Compound, organic thin film, photoelectric conversion element, imaging element, photosensor, and solid-state imaging device

Abstract

A compound represented by the following formula (1) (R1 to R4 are each independently a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group, etc.).

Description

Technical Field

[0001] The present invention relates to a compound, an organic thin film, a photoelectric conversion element, an imaging element, a photosensor, and a solid-state imaging device. Background Art

[0002] Conventional technologies for photoelectrically converting visible light into electrical signals are well known and are used, for example, in imaging elements. Such imaging elements are incorporated into solid-state imaging devices such as CCD (Charge Coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors. In recent years, as pixel size in solid-state imaging devices has been reduced, research has been conducted on organic photoelectric conversion films to address this trend. For example, Patent Documents 1 and 2 disclose organic photoelectric conversion films composed of subphthalocyanines and imides.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-32754

[0006] Patent Document 2: Japanese Patent Application No. 2018-512423

[0007] Patent Document 3: Japanese Patent Application No. 2014-506736 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Solid-state imaging devices are required to have both high spectroscopic selectivity and high S / N ratio. Therefore, solid-state imaging devices are expected to have high external quantum efficiency (EQE) and low dark current characteristics. In order to achieve both, there is a known method of configuring an electron transport layer and a hole blocking layer between the photoelectric conversion part and the electrode part, and / or configuring a hole transport layer and an electron blocking layer. Here, the electron transport layer, hole blocking layer and electron blocking layer widely used in the field of organic electronic devices are arranged at the interface between the electrode or the conductive film and other films in the film constituting the device. These layers respectively play the role of controlling the reverse movement of holes or electrons and adjusting unnecessary hole or electron leakage. As a material for such a layer, for example, Patent Document 3 discloses an example of using naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTCDA).

[0010] However, conventional hole-blocking layers and electron-blocking layers, such as those disclosed in Patent Document 3, have room for further improvement in suppressing leakage current in the dark.

[0011] The present invention aims to provide a novel compound and photoelectric conversion element material that can suppress leakage current in the dark and are particularly useful as a photoelectric conversion element material, as well as an organic thin film, a photoelectric conversion element, an imaging element, a photosensor, and a solid-state imaging device containing the compound.

[0012] Solutions for solving problems

[0013] The present invention is as follows.

[0014] [1] A compound represented by the following formula (1).

[0015]

[0016] (R1, R2, R3 and R4 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, and a monovalent heterocyclic group, and any adjacent R1, R2, R3 and R4 may be part of a fused aliphatic ring or a fused aromatic ring. The fused aliphatic ring and the fused aromatic ring may contain one or more atoms other than carbon.)

[0017] [2] The aforementioned compound, wherein the lowest unoccupied orbital energy level of the compound represented by the aforementioned formula (1) obtained by density functional theory is -6.00 eV or more and -3.80 eV or less.

[0018] [3] The above compound, which is a material for a photoelectric conversion element.

[0019] [4] An organic thin film comprising the above compound.

[0020] [5] The organic thin film has a light absorption band with a maximum absorption wavelength below 450 nm.

[0021] [6] A photoelectric conversion element comprising a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film.

[0022] The photoelectric conversion film includes the above-mentioned material for a photoelectric conversion element.

[0023] [7] A photoelectric conversion element comprising a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film.

[0024] The photoelectric conversion film includes the organic thin film.

[0025] [8] The above-mentioned photoelectric conversion element, wherein the photoelectric conversion film comprises a photoelectric conversion layer and an auxiliary layer,

[0026] The auxiliary layer is formed of only the organic thin film, or is formed of a plurality of films including the organic thin film.

[0027] [9] An imaging element comprising the above-mentioned photoelectric conversion element.

[0028]

[10] The above-mentioned imaging element is formed by stacking two or more of the above-mentioned photoelectric conversion elements.

[0029]

[11] An imaging element comprising a plurality of the above-mentioned photoelectric conversion elements arranged in an array.

[0030]

[12] A light sensor comprising the above-mentioned imaging element.

[0031]

[13] A solid-state imaging device comprising the above-mentioned imaging element.

[0032] Effects of the Invention

[0033] According to the present invention, there can be provided a novel compound and a photoelectric conversion element material that are particularly useful as a photoelectric conversion element material, as well as an organic thin film, a photoelectric conversion element, an imaging element, a photosensor, and a solid-state imaging device containing the compound. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic cross-sectional view partially showing an example of the photoelectric conversion element of the present invention. DETAILED DESCRIPTION

[0035] Hereinafter, the mode for implementing the present invention (hereinafter referred to as "this embodiment") will be described in detail with reference to the accompanying drawings as needed, but the present invention is not limited to the following embodiment. The present invention can be modified in various ways without departing from the scope of its purpose. It should be noted that in the accompanying drawings, the same symbols are marked for the same elements, and repeated descriptions are omitted. In addition, unless otherwise specified, the positional relationships such as up and down, left and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown in the drawings.

[0036] (Compound)

[0037] The compound of this embodiment is represented by the following formula (1) (hereinafter, this compound is also referred to as "compound (1)").

[0038]

[0039] Here, R1, R2, R3, and R4 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted linear, branched, or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, and a monovalent heterocyclic group, and any adjacent R1, R2, R3, and R4 may be part of a fused aliphatic ring or a fused aromatic ring. The fused aliphatic ring and the fused aromatic ring may contain one or more atoms other than carbon.

[0040] This compound (1) can suppress the leakage current in the dark, and in particular, shows excellent properties as a photoelectric conversion element material. The reason is still uncertain, but the present inventors consider it as follows. Among them, the reason is not limited to the following content. That is, compound (1) has a cyano group in its molecular structure, so that the energy level of the lowest unoccupied orbital of compound (1) decreases, and the energy level of the highest occupied orbital also decreases. As a result, compound (1) maintains a low energy level of the lowest unoccupied orbital and has a high energy gap. Thus, compound (1) can suppress the leakage current in the dark, and can obtain excellent properties as a photoelectric conversion element material.

[0041] Examples of the halogen atom include a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), and an iodine atom (I).

[0042] The straight-chain alkyl group may be a straight-chain alkyl group having 1 to 12 carbon atoms, and examples thereof include methyl (Me), ethyl (Et), n-propyl (n-Pr), n-butyl (n-Bu), n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl and n-dodecyl.

[0043] The branched alkyl group may be a branched alkyl group having 1 to 12 carbon atoms, and examples thereof include isopropyl (i-Pr), sec-butyl (s-Bu), tert-butyl (t-Bu), isopentyl, sec-pentyl, 3-pentyl, neopentyl, isohexyl, isooctyl, isononyl, isodecyl, and isododecyl. Furthermore, the linear or branched alkyl group may have a substituent. Examples of the substituent include halogen atoms such as fluorine atoms, monovalent groups having aromatic rings such as benzyl, naphthyl, and phenoxy groups, monovalent groups having heteroatoms such as alkoxy groups, aminoalkyl groups and thioalkyl groups, monovalent groups having heterocyclic rings such as pyridyl groups, hydroxyl groups, carboxyl groups, amino groups, and thiol groups.

[0044] The cyclic alkyl group may be a cyclic alkyl group having 3 to 10 carbon atoms, and examples thereof include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Furthermore, the cyclic alkyl group may have heteroatoms such as nitrogen, oxygen, and sulfur atoms in its ring. Examples of such cyclic alkyl groups include pyrrolidinyl, oxazolidinyl, pyrazolidinyl, thiazolidinyl, imidazolidinyl, dioxofuranyl, tetrahydrofuranyl, tetrahydrothienyl, piperazinyl, dioxanyl, and morpholinyl. Furthermore, monovalent groups such as hydroxyl, carboxyl, amino, and thiol groups may be bonded to the cyclic alkyl group.

[0045] Thioalkyl groups (-SR; hereinafter, R represents an alkyl group) and thioaryl groups (-SAr; hereinafter, Ar represents an aryl group) may include thioalkyl groups having 1 to 12 carbon atoms in the alkyl group and thioaryl groups having 6 to 16 carbon atoms in the aryl group. Thioalkyl and thioaryl groups may further have substituents such as amino groups, hydroxyl groups, halogen atoms, alkoxy groups, and thioalkyl groups. Examples of such thioalkyl and thioaryl groups include methylthio, ethylthio, phenylthio, tolylthio, aminophenylthio, hydroxyphenylthio, fluorophenylthio, dimethylphenylthio, and methylthiophenylthio.

[0046] The arylsulfonyl group (-SO2-Ar) may be an arylsulfonyl group having 6 to 16 carbon atoms in the aryl group, and examples thereof include benzenesulfonyl, toluenesulfonyl, dimethylbenzenesulfonyl, mesitylenesulfonyl, octylbenzenesulfonyl, and naphthylsulfonyl.

[0047] The aryloxy group (—O—Ar) may be an aryloxy group having 6 to 16 carbon atoms in an aryl group. The aryloxy group may have a substituent such as a cyano group, a halogen atom such as a fluorine atom, a hydroxyl group, an alkoxy group such as a methoxy group, an amino group, an alkylamino group, a thiol group, or an aryloxy group. Examples of such an aryloxy group include a phenoxy group, a cyanophenoxy group, a methylcyanophenoxy group, a dimethylcyanophenoxy group, a fluorocyanophenoxy group, a dicyanophenoxy group, a methoxycyanophenoxy group, a tricyanophenoxy group, a cyanonaphthyloxy group, a dicyanonaphthyloxy group, a 2-methylphenoxy group, a 3-methylphenoxy group, a 4-methylphenoxy group, a fluoromethylphenoxy group, a dimethylphenoxy group, a 3-hydroxyphenoxy group, a fluoro-3-hydroxyphenoxy group, a 2-hydroxyphenoxy group, a fluoro-2-hydroxyphenoxy group, a methoxyphenoxy group, an ethoxyphenoxy group, a fluorophenoxy group, a perfluorophenoxy group, a dimethoxyphenoxy group, an aminophenoxy group, an N,N-dimethylaminophenoxy group, a thiophenoxy group, a (trifluoromethyl)phenoxy group, a naphthyloxy group, a methoxynaphthyloxy group, a fluoronaphthyloxy group, and a phenoxyphenoxy group.

[0048] The alkylsulfonyl group (—SO 2 —R) may be an alkylsulfonyl group having an alkyl group with 1 to 12 carbon atoms, and examples thereof include a methylsulfonyl group, an ethylsulfonyl group, and an n-butylsulfonyl group.

[0049] The alkylamino group (herein, the alkylamino group is -NHR or -NR2, and the two R's may be the same or different) may be an alkylamino group having 1 to 12 carbon atoms in the alkyl group, and examples thereof include methylamino, ethylamino, n-propylamino, n-butylamino, n-pentylamino, n-hexylamino, n-heptylamino, n-octylamino, n-nonylamino, n-decylamino, n-dodecylamino, isopropylamino, sec-butylamino, tert-butylamino, isopentylamino, sec-pentylamino, 3-pentylamino, neopentylamino, isohexylamino, isoheptylamino, isooctylamino, isononylamino, isodecylamino, isododecylamino, dimethylamino, diethylamino, diisopropylamino, and isopropylethylamino.

[0050] As the arylamino group (here, the arylamino group is -NHAr or -NAr2, and the two Ars may be the same as or different from each other), it may be an arylamino group having 6 to 16 carbon atoms, for example, an aniline group, a toluidine group, a dimethylaniline group, an isopropylaniline group, a tert-butylaniline group, a fluoroaniline group, a trifluoromethylaniline group, a bis(trifluoromethyl)aniline group, a pyridylamino group, a methylpyridylamino group, a fluoropyridylamino group, a pyrimidinylamino group and a biphenylamino group.

[0051] The alkoxy group (-OR) may be an alkoxy group having 1 to 12 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentoxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-dodecyloxy group, an isopropoxy group, a sec-butoxy group, a tert-butoxy group, an isopentyloxy group, a sec-pentyloxy group, a 3-pentyloxy group, a neopentyloxy group, an isohexyloxy group, an isooctyloxy group, an isononyloxy group, an isodecyloxy group, and an isododecyloxy group.

[0052] The acylamino group (-NH-COR or -NH-COAr) may have 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group, and may have a halogen atom such as a fluorine atom, an alkoxy group, or a substituent such as a cyano group. Examples of such acylamino groups include acetylamino, propionylamino, benzylamino, methylbenzylamino, dimethylbenzylamino, methoxybenzylamino, cyanobenzylamino, and bis(trifluoromethyl)benzylamino.

[0053] The acyloxy group (-O-COR or -O-COAr) may have 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group. The acyloxy group may further have a halogen atom such as a fluorine atom or a substituent such as a cyano group, and may have a heteroatom such as a nitrogen atom in the aromatic ring. Examples of such acyloxy groups include benzoyloxy, methylbenzoyloxy, dimethylbenzoyloxy, cyanobenzoyloxy, fluorobenzoyloxy, bis(trifluoromethyl)benzoyloxy, pyridinecarboxyl, and methylpyridinecarboxyl groups.

[0054] The aryl group (-Ar) may be an aryl group having 6 to 16 carbon atoms. The aryl group may further have a substituent such as an amino group, a hydroxyl group, a thiol group, a halogen atom such as a fluorine atom, a nitro group, and a cyano group, and may have a heteroatom such as a nitrogen atom in the aromatic ring. Examples of such aryl groups include phenyl, methylphenyl, ethylphenyl, dimethylphenyl, trimethylphenyl, methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, methoxymethylphenyl, aminophenyl, diaminophenyl, aminomethylphenyl, hydroxyphenyl, dihydroxyphenyl, hydroxymethylphenyl, hydroxyethylphenyl, thiophenyl, methylthiophenyl, dithiophenyl, fluorophenyl, fluoromethylphenyl, trifluoromethylphenyl, perfluorophenyl, fluoro(trifluoromethyl)phenyl, bis(trifluoromethyl)phenyl, cyanophenyl, methylcyanophenyl, dimethylcyanophenyl, dicyanophenyl, methoxycyanophenyl, tricyanophenyl, dicyanophenyl, methylcyanopyridyl, (trifluoromethyl)cyanopyridyl, dimethylcyanopyridyl, dicyanopyridyl, methoxycyanopyridyl, tricyanopyridyl, cyanopyridyl, naphthyl, nitrophenyl, dinitrophenyl, nitrofluorophenyl, methylnaphthyl, ethylnaphthyl, dimethylnaphthyl, trimethylnaphthyl, methoxynaphthyl, dimethoxynaphthyl, trimethoxynaphthyl, aminonaphthyl, diaminonaphthyl, aminomethylnaphthyl, hydroxynaphthyl, dihydroxynaphthyl, hydroxymethylnaphthyl, hydroxyethylnaphthyl, thionaphthyl, methylthionaphthyl, dithionaphthyl, fluoronaphthyl, trifluoromethylnaphthyl, perfluoronaphthyl, di(trifluoromethyl)naphthyl, biphenyl, cyanobiphenyl.

[0055] The carboxamide group (herein, the carboxamide group is -CO-NH2, -CO-NHR, -CONR2, the two Rs may be the same as or different from each other, or may be -CONHAr or -CONAr2, and the two Ars may be the same as or different from each other) may be a carboxamide group having 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group, for example, a dimethylcarboxamide group and a diphenylcarboxamide group.

[0056] The alkoxycarbonyl group and the aryloxycarbonyl group (-COOR or -COOAr) may be an alkoxycarbonyl group having 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group, and examples thereof include a methoxycarbonyl group and a phenoxycarbonyl group.

[0057] The monovalent heterocyclic group may be a monovalent heterocyclic group having 3 to 14 carbon atoms, and examples thereof include furyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, oxazolyl, dioxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, triazolyl, indolyl, indolinyl, indolinazinyl, indazolyl, indoleninyl, benzofuranyl, benzothienyl, carbazolyl, diphenyl benzofuranyl, dibenzothiophenyl, pyridinyl, diazinyl, oxazinyl, thiazinyl, dioxazinyl, dithiophenyl, triazinyl, pyrimidinyl, pyrazinyl, pyridazinyl, quinolinyl, isoquinolinyl, cinnolinyl, phthalazinyl, quinazolinyl, naphthyridinyl, purinyl, pteridinyl, acridinyl, phenanthridinyl, phenanthrolinyl, xanthenyl, phenoxazinyl, thianthrenyl, morpholinyl, and phenazinyl.

[0058] In the compound (1) of the present embodiment, although not particularly limited, R1, R2, R3 and R4 are preferably each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group and a monovalent heterocyclic group, more preferably selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group and an optionally substituted linear, branched or cyclic alkyl group, and particularly preferably selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group and an alkyl group substituted with a halogen atom. By making the compound (1) have the above structure, the leakage current in the dark can be further suppressed.

[0059] In the present embodiment, R1, R2, R3 and R4 may be the same or different. From the viewpoint of more effectively and reliably bringing into play the effect of the present invention, there is no particular limitation, and preferably two of R1, R2, R3 and R4 are the same, and more preferably three of R1, R2, R3 and R4 are the same.

[0060] The compound (1) of this embodiment is not particularly limited. From the viewpoint of more effectively and reliably exerting the effects described in the present invention, it is preferred that at least one of R1, R2, R3 and R4 is a hydrogen atom, more preferably at least two or at least three of R1, R2, R3 and R4 are hydrogen atoms, and particularly preferably at least three of R1, R2, R3 and R4 are hydrogen atoms.

[0061] In this embodiment, when at least two of R1, R2, R3 and R4 are hydrogen atoms, there is no particular limitation. From the perspective of more effectively and reliably exerting the effects of the present invention, it is preferred that R1 and R2 are hydrogen atoms or R1 and R4 are hydrogen atoms.

[0062] The compound (1) of the present embodiment is not particularly limited. From the viewpoint of more effectively and reliably exhibiting the effects of the present invention, preferably R3 and R4 are hydrogen atoms, and more preferably R2, R3, and R4 are hydrogen atoms.

[0063] Furthermore, when R2, R3 and R4 are hydrogen atoms, R1 is preferably selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, and an optionally substituted linear, branched or cyclic alkyl group, a thioalkyl group, a thioaryl group, an arylsulfonyl group, an aryloxy group, an alkylsulfonyl group, an alkylamino group, an arylamino group, an alkoxy group, an acylamino group, an acyloxy group, an aryl group, a carboxamide group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group and a monovalent heterocyclic group, more preferably selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group, and an optionally substituted linear, branched or cyclic alkyl group, and particularly preferably selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group, a cyano group and an alkyl group substituted with a halogen atom.

[0064] From the viewpoint of more effectively and reliably exerting the effects of the present invention, the energy level of the lowest unoccupied molecular orbital (LUMO) of the compound (1) of this embodiment obtained by density functional theory is preferably not less than -6.00 eV and not more than -3.80 eV, more preferably not less than -5.50 eV and not more than -3.90 eV. For the compound (1) of this embodiment, the energy level of the lowest unoccupied molecular orbital of the compound (1) can be obtained by molecular simulation using density functional theory (for example, molecular simulation using Gaussian, a quantum chemical calculation program manufactured by Gaussian). In addition, the energy level of the lowest unoccupied molecular orbital obtained by density functional theory of the compound (1) of this embodiment can be adjusted by changing R1, R2, R3 and R4. From the viewpoint of setting the energy level of the lowest unoccupied molecular orbital within the above range, it is preferred that at least one of R1, R2, R3 and R4 is an electron-withdrawing group.

[0065] The molecular weight of the compound (1) of this embodiment is preferably 300 or more, more preferably 350 or more, and further preferably 400 or more. If the molecular weight is 300 or more, the physical property changes caused by the thermal motion of the molecules that may be caused by the heating operation or high-temperature use environment in the manufacturing process of the organic thin film using the compound (1) can be further suppressed. In addition, especially when the compound (1) is formed by vacuum evaporation, the molecular weight of the compound (1) is preferably 1000 or less, more preferably 950 or less, and further preferably 900 or less. If the molecular weight is 1000 or less, the heat energy required for sublimation when the organic thin film of the compound (1) is formed by vacuum evaporation can be suppressed to a lower level. As a result, a good thin film can be formed without thermal degradation of the compound (1). However, when the thin film is formed by solution coating, since such a problem is not easy to occur, the molecular weight of the compound (1) can be greater than 1000.

[0066] The temperature at which the weight loss rate of the compound (1) according to this embodiment upon heating in an inert gas atmosphere becomes within 5% of the weight before heating (hereinafter sometimes referred to as the "5% weight loss temperature") is preferably 200°C or higher, more preferably 250°C or higher. A 5% weight loss temperature of 200°C or higher can further suppress changes in physical properties due to molecular thermal motion, which may occur during heating operations or high-temperature usage environments in organic thin film production processes using the compound (1). The 5% weight loss temperature can be measured by differential thermal analysis.

[0067] The compound (1) of the present embodiment can be obtained by, for example, synthesizing as described later. In the product (100% by mass) obtained by synthesis, the content of compound (1) is preferably 90% by mass or more, more preferably 93% by mass or more, and further preferably 97% by mass or more. By making the content of compound (1) 90% by mass or more, it is possible to more effectively and reliably avoid the situation in which carriers generated by undesirable impurities are captured at impurity energy levels when compound (1) is used in a photoelectric conversion element. As a result, the recombination of carriers can be suppressed to obtain a photoelectric conversion element with more excellent performance. For the determination of the content, liquid chromatography, gas chromatography, elemental analysis, etc. can be listed, as long as it is a known method.

[0068] Preferred combinations of R1, R2, R3, and R4 are shown below, but compound (1) is not limited to these.

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] Specific examples of compound (1) are shown below, but compound (1) is not limited to these.

[0075]

[0076] Compound (1) can be synthesized, for example, according to the following scheme.

[0077]

[0078] More specifically, for example, a commercially available compound (α) can be imidized to obtain compound (1). For example, imidization can be performed by the method described in The Journal of Organic Chemistry, 86, 10501-10516 (2021). In addition, imidization can be performed using a compound into which R1 to R4 are introduced, or R1 to R4 can be introduced after imidization.

[0079] (Materials for photoelectric conversion elements)

[0080] The compound (1) of this embodiment can be used as a photoelectric conversion element material. More specifically, it can be used as a material contained in each layer of the photoelectric conversion element described below. From the perspective of more effectively and reliably exerting the effects of the present invention, the compound (1) is preferably contained in an auxiliary layer, and more preferably contained in at least one of an electron transport layer and a hole blocking layer.

[0081] In addition, the compound (1) of this embodiment can be used directly as a photosensitive material, or it can be mixed with other materials and used as a photosensitive composition. The content of the compound (1) in the photosensitive composition can be 50% by mass or more relative to the total amount of the composition. In addition, its content can be 95% by mass or less, 90% by mass or less, or 80% by mass or less. The materials other than the compound (1) in the above-mentioned photosensitive composition are not particularly limited as long as they are materials generally contained in photosensitive compositions. Examples of such materials include: n-type semiconductor materials, p-type semiconductor materials, and light absorbing materials described later. These can be used alone or in combination of two or more.

[0082] (Organic Film)

[0083] The organic thin film of the present embodiment comprises the compound (1) of the present embodiment or the above-mentioned photoelectric conversion element material. Such an organic thin film can be manufactured by a conventional dry film forming method or a wet film forming method. Specifically, examples include: resistance heating evaporation, electron beam evaporation, sputtering and molecular lamination as vacuum processes, coating methods such as casting, spin coating, dip coating, blade coating, wire rod coating and spraying as solution processes, printing methods such as inkjet printing, screen printing, offset printing and relief printing, and soft lithography methods such as microcontact printing. Generally, for photoelectric conversion element materials, from the viewpoint of ease of processing, it is desired to use them in a process in which the compound is applied in a solution state. However, in the case of a photoelectric conversion element such as a stacked organic thin film, since there is a risk that the coating solution erodes the underlying film, a dry film forming method such as resistance heating evaporation is preferred.

[0084] For example, in a dry film-forming method, a composition is prepared by mixing the photoelectric conversion element material of this embodiment and other materials corresponding to the use of the photoelectric conversion element as needed, and the composition is evaporated onto a substrate or other film under vacuum to obtain an organic thin film. In addition, in a wet film-forming method, a liquid composition is prepared by mixing the photoelectric conversion film of this embodiment and other materials corresponding to the use of the photoelectric conversion element as needed with a solvent, and the composition is applied and printed on a substrate or other film, and then dried to obtain an organic thin film.

[0085] The organic film of this embodiment may also contain materials other than the compound (1) which is the material for the photoelectric conversion element of this embodiment. The content of the compound (1) in the organic film of this embodiment is not particularly limited as long as it exhibits the performance required for use as a photoelectric conversion element material. For example, the content of the compound (1) relative to the total amount of the organic film may be 50% by mass or more, and from the perspective of more effectively and reliably exerting the effects of the present invention, it is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. The upper limit of the content of the compound (1) may be 100% by mass. When the organic film of this embodiment contains materials other than the compound (1), the materials are not particularly limited as long as they are generally used as materials for photoelectric conversion elements. Examples of such materials include: n-type semiconductor materials, p-type semiconductor materials, and light absorbing materials described later, as well as molybdenum oxide, alkali metals, and alkali metal compounds referred to as doping materials. These may be used alone or in combination of two or more.

[0086] The thickness of the organic thin film depends on the resistance value and charge mobility of each substance and is not particularly limited, but is usually 0.5 nm to 5000 nm, may be 1 nm to 1000 nm, or may be 5 nm to 500 nm.

[0087] From the viewpoint of more effectively and reliably exhibiting the effects of the present invention, the organic thin film of this embodiment preferably has a light absorption band with a maximum absorption wavelength of 450 nm or less.

[0088] (Photoelectric conversion element)

[0089] The photoelectric conversion element of this embodiment refers to a device that generates an electric charge corresponding to the amount of incident light, passes through a capacitor for accumulating the generated electric charge (hereinafter also referred to as an "accumulation unit") and a transistor circuit for reading out the electric charge (hereinafter also referred to as a "readout unit"), and outputs the electric charge to the outside of the photoelectric conversion element. Here, in the photoelectric conversion element, a photoelectric conversion film that absorbs at least a portion of the incident light is arranged between a pair of opposing electrodes, and light is incident on the photoelectric conversion element from above the electrodes. In addition, the photoelectric conversion film is a photosensitive film containing a material that absorbs at least a portion of the incident light in the infrared region, and holes and electrons are generated as a result of the incident light. In addition, the photoelectric conversion element of this embodiment may also have a photoelectric conversion element that generates an electric charge corresponding to the amount of incident light in the infrared region (hereinafter also referred to as an "infrared photoelectric conversion element"). Here, in the infrared photoelectric conversion element, a photoelectric conversion film that absorbs infrared light (hereinafter also referred to as an "infrared photoelectric conversion film") is arranged between a pair of opposing electrodes, and light is incident on the infrared photoelectric conversion element from above the electrodes. The infrared photoelectric conversion film is a photosensitive thin film containing a material that absorbs at least a portion of incident light in the infrared region (hereinafter also referred to as "infrared absorbing material"), and generates holes and electrons as a result of incident light.

[0090] Appropriate reference Figure 1 The photoelectric conversion element of this embodiment will be described. The photoelectric conversion element 100 includes a lower electrode 102 serving as a first electrode film, an upper electrode 106 serving as a second electrode film, and a photoelectric conversion film 110 positioned between the lower electrode 102 and the upper electrode 106. The photoelectric conversion element 100 may include a generally insulating substrate 101 on the side of the upper electrode 106 opposite the photoelectric conversion film 110.

[0091] When the photoelectric conversion film 110 has hole transport properties or electron transport properties, the lower electrode 102 and the upper electrode 106 play the following role: extract holes from the photoelectric conversion film 110 and capture them, or extract electrons and discharge them. The materials that can be used as these electrodes are not particularly limited as long as they have a certain degree of conductivity. It is preferably selected based on the adhesion with the adjacent photoelectric conversion film 110, electron affinity, ionization potential and stability. Examples of materials that can be used as electrodes include conductive metal oxides such as tin oxide (NESA), indium oxide, indium tin oxide (ITO) and indium zinc oxide (IZO); metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel and tungsten; inorganic conductive substances such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole and polyaniline; and carbon. These materials can be used alone or in combination.

[0092] The lower electrode 102, serving as the first electrode film, includes a light-transmitting conductive film, such as indium tin oxide (ITO). The material constituting the lower electrode 102 is not limited to ITO. Examples include tin oxide (SnO2)-based materials with dopants added, and zinc oxide-based materials with dopants added to zinc oxide (ZnO). Examples of zinc oxide-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga), and indium zinc oxide (IZO) with indium (In). Alternatively, examples of the material constituting the lower electrode 102 include CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, and ZnSnO3. The thickness of the lower electrode 102 can be, for example, greater than 5 nm and less than 3000 nm, greater than 5 nm and less than 500 nm, or greater than 10 nm and less than 300 nm.

[0093] The upper electrode 106, serving as the second electrode film, can be formed from a conductive film having the same optical transparency as the lower electrode 102, or from a metal commonly used in electrodes of photoelectric conversion elements, such as aluminum. Furthermore, in a solid-state imaging device using a solid-state imaging element as a single pixel, the upper electrode 106 can be separated for each pixel or formed as a common electrode for all pixels. The thickness of the upper electrode 106 can be, for example, from 5 nm to 3000 nm, from 5 nm to 500 nm, or from 10 nm to 300 nm.

[0094] The conductivity of the material used for electrodes such as the first electrode film and the second electrode film is not particularly limited as long as it does not excessively hinder the light reception of the photoelectric conversion element. However, from the perspective of the signal strength and power consumption of the photoelectric conversion element, the conductivity is preferably as high as possible. For example, as a transparent electrode, if it is an ITO film with a sheet resistance value of 300Ω / □ or less, it can fully function as an electrode. However, commercial products of substrates having an ITO film with a conductivity of about several Ω / □ (for example, 5 to 9Ω / □) are also available, and substrates with such high conductivity are desired.

[0095] The thickness of the electrode when using the ITO film can be arbitrarily selected in consideration of conductivity, but is generally between 5 nm and 3000 nm, preferably between 10 nm and 300 nm. Methods for forming films such as ITO include conventionally known vapor deposition methods, electron beam deposition methods, sputtering methods, chemical reaction methods, and coating methods. The ITO film provided on the substrate may be subjected to UV-ozone treatment or plasma treatment as needed.

[0096] Furthermore, when stacking multiple photoelectric conversion films that detect different wavelengths, the electrode film used between each photoelectric conversion film must transmit light of wavelengths other than the light detected by each photoelectric conversion film. From this perspective, the electrode film is preferably made of a material that transmits at least 90% of the incident light, and more preferably at least 95%. It should be noted that the electrode film mentioned above refers to the film of the electrode other than the pair of electrodes described above.

[0097] In addition, when the lower part of the photoelectric conversion element in this embodiment is further provided with a visible light photoelectric conversion part that senses infrared light or light in different visible light regions, the electrode used in the above-mentioned photoelectric conversion element preferably has a transmittance of the visible light and infrared light of more than 90%, and more preferably more than 95%.

[0098] As electrode materials that meet these requirements, transparent conductive oxides (TCOs) with high transmittance for visible and infrared light and low resistance are preferred. While thin films of metals such as gold can be used as electrodes, increasing the transmittance to 90% or higher significantly increases the resistance. Therefore, TCOs are preferred as electrodes. Particularly preferred TCOs are ITO, IZO, AZO, FTO, SnO2, TiO2, and ZnO2.

[0099] The method for forming the electrode is not particularly limited and can be appropriately selected in consideration of the suitability of the electrode material. When using a transparent electrode, as its forming method, specifically, wet methods such as printing and coating methods, physical methods such as vacuum evaporation, sputtering and ion plating, chemical methods such as CVD and plasma CVD methods can be listed. In addition, when the electrode material is a transparent conductive metal oxide such as ITO, as its forming method, for example, electron beam method, sputtering method, resistance heating evaporation method, chemical reaction method (such as sol-gel method, etc.) and a method of applying a dispersion of the metal oxide can be listed. Furthermore, UV-ozone treatment and plasma treatment can also be implemented on transparent conductive metal oxide films such as ITO.

[0100] The photoelectric conversion film 110 may include the photoelectric conversion element material of this embodiment, or may include the above-mentioned organic thin film. More specifically, for example, the photoelectric conversion film 110 includes a photoelectric conversion layer 104, a first auxiliary layer 103 located on the lower electrode film 102 side of the photoelectric conversion layer 104, and a second auxiliary layer 105 located on the upper electrode film 106 side of the photoelectric conversion layer 104. It should be noted that Figure 1 The photoelectric conversion film 110 shown includes a first auxiliary layer 103 and a second auxiliary layer 105, but the photoelectric conversion film may include only one of these auxiliary layers. Alternatively, the photoelectric conversion film may include only the photoelectric conversion layer 104 without any auxiliary layers. When the photoelectric conversion film does not include an auxiliary layer, the photoelectric conversion layer 104 is the aforementioned organic thin film. When the photoelectric conversion film includes an auxiliary layer, at least one of the photoelectric conversion layer 104 and the auxiliary layer is the aforementioned organic thin film. However, from the perspective of more effectively and reliably achieving the effects of the present invention, the auxiliary layer is preferably the aforementioned organic thin film containing the photoelectric conversion element material of this embodiment.

[0101] The photoelectric conversion layer 104 may be an organic semiconductor film commonly used as a photoelectric conversion layer, or may be the above-mentioned organic thin film. In addition, in the photoelectric conversion layer 110, these organic semiconductor films and organic thin films may be one layer or multiple layers. When it is a single layer, a p-type organic semiconductor film, an n-type organic semiconductor film, or a mixed film thereof (hereinafter referred to as a "bulk heterojunction structure") is used. On the other hand, when it is a multilayer, the number of layers may be about 2 to 10 layers, and it may be a structure in which any of the p-type organic semiconductor films, n-type organic semiconductor films, or mixed films thereof (hereinafter referred to as a "bulk heterojunction structure") are stacked, and a buffer layer may be inserted between the layers.

[0102] The photoelectric conversion layer 104 of the present embodiment may include the photoelectric conversion element material of the present embodiment, or may not include it, or may include materials other than the photoelectric conversion element material of the present embodiment. Among them, when the photoelectric conversion layer 104 includes at least one of an organic p-type semiconductor, an organic n-type semiconductor and a light absorbing material, it is preferred because the incident light energy of the desired wavelength can be more efficiently converted into an electrical signal. Among them, for the light absorbing material, if it is an organic p-type semiconductor, it is easy to supply electrons (i.e., the ionization potential is small), or if it is an organic n-type semiconductor, it is easy to accept electrons (i.e., the electron affinity is large), because the incident light energy can be more efficiently converted into an electrical signal, it is preferred. Here, the ionization potential (HOMO level) refers to the value measured by photoelectron yield spectroscopy or photoelectron spectroscopy. In addition, the electron affinity (LUMO level) refers to the band gap value calculated from the longest wavelength absorption end of the near-infrared light spectrum, and the value obtained by subtracting it from the above-mentioned HOMO level, or the value measured by reverse photoelectron spectroscopy.

[0103] When using an organic semiconductor film, the film may be one layer or more than two layers. The organic semiconductor film may be an organic p-type semiconductor film, an organic n-type semiconductor film, a light absorbing material film, or a mixed film thereof (bulk heterojunction structure). In particular, the organic semiconductor film preferably has a bulk heterojunction junction structure layer. In such a case, by making the photoelectric conversion film contain a bulk heterojunction junction structure, the shortcoming of the short carrier diffusion length of the photoelectric conversion film can be compensated, and the photoelectric conversion efficiency can be improved.

[0104] The thickness of the photoelectric conversion layer 104 may be, for example, not less than 0.5 nm and not more than 5000 nm, not less than 1 nm and not more than 1000 nm, or not less than 5 nm and not more than 500 nm.

[0105] Hereinafter, organic semiconductors will be described in detail.

[0106] Organic p-type semiconductors are donor-type organic semiconductors (hereinafter also referred to as "donor organic compounds"), primarily organic compounds with the property of readily donating electrons, typified by hole-transporting organic compounds. More specifically, they are organic compounds that have a low ionization potential when two organic materials are brought into contact. Therefore, any organic compound with electron-donating properties can be used as a donor organic compound.

[0107] Examples of such donor organic compounds include triarylamine compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, fused aromatic carbocyclic compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives), and metal complexes having nitrogen-containing heterocyclic compounds as ligands. It should be noted that the donor organic semiconductor is not limited to these compounds. As mentioned above, any organic compound having an ionization potential lower than that of the organic compound used as the acceptor organic compound can be used as the donor organic semiconductor.

[0108] Organic n-type semiconductors refer to acceptor organic semiconductors (hereinafter also referred to as "acceptor organic compounds"), primarily organic compounds with the property of readily accepting electrons, typified by electron-transporting organic compounds. More specifically, they refer to organic compounds that have a high electron affinity when two organic compounds are brought into contact. Therefore, any organic compound can be used as an acceptor organic compound as long as it has electron-accepting properties.

[0109] Examples of such acceptor organic compounds include condensed aromatic carbocyclic compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives, and fullerene derivatives), 5- to 7-membered heterocyclic compounds containing nitrogen atoms, oxygen atoms, and sulfur atoms (e.g., pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, and phenanthroline), , tetrazole, pyrazole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine, tetraazaindene, oxadiazole, imidazopyridine, pyrrolidine, pyrrolopyridine, thiadiazolopyridine, dibenzoazepine and tribenzoazepine), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, and metal complexes having nitrogen-containing heterocyclic compounds as ligands. It should be noted that the present invention is not limited to these. As mentioned above, any organic compound having an electron affinity higher than that of the organic compound used as the donor organic compound can be used as the acceptor organic semiconductor.

[0110] The light-absorbing material is a compound having a maximum light absorption wavelength in the visible light region, particularly between 450 nm and 650 nm. The absorption intensity of the light-absorbing material at the maximum light absorption wavelength is preferably greater than the absorption intensity of the donor organic compound or the acceptor organic compound at the maximum light absorption wavelength. This absorption intensity enables the light-absorbing material to selectively absorb incident light at its maximum light absorption wavelength. When incident light is absorbed by the light-absorbing material, photons are converted into excitons. Exciton separation occurs at the interface between the donor organic compound and the acceptor organic compound, efficiently generating hole and electron carriers.

[0111] As such a light absorbing material, a compound generally called a pigment can be used. Examples thereof include phthalocyanine derivatives, subphthalocyanine derivatives, quinacridone derivatives, porphyrin derivatives, naphthalene or perylene derivatives, phthalacetylenes, styryl derivatives, cyanine derivatives, hemicyanine derivatives, merocyanine derivatives, rhodacyanine derivatives, oxonol derivatives, hemioxonol derivatives, croconium derivatives, squarylium derivatives, azamethine derivatives, arylene derivatives, azo derivatives, azomethine derivatives, metallocene derivatives, fulgide derivatives, phenazine derivatives, phenothiazine derivatives, polyene derivatives, acridine derivatives, acridone derivatives, diphenylamine derivatives, triphenylamine, triarylamine derivatives such as naphthylamine and styrylamine, quinophthalone derivatives, phenoxazine derivatives, chlorophyll derivatives, rhodamine derivatives, diphenylmethane or triphenylmethane derivatives, xanthene derivatives. and compounds, acridine derivatives, phenoxazine derivatives, quinoline derivatives, oxazine derivatives, thiazine derivatives, quinone derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, indigo or thioindigo derivatives, pyrrole derivatives, pyridine derivatives, dipyrromethene derivatives, indole derivatives, diketopyrrolopyrrole derivatives, coumarin derivatives, fluorene derivatives, fluorenone derivatives, fluoranthene derivatives, anthracene derivatives, pyrene derivatives, carbazole derivatives, phenylenediamine derivatives, benzidine derivatives, phenanthroline derivatives, imidazole derivatives, oxazoline derivatives, thiazoline derivatives, triazole derivatives, thiadiazole derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiophene derivatives, selenophene derivatives, silole derivatives, germole derivatives, stilbene derivatives, phenylenevinylene derivatives, pentacene derivatives, rubrene derivatives, thienothiophene derivatives, benzodithiophene derivatives, xanthenoxanthene derivatives, and fullerene derivatives. It should be noted that the present invention is not limited to these. As mentioned above, any compound having an absorption intensity greater than the absorption intensity of the donor organic compound or the acceptor organic compound at the maximum light absorption wavelength can be used as a light absorbing material. In addition, the light absorbing material can also function as a donor organic compound or an acceptor organic compound.

[0112] The first auxiliary layer 103 includes, for example, at least one of a hole blocking layer and an electron transport layer. When the first auxiliary layer 103 includes both, the electron transport layer and the hole blocking layer are usually stacked in sequence starting from the photoelectric conversion layer 104 side. The electron transport layer serves to transport electrons generated by the photoelectric conversion layer 104 to the first electrode 102, and to block holes from moving from the first electrode 102 at the electron transport end to the photoelectric conversion layer 104. The hole blocking layer serves to hinder the movement of holes from the first electrode 102 to the photoelectric conversion layer 104, prevent recombination within the photoelectric conversion layer 104, reduce dark current, reduce noise, and expand the dynamic range. In addition, a single layer can have the functions of both a hole blocking layer and an electron transport layer.

[0113] The second auxiliary layer 105 includes, for example, at least one of an electron blocking layer and a hole transport layer. When the second auxiliary layer 105 includes both, the hole transport layer and the electron blocking layer are typically stacked sequentially starting from the photoelectric conversion layer 104 side. The hole transport layer serves to transport generated holes from the photoelectric conversion layer 104 to the second electrode 106, and to block electrons from the second electrode 106 at the hole transport end from moving to the photoelectric conversion layer 104. The electron blocking layer serves to hinder the movement of electrons from the second electrode 106 to the photoelectric conversion layer 104, prevent recombination within the photoelectric conversion layer 104, reduce dark current, reduce noise, and expand the dynamic range. In addition, a single layer may have the functions of both an electron blocking layer and a hole transport layer.

[0114] The photoelectric conversion element material of this embodiment may be included in either the first auxiliary layer 103 or the second auxiliary layer 105, but is preferably included in the first auxiliary layer 103. In the photoelectric conversion element of this embodiment, of these first auxiliary layer 103 and second auxiliary layer 105, the first auxiliary layer 103 preferably includes the above-mentioned organic thin film. Furthermore, the photoelectric conversion element material of this embodiment is more preferably included in at least one of the hole-blocking layer and the electron-transporting layer in the first auxiliary layer 103. In the photoelectric conversion element of this embodiment, at least one of the hole-blocking layer and the electron-transporting layer is preferably the above-mentioned organic thin film. This allows the effects of the present invention to be more effectively and reliably exerted.

[0115] Hereinafter, materials other than the photoelectric conversion element material of this embodiment that may be contained in each layer of the auxiliary layer will be described.

[0116] The material of the hole transport layer is not particularly limited as long as it is known as a hole transport layer in a photoelectric conversion element such as a solid-state imaging element. Examples thereof include polyaniline and doped materials thereof, and cyanide compounds described in International Publication No. 2006 / 019270.

[0117] More specifically, examples of materials constituting the hole transport layer include: selenium, iodides such as copper iodide (CuI), cobalt complexes such as layered cobalt oxides, CuSCN, molybdenum oxide (MoO3, etc.), nickel oxide (NiO, etc.), 4CuBr·3S (C4H9), and organic hole transport materials. Among them, examples of iodides include copper iodide (CuI). Examples of layered cobalt oxides include A x CoO2 (wherein A represents Li, Na, K, Ca, Sr or Ba, and 0≤X≤1). In addition, examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT; for example, the trade name "BaytronP" manufactured by Starck V-tec), fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeO-TAD), carbazole derivatives such as polyvinylcarbazole, triphenylamine derivatives, diphenylamine derivatives, polysilane derivatives, and polyaniline derivatives. Furthermore, materials for the hole transport layer include, for example, compound semiconductors having monovalent copper such as CuInSe2 and copper sulfide (CuS), gallium phosphide (GaP), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (FeO), bismuth oxide (Bi2O3), molybdenum oxide (MoO2) and chromium oxide (Cr2O3).

[0118] Furthermore, it is preferred that the hole transport layer have a higher LUMO level than that of the photoelectric conversion film because this layer can impart an electron blocking function with a rectifying effect that prevents electrons generated in the photoelectric conversion film from migrating toward the electrode. Such a hole transport layer is also referred to as an electron blocking layer.

[0119] Among the materials constituting the electron blocking layer, examples of low molecular weight organic compounds include aromatic diamine compounds such as N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) and 4,4'-bis[N-(naphthyl)-N-phenylamino]biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolones, stilbene derivatives, pyrazoline derivatives, tetrahydroimidazole, polyarylalkane, butadiene, 4,4',4"-tris(N-(3-methylphenyl)N-phenylamino)triphenylamine (m-MTDATA), porphyrin, copper tetraphenylporphyrin, phthalocyanine, copper phthalocyanine, and porphyrin compounds such as titanium phthalocyanine, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, Amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, and silazane derivatives. Examples of high-molecular-weight organic compounds include polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, as well as their derivatives. Even if they are not electron-donating compounds, as long as they have sufficient hole-transporting properties, they can be used as materials constituting the electron-blocking layer. Furthermore, among the materials constituting the electron-blocking layer, examples of inorganic compounds include calcium oxide, chromium oxide, copper chromium oxide, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, indium silver oxide, and metal oxides such as indium oxide, selenium, tellurium, and antimony sulfide. These can be used alone or in combination of two or more.

[0120] From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the hole transport layer is preferably 10 nm to 300 nm, more preferably 30 nm to 250 nm, and even more preferably 50 nm to 200 nm.

[0121] The method for forming the hole transport layer and the electron blocking layer can be any of the known ones, and can be any of the dry film forming methods such as vacuum evaporation method and the wet film forming methods such as solution coating method, but from the viewpoint of being able to level the coating surface, the wet film forming method is preferably used. As the dry film forming method, for example, evaporation methods such as vacuum evaporation method and sputtering method can be listed. Evaporation can be any of physical vapor deposition (PVD) and chemical vapor deposition (CVD), but physical vapor deposition such as vacuum evaporation is preferably used. As the wet film forming method, for example, inkjet method, spray method, nozzle printing method, spin coating method, dip coating method, casting method, die coating method, roller coating method, rod coating method and gravure coating method can be listed.

[0122] The material constituting the electron transport layer is not particularly limited as long as it is known as an electron transport layer in a photoelectric conversion element such as a solid-state imaging element. Examples thereof include: octaazaporphyrin, perfluorinated bodies of p-type semiconductors (such as perfluoropentacene, perfluorophthalocyanine, etc.), fullerenes, fullerene derivatives (such as [6,6]-phenyl-C61-butyric acid methyl ester; PCBM, etc.), organic compounds such as perylene, indenoindene and indenoindene derivatives, inorganic oxides such as titanium oxide (TiO2, etc.), nickel oxide (NiO), tin oxide (SnO2), tungsten oxide (WO2, WO3, W2O3, etc.), zinc oxide (ZnO), niobium oxide (Nb2O5, etc.), tantalum oxide (Ta2O5, etc.), yttrium oxide (Y2O3, etc.) and strontium titanate (SrTiO3, etc.). The electron transport layer may be porous or dense. When stacking them, it is preferred to stack the porous electron transport layer and the dense electron transport layer in this order from the photoelectric conversion film side.

[0123] Furthermore, it is preferred that the electron transport layer have a HOMO level lower than that of the photoelectric conversion film, as this provides a hole-blocking function with a rectifying effect that prevents holes generated in the photoelectric conversion film from migrating toward the counter electrode. Such an electron transport layer is also referred to as a hole-blocking layer.

[0124] Examples of materials constituting the hole blocking layer include oxadiazole derivatives such as 1,3-bis(4-tert-butylphenyl-1,3,4-oxadiazolyl)benzene (OXD-7), anthraquinone dimethane derivatives, diphenylquinone derivatives, bathocuproine, bathophenanthroline and derivatives thereof, triazine compounds, triazole compounds, tris(8-hydroxyquinolinol)aluminum complexes, bis(4-methyl-8 -quinoline) aluminum complex, silole compounds, porphyrin compounds, DCM (4-dicyanomethylidene-2-methyl-6-(4-(dimethylaminophenyl))-4H pyran) and other styrene compounds, naphthalenetetracarboxylic anhydride (NTCDA), naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic anhydride (PTCDA), perylenetetracarboxylic acid diimide and other n-type semiconductor materials, titanium oxide, zinc oxide and gallium oxide and other n-type inorganic oxides, and alkali metal fluorides such as lithium fluoride, sodium fluoride and cesium fluoride. Furthermore, those in which alkali metal compounds are doped into organic semiconductor molecules have the function of improving electrical bonding with the counter electrode and are therefore preferred. These can be used alone or in combination of two or more.

[0125] From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the electron transport layer is preferably 10 nm to 300 nm, more preferably 30 nm to 250 nm, and even more preferably 50 nm to 200 nm.

[0126] As a method for forming an electron transport layer and a hole blocking layer, it can be a conventionally known method, and it can be any of a dry film-forming method such as a vacuum evaporation method and a wet film-forming method such as a solution coating method, but from the viewpoint of being able to level the coating surface, a wet film-forming method is preferably used. As a dry film-forming method, for example, a evaporation method such as a vacuum evaporation method and a sputtering method can be listed. Evaporation can be any of physical vapor deposition (PVD) and chemical vapor deposition (CVD), but physical vapor deposition such as vacuum evaporation is preferred. As a wet film-forming method, for example, an inkjet method, a spray method, a nozzle printing method, a spin coating method, a dip coating method, a casting method, a die coating method, a roller coating method, a rod coating method, and a gravure coating method can be listed.

[0127] The photoelectric conversion element of this embodiment may include a single layer or two or more auxiliary layers different from the first auxiliary layer 103 between the first auxiliary layer 103 and the lower electrode 102. As such an auxiliary layer, for example, there can be listed: a hole injection layer that improves the hole injection property from the lower electrode 102 to the first auxiliary layer 103. As materials constituting the hole injection layer, for example, there can be listed: phthalocyanine derivatives, starburst amines such as m-MTDATA (4,4',4"-tris[phenyl(m-tolyl)amino]triphenylamine), polythiophenes such as PEDOT (poly(3,4-ethylenedioxythiophene)), and polymer materials such as polyvinylcarbazole derivatives. The thickness of the auxiliary layer may be the same as that of the first auxiliary layer 103.

[0128] The photoelectric conversion element of this embodiment may include a single layer or two or more auxiliary layers, different from the second auxiliary layer 105, between the second auxiliary layer 105 and the upper electrode 106. Examples of such auxiliary layers include an electron injection layer and an electron transport layer that improve the injection of electrons from the upper electrode 106 into the second auxiliary layer 105. Examples of materials constituting the electron injection layer include metals such as cesium, lithium, and strontium, as well as lithium fluoride. Materials constituting the electron transport layer may be the same as those described above. Furthermore, the thickness of this auxiliary layer may be the same as that of the second auxiliary layer 105.

[0129] The photoelectric conversion element of this embodiment may include, in addition to the above-mentioned layers, at least one of an interlayer contact improving layer and a crystallization preventing layer located between these layers.

[0130] The interlayer contact improvement layer serves to mitigate damage to the film immediately below, such as the photoelectric conversion film 110, during the formation of the upper electrode 106. In particular, high-energy particles present in the apparatus used to form the upper electrode 106, such as those produced by sputtering, can collide with the film immediately below, causing degradation, potentially leading to increased leakage current and decreased sensitivity. As a method to prevent this, it is preferable to provide an interlayer contact improvement layer above the film immediately below. Preferred materials for the interlayer contact improvement layer include organic substances such as copper phthalocyanine, NTCDA, PTCDA, [dipyrazino[2,3-F:2',3'-H]quinoxaline-2,3,6,7,10,11-hexacarbonitrile] (HATCN), acetylacetonate complexes, and BCP, organometallic compounds, or inorganic substances such as MgAg and MgO. The thickness of the interlayer contact improvement layer varies depending on the composition of the photoelectric conversion film, the thickness of the electrode film, etc., but is preferably greater than 2 nm and less than 500 nm from the perspective of selecting a material that does not absorb in the visible light region or using it with a thinner thickness.

[0131] As described above, the photoelectric conversion element of this embodiment is connected to a capacitor (i.e., an accumulation unit) for accumulating generated charge and a transistor circuit (i.e., a readout unit) for reading out the generated charge via a connection portion formed of a conductive material. Furthermore, the photoelectric conversion element may include, as necessary, a protective structure such as a protective film to protect against external air, a substrate to maintain strength, and a microlens for focusing light.

[0132] A readout section is provided to read out a signal corresponding to the charge generated in the photoelectric conversion film. The readout section is composed of, for example, a CCD, a CMOS circuit, or a TFT circuit, and is preferably shielded from light by a light-shielding layer disposed in the insulating layer. The readout circuit is electrically connected to the corresponding electrode via a connecting section. It should be noted that, in order to ensure the amount of charge required for reading, an accumulation section composed of a capacitor or the like may be sandwiched between the electrode and the connecting section. The connecting section is buried in the insulating layer and is a plug or the like for electrically connecting the electrode (for example, a transparent electrode or an opposing electrode) to the readout section. When the component thus constructed is a solid-state imaging element, if light is incident, the light is incident on the photoelectric conversion film and a charge is generated there. Electrons in the generated charge are captured (and accumulated) by one electrode, and holes are captured by another electrode. A voltage signal corresponding to the amount is output to the outside of the solid-state imaging element through the readout section.

[0133] (Image sensor)

[0134] If the imaging element of this embodiment includes the photoelectric conversion element of this embodiment, the configuration otherwise may be the same as that of conventional imaging elements. For example, the imaging element of this embodiment may include multiple photoelectric conversion elements of this embodiment in an array. In other words, by arranging multiple photoelectric conversion elements in an array, a solid-state imaging element is constructed that displays information about the incident position in addition to the amount of incident light.

[0135] The imaging element of this embodiment may have one photoelectric conversion element of this embodiment, or may be stacked with two or more. In the case where two or more photoelectric conversion elements of this embodiment are stacked, each photoelectric conversion element can selectively detect light of different wavelength bands and perform photoelectric conversion. For example, in the case where three or more photoelectric conversion elements of this embodiment are stacked, at least one can obtain a green signal, at least one other can obtain a blue signal, at least one other can obtain a red signal, and at least one other can obtain an infrared light color signal. Thus, the imaging element can obtain multiple color signals in one pixel without using a color filter. In addition, color signals other than the color signals detected by the photoelectric conversion element of this embodiment can also be sensed by a device having a conventionally known silicon photodiode.

[0136] In an imaging element, when a photoelectric conversion element arranged closer to the light source does not block (i.e., transmits) the absorption wavelength of another photoelectric conversion element arranged behind it when viewed from the light source side, a device having multiple photoelectric conversion elements and silicon photodiodes can be stacked.

[0137] In the imaging element, from the viewpoint of ease of molding, a portion of the photoelectric conversion element may be configured as a thin film on the same plane without structural partitions between adjacent photoelectric conversion elements.

[0138] The imaging element of this embodiment may further include a substrate. The substrate is used to stack various layers to manufacture the imaging element, or to enhance the mechanical strength of the imaging element. The type of substrate is not particularly limited; examples include semiconductor substrates, glass substrates, and plastic substrates.

[0139] (Light Sensor)

[0140] The optical sensor of this embodiment only needs to include the imaging element of this embodiment, and the other configurations may be the same as those of conventional optical sensors. This optical sensor can receive light from the imaging element of this embodiment and output an electrical signal corresponding to the amount of light received.

[0141] (Solid-state imaging device)

[0142] The solid-state imaging device of this embodiment only needs to include the imaging element of this embodiment, and other configurations may be the same as those of conventional solid-state imaging devices. The solid-state imaging device of this embodiment may be, for example, a CMOS image sensor, and may include a pixel portion as an imaging area on a semiconductor substrate, and may further include a peripheral circuit portion in the peripheral area or vertically below the pixel portion, the peripheral circuit portion including a row scanning portion, a horizontal selection portion, a column scanning portion, and a system control portion. The pixel portion includes the imaging element of this embodiment.

[0143] The photoelectric conversion element of this embodiment has the following advantages by using the photoelectric conversion element material of this embodiment. That is, the photoelectric conversion element of this embodiment is less likely to short-circuit or produce pinholes, so the dark current value is reduced. As a result, the photoelectric conversion element of this embodiment has excellent leakage prevention (especially in the dark). Furthermore, the photoelectric conversion element of this embodiment tends to easily show a high light-to-dark ratio, and in this case, it has more excellent leakage prevention. In addition, although the photoelectric conversion element material in the photoelectric conversion element of this embodiment is not easy to aggregate, its hole and electron transport properties are still excellent, so the photoelectric conversion efficiency becomes higher. Furthermore, the photoelectric conversion element of this embodiment has good heat resistance by using the photoelectric conversion element material of this embodiment, and its durability in the manufacturing process and practical environment is improved.

[0144] Example

[0145] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. It should be noted that the synthesized compound can be further purified by sublimation as needed.

[0146] <Synthesis example 1>

[0147]

[0148] A mixture obtained by adding 6.0 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride (1) (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2.6 g of 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) (1.0 molar equivalent relative to 1,4,5,8-naphthalenetetracarboxylic dianhydride (1)) to 90 mL of N,N-dimethylformamide (manufactured by Tokyo Chemical Industry Co., Ltd.) was stirred at 150°C for 8 hours. Thereafter, the mixture was cooled to room temperature and the solvent was distilled off under reduced pressure. Acetone was added to the solid obtained by distilling off the solvent, and water was slowly added while stirring, and the precipitate was filtered. After dissolving the precipitate with chloroform, sodium sulfate was added and the mixture was allowed to stand for 30 minutes. Subsequently, after filtering off the sodium sulfate, the solvent was distilled off under reduced pressure. After size exclusion chromatography using chloroform as the eluent, compound (2) was obtained as a pale yellow solid. The results of its NMR measurement are shown below.

[0149] 1 HNMR(500MHz,DMSO-d6): 8.72(dd,4H),8.07(d,2H),7.10(d,2H)

[0150] <Synthesis example 2>

[0151]

[0152] Compound (3) was obtained in the same manner as in Synthesis Example 1 except that 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of NMR measurement are shown below.

[0153] 1 HNMR (500MHz, DMSO-d6): 8.74(d,4H),8.39(d,1H),8.32(d,1H),8.10(dd,1H)

[0154] <Synthesis example 3>

[0155]

[0156] Compound (4) was obtained in the same manner as in Synthesis Example 1 except that 4-cyano-3-trifluoromethylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of NMR measurement are shown below.

[0157] 1 HNMR (500MHz, DMSO-d6): 8.73(d,4H),8.44(d,1H),8.28(d,1H),8.07(dd,1H)

[0158] <Synthesis example 4>

[0159]

[0160] To 90 mL of m-cresol (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.0 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride (1) (manufactured by Tokyo Chemical Industry Co., Ltd.), 6.1 g of isoquinoline (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.1 molar equivalents relative to 1,4,5,8-naphthalenetetracarboxylic dianhydride (1)) and 6.6 g of 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.5 molar equivalents relative to 1,4,5,8-naphthalenetetracarboxylic dianhydride (1)) were added to obtain a mixture, which was stirred at 180°C for 8 hours. Thereafter, the mixture was cooled to room temperature, methanol was added thereto, and the precipitate was filtered. Furthermore, after washing with methanol, an aqueous potassium carbonate solution was added and stirred for 5 minutes. Subsequently, after filtration, the mixture was washed with water and methanol, and purified by sublimation to obtain compound (5) as a white solid. The results of its NMR measurement are shown below.

[0161] 1 HNMR (500MHz, HFIP-d2): 8.93 (s, 4H), 8.77 (dm, 4H), 7.55 (dm, 4H)

[0162] <Synthesis example 5>

[0163]

[0164] Compound (6) was obtained in the same manner as in Synthesis Example 1 except that aniline (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of 4-aminobenzonitrile. The results of NMR measurement are shown below.

[0165] 1 HNMR (500MHz, DMSO-d6): 8.72 (q, 4H), 7.50 (m, 5H)

[0166] <Synthesis example 6>

[0167]

[0168] Compound (7) was obtained in the same manner as in Synthesis Example 1 except that 3,5-bis(trifluoromethyl)aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of NMR measurement are shown below.

[0169] 1 HNMR (500MHz, DMSO-d6): 8.75 (q, 4H), 8.34 (s, 3H)

[0170] [Fabrication and evaluation of organic thin films and photoelectric conversion elements]

[0171] In the following examples and comparative examples, an organic thin film and a photoelectric conversion element were produced using a vapor deposition machine, and current and voltage were applied and measured under the atmosphere. The produced photoelectric conversion element was placed in a measurement chamber, and current and voltage were applied and measured. When the current and voltage were applied and measured, a semiconductor parameter analyzer (manufactured by Keithley Corporation) was used. The irradiation of the irradiation light was carried out using a light source device (manufactured by Asahi Spectroscopy Co., Ltd., product name (PVL-3300)) under the conditions of an irradiation light wavelength of 550nm and an irradiation light half-value width of 20nm. The light-dark ratio is the value obtained by dividing the current value during light irradiation by the current value in the dark.

[0172] (Example 1)

[0173] On ITO transparent conductive glass (ITO manufactured by GEOMATEC Co., Ltd., thickness 100 nm), a 100 nm thick film of boron subphthalocyanine chloride (purified product manufactured by Sigma Aldrich, purity >99%) was formed as a photoelectric conversion layer. On this film, a 25 nm thick film of a sublimated purified product of tris(8-hydroxyquinolinolato)aluminum (Alq3) (manufactured by Tokyo Chemical Industry Co., Ltd.) was formed as an auxiliary layer 1 by resistance heating vacuum deposition. Subsequently, a 25 nm thick film of compound (2) was formed as an auxiliary layer 2 by resistance heating vacuum deposition. Subsequently, aluminum as an electrode was formed as a 100 nm thick film on the auxiliary layer 2 by vacuum deposition, thereby obtaining a photoelectric conversion element.

[0174] The resulting photoelectric conversion element was tested using ITO and aluminum electrodes and a voltage of 3 V was applied. The current values ​​in the dark and under light irradiation were measured. The light-dark ratio was calculated based on the measurement results. The results are shown in Table 1. It should be noted that the dark current value is expressed as a relative value, with the value of Comparative Example 1, described later, set to 1.

[0175] (Example 2)

[0176] A single-layer organic thin film and a photoelectric conversion element were prepared in the same manner as in Example 1 except that Compound (3) was used instead of Compound (2). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0177] (Example 3)

[0178] A single-layer organic thin film and a photoelectric conversion element were prepared in the same manner as in Example 1 except that Compound (4) was used instead of Compound (2). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0179] (Comparative Example 1)

[0180] A single-layer organic thin film and a photoelectric conversion element were prepared in the same manner as in Example 1 except that Compound (1) was used instead of Compound (2). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0181] (Comparative Example 2)

[0182] A single-layer organic thin film and a photoelectric conversion element were prepared in the same manner as in Example 1 except that Compound (5) was used instead of Compound (2). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0183] (Comparative Example 3)

[0184] A single-layer organic thin film and a photoelectric conversion element were prepared in the same manner as in Example 1 except that Compound (6) was used instead of Compound (2). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0185] (Comparative Example 4)

[0186] A single-layer organic thin film and a photoelectric conversion element were prepared in the same manner as in Example 1 except that Compound (7) was used instead of Compound (2). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0187] [Table 1]

[0188]

[0189] The results shown in Table 1 indicate that the photoelectric conversion elements of the present invention exhibit low dark current values, thereby exhibiting superior leakage prevention (particularly in the dark). In particular, it is shown that some examples exhibit a high light-to-dark ratio, demonstrating superior leakage prevention. In summary, the compounds of the present invention are suitable as materials for photoelectric conversion elements, particularly as materials included in the electron transport layer and hole blocking layer of photoelectric conversion elements.

[0190] Industrial applicability

[0191] By using a photoelectric conversion element material comprising the compound (1) of the present invention, a photoelectric conversion element having excellent properties such as hole or electron leakage prevention, transportability, and heat resistance, visible light transparency, etc. can be provided. Therefore, the compound (1) of the present invention, the photoelectric conversion element material, the organic film, and the photoelectric conversion element have industrial applicability in the field requiring such properties. Specifically, as a solid-state imaging element, there are imaging elements in medical cameras such as security cameras, vehicle-mounted cameras, drone cameras, agricultural cameras, industrial cameras, and endoscope cameras, cameras for game consoles, digital still cameras, digital video cameras, mobile phone cameras, and cameras for mobile devices other than the above; image reading elements in fax machines, scanners, and copiers; and also in optical sensors in biological and chemical sensors, etc. There is industrial applicability. In addition, as a display utilizing electroluminescence, there is industrial applicability in television displays, touch displays, digital signage, wearable displays, electronic paper, and head-up displays in mobile applications.

[0192] This application is based on Japanese patent application (Japanese Patent Application No. 2023-040388) filed on March 15, 2023, the contents of which are incorporated herein by reference.

[0193] Description of Reference Numerals

[0194] 100 ...photoelectric conversion element, 101 ...substrate, 102 ...lower electrode, 103 ...first auxiliary layer, 104 ...photoelectric conversion layer, 105 ...second auxiliary layer, 106 ...upper electrode, 110 ...photoelectric conversion film.

Claims

1. A compound represented by the following formula (1): R1, R2, R3 and R4 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a thiol group, an amino group, a cyano group, a carboxyl group, a nitro group, a linear or branched alkyl group having 1 to 12 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, and an alkoxy group having 1 to 12 carbon atoms, which is optionally substituted with a halogen atom.

2. The compound according to claim 1, wherein The lowest unoccupied orbital energy level of the compound represented by the formula (1) obtained by density functional theory is -6.00 eV or more and -3.80 eV or less. The compound according to claim 1 , which is a material for a photoelectric conversion device. An organic thin film comprising the compound according to claim 1 . The organic thin film according to claim 4 , which has a light absorption band with a maximum absorption wavelength of 450 nm or less.

6. A photoelectric conversion element comprising a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film. The photoelectric conversion film comprises the photoelectric conversion element material according to claim 3 .

7. A photoelectric conversion element comprising a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film. The photoelectric conversion film comprises the organic thin film according to claim 4 .

8. The photoelectric conversion element according to claim 7, wherein The photoelectric conversion film comprises a photoelectric conversion layer and an auxiliary layer. The auxiliary layer is formed of only the organic thin film, or is formed of a plurality of films including the organic thin film. 9 . An imaging element comprising the photoelectric conversion element according to claim 6 . 10 . The imaging element according to claim 9 , wherein two or more photoelectric conversion elements are stacked. 11 . An imaging element comprising a plurality of the photoelectric conversion elements according to claim 6 or 7 arranged in an array. 12 . A photosensor comprising the imaging element according to claim 9 . 13 . A solid-state imaging device comprising the imaging element according to claim 9 .

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