Positive hole transport promoting material, material for light-receiving element, cyanide compound, and organic light-receiving element

Abstract

Provided are a material for a light receiving element having excellent hole transport characteristics, and an organic light receiving element using the same.　A material for a light receiving element is used that includes a compound represented by general formula (1) or general formula (2). Ar2 and Ar3 are preferably cyano groups. Ar4 and Ar5 are preferably cyano groups.

Description

Technical Field

[0001] The present invention relates to a hole transport promoting material, a material for a light receiving element, a cyano compound, and an organic light receiving element.

Background Art

[0002] A light receiving element is an element having a function of converting received light into an electric signal or electric energy. Among light receiving elements, light receiving elements for imaging elements are used in applications such as mobile phones and cameras, and their development is being actively carried out.

[0003] In recent years, the market requirements for light receiving elements for imaging elements have been increasing, and materials having excellent characteristics in terms of charge transport characteristics, dark current, quantum efficiency, etc. are required. As an organic light receiving element having a light receiving layer made of an organic material, a laminated structure having a charge transport layer such as a hole transport layer that transports holes generated in the light receiving layer to the first electrode and an electron transport layer that transports electrons generated in the light receiving layer to the second electrode is common (see, for example, Patent Document 1). However, even with such a charge transport layer, the charge transport characteristics are not sufficient, and an organic light receiving element having better charge transport characteristics is required. Furthermore, when a charge transport layer having high charge transport characteristics is used, the dark current characteristics of the organic light receiving element tend to deteriorate, and it is required to improve these two characteristics simultaneously.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a material for a light receiving element having excellent hole transport characteristics and an organic light receiving element using the same.

Means for Solving the Problem

[0006] The inventors of the present invention have found that the above problems can be solved by providing a layer containing a specific cyano compound between a hole transport layer responsible for hole transport and an electrode to which holes are transported, and have completed the present invention.

[0007] Aspects of the present invention relate to the following hole transport promoting materials, materials for light receiving elements, cyano compounds, and organic light receiving elements.

[0008] [1] A hole transport promoting material containing a compound represented by the following general formula (1) or general formula (2).

Chemical formula

Chemical formula

[0009] [2] The hole transport promoting material according to [1], wherein Ar 2 and Ar 3 are cyano groups. [3] The hole transport promoting material according to [1] or [2], wherein Ar 4 and Ar 5 are cyano groups.

[0010] [4] A material for a light receiving element, comprising a compound represented by the following general formula (1) or general formula (2).

Chemical formula

Chemical formula

[0011] [5] The light-receiving element material for an organic imaging element according to [4], which is a material for an organic imaging element for a light-receiving element. [6] The light-receiving element material according to [4] or [5], which is a hole transport promoting material for an organic imaging element for a light-receiving element. [7] The light-receiving element material according to any one of [4] to [6], wherein Ar 2 and Ar 3 are cyano groups. [8] Ar 4 and Ar 5The material for a light-receiving element according to any one of [4] to [7], wherein the group is a cyano group.

[0012] [9] A cyano compound represented by the following general formula (3), general formula (4), general formula (5), or general formula (6).

Chemical formula

[0013]

[10] Ar 2 and Ar 3 is a cyano group, the cyano compound according to [9].

[11] Comprising a first electrode and a second electrode, having an organic layer between the first electrode and the second electrode, the organic layer having at least a light-receiving layer, a hole transport layer, and a hole transport promoting layer, the hole transport promoting layer containing a compound having a partial structure represented by the following formula (Q), an organic light-receiving element. [Chemical formula] (In formula (Q), the portions where the solid line and the broken line are parallel each independently represent a single bond or a double bond, and * represents a bond.)

[0014]

[12] Comprising a first electrode and a second electrode, having an organic layer between the first electrode and the second electrode, the organic layer having at least a light-receiving layer, a hole transport layer, and a hole transport promoting layer, the hole transport promoting layer containing a compound represented by the following general formula (1) or general formula (2), an organic light-receiving element. [Chemical formula] (In formulas (1) and (2), Y 1 、Y 2 、Y 3 、Y 4 、Y 5 and Y 6 each independently represents a nitrogen atom or C-H; Y 1 and Y 2 at least one of which is a nitrogen atom; Y 3 、Y 4 、Y 5 and Y 6 at least one of which is a nitrogen atom; Ar 1 、Ar 2 and Ar 3 each independently is a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; X 1 is either of the divalent groups represented by the following formula (a) or (b).)

Chemical formula

[0015]

[13] The organic light-receiving element according to

[11] or

[12] , wherein the hole transport layer and the hole transport promoting layer are adjacent to each other.

[14] The organic light-receiving element according to any one of

[11] to

[13] , wherein the light-receiving layer is a layer composed of at least two components.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a material for a light-receiving element having excellent hole transport characteristics and an organic light-receiving element using the same.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0018] <Material for Light-Receiving Element> The material for a light-receiving element of this embodiment contains a compound represented by the following general formula (1) or general formula (2). In this specification, "material" also includes compounds.

[0019]

Chemical formula

[0020] In formulas (1) and (2), Y 1 、Y 2 、Y 3 、Y 4 、Y 5 and Y 6 each independently represents a nitrogen atom or C-H; Y 1 and Y 2 at least one of them is a nitrogen atom; Y 3 、Y 4 、Y 5 and Y 6 at least one of them is a nitrogen atom; Ar 1 、Ar 2 and Ar 3 each independently is a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; X 1 is either of the divalent groups represented by the following formula (a) or (b).

[0021] [Chemical formula]

[0022] In formula (a), Ar 4 and Ar 5 each independently represent a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group.

[0023] By providing a layer containing the material for a light-receiving element represented by the above general formula (1) or general formula (2) between a hole transport layer responsible for hole transport and an electrode to which holes are transported, the hole transport ability of the light-receiving element can be significantly improved.

[0024] [Compound represented by general formula (1)] As the compound represented by general formula (1), preferred embodiments are as follows in view of the fact that the hole transport ability of the light-receiving element can be significantly improved.

[0025] Y 1 and Y 2 are both preferably nitrogen atoms.

[0026] Ar 1 、 Ar 2 、 Ar 3 、 Ar 4 and Ar 5 Examples of the aryl group having 6 to 18 carbon atoms represented by Ar include a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, a phenanthryl group, an anthryl group, a fluorenyl group, a dimethylfluorenyl group, a spirofluorenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a tetracenyl group, a chrysenyl group, and the like. Among these, a phenyl group, a biphenylyl group, and a naphthyl group are preferable. Among the substituents of the aryl group having 6 to 18 carbon atoms, examples of the fluoroalkyl group include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, an undecafluoropentyl group, a tridecafluorohexyl group, and the like. Among these, a trifluoromethyl group is preferable.

[0027] Ar 1 、 Ar 2 、 Ar 3 、 Ar 4 and Ar 5Examples of the heteroaryl group having 3 to 17 carbon atoms represented by include, for example, pyridyl group, bipyridyl group, terpyridyl group, phenylpyridyl group, diphenylpyridyl group, pyridylphenyl group, pyrazyl group, phenylpyrazyl group, pyrazylphenyl group, pyrimidyl group, phenylpyrimidyl group, diphenylpyrimidyl group, pyrimidylphenyl group, triazyl group, phenyltriazyl group, diphenyltriazyl group, diphenyltriazylphenyl group, quinolyl group, phenylquinolyl group, quinolylphenyl group, isoquinolyl group, phenylisoquinolyl group, isoquinolylphenyl group, azaanthryl group, diazaanthryl group, triazaanthryl group, tetraazaanthryl group, azaphenanthryl group, diazaphenanthryl group, triazaphenanthryl group, tetraazaphenanthryl group, azapyrenyl group, diazapyrenyl group, triazapyrenyl group, tetraazapyrenyl group, azafluoranthenyl group, diazafluoranthenyl group, triazafluoranthenyl group, tetraazafluoranthenyl group, azatriphenylenyl group, diazatriphenylenyl group, triazatriphenylenyl group, tetraazatriphenylenyl group, pentaazatriphenylenyl group, hexaazatriphenylenyl group and the like. Among these, pyridyl group and pyridylphenyl group are preferable. Among the substituents of the heteroaryl group having 3 to 17 carbon atoms, examples of the fluoroalkyl group include trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, undecafluoropentyl group, tridecafluorohexyl group and the like. Among these, trifluoromethyl group is preferable.

[0028] Ar 1 is preferably a hydrogen atom, a fluoro group, a cyano group, a phenyl group or a pyridyl group. Ar 2 and Ar 3 is preferably a cyano group, a trifluoromethyl group, a fluoro group or a phenyl group. X 1 is preferably a divalent group represented by formula (a). In formula (a), Ar 4 and Ar 5 is preferably a cyano group, a trifluoromethyl group, a pyridyl group or a phenyl group.

[0029] [Compound represented by general formula (2)] As the compound represented by general formula (2), preferred embodiments are as follows in that the hole transport ability of the light receiving element can be remarkably improved.

[0030] Y 3 、Y 4 、Y 5 and Y 6 Among them, the number of nitrogen atoms is preferably 2 or more, more preferably 3 or more, and even more preferably 4. Y 3 、Y 4 、Y 5 and Y 6 Among them, Y 3 and Y 4 are both preferably nitrogen atoms.

[0031] Ar 1 、Ar 2 、 Ar 3 、Ar 4 and Ar 5 Examples of the aryl group having 6 to 18 carbon atoms represented by Ar include phenyl group, biphenylyl group, terphenylyl group, naphthyl group, phenanthryl group, anthryl group, fluorenyl group, dimethylfluorenyl group, spirofluorenyl group, pyrenyl group, fluoranthenyl group, triphenylenyl group, tetracenyl group, chrysenyl group and the like. Among these, phenyl group, biphenylyl group, and naphthyl group are preferred. Among the substituents of the aryl group having 6 to 18 carbon atoms, examples of the fluoroalkyl group include trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, undecafluoropentyl group, tridecafluorohexyl group and the like. Among these, trifluoromethyl group is preferred.

[0032] Ar 1 、Ar 2 and Ar 3Examples of the heteroaryl group having 3 to 17 carbon atoms represented by include, for example, pyridyl group, bipyridyl group, terpyridyl group, phenylpyridyl group, diphenylpyridyl group, pyridylphenyl group, pyrazyl group, phenylpyrazyl group, pyrazylphenyl group, pyrimidyl group, phenylpyrimidyl group, diphenylpyrimidyl group, pyrimidylphenyl group, triazyl group, phenyltriazyl group, diphenyltriazyl group, diphenyltriazylphenyl group, quinolyl group, phenylquinolyl group, quinolylphenyl group, isoquinolyl group, phenylisoquinolyl group, quinolylphenyl group, group, azaanthryl group, diazaanthryl group, triazaanthryl group, tetraazaanthryl group, azaphenanthryl group, diazaphenanthryl group, triazaphenanthryl group, tetraazaphenanthryl group, azapyrenyl group, diazapyrenyl group, triazapyrenyl group, tetraazapyrenyl group, azafluoranthenyl group, diazafluoranthenyl group, triazafluoranthenyl group, tetraazafluoranthenyl group, azatriphenylenyl group, diazatriphenylenyl group, triazatriphenylenyl group, tetraazatriphenylenyl group, pentaazatriphenylenyl group, hexaazatriphenylenyl group and the like. Among these, a pyridyl group and pyridylphenyl are preferable. Among the substituents of the heteroaryl group having 3 to 17 carbon atoms, examples of the fluoroalkyl group include, for example, trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, undecafluoropentyl group, tridecafluorohexyl group and the like. Among these, a trifluoromethyl group is preferable.

[0033] Ar 1 is preferably a hydrogen atom, a fluoro group, a cyano group, a phenyl group, or a pyridyl group. Ar 2 and Ar 3 is preferably a cyano group, a trifluoromethyl group, a fluoro group, or a phenyl group. X 1 is preferably a divalent group represented by formula (a). In formula (a), Ar 4 and Ar 5 is preferably a cyano group, a trifluoromethyl group, a pyridyl group, or a phenyl group.

[0034] Specific examples of the compound represented by the formula (1) or (2) include compounds (A-1) to (A-90) shown below.

[0035]

Chemical formula

[0036]

Chemical formula

[0037]

Chemical formula

[0038]

Chemical formula

[0039]

Chemical formula

[0040] The material for a light-receiving element containing the compound represented by the general formula (1) or general formula (2) can be synthesized by a known method. For example, it can be synthesized by the method disclosed in International Publication No. 2008 / 072586 etc.

[0041] [Use of the material for a light-receiving element] The material for a light-receiving element of this embodiment is preferably used as a material for a light-receiving element of an organic imaging element. The material for a light-receiving element of this embodiment is used as a hole transport promoting material. The material for a light-receiving element of this embodiment is preferably used as a hole transport promoting material for a light-receiving element of an organic imaging element. A hole transport promoting material is a material that constitutes a hole transport promoting layer provided between a hole transport layer responsible for hole transport and an electrode to which holes are transported. By providing the hole transport promoting layer, the hole transport ability from the hole transport layer to the electrode can be significantly improved.

[0042] <Positive hole transport promoting material> The positive hole transport promoting material of this embodiment contains a compound represented by the following general formula (1) or general formula (2).

[0043]

Chemical formula

[0044] In formulas (1) and (2), Y 1 、Y 2 、Y 3 、Y 4 、Y 5 and Y 6 each independently represents a nitrogen atom or C-H; Y 1 and Y 2 at least one of them is a nitrogen atom; Y 3 、Y 4 、Y 5 and Y 6 at least one of them is a nitrogen atom; Ar 1 、Ar 2 and Ar 3 each independently represents a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; X 1 is either a divalent group represented by the following formula (a) or (b).

[0045]

Chemical formula

[0046] In formula (a), Ar 4 and Ar 5 each independently represents a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group.

[0047] By providing a hole transport promoting layer containing the hole transport promoting material represented by the above general formula (1) or general formula (2) between a hole transport layer responsible for hole transport and an electrode to which holes are transported, the hole transport ability of the light receiving element can be remarkably improved.

[0048] Preferred embodiments of the compound represented by general formula (1) and the compound represented by general formula (2) are the same as those of the compound represented by general formula (1) and the compound represented by general formula (2) used in the above-described material for a light receiving element, and the description thereof is omitted here.

[0049] <Cyano compound> The cyano compound of the present embodiment is represented by the following general formula (3), general formula (4), general formula (5), or general formula (6).

[0050] [Chemical formula]

[0051] In formulas (3), (4), (5), and (6), Y 1 , Y 2 , Y 3 , Y 4 , Y 5 and Y 6 each independently represents a nitrogen atom or C-H; Y 1and Y 2 at least one of which is a nitrogen atom; Y 3 Y 4 Y 5 and Y 6 at least one of which is a nitrogen atom; Ar 6 is a cyano group, a fluoro group, a chloro group, a bromo group, an iodo group a fluoroalkyl group, a fluoro group, a fluoroalkyl group, or an aryl group having 6 to 18 carbon atoms substituted with a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; However, when Y 5 and Y 6 are C-H, Ar 6 may be a hydrogen atom; Ar 2 and Ar 3 are each independently a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, a fluoro group, a fluoroalkyl group, or an aryl group having 6 to 18 carbon atoms substituted with a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group.

[0052] By providing a layer containing a cyano compound represented by General Formula (3), General Formula (4), General Formula (5) or General Formula (6) between a hole transport layer responsible for hole transport and an electrode to which holes are transported, the hole transport ability of the light receiving element can be remarkably improved.

[0053] As the cyano compound represented by General Formula (3), General Formula (4), General Formula (5) or General Formula (6), preferred embodiments are as follows in view of the fact that the hole transport ability of the light receiving element can be remarkably improved.

[0054] Y 1 and Y 2 are preferably nitrogen atoms in all cases. Y 3 、Y 4 、Y 5 and Y 6 Among them, the number of nitrogen atoms is preferably 2 or more, more preferably 3 or more, and even more preferably 4. Y 3 、Y 4 、Y 5 and Y 6 Among them, Y 3 and Y 4 are preferably nitrogen atoms in all cases.

[0055] Ar 2 、Ar 3 and Ar 6 Examples of the aryl group having 6 to 18 carbon atoms represented by Ar include a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, a phenanthryl group, an anthryl group, a fluorenyl group, a dimethylfluorenyl group, a spirofluorenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a tetracenyl group, a chrysenyl group, and the like. Among these, a phenyl group, a biphenylyl group, and a naphthyl group are preferable. Among the substituents of the aryl group having 6 to 18 carbon atoms, examples of the fluoroalkyl group include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, an undecafluoropentyl group, a tridecafluorohexyl group, and the like. Among these, a trifluoromethyl group is preferable.

[0056] Ar 2 、Ar 3 and Ar 6Examples of the heteroaryl group having 3 to 17 carbon atoms represented by include, for example, pyridyl group, bipyridyl group, terpyridyl group, phenylpyridyl group, diphenylpyridyl group, pyridylphenyl group, pyrazyl group, phenylpyrazyl group, pyrazylphenyl group, pyrimidyl group, phenylpyrimidyl group, diphenylpyrimidyl group, pyrimidylphenyl group, triazyl group, phenyltriazyl group, diphenyltriazyl group, diphenyltriazylphenyl group, quinolyl group, phenylquinolyl group, quinolylphenyl group, isoquinolyl group, phenylisoquinolyl group, quinolylphenyl group, group, azaanthryl group, diazaanthryl group, triazaanthryl group, tetraazaanthryl group, azaphenanthryl group, diazaphenanthryl group, triazaphenanthryl group, tetraazaphenanthryl group, azapyrenyl group, diazapyrenyl group, triazapyrenyl group, tetraazapyrenyl group, azafluoranthenyl group, diazafluoranthenyl group, triazafluoranthenyl group, tetraazafluoranthenyl group, azatriphenylenyl group, diazatriphenylenyl group, triazatriphenylenyl group, tetraazatriphenylenyl group, pentaazatriphenylenyl group, hexaazatriphenylenyl group, etc. Among these, a pyridyl group and a pyridylphenyl group are preferable. Among the substituents of the heteroaryl group having 3 to 17 carbon atoms, examples of the fluoroalkyl group include, for example, trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, undecafluoropentyl group, tridecafluorohexyl group, etc. Among these, a trifluoromethyl group is preferable.

[0057] Ar 2 and Ar 3 As, a cyano group, a trifluoromethyl group, a fluoro group, and a phenyl group are preferable. Ar 6 As, a fluoro group, a bromo group, a cyano group, a phenyl group, and a pyridyl group are preferable.

[0058] <Organic Photoreceptor Element> The organic photoreceptor element of this embodiment includes a first electrode and a second electrode, and has an organic layer between the first electrode and the second electrode. The organic layer has at least a light-receiving layer, a hole transport layer, and a hole transport promoting layer, and the hole transport promoting layer contains a compound having a partial structure represented by the following general formula (Q), or a compound represented by general formula (1) or general formula (2).

[0059]

Chemical formula

[0060]

Chemical formula

[0061] In formulas (1) and (2), Y 1 , Y 2 , Y 3 , Y 4 , Y 5 and Y 6 each independently represent a nitrogen atom or C-H; Y 1 and Y 2 at least one of them is a nitrogen atom; Y 3 , Y 4 , Y 5 and Y 6 at least one of them is a nitrogen atom; Ar 1 , Ar 2 and Ar 3 each independently represent a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group. n represents an integer from 1 to 4; X 1 is either of the divalent groups represented by the following formula (a) or (b).

[0062]

Chemical formula

[0063] In formula (a), Ar 4 and Ar 5 are each independently a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group.

[0064] By providing a hole transport promoting layer containing a compound having the partial structure represented by the above general formula (Q), or a compound represented by the above general formula (1) or general formula (2) between a hole transport layer responsible for hole transport and a first electrode to which holes are transported, the hole transport ability of the light receiving element can be significantly improved.

[0065] The compound having the partial structure represented by the above general formula (Q) is preferably a compound having a condensed ring structure of 3 rings or more, and more preferably is bonded to a nitrogen atom or a carbon atom at the bond. Preferred embodiments of the compound having the partial structure represented by the above general formula (Q) are the same as the compounds (A-1) to (A-90) mentioned as the compounds used for the above-described light receiving element materials.

[0066] Preferred embodiments of the compound represented by general formula (1) and the compound represented by general formula (2) are the same as those of the compound represented by general formula (1) and the compound represented by general formula (2) used for the above-described light receiving element materials, and the description thereof is omitted here.

[0067] The laminated structure of the organic light-receiving element of the present embodiment is not particularly limited, and examples thereof include the structures of (i) and (ii).

[0068] (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

[0069] Hereinafter, the organic light-receiving element of the present embodiment will be described in more detail with reference to FIG. 1 by taking the structure of (ii) above as an example. FIG. 1 is a schematic cross-sectional view showing an example of the laminated structure of the organic light-receiving element of the present embodiment.

[0070] The organic light-receiving element 100 includes a first electrode 1, a hole transport promoting layer 2, a hole transport layer 3, a light-receiving layer 4, an electron transport layer 5, and a second electrode 6 in this order. However, some of these layers may be omitted, or conversely, other layers may be added. Among the above layers, the hole transport promoting layer 2, the hole transport layer 3, the light-receiving layer 4, and the electron transport layer 5 constitute the organic layer 10.

[0071] In the organic light-receiving element 100 shown in FIG. 1, light is incident from below the transparent first electrode 1 and received by the light-receiving layer 4. Further, a voltage is applied to the organic light-receiving element 100 so that holes among the charges (holes and electrons) generated by photoelectric conversion in the light-receiving layer 4 are moved to the first electrode 1 and electrons are moved to the second electrode 6. That is, the first electrode 1 is used as a hole collection electrode, and the second electrode 6 is used as an electron collection electrode. In FIG. 1, the substrate provided on the lower surface of the first electrode 1 is omitted. The substrate here is not particularly limited, and examples thereof include a glass plate, a quartz plate, a plastic plate, etc. Further, in the case of a configuration in which light is incident from the substrate side, the substrate is transparent to the wavelength of the light. Hereinafter, each of the above layers will be described.

[0072] [First electrode 1] The first electrode 1 is provided on the substrate. In the case of an organic light-receiving element configured such that light passes through the first electrode 1 and enters the light-receiving layer 4, the first electrode is formed of a transparent material that passes or substantially passes the light.

[0073] The transparent material used for the first electrode 1 is not particularly limited. Examples 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.

[0074] In the case of an organic light-receiving element configured such that light enters the light-receiving layer 4 only from the side of the second electrode 6, the transmission characteristics of the first electrode 1 are not important. Therefore, examples of the material used for the first electrode in this case include gold, iridium, molybdenum, palladium, platinum, etc.

[0075] [Hole transport promoting layer 2] A hole transport promoting layer 2 is provided between the first electrode 1 and the hole transport layer 3 described later. The hole transport promoting layer 2 is provided to promote the hole transport from the hole transport layer 3 to the first electrode 1. The hole transport promoting layer 2 contains a compound having a partial structure represented by the general formula (Q), or a compound represented by the general formula (1) or the general formula (2). In addition, compounds other than the above compounds can also be contained. Examples of the compounds that can be contained in the hole transport promoting layer 2 include conventionally known hole transport materials, and the compounds exemplified for the hole transport layer 3 described later.

[0076] [Hole transport layer 3] A hole transport layer 3 is provided between the hole transport promoting layer 2 and the light-receiving layer 4. The hole transport layer 3 serves to transport the holes generated in the light-receiving layer 4 from the light-receiving layer 4 to the first electrode 1 and to block the electrons generated in the light-receiving layer 4 from moving toward the first electrode 1 side. Depending on the application, it may also serve to block electron injection from the first electrode 1.

[0077] The hole transport layer 3 may have a single-layer structure composed of one or more materials, or may have a laminated structure composed of a plurality of layers of the same composition or different compositions.

[0078] The hole transport layer 3 preferably contains 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, chrysenedithiophene compounds, benzothienobenzothiophene compounds, indolocarbazole compounds, etc. Among these, fluorene compounds, naphthodithiophene compounds, naphthothienothiophene compounds, benzodifuran compounds, benzothiophene compounds, naphthobisbenzothiophene compounds, chrysenedithiophene compounds, benzothienobenzothiophene compounds, indolocarbazole compounds, etc. are preferred, and particularly fluorene compounds, chrysenedithiophene compounds, benzothienobenzothiophene compounds, indolocarbazole compounds are preferred.

[0079] Specific examples of well-known hole transport materials include N,N'-bis(1-naphthyl)-1,1-biphenyl-4,4'-diamine (NPD), 9,9'-(9,9'-spirobi[9H-fluorene]-2,7'-diyl)bis[9H-carbazole], 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene (DiPh-BTBT), benzo[1,2-b:3,4-b':5,6-b'']trifuran compounds, benzo[1,2-b:3,4-b':5,6-b'']trithiophene compounds, naphtho[1,2-b:5,6-b']dithiophene, naphtho[2,3-b]naphtho[2',3':4,5]thieno[2,3-d]thiophene, benzo[1,2-b:4,5-b']difuran, benzo[1,2-b:4,5-b']dithiophene, benzo[1,2-b:4,5-b']bis[1]benzothiophene, naphtho[1,2-b:5,6-b']bis[1]benzothiophene, chryseno[1,2-b:8,7-b']dithiophene, [1]benzothieno[3,2-b][1]benzothiophene, the compounds (ic-1), (ic-2) and (ic-3) shown below, and the like.

[0080] [Chemical formula]

[0081] [Light-receiving layer 4] A light-receiving layer 4 is provided between the hole transport layer 3 and the electron transport layer 5 described later. Examples of materials for the light-receiving layer 4 include materials having a photoelectric conversion function.

[0082] The light-receiving layer 4 may have a single-layer structure composed of one kind or two or more kinds of materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. Examples of materials used for the light-receiving layer 4 having a single-layer structure composed of one kind of material include, for example, (1) coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives, and the like. Examples of materials used for the light-receiving layer 4 having a single-layer structure composed of two materials include, for example, the combinations of (i) coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives, and (ii) fullerene and its derivatives described above. The light-receiving layer 4 made of these materials may be formed by vapor deposition in a state where the powders are previously mixed, or may be formed by co-vapor deposition at an arbitrary ratio. Examples of materials used for the light-receiving layer 4 having a single-layer structure composed of three materials include combinations of (i) coumarin and its derivatives, quinacridone and its derivatives, phthalocyanine and its derivatives, (ii) fullerene and its derivatives, and (iii) hole transport materials described above. The light-receiving layer 4 made of these materials may be formed by vapor deposition in a state where the powders are previously mixed, or may be formed by co-vapor deposition at an arbitrary ratio.

[0083] Specific examples of (i) 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). Specific examples of (ii) fullerene and its derivatives include

[60] fullerene,

[70] fullerene, and [6,6]-phenyl-C61-butyric acid methyl ester (

[60] PCBM). (iii) Preferred compounds and specific examples of hole transport materials include the same ones as those described for the hole transport layer 3 above.

[0084] Moreover, the material having a photoelectric conversion function is not limited to being contained only in the light-receiving layer. For example, the material having a photoelectric conversion function may be contained in a layer (hole transport layer 3 or electron transport layer 5) adjacent to the light-receiving layer 4.

[0085] [Electron transport layer 5] An electron transport layer 5 is provided between the light-receiving layer 4 and the second electrode 6 described below. The electron transport layer 5 serves to transport the electrons generated in the light-receiving layer 4 to the second electrode 6 and to block the movement of holes from the second electrode 6, which is the destination of the electrons, to the light-receiving layer 4. Depending on the application, it may also serve to block hole injection from the second electrode 6.

[0086] In addition, known electron transport materials can be incorporated into the electron transport layer 5. Examples of known electron transport materials include fullerene, fullerene 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), Bphen (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 diimide, and N,N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxylic diimide.

[0087] The electron transport layer 5 may have a single-layer structure composed of one or more materials, or a laminated structure composed of multiple layers of the same composition or different compositions.

[0088] [Second Electrode 6] The second electrode 6 is provided on the electron transport layer 5. Examples of the material of the second electrode 6 include indium tin oxide (ITO), indium zinc oxide (IZO), sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2O3) mixture, indium, lithium / aluminum mixture, gold, platinum, rare earth metals, molybdenum oxide, and the like. Note that the first electrode 1 and the second electrode 6 may be the same or different from each other.

[0089] [Method for forming each layer] Each layer excluding the first electrode 1 and the second electrode 6 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) into a thin film by a known method such as a vacuum evaporation method, a spin coating method, a casting method, or an LB (Langmuir-Blodgett method). There is no particular limitation on the film thickness of each layer formed in this way, and it can be appropriately selected according to the situation. Usually, it is in the range of 5 nm or more and 5 μm or less.

[0090] The first electrode 1 and the second electrode 6 can be formed by thinning the electrode material into a thin film by a method such as evaporation or sputtering. A pattern may be formed through a mask having a desired shape during evaporation or sputtering, or a pattern having a desired shape may be formed by photolithography after forming a thin film by evaporation, sputtering, or the like.

[0091] The film thickness of the first electrode 1 and the second electrode 6 is preferably 1 μm or less, and more preferably 10 nm or more and 200 nm or less.

[0092] The first electrode 1 and the second electrode 6 may have the materials constituting them swapped as necessary (also referred to as an inverted structure). In the case of such a structure, the organic light-receiving element is configured such that light passes through the second electrode 6 and is incident on the light-receiving layer 4.

[0093] The imaging device provided with the organic light-receiving element of this embodiment can be applied to, for example, the imaging elements of digital cameras, digital video cameras, and the imaging elements incorporated in mobile phones and the like.

Example

[0094] Hereinafter, the present invention will be described in more detail based on examples, but the present invention should not be construed as being limited in any way by these examples.

[0095] <Synthesis Example> [Synthesis Example 1: Synthesis of Compound (A-37)]

Chemical formula

[0096] Under an argon stream, ninhydrin (2.00 g, 11.2 mmol) and 1,2-diamino-4,5-dicyanopyrazine (1.78 g, 11.2 mmol) were suspended in a mixed solvent of 58 mL of water, 88 mL of ethanol, and 4 mL of acetic acid, and heated at 80 °C for 17 hours. After allowing to cool to room temperature, water was added to the reaction mixture. The resulting solid was collected by filtration and purified by recrystallization from toluene to obtain 11-oxo-11H-indeno[1,2-b]quinoxaline-7,8-dicarbonitrile represented by the above formula (2.61 g, yield 82%). 1 HNMR (DMSO-d6) δ (ppm): 7.84 (t, J = 7.5 Hz, 1H), 7.96 (dd, J = 7.6, 1.2 Hz, 1H), 8.00 (brd, J = 7.6 Hz, 1H), 8.19 (brd, J = 7.5 Hz, 1H), 8.99 (s, 1H), 9.09 (s, 1H)

[0097]

Chemical formula

[0098] Under an argon stream, 11-oxo-11H-indeno[1,2-b]quinoxaline-7,8-dicarbonitrile (2.00 g, 7.09 mmol) and malononitrile (0.56 g, 8.51 mmol) obtained above were suspended in 142 mL of DMF and stirred at room temperature for 17 hours. 100 mL of water was added to the resulting reaction mixture. The resulting solid was collected by filtration and purified by recrystallization from a mixed solvent of toluene and methanol to obtain the target compound (A-37) (2.20 g, yield 94%). 1 HNMR (DMSO-d6) δ (ppm): 7.96 (brs, 2H), 8.25 (brd, J = 7.1 Hz, 1H), 8.52 (brd, J = 7.0 Hz, 1H), 8.97 (brs, 1H), 9.03 (brs, 1H)

[0099] [Synthesis Example 2: Synthesis of Compound (A-55)]

Chemical Structure

[0100] Under an argon stream, 9-oxo-9H-indeno[1,2-b]pyrazine-1,3-dicarbonitrile (10.0 g, 43.1 mmol) was suspended in a mixed solvent of 120 mL of trifluoroacetic acid and 50 mL of sulfuric acid and cooled to 0 °C. To the resulting mixed solution, NBS (8.43 g, 47.4 mmol) was added and stirred for 20 minutes, and then stirred at room temperature for 22 hours. 300 mL of water was added to the resulting mixed solution, and the resulting solid was collected by filtration. The resulting solid was washed with acetonitrile to obtain 7-bromo-9-oxo-9H-indeno[1,2-b]pyrazine-1,3-dicarbonitrile represented by the above formula (3.18 g, yield 24%). 1 HNMR (CDCl3) δ (ppm): 7.94 (d, J = 8.1 Hz, 1H), 8.00 (dd, J = 8.0, 1.8 Hz, 1H), 8.11 (dd, J = 1.8, 0.5 Hz, 1H)

[0101] [Chemical]

[0102] Under an argon stream, 7-bromo-9-oxo-9H-indeno[1,2-b]pyrazine-1,3-dicarbonitrile (0.60 g, 1.93 mmol) obtained above and malononitrile (0.15 g, 2.31 mmol) were suspended in 100 mL of DMF and stirred at room temperature for 17 hours. 300 mL of water was added to the resulting reaction mixture. The resulting solid was collected by filtration and purified by recrystallization from a mixed solvent of toluene and methanol to obtain the target compound (A-55) (0.45 g, yield 65%). 1 HNMR (CDCl3) δ (ppm): 8.01 (s, 1H), 8.01 (s, 1H), 8.74 (s, 1H)

[0103] [Fabrication and Evaluation of Hole-Only Device 1] [Device Example 1] A hole-only device having a structure consisting of a first electrode / hole injection layer / hole transport layer / hole transport promoting layer / second electrode was fabricated, and the hole transport characteristics of the device were evaluated. (First Electrode) As a substrate having a first electrode on its surface, a glass substrate with an ITO transparent electrode patterned in stripes with an ITO film (film thickness 110 nm) was prepared. After washing this substrate with isopropyl alcohol, surface treatment was performed by ozone ultraviolet cleaning.

[0104] (Preparation for Vacuum Deposition) On the surface of the substrate subjected to the above surface treatment where the ITO film was formed, vacuum deposition of each layer was performed by the vacuum deposition method, and each layer was laminated and formed. First, the above glass substrate was introduced into a vacuum deposition chamber and evacuated to 1.0×10 -4 Pa. Then, they were respectively fabricated according to the film formation conditions of each layer in the following order.

[0105] (Fabrication of Hole Injection Layer) 1 nm of MoO3 was deposited on the ITO film to fabricate a hole injection layer. (Fabrication of Hole Transport Layer) Sublimation-purified N,N’-bis(1-naphthyl)-1,1-biphenyl-4,4’-diamine (NPD) shown below was deposited to a thickness of 30 nm to fabricate a hole transport layer. (Fabrication of Hole Transport Promotion Layer) Sublimation-purified compound (A-19) shown below was deposited to a thickness of 15 nm to fabricate a hole transport promotion layer. Compound (A-19) was synthesized according to the method disclosed in International Publication No. WO2008 / 072586.

[0106] (Fabrication of Second Electrode) Ag was deposited to a thickness of 80 nm to fabricate a two-layer second electrode.

[0107] [Chemical Formula]

[0108] (Evaluation of Hole Transport Ability of Hole-Only Device) A positive and a negative electric field were applied to the first and second electrodes of the hole-only device of Device Example 1, respectively, and the voltage value at a current density of 10 mA / cm 2 was measured. The obtained results are shown in Table 1.

[0109] [Device Example 2] A hole-only device was fabricated in the same manner as in Device Example 1, except that compound (A-1) shown below was used instead of compound (A-19) used in the fabrication of the hole transport promotion layer. Compound (A-1) was synthesized according to the method disclosed in International Publication No. WO2008 / 072586. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Device Example 1. The results are shown in Table 1.

[0110] [Chemical Formula]

[0111] [Device Comparative Example 1] In Example 1, a hole-only device was fabricated in the same manner as in Device Example 1, except that the triazine derivative (NPT) shown below was used instead of the compound (A-19) used in the fabrication of the hole transport promoting layer. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Device Example 1. The results are shown in Table 1.

[0112] [Chemical formula]

[0113] [Device Comparative Example 2] In Device Example 1, a hole-only device was fabricated in the same manner as in Device Example 1, except that it did not have a hole transport promoting layer. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Device Example 1. The results are shown in Table 1.

[0114] [Device Comparative Example 3] In Device Example 1, a hole-only device was fabricated in the same manner as in Device Example 1, except that 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN) shown below was used instead of the compound (A-19) used in the fabrication of the hole transport promoting layer. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Device Example 1. The results are shown in Table 1.

[0115] [Chemical formula]

[0116] [Table 1]

[0117] [Fabrication and Evaluation of Hole-Only Device 2] [Device Example 3] A hole-only device having a structure composed of a first electrode / hole injection layer / hole transport layer / hole transport promotion layer / second electrode was fabricated, and the hole transport characteristics of the device were evaluated. (First electrode) As a substrate having the first electrode on its surface, a glass substrate with an ITO transparent electrode in which an ITO film (film thickness: 110 nm) was patterned in a stripe shape was prepared. After washing this substrate with isopropyl alcohol, surface treatment was performed by ozone ultraviolet cleaning. (Preparation for vacuum deposition) Among the two surfaces of the substrate subjected to the above surface treatment, on the surface where the ITO film was formed, each layer was deposited by vacuum deposition using a vacuum deposition method, and each layer was laminated and formed. First, the glass substrate was introduced into a vacuum deposition chamber and evacuated to 1.0×10 -4 Pa. Then, they were respectively fabricated according to the film formation conditions of each layer in the following order. (Fabrication of hole injection layer) MoO3 was deposited on the ITO film to a thickness of 1 nm to fabricate a hole injection layer. (Fabrication of hole transport layer) The sublimation-purified N,N'-bis(1-naphthyl)-1,1-biphenyl-4,4'-diamine (NPD) mentioned above was deposited to a thickness of 100 nm to fabricate a hole transport layer. (Fabrication of hole transport promotion layer) The sublimation-purified compound (A-19) mentioned above was deposited to a thickness of 10 nm to fabricate a hole transport promotion layer. (Fabrication of second electrode) Au was deposited to a thickness of 80 nm to fabricate a two-layer second electrode.

[0118] (Evaluation of hole transport ability of hole-only device) A positive and a negative electric field were respectively applied to the first electrode and the second electrode of the hole-only device of Device Example 3, and the voltage value at a current density of 10 mA / cm 2 was measured. The obtained results are shown in Table 2.

[0119] [Device Example 4] In Device Example 1, a hole-only device was fabricated in the same manner as in Device Example 3, except that the aforementioned compound (A-1) was used instead of the compound (A-19) used for fabricating the hole transport promoting layer. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Example 3. The results are shown in Table 2.

[0120] [Device Comparative Example 4] In Device Example 3, a hole-only device was fabricated in the same manner as in Device Example 3, except that the aforementioned NPT was used instead of the compound (A-19) used for fabricating the hole transport promoting layer. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Device Example 3. The results are shown in Table 2.

[0121] [Device Comparative Example 5] In Device Example 3, a hole-only device was fabricated in the same manner as in Device Example 3, except that it did not have a hole transport promoting layer. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Device Example 3. The results are shown in Table 2.

[0122] [Device Comparative Example 6] In Example 3, a hole-only device was fabricated in the same manner as in Device Example 3, except that the aforementioned HAT-CN was used instead of the compound (A-19) used for fabricating the hole transport promoting layer. The hole transport ability of the obtained hole-only device was evaluated in the same manner as in Device Example 3. The results are shown in Table 2.

[0123]

Table 2

[0124] From the results in Tables 1 and 2, it can be seen that by using A-1 or A-19 in combination with a hole transport material as a hole transport promoting material, the hole transport ability is significantly improved.

[0125] [Fabrication and Evaluation of Photoelectric Conversion Element] [Element Example 5] A photoelectric conversion element 100 having a laminated structure composed of a substrate / second electrode 6 / electron transport layer 5 / photoelectric conversion layer 4 / hole transport layer 3 / hole transport promoting layer 2 / first electrode 1 was fabricated, and the dark current and external quantum efficiency of the photoelectric conversion element were evaluated. (Preparation of substrate and second electrode 6) As a substrate provided with the second electrode on its surface, a glass substrate with an ITO transparent electrode in which a 2 mm-wide indium tin oxide (ITO) film (film thickness 110 nm) was patterned in a stripe shape was prepared. Then, this substrate was washed with isopropyl alcohol and then surface-treated by ozone ultraviolet cleaning. (Preparation for vacuum evaporation) On the substrate subjected to the surface treatment after cleaning, each layer was formed by vacuum evaporation using the vacuum evaporation method, and each layer was laminated. First, the glass substrate was introduced into the vacuum evaporation chamber and the pressure was reduced to 7.0×10 -5 Pa. Then, they were respectively fabricated according to the film formation conditions of each layer in the following order. (Fabrication of electron transport layer 5) The sublimation-purified compound 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-methylpyrimidine was formed into a film with a thickness of 10 nm at a rate of 0.03 nm / second to fabricate the electron transport layer 5. (Fabrication of photoelectric conversion layer 4) N,N-dimethylquinacridone and fullerene C60 were formed into a film with a thickness of 125 nm at a ratio of 4:1 (mass ratio) to fabricate the photoelectric conversion layer 4. The film formation rate was 0.13 nm / second. (Fabrication of hole transport layer 3) N,N'-di-1-naphthyl-N,N'-diphenylbenzidine (α-NPD) was formed into a film with a thickness of 10 nm at a rate of 0.10 nm / second to fabricate the hole transport layer 3. (Fabrication of hole transport promoting layer 2) Compound (A-19) was formed into a film with a thickness of 10 nm at a rate of 0.20 nm / second to fabricate the hole transport promoting layer 2. (Fabrication of first electrode 1) Finally, a metal mask was arranged so as to be perpendicular to the ITO stripes on the substrate, and the first electrode 1 was formed. The first electrode was formed by depositing 80 nm of Au. The deposition rate of Au was 0.1 nm / second.

[0126] As described above, a photoelectric conversion element 100 having an area of 4 mm as shown in FIG. 1 was fabricated. When a voltage of 2.5 V as an absolute value was applied to the photoelectric conversion element fabricated as described above so that electrons were transported to the second electrode 6 side and holes were transported to the first electrode 1 side, the current in the dark (dark current) and the external quantum efficiency were evaluated. The dark current was measured using a source measure unit 2636B manufactured by Keithley Instruments, Inc. For the measurement of the external quantum efficiency, a solar cell spectral sensitivity measurement device (manufactured by Soma Optical Co., Ltd.) was used. The wavelength of the irradiation light was 560 nm, and the measurement was performed at an intensity of 50 μW / cm 2 2 . The results are shown in Table 3. The dark current and the external quantum efficiency are relative values based on the results in Element Comparative Example 7 (1.00) and (100) described later, respectively. A lower numerical value of the dark current indicates better performance, and a higher numerical value of the external quantum efficiency indicates better performance.

[0127] [Element Comparative Example 7] In Element Example 5, a photoelectric conversion element of Element Comparative Example 7 was fabricated in the same manner as in Element Example 5, except that the hole transport promoting layer 2 was not provided, and the dark current and the external quantum efficiency were measured in the same manner as in Element Example 5. The results are shown in Table 3.

[0128] [Element Comparative Example 8] In the fabrication of the hole transport promoting layer 2 of Element Example 5, a photoelectric conversion element of Element Comparative Example 8 was fabricated in the same manner as in Element Example 5, except that HAT-CN was used instead of the compound (A-19), and the dark current and the external quantum efficiency were measured in the same manner as in Element Example 5. The results are shown in Table 3.

[0129]

Table 3

[0130] ​As shown in Table 3, in the device of the device example using the material for the photoelectric conversion element for a specific imaging device, the dark current was suppressed and a high external quantum efficiency was obtained as compared with the device of the device comparative example.

[0131] <Evaluation of the film quality of the hole transport promoting layer> [Reference Example 1] In Device Example 1, for the laminate in which a hole transport promoting layer was formed on the first electrode, the arithmetic mean roughness (nm) of the surface of the hole transport promoting layer was measured using an atomic force microscope (manufactured by Shimadzu Corporation, SPM-9600). The results are shown in FIG. 2 together with the AFM image of the hole transport promoting layer.

[0132] [Comparative Reference Example 1] In Reference Example 1, instead of the compound (A-19) used for the production of the hole transport promoting layer, a laminate in which 30 nm of HAT-CN was formed on the first electrode was produced, and the film quality was evaluated in the same manner as in Reference Example 1. The results are shown in FIG. 2. Note that HAT-CN is a typical hole injection material for organic EL.

[0133]

Chemical formula

[0134] From the results of FIG. 2, it can be seen that the hole transport promoting layer of Reference Example 1 produced using the compound (A-19) has a flatter film quality than the hole transport promoting layer of Comparative Reference Example 1 produced using HAT-CN. Since the film quality is flat, in the hole-only device of Device Example 1, the adhesion to the adjacent layer is improved, and as a result, it is considered that hole transport was efficiently performed.

[0135] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the essence and scope of the present invention.

[0136] The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2021-112797 filed on July 7, 2021 are hereby incorporated by reference in their entirety and made a part of the disclosure of the specification of the present invention.

Explanation of Reference Numerals

[0137] 1 First electrode 2 Hole transport promoting layer 3 Hole transport layer 4 Light-receiving layer (photovoltaic conversion layer) 5 Electron transport layer 6 Second electrode 10 Organic layer 100 Organic light-receiving element

Claims

1. A hole transport promoting material containing a compound represented by the following general formula (2). 【Chemical Formula 1】 (In formula (2), Y ３ 、 Y ４ 、 Y ５ and Y ６ each independently represents a nitrogen atom or C-H; Y ３ 、 Y ４ 、 Y ５ and Y ６ Among them, at least one is a nitrogen atom; Ar １ 、 Ar ２ and Ar ３ are each independently, a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; X １ is any of the divalent groups represented by the following formula (a) or (b).) 【Chemical 2】 (In formula (a), Ar ４ and Ar ５ are each independently a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group.)

2. Ar ２ and Ar ３ The hole transport promoting material according to claim 1, wherein is a cyano group.

3. Ar ４ and Ar ５ The hole transport promoting material according to claim 1 or 2, wherein Ar is a cyano group.

4. A material for a light-receiving element containing a compound represented by the following general formula (2). 【Chemical 3】 (In formula (2), Y ３ 、 Y ４ 、 Y ５ and Y ６ each independently represents a nitrogen atom or C-H; Y ３ 、Y ４ 、Y ５ and Y ６ Among them, at least one is a nitrogen atom; Ar １ 、 Ar ２ and Ar ３ are each independently, a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; X １ is either a divalent group represented by the following formula (a) or (b). [Chemical Formula 4] (In formula (a), Ar ４ and Ar ５ are each independently a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group.)

5. The material for a light-receiving element according to claim 4, which is a material for an organic imaging element for a light-receiving element.

6. The material for a light-receiving element according to claim 4 or 5, which is a hole transport promoting material for an organic imaging element for a light-receiving element.

7. Ar ２ and Ar ３ The material for a light-receiving element according to claim 4 or 5, wherein Ar is a cyano group.

8. Ar ４ and Ar ５ The material for a light-receiving element according to claim 4 or 5, wherein is a cyano group.

9. A cyano compound represented by the following general formula (3), general formula (4), general formula (5), or general formula (6). 【Chemical Formula 5】 (In formulas (3) and (5), Y １ and Y ２ each independently represents a nitrogen atom or C—H; Y １ and Y ２ wherein at least one of them is a nitrogen atom; Ar ６ is a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; Ar ２ and Ar ３ are each independently a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, An aryl group having 6 to 18 carbon atoms substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group. In formulas (4) and (6), Y ３ 、Y ４ 、Y ５ and Y ６ each independently represents a nitrogen atom or C-H; Y ３ 、Y ４ 、Y ５ and Y ６ at least one of which is a nitrogen atom; Ar ６ is a cyano group, a fluoro group, a chloro group, a bromo group, an iodo group a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; However, Y ５ and Y ６ in the case of C-H, Ar ６ may be a hydrogen atom; Ar ２ and Ar ３ each independently a hydrogen atom, a cyano group, a fluoro group, a fluoroalkyl group, an aryl group having 6 to 18 carbon atoms substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group. )

10. Ar ２ and Ar ３ The cyano compound according to claim 9, wherein Ar and Ar are each a cyano group.

11. An organic light-receiving element comprising a first electrode and a second electrode, having an organic layer between the first electrode and the second electrode, wherein the organic layer has at least a light-receiving layer, a hole transport layer, and a hole transport promoting layer, and the hole transport promoting layer contains a compound having a partial structure represented by the following formula (Q). (The formula (Q) has a condensed ring structure condensed only by a 5-membered ring or a 6-membered ring. In the part where the solid line and the broken line are parallel, each independently represents a single bond or a double bond, and * represents a bond. The bond is bonded to a nitrogen atom or a carbon atom constituting the condensed ring structure, provided that at least one of the bonds is bonded to the nitrogen atom. ) 【Chemical Formula 6】

12. An organic light-receiving element comprising a first electrode and a second electrode, having an organic layer between the first electrode and the second electrode, wherein the organic layer has at least a light-receiving layer, a hole transport layer, and a hole transport promoting layer, and the hole transport promoting layer contains a compound represented by the following general formula (1) or general formula (2). (In formulas (1) and (2), 【Chemical Formula 7】 a hydrogen atom, Y １ 、 Y ２ 、 Y ３ 、 Y ４ 、 Y ５ and Y ６ each independently represents a nitrogen atom or C-H; Y １ and Y ２ at least one of which is a nitrogen atom; Y ３ 、 Y ４ 、 Y ５ and Y ６ Among them, at least one is a nitrogen atom; Ar １ 、 Ar ２ and Ar ３ are each independently, a cyano group, a fluoro group, a fluoroalkyl group, a fluoro group, a fluoroalkyl group, or an aryl group having 6 to 18 carbon atoms which may be substituted with a cyano group, or a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; (In formula (a), X １ is either a divalent group represented by the following formula (a) or (b). [Chemical Formula 8] a cyano group, Ar ４ and Ar ５ are each independently, a fluoro group, a fluoroalkyl group, a fluoro group, a fluoroalkyl group, or an aryl group having 6 to 18 carbon atoms which may be substituted with a cyano group, or An aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or A heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group. )

13. The organic light-receiving element according to claim 11 or 12, wherein the hole transport layer and the hole transport promoting layer are adjacent to each other.

14. The organic light-receiving element according to claim 11 or 12, wherein the light-receiving layer is a layer composed of at least two components.

15. A hole transport promoting material for a light-receiving element used in a light-receiving element in which a hole transport promoting layer containing a hole transport promoting material is provided between a hole transport layer responsible for hole transport and an electrode to which holes are transported, The hole transport promoting material contains a compound represented by the following general formula (1). 【Chemical Formula 9】 (In formula (1), Y １ and Y ２ each independently represents a nitrogen atom or C-H; Y １ and Y ２ at least one of which is a nitrogen atom; Ar １ 、 Ar ２ and Ar ３ are each independently, A hydrogen atom, A cyano group, A fluoro group, A fluoroalkyl group, An aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or A heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; X １ is either a divalent group represented by the following formula (a) or (b).) 【Chemical Formula 10】 (In formula (a), Ar ４ and Ar ５ are each independently A cyano group, A fluoro group, A fluoroalkyl group, An aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or A heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group. )

16. A material for a light-receiving element used in a light-receiving element in which a layer containing a material for a light-receiving element is provided between a hole transport layer responsible for hole transport and an electrode to which holes are transported, The material for a light-receiving element contains a compound represented by the following general formula (1). 【Chemical 11】 (In formula (1), Y １ and Y ２ each independently represents a nitrogen atom or C-H; Y １ and Y ２ at least one of which is a nitrogen atom; Ar １ 、 Ar ２ and Ar ３ are each independently, A hydrogen atom, A cyano group, A fluoro group, A fluoroalkyl group, An aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or A heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group; n represents an integer from 1 to 4; X １ is either a divalent group represented by the following formula (a) or (b). 【Chemical 12】 (In formula (a), Ar ４ and Ar ５ are each independently A cyano group, A fluoro group, A fluoroalkyl group, An aryl group having 6 to 18 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group, or represents a heteroaryl group having 3 to 17 carbon atoms which may be substituted with a fluoro group, a fluoroalkyl group, or a cyano group.)

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