transport material in the first embodiment can be used as the material for the electron transport layer 15. Alternatively, the electron transport material may be an alkali metal halide such as sodium fluoride or cesium fluoride, an alkaline earth metal halide such as calcium fluoride, a carbonate such as cesium carbonate, or an inorganic n-type semiconductor such as titanium oxide or zinc oxide.

[0166] [Second Electrode 16] The second electrode 16 may be made of, for example, a metal such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, or lead, or an alloy thereof, but is not limited to these.

[0167] The materials constituting the first electrode 11 and the second electrode 16 may be interchanged as necessary (also called an inverted structure). In such a structure, a photoelectric conversion element is formed in which light passes through the second electrode 16 and enters the light-receiving layer 14.

[0168] [Method of Forming Each Layer] The method of forming each layer is not particularly limited. For example, the first electrode 11, the hole transport promotion layer 12, the hole transport layer 13, the light-receiving layer 14, the electron transport layer 15, and the second electrode 16 may be sequentially laminated on a substrate using a vapor deposition method, a spin coating method, a casting method, a pattern transfer method, or the like. Alternatively, the hole transport promotion layer 12, the hole transport layer 13, the light-receiving layer 14, and the electron transport layer 15 may be laminated, and then the first electrode 11 and the second electrode 16 may be formed on this laminate by transfer, vapor deposition, sputtering, or the like.

[0169] The photoelectric conversion element of the present invention and the method for forming each layer of the element are not limited to the elements and methods shown in the above-mentioned embodiments. For example, the materials of the first electrode, the light-receiving layer (or the light-emitting layer), the electron transport layer, and the second electrode can be appropriately replaced with other known materials. In addition, the hole transport promotion layer and the hole transport layer can be replaced with a layer formed by mixing the imide compound (1) and a hole transport material.

[0170] The present invention will be described in more detail below with reference to examples, but the present invention should not be construed as being limited to these examples. １ For H-NMR measurements, a Bruker ASCEND HD (400 MHz; manufactured by BRUKER) was used. １ H-NMR was performed in deuterated chloroform (CDCl ３ The measurement was performed using tetramethylsilane (TMS) as an internal standard. Commercially available reagents were used for the measurement.

[0171] (Synthesis reference example 1) Under an argon atmosphere, naphthalene-1,4,5,8-tetracarboxylic dianhydride (10.6 g, 39.5 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (2.89 g, 15.1 mmol) were suspended in N,N-dimethylformamide (80 mL) and stirred at 120°C for 1 hour. Subsequently, aniline (2.33 g, 25.0 mmol) was added to the reaction solution, and the mixture was stirred at 120°C for 2 hours. After cooling to room temperature, low boiling points were distilled off, and the resulting solid was washed with hot chloroform. The solid obtained by distilling off low boiling points from the filtrate after washing was purified by recrystallization from 1,4-dioxane to give 7-phenyl-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (yield: 5.24 g, 61%). １ H-NMR (CDCl ３ ) δ (ppm): 8.87 (m, 4H), 7.62-7.52 (m, 3H), 7.34-7.31 (m, 2H).

[0172] (Synthesis reference example 2) Under an argon atmosphere, naphthalene-1,4,5,8-tetracarboxylic dianhydride (10.6 g, 39.5 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (2.89 g, 15.1 mmol) were suspended in N,N-dimethylformamide (80 mL) and stirred at 120°C for 1 hour. Then, 4-aminopyridine (2.35 g, 25.0 mmol) was added to the reaction solution, and the mixture was stirred at 120°C for 16 hours. After cooling to room temperature, low boiling points were distilled off, and water was added to the resulting suspension, and the precipitated solid was collected by filtration. The collected solid was washed with hot chloroform, and low boiling points were distilled off from the resulting filtrate. The resulting solid was suspended in acetic anhydride (10 mL) and heated with stirring at 120°C for 1 hour. After cooling to room temperature, the precipitated solid was collected by filtration to give 7-(pyridin-4-yl)-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (yield: 1.89 g, 22%). １ H-NMR (CDCl ３ ) δ (ppm): 8.89-8.87 (m, 6H), 7.33 (d, J=4.5Hz, 2H).

[0173] (Synthesis reference example 3) Under an argon atmosphere, naphthalene-1,4,5,8-tetracarboxylic dianhydride (10.6 g, 39.5 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (2.89 g, 15.1 mmol) were suspended in N,N-dimethylformamide (80 mL) and stirred at 120°C for 1 hour. Then, 4-aminobenzonitrile (2.95 g, 25.0 mmol) was added to the reaction solution, and the mixture was stirred at 120°C for 16 hours. After cooling to room temperature, low boiling points were distilled off, and water was added to the resulting suspension, and the precipitated solid was collected by filtration. The collected solid was washed with hot chloroform, and low boiling points were distilled off from the resulting filtrate. The resulting solid was suspended in acetic anhydride (10 mL) and heated with stirring at 120°C for 1 hour. After cooling to room temperature, the precipitated solid was collected by filtration to give 4-(1,3,6,8-tetraoxo-1,3,6,8-tetrahydro-7H-isochromeno[6,5,4-def]isoquinolin-7-yl)benzonitrile (yield 1.50 g, 16%). １ H-NMR (CDCl ３ ) δ (ppm): 8.91-8.88 (m, 4H), 7.91 (d, J=8.6Hz, 2H), 7.49 (d, J=8.6Hz, 2H).

[0174] (Synthesis reference example 4) Under an argon atmosphere, naphthalene-1,4,5,8-tetracarboxylic dianhydride (15.0 g, 55.9 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (4.02 g, 21.0 mmol) were suspended in N,N-dimethylformamide (500 mL). After stirring this reaction solution at 120°C for 1 hour, 4-aminophthalonitrile (5.00 g, 34.9 mmol) was added and the mixture was stirred at 120°C for an additional 17 hours. After allowing to cool to room temperature, low boiling points were distilled off under reduced pressure, and water was added to the resulting suspension. The precipitated solid was collected by filtration, suspended in acetic anhydride (100 mL), and heated and stirred at 120°C for 1 hour. After allowing to cool to room temperature, the solid was filtered off, and water was added to the filtrate, and the precipitated solid was collected by filtration. The collected solid was purified by recrystallization from 1,4-dioxane to obtain the target compound, 4-(1,3,6,8-tetraoxo-1,3,6,8-tetrahydro-7H-isochromeno[6,5,4-def]isoquinolin-7-yl)phthalonitrile (yield: 4.87 g, 35%). １ H-NMR (DMSO-d ６ ) δ (ppm): 8.77-8.70 (m, 4H), 8.40 (d, J = 8.3Hz, 1H), 8.32 (d, J = 1.9Hz, 1H), 8.10 (dd, J = 8.3, 1.9Hz, 1H).

[0175] (Synthesis Example 1: Synthesis of Compound (C-2)) Under an argon atmosphere, 7-phenyl-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (2.00 g, 5.83 mmol) obtained in Synthesis Reference Example 1 and 2,3-diaminomaleonitrile (693 mg, 6.41 mmol) were suspended in pyridine (200 mL) and stirred for 16 hours at 120 ° C. After cooling to room temperature, low boiling points were distilled off and the resulting solid was washed with 1.0 M aqueous hydrochloric acid. The resulting solid was purified by silica gel column chromatography (toluene / ethyl acetate = 8 / 2) to obtain the target compound (C-2) 1,3,6-trioxo-2-phenyl-1,2,3,6-tetrahydrobenzo[lmn]imidazo[2,1-b][3,8]phenanthroline-8,9-dicarbonitrile as an orange solid (yield 581 mg, 24%). １ H-NMR (CDCl３ ) δ (ppm): 9.09 (d, J = 7.6 Hz, 1H), 8.97 (d, J = 7.6 Hz, 1H), 8.95 (d, J = 7.6 Hz, 1H), 8.91 (d, J=7.6Hz, 1H), 7.63-7.52 (m, 3H), 7.35-7.32 (m, 2H).

[0176] (Synthesis Example 2: Synthesis of Compound (C-6)) Under an argon atmosphere, 7-phenyl-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (687 mg, 2.00 mmol) obtained in Synthesis Reference Example 1, 4,5-diaminophthalonitrile (633 mg, 4.00 mmol), and 1,4-diazabicyclo[2.2.2]octane (112 mg, 1.00 mmol) were suspended in dimethylacetamide (40 mL), and the suspension was stirred for 14 hours at 150° C. After allowing to cool to room temperature, the solvent was distilled off under reduced pressure, and the resulting solid was washed with water. The obtained solid was purified by silica gel column chromatography (hexane / ethyl acetate=3 / 7) to obtain the target compound (C-6) 1,2,3,6-tetrahydro-1,3,6-trioxo-2-phenylbenzo[lmn]benzimidazo[2,1-b][3,8]phenanthroline-9,10-dicarbonitrile as a yellow solid (yield: 411 mg, 44%). １ H-NMR (CDCl ３ ) δ (ppm): 9.14 (d, J = 7.6 Hz, 1H), 9.08 (d, J = 7.6 Hz, 1H), 9.07 (s, 1H), 8.96 (d, J = 7.6 Hz, 1H), 8.94 (d, J=7.6Hz, 1H), 8.38 (s, 1H), 7.64-7.54 (m, 3H), 7.38-7.32 (m, 2H).

[0177] (Synthesis Example 3: Synthesis of Compound (C-10)) Under a nitrogen atmosphere, 7-phenyl-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (340 mg, 1.0 mmol) obtained in Synthesis Reference Example 1 and diaminodicyanopyrazine (176 mg, 1.1 mmol) were dissolved in N,N-dimethylacetamide (10 mL) and stirred for 24 hours at 150°C. After cooling to room temperature, low boiling points were distilled off under reduced pressure, and the resulting residue was purified by silica gel column chromatography and gel permeation chromatography to obtain the target compound (C-10) 1,2,3,6-tetrahydro-1,3,6-trioxo-2-phenylbenzo[imn]pyrazino[2',3':4,5]imidazo[2,1-b][3,8]phenanthroline-9,10-dicarbonitrile (yield 210 mg, 45%). １ H-NMR (CDCl ３ ) δ (ppm): 9.22 (d, J = 7.6 Hz, 1H), 9.02 (d, J = 7.6 Hz, 1H), 8.82 (d, J = 7.6 Hz, 2H), 7.61-7.45 (m, 5H)

[0178] (Synthesis Example 4: Synthesis of compound (C-52)) Under an argon atmosphere, 7-(pyridin-4-yl)-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (300 mg, 0.87 mmol) obtained in Synthesis Reference Example 2 and 2,3-diaminomaleonitrile (104 mg, 0.96 mmol) were suspended in pyridine (30 mL), and the suspension was stirred at 120° C. for 16 hours. After cooling to room temperature, low boiling points were distilled off, and the resulting solid was purified by silica gel column chromatography (toluene / ethyl acetate / methanol=5 / 4 / 1) and recrystallization (1,4-dioxane) to obtain the target compound (C-52) 1,3,6-trioxo-2-(pyridin-4-yl)-1,2,3,6-tetrahydrobenzo[lmn]imidazo[2,1-b][3,8]phenanthroline-8,9-dicarbonitrile as an orange solid (yield 52 mg, 14%). １ H-NMR (CDCl ３) δ (ppm): 9.10 (d, J = 7.6 Hz, 1H), 8.99 (m, 1H), 8.97 (m, 1H), 8.93 (m, 1H), 8.88 (m, 2H), 7.33 (d, J = 4.5Hz, 2H).

[0179] (Synthesis Example 5: Synthesis of compound (C-72)) Under an argon atmosphere, 4-(1,3,6,8-tetraoxo-1,3,6,8-tetrahydro-7H-isochromeno[6,5,4-def]isoquinolin-7-yl)benzonitrile (370 mg, 1.10 mmol) obtained in Synthesis Reference Example 3 and 2,3-diaminomaleonitrile (120 mg, 1.10 mmol) were suspended in pyridine (30 mL), and the suspension was stirred at 120° C. for 24 hours. After cooling to room temperature, low boiling points were distilled off, and the resulting solid was purified by silica gel column chromatography (toluene / ethyl acetate=8 / 2) to obtain the target compound (C-72), 2-(4-cyanophenyl)-1,3,6-trioxo-1,2,3,6-tetrahydrobenzo[lmn]imidazo[2,1-b][3,8]phenanthroline-8,9-dicarbonitrile, as an orange solid (yield: 30 mg, 7%). １ H-NMR (CDCl ３ ) δ (ppm): 9.10 (d, J = 7.7 Hz, 1H), 9.00 (d, J = 7.7 Hz, 1H), 8.96 (d, J = 7.7 Hz, 1H), 8.91 (d, J=7.7Hz, 1H), 7.91 (d, J=8.0Hz, 2H), 7.50 (d, J=8.0Hz, 2H).

[0180] (Synthesis Example 6: Synthesis of compound (C-82)) Under a nitrogen atmosphere, 4-(1,3,6,8-tetraoxo-3,6,7,8-tetrahydro-1H-naphtho[2,1,8-def]isochrome-7-yl)phthalonitrile (8.18 g, 19.6 mmol) obtained in Synthesis Reference Example 4 and diaminomaleonitrile (2.34 g, 21.6 mmol) were dissolved in N,N-dimethylacetamide (190 mL) and stirred for 17 hours at 150 ° C. After cooling to room temperature, low boiling points were distilled off under reduced pressure, and the resulting residue was purified by silica gel column chromatography and gel permeation chromatography to obtain the target compound (C-82) 2-(3,4-dicyanophenyl)-1,3,6-trioxo-1,2,3,6-tetrahydrobenzo[lmn]imidazo[2,1-b][3,8]phenanthroline-8,9-dicaltonitrile (yield 266 mg, 3%). １ H-NMR (CDCl ３ ) δ (ppm): 9.11 (d, J = 7.6 Hz, 1H), 9.00 (d, J = 7.7 Hz, 1H), 8.97 (d, J = 7.7 Hz, 1H), 8.93 (d, J =7.6Hz, 1H), 8.04 (d, J = 8.3Hz, 1H), 7.85 (d, J = 2.1Hz, 1H), 7.77 (dd, J = 8.3, 2.1Hz, 1H).

[0181] (Synthesis Example 7: Synthesis of compound (C-394)) Under an argon atmosphere, 7-phenyl-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (103 mg, 0.300 mmol) obtained in Synthesis Reference Example 1 and 4,5-dichloro-1,2-phenylenediamine (106 mg, 0.600 mmol) were suspended in acetic acid (6 mL) and stirred under reflux for 14 hours. After cooling to room temperature, the reaction mixture was filtered, and the resulting solid was washed with water to obtain the target compound (C-394), 9,10-dichloro-2-phenylbenzo[lmn]benzimidazo[2,1-b][3,8]phenanthroline-1,3,6(2H)-trione, as an orange solid (yield 145 mg, 100%). １ H-NMR (CDCl ３) δ (ppm): 9.02 (d, J = 7.6 Hz, 1H), 9.01 (d, J = 7.6 Hz, 1H), 8.90 (d, J = 7.6 Hz, 1H), 8.88 (d, J=7.6Hz, 1H), 8.70 (s, 1H), 8.03 (s, 1H), 7.64-7.53 (m, 3H), 7.39-7.32 (m, 2H).

[0182] Synthesis Example 8: Synthesis of Compound C-398 Under an argon atmosphere, 7-phenyl-1H-isochromeno[6,5,4-def]isoquinoline-1,3,6,8(7H)-tetraone (100 mg, 0.291 mmol) obtained in Synthesis Reference Example 1 and 4,5-dimethyl-1,2-phenylenediamine (79.3 mg, 0.582 mmol) were suspended in acetic acid (5.8 mL) and stirred under reflux for 2 hours. After cooling to room temperature, the reaction mixture was filtered, and the resulting solid was washed with water to obtain the target compound (C-398), 9,10-dimethyl-2-phenylbenzo[lmn]benzimidazo[2,1-b][3,8]phenanthroline-1,3,6(2H)-trione, as an orange solid (yield 111 mg, 86%). １ H-NMR (CDCl ３ ) δ (ppm): 8.97 (d, J = 7.6 Hz, 1H), 8.96 (d, J = 7.6 Hz, 1H), 8.87 (d, J = 7.6 Hz, 1H), 8.83 (d, J=7.6Hz, 1H), 8.32 (s, 1H), 7.69 (s, 1H), 7.63-7.51 (m, 3H), 7.38-7.32 (m, 2H).

[0183] [Compounds used in evaluation]

[0184] <Preparation and Evaluation of Hole-Only Device 1> [Element Example 1] A hole-only device having a structure consisting of a first electrode / first hole injection layer / hole transport layer / hole transport promotion layer / second electrode was prepared, and the hole transport properties of the device were evaluated. (First Electrode) A glass substrate with an ITO transparent electrode, on whose surface an ITO film (thickness 110 nm) was patterned in a stripe pattern, was prepared as a substrate having a first electrode. This substrate was washed with isopropyl alcohol and then subjected to surface treatment by ozone ultraviolet cleaning.

[0185] (Preparation for Vacuum Vapor Deposition) Each layer was vacuum-deposited by a vacuum deposition method on the surface on which the ITO film was formed, of the two surfaces of the substrate that had been subjected to the surface treatment described above. First, the glass substrate was placed in a vacuum deposition chamber, and 1.0 × 10 －４ The pressure was reduced to Pa. Then, each layer was formed in the following order according to the film formation conditions.

[0186] (Fabrication of the first hole injection layer) ３ A 1 nm thick film was formed to prepare a hole injection layer. (Preparation of Hole Transport Layer) A 100 nm thick film of (HTL-1) was formed as a hole transport material to prepare a hole transport layer. (HTL-1) was synthesized by the method described in JP 2018-193371 A. (Preparation of Hole Transport Promotion Layer) A 10 nm thick film of the sublimation-purified compound (A-60) was formed to prepare a hole transport promotion layer.

[0187] (Fabrication of Second Electrode) A 80 nm thick Au film was formed to fabricate a second electrode.

[0188] (Evaluation of hole transport capability of hole-only device) A positive electric field and a negative electric field of 0.1 mA / cm were applied to the first electrode and the second electrode of the hole-only device of Example 1, respectively. ２ The voltage value at a current density of 1000 kJ / s was measured. The results are shown in Table 1.

[0189] A hole-only device was fabricated in the same manner as in Element Example 1, except that compound (NPT) was used instead of compound (C-2) used in the preparation of the hole transport promotion layer in Example 1. The hole transport ability of the resulting hole-only device was evaluated in the same manner as in Element Example 1. The results are shown in Table 1.

[0190] [Comparative Element Example 2] A hole-only device was fabricated in the same manner as in Element Example 1, except that the hole-transport promoting layer was not provided. The hole-transport capability of the resulting hole-only device was evaluated in the same manner as in Element Example 1. The results are shown in Table 1.

[0191]

[0192] The element of element example 1 using compound (C-2) as the hole transport promoting material (HOD voltage of 2.42 V) had a lower HOD voltage than the element of element comparative example 1 using the known material NPT (HOD voltage of 6.41 V) and the element of element comparative example 2 using no hole transport promoting material (HOD voltage of 6.26 V). Note that, similar to element example 1, compounds (C-6), (C-10), (C-52), (C-72), and (C-82) synthesized in Synthesis Examples also showed an effect of improving transport capability as a hole transport promoting material (reduction in HOD voltage).

[0193] <Preparation and Evaluation of Photoelectric Conversion Element> [Element Example 2] A photoelectric conversion element 1 having a layered structure consisting of a substrate / second electrode 16 / electron transport layer 15 / light-receiving layer 14 / hole transport layer 13 / hole transport promotion layer 12 / first electrode 11 was prepared, and the dark current and external quantum efficiency of the photoelectric conversion element were evaluated.

[0194] (Preparation of Substrate and Second Electrode 16) A glass substrate with an ITO transparent electrode, on which a 2 mm wide ITO film (film thickness 110 nm) was patterned in stripes, was prepared as a substrate having a second electrode on its surface. Next, this substrate was washed with isopropyl alcohol, and then subjected to surface treatment by ozone ultraviolet cleaning. (Preparation of Vacuum Vapor Deposition) Each layer was vacuum-deposited by vacuum deposition on the surface-treated substrate after cleaning, and each layer was laminated. First, the glass substrate was placed in a vacuum deposition chamber, and 7.0 × 10 －５The pressure was reduced to 100 Pa. Then, each layer was fabricated in the following order according to the film formation conditions. (Fabrication of Electron Transport Layer 15) The compound 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-methylpyrimidine, which had been purified by sublimation, was deposited to a thickness of 10 nm at a rate of 0.03 nm / sec to fabricate the electron transport layer 15. (Fabrication of Light Receiving Layer 14) N,N-dimethylquinacridone and fullerene C60 were mixed in a mass ratio of 4:1 to fabricate the light receiving layer 14, forming a film of 250 nm. The film formation rate was 0.13 nm / sec. (Fabrication of Hole Transport Layer 13) The hole transport material (HTL-1) was deposited to a thickness of 10 nm at a rate of 0.10 nm / sec to fabricate the hole transport layer 13. (Preparation of Hole Transport Promotion Layer 12) Compound (C-2) was deposited at a rate of 0.20 nm / sec to form a 10 nm film, thereby preparing a hole transport promotion layer 12. (Preparation of First Electrode 11) Finally, a metal mask was placed perpendicular to the ITO stripes on the substrate, and the first electrode 11 was formed. The first electrode was prepared by depositing an Au film to a thickness of 80 nm. The Au film formation rate was 0.1 nm / sec.

[0195] From the above, the area is 4 mm ２ A photoelectric conversion element 1 shown in FIG. 1 was fabricated. A voltage of 2.5 V (absolute value) was applied to the photoelectric conversion element fabricated as described above so that electrons were transported to the second electrode 16 side and holes were transported to the first electrode 11 side. The current in a dark place (dark current) and external quantum efficiency were evaluated. Dark current (A / cm ２ The external quantum efficiency was measured using a solar cell spectral response measurement device (manufactured by Soma Optical Co., Ltd.). The wavelength of the irradiated light was 560 nm and the intensity was 50 μW / cm. ２ The measurements were carried out at 100°C. The results are shown in Table 2. The external quantum efficiency is a relative value, with the result of Comparative Example 3 of the device described below being set as the reference value (100). The lower the dark current value, the better the performance, and the higher the external quantum efficiency value, the better the performance.

[0196] A photoelectric conversion element of Comparative Example 3 was prepared in the same manner as in Example 2, except that compound (NPT) was used instead of compound (C-2) in the preparation of the hole transport promotion layer 12, and the dark current and external quantum efficiency were measured in the same manner as in Example 2. The results are shown in Table 2.

[0197] A photoelectric conversion element of Comparative Example 4 was prepared in the same manner as in Example 2, except that the hole transport promotion layer 12 was not provided, and the dark current and external quantum efficiency were measured in the same manner as in Example 2. The results are shown in Table 2.

[0198]

[0199] As shown in Table 2, the element of Element Example 2 using the material for a photoelectric conversion element of the present invention exhibited a suppressed dark current and a high external quantum efficiency compared to the elements of Element Comparative Example 3 and Element Comparative Example 4. Note that, similar to Element Example 2, the compounds (C-6), (C-10), (C-52), (C-72), and (C-82) synthesized in Synthesis Examples also exhibited suppressed dark current and improved external quantum efficiency.

[0200] The photoelectric conversion element of the present invention contains the imide compound (1) of the formula above, thereby improving the hole transport ability and enabling more efficient photoelectric conversion when used in a photoelectric conversion element. Furthermore, the photoelectric conversion element of the present invention contains the imide compound (1) of the formula above, thereby suppressing dark current and increasing external quantum efficiency.

[0201] REFERENCE SIGNS LIST 1 Photoelectric conversion element 11 First electrode 12 Hole transport promoting layer 13 Hole transport layer 14 Light receiving layer 15 Electron transport layer 16 Second electrode

Claims

1. A photoelectric conversion element comprising a first electrode, a second electrode, and a light-receiving layer and an organic layer disposed between the first electrode and the second electrode, wherein the organic layer comprises a hole transport layer, and a hole transport promotion layer containing an imide compound represented by the following formula (1), or comprises a layer comprising a mixture of a hole transport material and an imide compound represented by the following formula (1): (In formula (1), ring A represents an aromatic hydrocarbon ring having 6 to 20 carbon atoms which may be substituted (which may be a single ring, a condensed ring, or a linked ring containing a plurality of rings); ring B represents an imidazole ring or a condensed imidazole ring having 5 to 20 carbon atoms; R １ each independently represents a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group consisting of two or more of the above groups or atoms; n represents 0, 1, 2, 3, or 4; provided that when ring B is an imidazole ring, n represents 0, 1, or 2; Ar １ represents an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be substituted (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a heteroaromatic group having 2 to 20 carbon atoms which may be substituted (which may be a single ring, a condensed ring, or a linked ring containing multiple rings); the substituents which may be substituted on the aromatic hydrocarbon ring, the aromatic hydrocarbon group, or the heteroaromatic group include a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms which may be a single ring, a condensed ring, or a linked ring containing multiple rings, or a group in which two or more of the above groups or atoms are combined.

2. The photoelectric conversion element according to claim 1, wherein the light-receiving layer is a layer containing at least two kinds of organic components.

3. The photoelectric conversion element according to claim 1, wherein the organic layer comprises the hole transport layer and the hole transport promotion layer containing the imide compound represented by formula (1), and the hole transport promotion layer is adjacent to the hole transport layer.

4. The photoelectric conversion element according to claim 1, wherein the organic layer includes a layer formed by mixing the hole transport material and the imide compound represented by formula (1).

5. R in the above formula (1) １ 5. The photoelectric conversion element according to claim 1, wherein at least one of the groups represented by the formula (I) is a cyano group.

6. The photoelectric conversion element according to any one of claims 1 to 4, wherein n in the formula (1) is 1 or 2.

7. The photoelectric conversion element according to any one of claims 1 to 4, wherein ring A in the formula (1) is a benzene ring or a naphthalene ring.

8. Ar in the above formula (1) １ is an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted pyridyl group, an optionally substituted pyrazyl group, an optionally substituted pyrimidyl group, an optionally substituted triazyl group, an optionally substituted quinolyl group, an optionally substituted isoquinolyl group, an optionally substituted quinoxalyl group, or an optionally substituted quinazolinyl group.

9. Ar in the above formula (1) １ is a phenyl group, a cyanophenyl group, a dicyanophenyl group, a naphthyl group, a cyanonaphthyl group, a dicyanonaphthyl group, a pyridyl group, a cyanopyridyl group, a dicyanopyridyl group, a pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a pyrazyl group, a cyanopyrazyl group, a dicyanopyrazyl group, a quinolyl group, a cyanoquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a quinazolinyl group, or a cyanoquinazolinyl group.

10. A hole transport promoting material represented by the following formula (1a): (In formula (1a), ring C represents an aromatic hydrocarbon ring having 6 to 20 carbon atoms which may be substituted (which may be a single ring, a condensed ring, or a linked ring containing a plurality of rings); ring D represents an imidazole ring or a condensed imidazole ring having 5 to 20 carbon atoms; R ２ each independently represents a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a group consisting of two or more of the above groups or atoms in combination; m represents 0, 1, 2, 3, or 4; provided that when ring D is an imidazole ring, m represents 0, 1, or 2; Ar ２ represents an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be substituted (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or a heteroaromatic group having 2 to 20 carbon atoms which may be substituted (which may be a single ring, a condensed ring, or a linked ring containing multiple rings); the substituents which may be substituted on the aromatic hydrocarbon ring, the aromatic hydrocarbon group, or the heteroaromatic group include a hydroxyl group, a carboxyl group, a formyl group, an acyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a trifluoromethyl group, a methyl group, a fluoroalkyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group having 2 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms which may be a single ring, a condensed ring, or a linked ring containing multiple rings), a heteroaromatic group having 2 to 20 carbon atoms which may be a single ring, a condensed ring, or a linked ring containing multiple rings, or a group in which two or more of the above groups or atoms are combined.

11. R in the above formula (1a) ２ 11. The hole transport promoting material according to claim 10, wherein at least one of the groups is a cyano group.

12. The hole transport promoting material according to claim 10, wherein m in formula (1a) is 1 or 2.

13. The hole transport promoting material according to claim 10, wherein ring C in formula (1a) is a benzene ring or a naphthalene ring.

14. Ar in the above formula (1a) ２ is an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted pyridyl group, an optionally substituted pyrazyl group, an optionally substituted pyrimidyl group, an optionally substituted triazyl group, an optionally substituted quinolyl group, an optionally substituted isoquinolyl group, an optionally substituted quinoxalyl group, or an optionally substituted quinazolinyl group.

15. Ar in the above formula (1a) ２ The hole transport promoting material according to claim 10, wherein is a phenyl group, a cyanophenyl group, a dicyanophenyl group, a naphthyl group, a cyanonaphthyl group, a dicyanonaphthyl group, a pyridyl group, a cyanopyridyl group, a dicyanopyridyl group, a pyrimidyl group, a cyanopyrimidyl group, a dicyanopyrimidyl group, a pyrazyl group, a cyanopyrazyl group, a dicyanopyrazyl group, a quinolyl group, a cyanoquinolyl group, an isoquinolyl group, a cyanoisoquinolyl group, a quinazolinyl group, or a cyanoquinazolinyl group.

16. An imide compound represented by formula (1b): In formula (1b), p represents 0, 1, or 2; q represents 1, 2, 3, 4, or 5; X １ is a nitrogen atom or C-R ６ Represents: X ２ is a nitrogen atom or C-R ７ Represents: Ar ３ represents a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings); R ３ represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxyl group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may be a group consisting of two or more of the above groups or atoms in combination; R ４ , R ５ , R ６ , and R ７ each independently represents a hydrogen atom or a cyano group; ４ , R ５ , R ６ , and R ７ At least two of these are cyano groups.) 17. Ar in the above formula (1b) ３ The imide compound according to claim 16, wherein is a phenyl group, a naphthyl group, an anthryl group, a phenanthrenyl group, a triphenylenyl group, a pyridyl group, a pyrazyl group, or a pyrimidyl group.

18. An imide compound represented by formula (1c): (In formula (1c), k represents 0, 1, 2, 3, 4, or 5; ring E represents an imidazole ring or a fused imidazole ring having 5 to 20 carbon atoms; r represents 1, 2, 3, or 4; provided that when ring E is an imidazole ring, r represents 1 or 2; R ８ each independently represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxyl group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may be a group consisting of two or more of the above groups or atoms; ４ represents a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 18 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings); R ９ each independently represents a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxyl group, a heteroaromatic group having 2 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), or an aromatic hydrocarbon group having 6 to 20 carbon atoms (which may be a single ring, a condensed ring, or a linked ring containing multiple rings), and may be a group consisting of a combination of two or more of the above groups or atoms.

19. R in the above formula (1c) ９ The imide compound according to claim 18 , wherein at least one of the groups is a cyano group.

20. Ar in the above formula (1c) ４ The imide compound according to claim 18, wherein is a phenyl group, a naphthyl group, an anthryl group, a phenanthrenyl group, a triphenylenyl group, a pyridyl group, a pyrazyl group, or a pyrimidyl group.

21. The imide compound according to claim 18, wherein ring E in formula (1c) is an imidazole ring, a benzimidazole ring, or an imidazopyrazine ring.

Images