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

Abstract

Provided is a compound represented by general formula (1). In formula (1), X1 and X2 are each independently selected from the group consisting of a methine group and a nitrogen atom, n is an integer of 0-3, R1 and R2 are each independently a hydrogen atom, a halogen atom, or a monovalent organic group, R1 and / or R2 is a monovalent organic group having a Hammett substituent constant σp of 0.50 or greater, and the adjacent R1 and R2 moieties may be a part of a fused ring, the fused ring optionally including one or more atoms other than carbon.

Description

Compounds, organic thin films, photoelectric conversion elements, image sensors, optical sensors, and solid-state imaging devices

[0001] This disclosure relates to compounds, organic thin films, photoelectric conversion elements, image sensors, optical sensors, and solid-state imaging devices.

[0002] Conventionally, a technology for converting visible light into electrical signals via photoelectric conversion has been known and is used, for example, in image sensors. Such image sensors are provided in solid-state imaging devices such as CCD (Charge Coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors. In recent years, there has been a trend towards reducing the pixel size in solid-state imaging devices, and organic photoelectric conversion films are being investigated to address this. For example, Patent Documents 1 and 2 disclose organic photoelectric conversion films composed of subphthalocyanines and imides.

[0003] Furthermore, solid-state imaging devices are required to achieve both high spectral selectivity and a high signal-to-noise ratio. Therefore, it is desirable for solid-state imaging devices to have high external quantum efficiency (EQE) and low dark current characteristics. To achieve such a balance, a method is known in which an electron transport layer and a hole blocking layer, and / or a hole transport layer and an electron blocking layer, are placed between the photoelectric conversion unit and the electrode unit. Here, electron transport layers, hole blocking layers, and electron blocking layers, which are widely used in the field of organic electronic devices, are placed at the interface between an electrode or conductive film and other films in the film constituting the device. These layers play a role in controlling the reverse movement of holes or electrons, respectively, and adjusting unnecessary leakage of holes or electrons. As a material used for such layers, for example, Patent Document 3 shows an example using 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA).

[0004] Japanese Patent Publication No. 2018-32754, Japanese Patent Publication No. 2018-512423, Japanese Patent Publication No. 2014-506736

[0005] However, in the conventional hole blocking layers and electron blocking layers including those disclosed in Patent Document 3, there is still room for further improvement in suppressing the leakage current in the dark and having high wavelength selectivity. Therefore, the development of novel compounds that are more useful as materials for photoelectric conversion elements is required.

[0006] An object of the present invention is to provide a novel compound particularly useful as a material for a photoelectric conversion element, a material for a photoelectric conversion element, an organic thin film containing the compound, a photoelectric conversion element, an imaging element, an optical sensor, and a solid imaging device.

[0007] The present invention is as follows. [1] A compound represented by the following formula (1). (In formula (1), X , ３ , ３ , ４ , ５ , ２ , ３ and X ２ are each independently selected from the group consisting of a methine group and a nitrogen atom, n is an integer of 0 or more and 3 or less, R １ and R ２ are each independently a hydrogen atom, a halogen atom or a monovalent organic group, and at least one of R １ and R ２ is a monovalent organic group having a Hammett substituent constant σp of 0.50 or more, and adjacent R １ and R ２ may be part of a condensed ring, and the condensed ring may contain one or more atoms other than carbon.) [2] The compound according to [1], wherein at least one of R １ and R ２ is a cyano group, a nitro group, a trifluoromethyl group, or a sulfonyl group. [3] A compound represented by the following formula (2). (In formula (2), X ３ and X ４ are each independently selected from the group consisting of a methine group and a nitrogen atom, X ５ is an oxygen atom or NR ３ , n is an integer of 0 or more and 3 or less, R ３(The group is selected from hydrogen atoms, halogen atoms, hydroxyl groups, thiol groups, amino groups, cyano groups, carboxyl groups, nitro groups, and optionally substituted linear, branched, or cyclic alkyl groups, thioalkyl groups, thioaryl groups, arylsulfonyl groups, aryloxy groups, alkylsulfonyl groups, alkylamino groups, arylamino groups, alkoxy groups, acylamino groups, acyloxy groups, aryl groups, carboxyamide groups, carboalkoxy groups, carboaryloxy groups, acyl groups, and monovalent heterocyclic groups.) [4] The compound according to any one of [1] to [3], wherein the energy level of the lowest unoccupied orbital obtained by density functional theory is between -6.00 eV and -3.80 eV. [5] The compound according to any one of [1] to [4], wherein the difference between the energy level of the lowest unoccupied orbital and the energy level of the highest occupied orbital obtained by density functional theory is between 3.0 eV and 4.0 eV. [6] A compound according to any one of [1] to [5], which is a material for a photoelectric conversion element. [7] An organic thin film containing a compound according to any one of [1] to [6]. [8] An organic thin film according to [7], having a maximum absorption wavelength of 450 nm or less in the light absorption band. [9] 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, wherein the photoelectric conversion film contains the material for a photoelectric conversion element according to [6].

[10] 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, wherein the photoelectric conversion film contains the organic thin film according to [7] or [8].

[11] The photoelectric conversion element according to

[10] , wherein the photoelectric conversion film comprises a photoelectric conversion layer and an auxiliary layer, and the auxiliary layer consists only of the organic thin film or of a plurality of films including the organic thin film.

[12] An image sensor comprising the photoelectric conversion element according to any one of [9] to

[11] .

[13] The image sensor according to

[12] , which is a laminate containing two or more of the photoelectric conversion elements.

[14] An image sensor in which a plurality of photoelectric conversion elements according to any one of [9] to

[11] are arranged in an array.

[15] An optical sensor comprising the image sensor according to any one of

[12] to

[14] .

[16] A solid-state imaging device comprising an image sensor as described in any of

[12] to

[14] .

[0008] According to the present invention, it is possible to provide novel compounds particularly useful for photoelectric conversion elements, materials for photoelectric conversion elements, and organic thin films containing the compound, photoelectric conversion elements, image sensors, optical sensors, and solid-state imaging devices.

[0009] This is a schematic cross-sectional view partially showing an example of the photoelectric conversion element of the present invention. This is a schematic cross-sectional view partially showing another example of the photoelectric conversion element of the present invention.

[0010] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"), with reference to the drawings as necessary. However, the present invention is not limited to the embodiments described below. The present invention can be modified in various ways without departing from its essence. In the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Moreover, the dimensional ratios in the drawings are not limited to those shown.

[0011] In this specification, Hammett's substituent constant σp is defined as log(K / K). ０ ) is expressed as, where K and K ０ σp is the dissociation constant of para-substituted and unsubstituted benzoic acid at 25°C in water. The Hammett substituent constants σp for each atom and organic group are described, for example, in the Journal of Synthetic Organic Chemistry, Japan, Vol. 23, No. 8 (1965). In this embodiment, the atoms and organic groups identified by the Hammett substituent constant σp are not limited to atoms and organic groups whose substituent constant σp is known as described in the above-mentioned literature, but also include atoms and organic groups whose substituent constant σp is not known, but whose substituent constant σp measured based on Hammett's rule falls within the range shown in this embodiment. The Hammett substituent constants σp for typical atoms and organic groups are as follows.

[0012]

[0013] In this specification, an organic group is a group comprising at least one element selected from the group consisting of C, N, O, and S.

[0014] In this specification, examples of halogen atoms include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0015] In this specification, the linear alkyl group which may have substituents may be a linear alkyl group having 1 to 12 carbon atoms in the alkyl group, for example, a methyl group (Me), an ethyl group (Et), an n-propyl group (n-Pr), an n-butyl group (n-Bu), an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, and an n-dodecyl group.

[0016] In this specification, branched alkyl groups that may have substituents may be branched alkyl groups having 1 to 12 carbon atoms in the alkyl group, and examples include isopropyl group (i-Pr), sec-butyl group (s-Bu), tert-butyl group (t-Bu), isopentyl group, sec-pentyl group, 3-pentyl group, neopentyl group, isohexyl group, isooctyl group, isononyl group, isodecyl group and isododecyl group. Linear or branched alkyl groups may also have substituents. Examples of substituents include halogen atoms such as fluorine atoms, monovalent groups having aromatic rings such as benzyl groups, naphthyl groups and phenoxy groups, monovalent groups having heteroatoms such as alkoxy groups, aminoalkyl groups and thioalkyl groups, monovalent groups having heterocycles such as pyridyl groups, hydroxyl groups, carboxyl groups, amino groups and thiol groups.

[0017] In this specification, a cyclic alkyl group which may have substituents may be a cyclic alkyl group having 3 to 10 carbon atoms in the alkyl group, for example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Furthermore, the cyclic alkyl group may have heteroatoms such as a nitrogen atom, an oxygen atom, and a sulfur atom in its ring. For example, such cyclic alkyl groups include a pyrrolidinyl group, an oxazolidinyl group, a pyrazolidinyl group, a thiazolidinyl group, an imidazolidinyl group, a dioxofuranyl group, a tetrahydrofuranyl group, a tetrahydrothiophenyl group, a piperazinyl group, a dioxanyl group, and a morpholinyl group. In addition, a monovalent group such as a hydroxyl group, a carboxyl group, an amino group, and a thiol group may be bonded to the cyclic alkyl group.

[0018] In this specification, the optionally substituted thioalkyl groups (-SR; hereafter, R represents an alkyl group) and thioaryl groups (-SAr; hereafter, Ar represents an aryl group) may be 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. Furthermore, the thioalkyl groups and thioaryl groups may have substituents such as an amino group, a hydroxyl group, a halogen atom, an alkoxy group, or a thioalkyl group. Examples of such thioalkyl groups and thioaryl groups include methylthio, ethylthio, phenylthio, toluylthio, aminophenylthio, hydroxyphenylthio, fluorophenylthio, dimethylphenylthio, and methylthiophenylthio.

[0019] In this specification, an arylsulfonyl group which may have a substituent (-SO ２ The -Ar) group may be an arylsulfonyl group having 6 to 16 carbon atoms in the aryl group, for example, a phenylsulfonyl group, a toluenesulfonyl group, a dimethylbenzenesulfonyl group, a mesitylenesulfonyl group, an octylbenzenesulfonyl group, and a naphthalenesulfonyl group.

[0020] In this specification, the optionally substituted aryloxy group (-O-Ar) may be an aryloxy group having 6 to 16 carbon atoms in the aryl group. Furthermore, the aryloxy group may have further substituents 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, and an aryloxy group. Examples of such aryloxy groups 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 cyanonaphthoxy group, a dicyanonaphthoxy group, a 2-methylphenoxy group, a 3-methylphenoxy group, a 4-methylphenoxy group, a fluoromethylphenoxy group, a dimethylphenoxy group, a 3-hydroxyphenoxy group, Examples include fluoro-3-hydroxyphenoxy group, 2-hydroxyphenoxy group, fluoro-2-hydroxyphenoxy group, methoxyphenoxy group, ethoxyphenoxy group, fluorophenoxy group, perfluorophenoxy group, dimethoxyphenoxy group, aminophenoxy group, N,N-dimethylaminophenoxy group, thiophenoxy group, (trifluoromethyl)phenoxy group, naphthoxy group, methoxynaphthoxy group, fluoronaphthoxy group, and phenoxyphenoxy group.

[0021] In this specification, alkylsulfonyl groups which may have substituents (-SO ２ -R) may be an alkylsulfonyl group having 1 to 12 carbon atoms in the alkyl group, for example, a mesyl group, an ethylsulfonyl group, and an n-butylsulfonyl group.

[0022] In this specification, alkylamino groups which may have substituents (-NHR or -NR ２The two Rs may be the same or different from each other.) The alkyl group may be an alkylamino group having 1 to 12 carbon atoms, for example, methylamino group, ethylamino group, n-propylamino group, n-butylamino group, n-pentylamino group, n-hexylamino group, n-heptylamino group, n-octylamino group, n-nonylamino group, n-decylamino group, n-dodecylamino group, isopropylamino group, sec-butylamino group, tert-butylamino group, isopentylamino group, sec-pentylamino group, 3-pentylamino group, neopentylamino group, isohexylamino group, isoheptylamino group, isooctylamino group, isononylamino group, isodecylamino group and isododecylamino group, dimethylamino group, diethylamino group, diisopropylamino group and isopropylethylamino group.

[0023] In this specification, an arylamino group which may have a substituent (-NHAr or -NAr) ２ The two Ar groups may be the same or different. The aryl group may be an arylamino group having 6 to 16 carbon atoms, for example, anyl group, toluidinyl group, dimethylanilyl group, isopropylarilinyl group, t-butylanilyl group, fluoroanilyl group, trifluoromethylanilyl group, bis(trifluoromethyl)anilyl group, pyridylamino group, methylpyridylamino group, fluoropyridylamino group, pyrimidylamino group, and biphenylamino group.

[0024] In this specification, the alkoxy group (-OR), which may have substituents, may be an alkoxy group having 1 to 12 carbon atoms, and examples include a methoxy group, an ethoxy group, an n-propoxy group, an n-butyroxy group, an n-pentoxy group, an n-hexoxy group, an n-heptoxy group, an n-octoxy group, an n-nonoxy group, an n-decoxy group and an n-dodecoxy group, an isopropoxy group, an sec-butyroxy group, an tert-butyroxy group, an isopentoxy group, an sec-pentoxy group, an 3-pentoxy group, an neopentoxy group, an isohexoxy group, an isooctoxy group, an isononoxy group, an isodecoxoxy group and an isododecoxy group.

[0025] In this specification, the optionally substituted 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 substituents such as halogen atoms like fluorine, alkoxy groups, and cyano groups. Examples of such acylamino groups include acetylamino group, propionylamino group, benzoylamino group, methylbenzoylamino group, dimethylbenzoylamino group, methoxybenzoylamino group, cyanobenzoylamino group, and bis(trifluoromethyl)benzoylamino group.

[0026] In this specification, the acyloxy group (-O-COR or -O-COAr), which may have substituents, 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 substituents such as a halogen atom such as a fluorine atom and a cyano group, and may have a heteroatom such as a nitrogen atom in the aromatic ring. Examples of such acyloxy groups include benzoyloxy group, toluyloxy group, dimethylbenzoyloxy group, cyanobenzoyloxy group, fluorobenzoyloxy group, bis(trifluoromethyl)benzoyloxy group, pyridinecarboxyl group, and methylpyridinecarboxyl group.

[0027] In this specification, the optionally substituted aryl group (-Ar) may be an aryl group having 6 to 16 carbon atoms. The aryl group may further have substituents 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 group, methylphenyl group, ethylphenyl group, dimethylphenyl group, trimethylphenyl group, methoxyphenyl group, dimethoxyphenyl group, trimethoxyphenyl group, methoxymethylphenyl group, aminophenyl group, diaminophenyl group, aminomethylphenyl group, hydroxyphenyl group, dihydroxyphenyl group, hydroxymethylphenyl group, hydroxyethylphenyl group, thiophenyl group, methylthiophenyl group, dithiophenyl group, fluorophenyl group, fluoromethylphenyl group, trifluoromethylphenyl group, perfluorophenyl group, fluoro(trifluoromethyl)phenyl group, bis(trifluoromethyl)phenyl group, cyanophenyl group, methylcyanophenyl group, dimethylcyanophenyl group, dicyanophenyl group, methoxycyanophenyl group, tricyanophenyl group, and dicyanophenyl group. Examples include methylcyanopyridyl group, (trifluoromethyl)cyanopyridyl group, dimethylcyanopyridyl group, dicyanopyridyl group, methoxycyanopyridyl group, tricyanopyridyl group, cyanopyridyl group, naphthyl group, nitrophenyl group, dinitrophenyl group, nitrofluorophenyl group, methylnaphthyl group, ethylnaphthyl group, dimethylnaphthyl group, trimethylnaphthyl group, methoxynaphthyl group, dimethoxynaphthyl group, trimethoxynaphthyl group, aminonaphthyl group, diaminonaphthyl group, aminomethylnaphthyl group, hydroxynaphthyl group, dihydroxynaphthyl group, hydroxymethylnaphthyl group, hydroxyethylnaphthyl group, thionaphthyl group, methylthionaphthyl group, dithionaphthyl group, fluoronaphthyl group, trifluoromethylnaphthyl group, perfluoronaphthyl group, di(trifluoromethyl)naphthyl group, biphenyl group, and cyanobiphenyl group.

[0028] In this specification, a carboxyamide group which may have a substituent (where the carboxyamide group is -CO-NH ２ , -CO-NHR, -CONR ２ The two Rs may be the same or different, and can be -CONHAr or -CONAR. ２ The two Ar groups may be the same or different. The alkyl group may be a carboxyamide group having 1 to 12 carbon atoms or an aryl group having 6 to 16 carbon atoms, for example, a dimethylcarboxyamide group and a diphenylcarboxyamide group.

[0029] In this specification, the optionally substituted carboalkoxy group or carboaryloxy group (-COOR or -COOAr) may be a carboalkoxy group or carboaryloxy group having 1 to 12 carbon atoms in the alkyl group or 6 to 16 carbon atoms in the aryl group, for example, a carbomethoxy group or a carbophenoxy group.

[0030] In this specification, the optionally substituent monovalent heterocyclic group may be a monovalent heterocyclic group having 3 to 14 carbon atoms, for example, a furanyl group, a thienyl group, a pyrrolyl group, a pyrazolyl group, an imidazolyl group, a triazolyl group, an oxazolyl group, a dioxazolyl group, an isoxazolyl group, an oxadiazolyl group, a thiazolyl group, an isothiazolyl group, a thiadiazolyl group, a triazolyl group, an indolyl group, an indolinyl group, an indolidinyl group, an indazolinyl group, an indoleninyl group, a benzofuranyl group, a benzothienyl group, or a carbazolyl group. Examples include dibenzofuranyl group, dibenzothienyl group, pyridinyl group, diazinyl group, oxazinyl group, thiadinyl group, dioxynyl group, dithienyl group, triazinyl group, pyrimidinyl group, pyrazinyl group, pyridadinyl group, quinolinyl group, isoquinolinyl group, sinnonillyl group, phthalazinyl group, quinazolinyl group, naphthilidinyl group, prinyl group, pteridinyl group, acridinyl group, phenanthridine group, phenanthrolinyl group, xanthenyl group, phenoxadinyl group, thianthrenyl group, morpholinyl group, and phenadinyl group.

[0031] (Compound represented by formula (1)) A compound according to one aspect of this embodiment is represented by the following formula (1) (hereinafter also referred to simply as compound (1)). Here, in equation (1), X １ and X ２ Each is independently selected from the group consisting of a methine group and a nitrogen atom, n is an integer between 0 and 3, and R １ and R ２ Each of these is independently a hydrogen atom, a halogen atom, or a monovalent organic group, and R １ and R ２ At least one of them is a monovalent organic group with Hammett substituent constant σp of 0.50 or greater, and adjacent R １ and R ２ This may be part of a fused ring, and the fused ring may contain one or more atoms other than carbon.

[0032] Compound (1) is a novel compound useful as a material for photoelectric conversion elements. The reason for this is not clear, but the inventors believe it to be as follows. However, the reason is not limited to the following. That is, compound (1) has a structure in which the π-conjugated system is spread throughout the entire compound, R １ , and R ２ The presence of at least one electron-withdrawing group in compound (1) can lower the energy level of the lowest unoccupied orbital, thereby allowing the difference between the energy level of the lowest unoccupied orbital and the energy level of the highest occupied molecular orbital (HOMO) to be within a desired range.

[0033] In compound (1) of this embodiment, X １ and X ２ Each of these is not particularly limited, but from the viewpoint of more effectively and reliably achieving the effects of the present invention, it is more preferable that each be a nitrogen atom. Also, in compound (1), X １ and X ２ These elements may be identical or different, and are not particularly limited, but it is preferable that they be identical.

[0034] In compound (1) of this embodiment, n is not particularly limited, but is preferably an integer between 0 and 2, and more preferably 0 or 1.

[0035] In compound (1) of this embodiment, R １ and R ２ While not particularly limited, each is preferably independently selected from the group consisting of hydrogen atoms, halogen atoms excluding fluorine atoms, hydroxyl groups, thiol groups, amino groups, cyano groups, carboxyl groups, nitro groups, and optionally substituted linear, branched, or cyclic alkyl groups, thioalkyl groups, thioaryl groups, arylsulfonyl groups, aryloxy groups, alkylsulfonyl groups, alkylamino groups, arylamino groups, alkoxy groups, acylamino groups, acyloxy groups, aryl groups, carboxyamide groups, carboalkoxy groups, carboaryloxy groups, acyl groups, and monovalent heterocyclic groups; more preferably selected from the group consisting of hydrogen atoms, chlorine atoms, bromine atoms, iodine atoms, nitro groups, cyano groups, and optionally substituted linear, branched, or cyclic alkyl groups, R １ and R ２ It is particularly preferable that one or more of these groups are cyano, nitro, trifluoromethyl, or sulfonyl groups. Having the above-described structure of compound (1) allows for greater suppression of leakage current in the dark and tends to exhibit superior wavelength selectivity. Furthermore, the 5% or 10% mass loss temperature, as described later, tends to be higher, resulting in improved manufacturability.

[0036] In compound (1) of this embodiment, R １ and R ２ They may be the same or different.

[0037] In compound (1) below, R １ and R ２ The preferred combinations are shown. However, compound (1) is not limited to these.

[0038] Specific examples of compound (1) are shown below. However, compound (1) is not limited to these examples.

[0039]

[0040]

[0041] (Compound represented by formula (2)) Another compound according to this embodiment is represented by the following formula (2) (hereinafter also referred to simply as compound (2)). Here, in equation (2), X ３ and X ４ Each is independently selected from the group consisting of a methine group and a nitrogen atom, X ５ is an oxygen atom or NR ３ And n is an integer between 0 and 3, and R ３ This is selected from the group consisting of hydrogen atoms, halogen atoms, hydroxyl groups, thiol groups, amino groups, cyano groups, carboxyl groups, nitro groups, and optionally substituted linear, branched, or cyclic alkyl groups, thioalkyl groups, thioaryl groups, arylsulfonyl groups, aryloxy groups, alkylsulfonyl groups, alkylamino groups, arylamino groups, alkoxy groups, acylamino groups, acyloxy groups, aryl groups, carboxyamide groups, carboalkoxy groups, carboaryloxy groups, acyl groups, and monovalent heterocyclic groups.

[0042] In compound (2) of this embodiment, X ３ and X ４ Each of these is not particularly limited, but from the viewpoint of more effectively and reliably achieving the effects of the present invention, it is more preferable that each be a nitrogen atom. Also, in compound (2), X ３ and X ４ These elements may be identical or different, and are not particularly limited, but it is preferable that they be identical.

[0043] In compound (2) of this embodiment, n is not particularly limited, but is preferably an integer between 0 and 2, and more preferably 0 or 1.

[0044] In compound (2) of this embodiment, R ３The group is not particularly limited, but is preferably a hydrogen atom, a halogen atom, a cyano group, a nitro group, a perfluoroalkyl group, or an aryl group. Having the above-described structure of compound (2) allows for greater suppression of leakage current in the dark and tends to exhibit superior wavelength selectivity. Furthermore, the 5% or 10% mass loss temperature, described later, tends to be higher, resulting in improved manufacturability.

[0045] Specific examples of compound (2) are shown below. However, compound (2) is not limited to these examples.

[0046]

[0047]

[0048] The energy levels of the lowest unoccupied molecular orbitals (LUMO) obtained by density functional theory for compounds (1) and (2) of this embodiment (hereinafter simply referred to as "compounds (1) and (2)") are preferably between -6.00 eV and -3.80 eV, and more preferably between -5.50 eV and -3.65 eV, from the viewpoint of more effectively and reliably achieving the effects of the present invention. For compounds (1) and (2) of this embodiment, structural optimization can be performed by molecular simulation using density functional theory (for example, molecular simulation using the quantum chemistry calculation program Gaussian from Gaussian Inc.) to determine the energy levels of the lowest unoccupied orbitals of compounds (1) and (2). Furthermore, the energy levels of the lowest unoccupied orbitals obtained by density functional theory for compounds (1) and (2) of this embodiment are not particularly limited, however R １ , R ２ , or R ３ This may be adjusted by changing R. With respect to keeping the energy level of the lowest unoccupied orbital within the above range, in compound (1), １ , and R ２ Preferably, at least one of them is an electron-withdrawing group, R １ and R ２At least one of them is more preferably a cyano group or an alkyl group substituted with a halogen atom. In compound (2), there are no particular limitations, but R ３ R is preferably a hydrogen atom, a halogen atom, a cyano group, a nitro group, a perfluoroalkyl group, and an aryl group. ３ It is more preferable that the group is a hydrogen atom, a cyano group, a perfluoroalkyl group, or an aryl group.

[0049] The difference (eV) between the energy level of the lowest unoccupied orbital and the energy level of the highest occupied molecular orbital (HOMO) obtained by density functional theory for compounds (1) and (2) of this embodiment ([energy level of the highest occupied orbital] - [energy level of the lowest unoccupied orbital]) is preferably 3.0 eV or more and 4.0 eV or less. By keeping the difference in energy levels within the above range, when used as a material for photoelectric conversion elements, the leakage current in the dark tends to be reduced.

[0050] The compounds (1) and (2) of this embodiment preferably have a molecular weight of 300 or more, more preferably 330 or more, and even more preferably 350 or more. A molecular weight of 300 or more can further suppress changes in physical properties caused by thermal motion of molecules that may occur during heating operations in the manufacturing process of organic thin films using compounds (1) and (2) or in high-temperature operating environments. In particular, when compounds (1) and (2) are formed by vacuum deposition, the molecular weights of (1) and (2) are preferably 1000 or less, more preferably 950 or less, and even more preferably 900 or less. A molecular weight of 1000 or less can further reduce the thermal energy required for sublimation when forming organic thin films of compounds (1) and (2) by vacuum deposition. As a result, compounds (1) and (2) do not deteriorate due to heat, and good thin films can be formed. However, when thin films are formed by solution coating, such problems are less likely to occur, so the molecular weights of compounds (1) and (2) may be greater than 1000.

[0051] The compounds (1) and (2) of this embodiment preferably have a temperature at which their mass decreases by 5% from their mass before heating (hereinafter also referred to as the "5% mass loss temperature"), measured under the following condition 1, that is between 430°C and 550°C. When the 5% mass loss temperature is within the above range, changes in physical properties caused by thermal motion of molecules that may occur during heating operations in the manufacturing process of organic thin films using compounds (1) and (2) or in high-temperature operating environments can be further suppressed. (Condition 1) Pressure: 0.10 MPa Nitrogen: 200 mL / min Heating conditions: Heating from 20°C to 550°C at a rate of 10°C / min

[0052] The compounds (1) and (2) of this embodiment preferably have a temperature at which the mass decreases by 10% from the mass before heating (hereinafter also referred to as the "10% mass loss temperature"), measured under the following condition 2, is 220°C or higher and 400°C or lower. When the 10% mass loss temperature is within the above range, changes in physical properties caused by thermal motion of molecules that may occur during heating operations in the manufacturing process of organic thin films using compounds (1) and (2) or in high-temperature operating environments can be further suppressed. (Condition 2) Pressure: 1 Pa Heating conditions: Heating from 20°C to 450°C at a rate of 10°C / min

[0053] Compounds (1) and (2) can be synthesized, for example, using the following scheme.

[0054] More specifically, compound (E) can be obtained by, for example, adding compound (D) to commercially available (A). More specifically, it can be synthesized by referring to, for example, the method described in Japanese Patent Publication No. 2014-520394.

[0055] Compounds (1) and (2) of this embodiment are obtained, for example, by synthesis as described above. In the product obtained by synthesis (100% by mass), the content of compounds (1) and (2) is preferably 90% by mass or more, more preferably 93% by mass, and even more preferably 97% by mass or more. By having a content of compounds (1) and (2) of 90% by mass or more, when compounds (1) and (2) are used in a photoelectric conversion element or image sensor, the trapping of carriers to impurity levels caused by unintended impurities can be more effectively and reliably avoided. As a result, carrier recombination can be suppressed, and a photoelectric conversion element or image sensor with superior performance can be obtained. The content can be measured by liquid chromatography, gas chromatography, elemental analysis, etc., but any known method is acceptable.

[0056] (Materials for Photoelectric Conversion Elements) Compounds (1) and (2) of this embodiment are used as materials for photoelectric conversion elements. More specifically, they are used as materials included in each layer of the photoelectric conversion element described later. Among these, from the viewpoint of achieving the effects of the present invention more effectively and reliably, compounds (1) and (2) are preferably included in the photoelectric conversion film, more preferably in the auxiliary layer, and particularly preferably in at least one of the electron transport layer and the hole blocking layer.

[0057] Furthermore, compounds (1) and (2) of this embodiment can be used as photosensitive materials as is, or they can be mixed with other materials to form a photosensitive composition. The content of compounds (1) and (2) in the photosensitive composition may be 50% by mass or more, based on the total amount of the composition. Alternatively, the content may be 95% by mass or less, 90% by mass or less, or 80% by mass or less. The materials other than compounds (1) and (2) in the above photosensitive composition are not particularly limited as long as they are included in a normal photosensitive composition. Examples of such materials include n-type semiconductor materials, p-type semiconductor materials, and light-absorbing materials, which will be described later. These can be used individually or in combination of two or more.

[0058] (Organic Thin Film) The organic thin film of this embodiment includes compounds (1) and (2) of this embodiment or the photoelectric conversion element material described above. Such organic thin films can be fabricated by general dry or wet deposition methods. Specifically, examples include vacuum processes such as resistance heating deposition, electron beam deposition, sputtering, and molecular stacking; solution processes such as casting, spin coating, dip coating, blade coating, wire bar coating, and spray coating; printing methods such as inkjet printing, screen printing, offset printing, and letterpress printing; and soft lithography methods such as microcontact printing. Generally, from the viewpoint of ease of processing, it is desirable that photoelectric conversion element materials be used in processes that coat the compound in a solution state. However, in the case of photoelectric conversion elements in which organic thin films are stacked, dry deposition methods such as resistance heating deposition are preferred because the coating solution may damage the underlying film.

[0059] For example, in a dry deposition method, the photoelectric element material of this embodiment and, if necessary, other materials depending on the application of the photoelectric element are mixed to form a composition, and an organic thin film can be obtained by depositing the composition onto a substrate or other film under vacuum. Alternatively, in a wet deposition method, the photoelectric element film of this embodiment and, if necessary, other materials depending on the application of the photoelectric element are mixed with a solvent to form a liquid composition, which is then coated onto a substrate or other film, printed, and further dried to obtain an organic thin film.

[0060] The organic thin film of this embodiment may contain materials other than compounds (1) and (2), which are photoelectric element materials of this embodiment. The content of compound (1) or (2) in the organic thin film of this embodiment is not particularly limited as long as it exhibits the performance necessary for use as a photoelectric element material. For example, the content may be 50% by mass or more of the total amount of the organic thin film, but from the viewpoint of more effectively and reliably achieving the effects of the present invention, it is preferable to be 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The upper limit of the content may be 100% by mass. If the organic thin film of this embodiment contains materials other than compounds (1) and (2), the materials are not particularly limited as long as they are commonly used as photoelectric element materials. Examples of such materials include n-type semiconductor materials, p-type semiconductor materials, and light-absorbing materials, as well as molybdenum oxide, alkali metals, and alkali metal compounds, which are called doping materials and will be described later. These can be used individually or in combination of two or more.

[0061] The thickness of the organic thin film cannot be limited as it depends on the resistance and charge mobility of each material, but it is usually between 0.5 nm and 5000 nm, and may also be between 1 nm and 1000 nm, or between 5 nm and 500 nm.

[0062] From the viewpoint of more effectively and reliably achieving the effects of the present invention, the organic thin film of this embodiment preferably has a maximum absorption wavelength of 450 nm or less in the light absorption band. The measurement of the maximum absorption wavelength of the organic thin film is not particularly limited, but it can be measured by the method described in the examples below.

[0063] (Photoelectric Conversion Element) The photoelectric conversion element in this embodiment generates an electric charge corresponding to the amount of incident light and outputs it to the outside of the photoelectric conversion element via a capacitor for storing the generated charge (hereinafter also referred to as the "storage unit") and a transistor circuit for reading out the charge (hereinafter also referred to as the "readout unit"). Here, the photoelectric conversion element is a photoelectric conversion film that absorbs at least a portion of the incident light placed between a pair of opposing electrodes, and light is incident on the photoelectric conversion element from above the electrodes. The photoelectric conversion film is a photosensitive thin film containing a material that absorbs at least a portion of the incident light in the infrared region, and generates holes and electrons as a result of the incidence of light. Furthermore, 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 the "infrared photoelectric conversion element"). Here, the infrared photoelectric conversion element is defined as having a photoelectric conversion film that absorbs infrared light (hereinafter also referred to as the "infrared photoelectric conversion film") placed 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 the incident light in the infrared region (hereinafter also referred to as the "infrared absorbing material"), and generates holes and electrons as a result of the incidence of light.

[0064] The photoelectric conversion element of this embodiment will be described with reference to Figure 1 as appropriate. The photoelectric conversion element 100 comprises a lower electrode 102 which is a first electrode film, an upper electrode 106 which is a second electrode film, and a photoelectric conversion film 110 located between the lower electrode 102 and the upper electrode 106. The photoelectric conversion element 100 may also have a substrate 101, which is normally insulating, on the side of the upper electrode 106 opposite to the photoelectric conversion film 110.

[0065] The lower electrode 102 and the upper electrode 106 play a role in extracting and collecting holes or extracting and ejecting electrons from the photoelectric conversion film 110, if the photoelectric conversion film 110 has hole-transporting or electron-transporting properties. The materials that can be used as these electrodes are not particularly limited as long as they have a certain degree of conductivity, but it is preferable to select them considering adhesion to 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 may be used individually or in combination of multiple types.

[0066] The lower electrode 102, which is the first electrode film, is made of a light-transmitting conductive film, for example, indium tin oxide (ITO). The material constituting the lower electrode 102 is not limited to ITO, but for example, dopant-doped tin oxide (SnO ２ Examples of zinc oxide-based materials include zinc oxide (ZnO) with added dopants, and zinc oxide-based materials obtained by adding dopants to zinc oxide (ZnO). Examples of zinc oxide-based materials include aluminum zinc oxide (AZO) with added aluminum (Al) as a dopant, gallium zinc oxide (GZO) with added gallium (Ga), and indium zinc oxide (IZO) with added indium (In). Alternatively, examples of materials constituting the lower electrode 102 include CuI, InSbO ４ , ZnMgO, CuInO ２ MgIN ２ O ４ , CdO, and ZnSnO ３ The following are also possible. The thickness of the lower electrode 102 is, for example, 5 nm or more and 3000 nm or less, and may be 5 nm or more and 500 nm or less, or 10 nm or more and 300 nm or less.

[0067] The upper electrode 106, which is the second electrode film, may be made of a conductive film having the same light-transmitting properties as the lower electrode 102, or it may be made of a metal commonly used for electrodes of photoelectric conversion elements, such as aluminum. Furthermore, in a solid-state imaging device that uses a solid-state image sensor as a single pixel, this upper electrode 106 may be separated for each pixel, or it may be formed as a common electrode for each pixel. The thickness of the upper electrode 106 is, for example, 5 nm to 3000 nm, may be 5 nm to 500 nm, or 10 nm to 300 nm.

[0068] The conductivity of the materials used for electrodes, such as the first and second electrode films, is not particularly limited as long as it does not unnecessarily hinder the light reception of the photoelectric conversion element. However, from the viewpoint of signal strength and power consumption of the photoelectric conversion element, it is preferable to have the highest possible conductivity. For example, as a transparent electrode, an ITO film with a sheet resistance of 300 Ω / sq or less is sufficient for functioning as an electrode. However, commercially available substrates equipped with ITO films having conductivity of several Ω / sq (for example, 5 to 9 Ω / sq) are also available, and substrates with such high conductivity are desirable.

[0069] When using an ITO film, the electrode thickness can be arbitrarily selected considering conductivity, but is usually 5 nm to 3000 nm, preferably 10 nm to 300 nm. Methods for forming ITO films include conventionally known methods such as vapor deposition, electron beam method, sputtering, chemical reaction method, and coating method. The ITO film provided on the substrate may be subjected to UV-ozone treatment or plasma treatment as needed.

[0070] Furthermore, when stacking multiple photoelectric conversion films with different wavelengths to be detected, the electrode films used between each photoelectric conversion film must transmit light of wavelengths other than those detected by each respective photoelectric conversion film. From this viewpoint, it is preferable to use a material that transmits 90% or more of the incident light for the electrode films, and more preferably a material that transmits 95% or more of the light. Note that the electrode films mentioned above are the electrode films other than the pair of electrodes described above.

[0071] Furthermore, if a visible light photoelectric conversion unit that senses infrared light or light in a different visible light range is provided below the photoelectric conversion element in this embodiment, the electrodes used in the photoelectric conversion element preferably have a transmittance of 90% or more for visible light and infrared light, and more preferably 95% or more.

[0072] As electrode materials that satisfy these conditions, transparent conductive oxides (TCOs) with high transmittance to visible and infrared light and low resistance are preferred. Although thin metal films such as gold can also be used as electrodes, the resistance increases drastically when trying to achieve a transmittance of 90% or more. Therefore, TCOs are preferred as electrodes. In particular, ITO, IZO, AZO, FTO, and SnO are preferred as TCOs. ２ , TiO ２ and ZnO ２ It is preferable.

[0073] The method for forming electrodes is not particularly limited and can be appropriately selected considering its suitability with the electrode material. When transparent electrodes are used, specific methods for forming them include wet methods such as printing and coating, physical methods such as vacuum deposition, sputtering, and ion plating, and chemical methods such as CVD and plasma CVD. Furthermore, when the electrode material is a transparent conductive metal oxide such as ITO, methods for forming it include, for example, electron beam methods, sputtering, resistance heating deposition, chemical reaction methods (e.g., sol-gel method), and methods of coating a dispersion of the metal oxide. In addition, UV-ozone treatment and plasma treatment can be applied to films of transparent conductive metal oxides such as ITO.

[0074] Furthermore, from the viewpoint of more effectively and reliably achieving the effects of the present invention, the photoelectric conversion element of this embodiment comprises a first electrode film, a second electrode film, and a photoelectric conversion film located between the first electrode film and the second electrode film, wherein the photoelectric conversion film comprises a photoelectric conversion layer and two auxiliary layers located between the photoelectric conversion layer and the second electrode film, and it is preferable that the auxiliary layer closer to the second electrode film contains compound (1) or (2) of this embodiment, which is a material for photoelectric conversion elements.

[0075] The exact factors that enable such a photoelectric conversion element to suppress leakage current in the dark are unclear, but the inventors believe the following. The photoelectric conversion element of this embodiment includes two auxiliary layers between the photoelectric conversion layer and the second electrode film, with the auxiliary layer closer to the second electrode film containing compound (1) or (2). As a result, the relatively low HOMO level of compound (1) or (2) provides a rectifying effect that suppresses the movement of electrons generated in the photoelectric conversion layer to the second electrode film, and as a result, it is thought that leakage current in the dark (hereinafter also referred to as "dark current") can be suppressed. However, the factors are not limited to this. Furthermore, the photoelectric conversion element of this embodiment can also have high photoelectric conversion efficiency. This is thought to be because the auxiliary layer closer to the second electrode film contains compound (1) or (2), which increases the chemical affinity between the second electrode film and the photoelectric conversion film, and makes the energy gradient for moving electrons to the second electrode film smoother. However, the factors are not limited to this.

[0076] In one aspect of this embodiment, the photoelectric conversion film 110 may include the material for the photoelectric conversion element of this embodiment, or it may include the organic thin film described above. More specifically, for example, the photoelectric conversion film 110 comprises 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. Although the photoelectric conversion film 110 shown in Figure 1 includes the first auxiliary layer 103 and the second auxiliary layer 105, the photoelectric conversion film may include only one of these auxiliary layers. Alternatively, the photoelectric conversion film may not include either auxiliary layer and may include only the photoelectric conversion layer 104. When the photoelectric conversion film does not include an auxiliary layer, the photoelectric conversion layer 104 is the organic thin film described above, and when the photoelectric conversion film includes an auxiliary layer, at least one of the photoelectric conversion layer 104 and the auxiliary layer is the organic thin film described above. However, from the viewpoint of achieving the effects of the present invention more effectively and reliably, it is preferable that the auxiliary layer is the organic thin film containing the photoelectric conversion element material of this embodiment.

[0077] In one embodiment of this design, the photoelectric conversion film 110 comprises a photoelectric conversion layer 104 and a second auxiliary layer 105 and a third auxiliary layer 107 located between the photoelectric conversion layer 104 and the upper electrode 106. Of these auxiliary layers 105 and 107, the third auxiliary layer 107, which is closer to the upper electrode 106, is adjacent to the upper electrode 106, while the second auxiliary layer 105 is located on the photoelectric conversion layer 104 side of the third auxiliary layer 107. Although the photoelectric conversion film 110 shown in Figure 2 comprises a first auxiliary layer 103, a second auxiliary layer 105, and a third auxiliary layer 107, the photoelectric conversion film does not necessarily have an auxiliary layer between the lower electrode 102 and the photoelectric conversion layer 104.

[0078] The photoelectric conversion layer 104 may be an organic semiconductor film commonly used as a photoelectric conversion layer, or it may be the organic thin film described above. Furthermore, in the photoelectric conversion layer 104, the organic semiconductor film and organic thin film may be one layer or multiple layers. If there is one layer, a p-type organic semiconductor film, an n-type organic semiconductor film, or a mixed film thereof (hereinafter referred to as a "bulk heterostructure") may be used. On the other hand, if there are multiple layers, the number of layers may be about 2 to 10 layers, and the structure is made by stacking any of the p-type organic semiconductor film, an n-type organic semiconductor film, or a mixed film thereof (hereinafter referred to as a "bulk heterostructure"), and buffer layers may be inserted between the layers.

[0079] The photoelectric conversion layer 104 in this embodiment may or may not contain the photoelectric conversion element material of this embodiment, and may contain materials other than the photoelectric conversion element material of this embodiment. Among these, it is preferable that the photoelectric conversion layer 104 contains at least one of the following: an organic p-type semiconductor, an organic n-type semiconductor, and a light-absorbing material, as this allows for more efficient conversion of incident light energy of a desired wavelength into an electrical signal. Among these, it is preferable that the light-absorbing material is either an organic p-type semiconductor that readily donates electrons and has a small ionization potential, or an organic n-type semiconductor that readily accepts electrons and has a large electron affinity, as this allows for even more efficient conversion of incident light energy into an electrical signal. Here, the ionization potential (HOMO level) refers to the value measured by photoelectron yield spectroscopy or photoelectron spectroscopy. The electron affinity (LUMO level) refers to the value obtained by calculating the energy band gap value from the longest wavelength absorption edge of the near-infrared spectral spectrum and subtracting it from the HOMO level, or the value measured by inverse photoelectron spectroscopy.

[0080] When using an organic semiconductor film, the film may consist of one layer or two or more 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 (bulk heterostructure) thereof. In particular, it is preferable that the organic semiconductor film has a bulk heterojunction structure layer. In such a case, by incorporating a bulk heterojunction structure into the photoelectric conversion film, the disadvantage of the short carrier diffusion length of the photoelectric conversion film can be compensated for, and the photoelectric conversion efficiency can be improved.

[0081] The thickness of the photoelectric conversion layer 104 may be, for example, 0.5 nm or more and 5000 nm or less, 1 nm or more and 1000 nm or less, or 5 nm or more and 500 nm or less.

[0082] The following provides a detailed explanation of organic semiconductors.

[0083] Organic p-type semiconductors are donor organic semiconductors (hereinafter also called "donor organic compounds"), mainly represented by hole-transporting organic compounds, which are organic compounds that readily donate electrons. More specifically, they refer to the organic compound with the lower 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.

[0084] 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, condensed aromatic carbocyclic compounds (e.g., naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluorantene derivatives), and metal complexes having nitrogen-containing heterocyclic compounds as ligands. However, as mentioned above, any organic compound with a lower ionization potential than the organic compound used as the acceptor organic compound can be used as a donor organic semiconductor.

[0085] Organic n-type semiconductors are acceptor organic semiconductors (hereinafter also referred to as "acceptor organic compounds"), mainly represented by electron-transporting organic compounds, and refer to organic compounds that have a property of readily accepting electrons. More specifically, they refer to the organic compound with the greater electron affinity when two organic compounds are used in contact. Therefore, any organic compound that has electron-accepting properties can be used as an acceptor organic compound.

[0086] 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, fluorantene derivatives, fullerene derivatives), and 5-7 membered heterocyclic compounds containing nitrogen, oxygen, and sulfur atoms (e.g., pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, Examples include metal complexes having pyrazoles, imidazoles, thiazoles, oxazoles, indazoles, benzimidazoles, benzotriazoles, benzoxazoles, benzothiazoles, carbazoles, purines, triazolopyridazines, triazolopyrimidines, tetrazaidene, oxadiazoles, imidazopyridines, pyrridines, pyrrolopyridines, thiadiazolopyridines, dibenzazepines, and tripenzazepines), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, and nitrogen-containing heterocyclic compounds as ligands. However, as mentioned above, any organic compound with a greater electron affinity than the organic compound used as the donor organic compound can be used as an acceptor organic semiconductor.

[0087] The light-absorbing material is a compound having a maximum light absorption wavelength in the visible light range, particularly in the range of 450 nm to 650 nm. It is desirable that the absorption intensity of the light-absorbing material at its maximum light absorption wavelength is greater than the absorption intensity of the donor organic compound or the acceptor organic compound at its maximum light absorption wavelength. Having such an absorption intensity allows for selective absorption of incident light at the light-absorbing material's maximum light absorption wavelength. After the incident light is absorbed by the light-absorbing material and the photons become excitons, exciton separation occurs at the interface between the donor organic compound and the acceptor organic compound, efficiently generating hole and electron carriers.

[0088] As such light-absorbing materials, compounds generally called dyes can be used. For example, phthalocyanine derivatives, subphthalocyanine derivatives, quinacridone derivatives, porphyrin derivatives, naphthalene or perylene derivatives, phthaloperylene derivatives, styryl derivatives, cyanine derivatives, hemicyanine derivatives, merocyanine derivatives, rhodacyanine derivatives, oxonol derivatives, hemioxonol derivatives, croconium derivatives, squarylium derivatives, azametine derivatives, allylidene derivatives, azo derivatives, azomethine derivatives, metallocene derivatives, fulgide derivatives, phenazine derivatives, phenothiazine derivatives, polyene derivatives, acridine derivatives, acridinone derivatives, diphenylamine derivatives, triarylamine derivatives such as triphenylamine, naphthylamine and styrylamine, quinophthalone derivatives, phenoxazine derivatives, chlorophyll derivatives, rhodamine derivatives, diphenylmethane or triphenylmethane derivatives, xanthene derivatives, acridine derivatives, phenoxazine derivatives, quinoline derivatives, oxazine Examples of derivatives include thiazine derivatives, quinone derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, indigo or thioindigo derivatives, pyrrole derivatives, pyridine derivatives, dipyrine derivatives, indole derivatives, diketopyrrolopyrrole derivatives, coumarin derivatives, fluorene derivatives, fluorenone derivatives, fluorantene 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, thiazoline derivatives, oxazole derivatives, thiazoline derivatives, oxadiazole derivatives, thiophene derivatives, selenofen derivatives, silole derivatives, germole derivatives, stilbene derivatives, phenylenevinylene derivatives, pentacene derivatives, rubrene derivatives, thienothiophene derivatives, benzodithiophene derivatives, xanthenoxanthene derivatives, and fullerene derivatives. Furthermore, as mentioned above, any compound whose absorption intensity is greater than that of the donor organic compound or acceptor organic compound at the maximum light absorption wavelength can be used as a light-absorbing material.Furthermore, light-absorbing materials can also function as either donor or acceptor organic compounds.

[0089] In one embodiment of this design, the first auxiliary layer 103 may be a single layer or two or more layers. The first auxiliary layer 103 may comprise at least one of a hole blocking layer and an electron transport layer. When the first auxiliary layer 103 comprises two of these, they are usually stacked in the order of electron transport layer and hole blocking layer, starting from the photoelectric conversion layer 104 side. The electron transport layer plays the role of transporting electrons generated in the photoelectric conversion layer 104 to the first electrode 102 and blocking the movement of holes from the first electrode 102 to the photoelectric conversion layer 104. The hole blocking layer prevents the movement of holes from the first electrode 102 to the photoelectric conversion layer 104, prevents recombination within the photoelectric conversion layer 104, reduces dark current, reduces noise, and expands the dynamic range. Alternatively, one layer may have both the functions of a hole blocking layer and an electron transport layer. The thickness of the first auxiliary layer 103 is preferably 10 nm to 300 nm, more preferably 30 nm to 250 nm, and even more preferably 50 nm to 200 nm, from the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency.

[0090] In one embodiment of this design, the second auxiliary layer 105 may be a single layer or two or more layers. The second auxiliary layer 105 may comprise at least one of an electron blocking layer and a hole transport layer. When the second auxiliary layer 105 comprises two of these, they are usually stacked in the order of a hole transport layer and an electron blocking layer, starting from the photoelectric conversion layer 104 side. The hole transport layer plays the role of transporting generated holes from the photoelectric conversion layer 104 to the second electrode 106 and blocking the movement of electrons from the second electrode 106 to the photoelectric conversion layer 104. The electron blocking layer prevents the movement of electrons from the second electrode 106 to the photoelectric conversion layer 104, prevents recombination within the photoelectric conversion layer 104, reduces dark current, reduces noise, and expands the dynamic range. Alternatively, one layer may have both the functions of an electron blocking layer and a hole transport layer. The thickness of the second auxiliary layer 105 is preferably 5 nm to 200 nm, more preferably 15 nm to 130 nm, and even more preferably 25 nm to 100 nm, from the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency.

[0091] In one embodiment of this design, the third auxiliary layer 107 is an auxiliary layer closer to the upper electrode 106 than the second auxiliary layer 105, and may be, for example, a hole blocking layer. The hole blocking layer prevents the movement of holes from the second electrode 106 to the photoelectric conversion layer 104, prevents recombination within the photoelectric conversion layer 104, reduces dark current, reduces noise, and expands the dynamic range. At least one of the layers located between the photoelectric conversion layer 104 and the upper electrode 106 may have the functions of both a hole blocking layer and an electron transport layer. From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the third auxiliary layer 107 is preferably 5 nm to 200 nm, more preferably 15 nm to 130 nm, and even more preferably 25 nm to 100 nm.

[0092] The material for the photoelectric conversion element of this embodiment may be included in any of the first auxiliary layer 103, the second auxiliary layer 105, and the third auxiliary layer 107, but it is preferable that it be included in the first auxiliary layer 103 and / or the third auxiliary layer 107. In the photoelectric conversion element of this embodiment, it is preferable that the first auxiliary layer 103 and / or the third auxiliary layer 107 contain the above-mentioned organic thin film. Furthermore, it is more preferable that the material for the photoelectric conversion element of this embodiment is included in at least one of the hole blocking layer and the electron transport layer in the first auxiliary layer 103 and / or the third auxiliary layer 107. In the photoelectric conversion element of this embodiment, it is preferable that at least one of the hole blocking layer and the electron transport layer is the above-mentioned organic thin film. These features allow the effects of the present invention to be achieved more effectively and reliably.

[0093] In one aspect of this embodiment, compounds (1) and (2) of this embodiment are included in at least the third auxiliary layer 107 of these auxiliary layers. The third auxiliary layer 107 may contain materials other than compounds (1) and (2). The content of compounds (1) and (2) in the third auxiliary layer 107 is not particularly limited as long as it exhibits the performance necessary for use as an auxiliary layer close to the upper electrode 106. For example, the content may be 50% by mass or more of the total amount of the third auxiliary layer 107, but from the viewpoint of more effectively and reliably achieving the effect of suppressing leakage current in the dark according to the present invention, it is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The upper limit of the content may be 100% by mass.

[0094] The following describes the compounds (1), (2), and materials other than the photoelectric conversion element material that may be included in each layer of the auxiliary layer in this embodiment.

[0095] The material for the hole transport layer is not particularly limited as long as it is known as a hole transport layer in photoelectric conversion elements such as solid-state image sensors. Examples include polyaniline and its doping materials, and cyanide compounds described in International Publication No. 2006 / 019270.

[0096] More specifically, the materials that constitute the hole transport layer include selenium, iodides such as copper iodide (CuI), cobalt complexes such as layered cobalt oxide, CuSCN, and molybdenum oxide (MoO). ３ (etc.), nickel oxide (NiO etc.), 4CuBr・3S (C ４ H ９ Examples include iodides and organic hole transporters. Among these, copper iodide (CuI) is an example of an iodide. Examples of layered cobalt oxides include AxCoO ２ (Here, A represents Li, Na, K, Ca, Sr, or Ba, and 0 ≤ X ≤ 1.) Examples of organic hole transporters include polythiophene derivatives such as poly-3-hexylthiophene (P3HT), poly(3,4-ethylenedioxythiophene), (PEDOT; for example, the trade name "Baytron P" from Starck Vitek), 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, as a material for the hole transport layer, for example, CuInSe ２ and compound semiconductors having monovalent copper such as copper sulfide (CuS), gallium phosphide (GaP), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (FeO), bismuth oxide (Bi ２ O ３ ), molybdenum oxide (MoO ２ ), and chromium oxide (Cr ２ O ３ ) are some examples.

[0097] Furthermore, it is preferable that the hole transport layer has a LUMO level higher than the LUMO level of the photoelectric conversion film, as this provides an electron blocking function that has a rectifying effect that suppresses the movement of electrons generated in the photoelectric conversion film toward the electrode side. Such a hole transport layer is also called an electron blocking layer.

[0098] Among the materials constituting the electron blocking layer, low molecular weight organic compounds include, for example, aromatic diamine compounds such as N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) and 4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolon, stilbene derivatives, pyrazoline derivatives, tetrahydroimidazole, polyarylalkane, butadiene, and 4,4',4''tris(N-(3-methylphenyl)N-phenyl Examples of porphyrin compounds include porphyrin (m-MTDATA), tetraphenylporphyrin copper, phthalocyanine, copper phthalocyanine, and titanium phthalocyanine oxide; triazole derivatives, oxadizaazole 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 polymeric organic compounds include polymers such as phenylenevinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, as well as their derivatives. Even if a compound is not electron-donating, if it has sufficient hole transport properties, it can be used as a material to constitute the electron blocking layer. Furthermore, examples of inorganic compounds among the materials constituting the electron blocking layer include metal oxides such as calcium oxide, chromium oxide, chromium copper 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 iridium oxide, as well as selenium, tellurium, and antimony sulfide. These can be used individually or in combination of two or more.

[0099] 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 or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and still more preferably 50 nm or more and 200 nm or less.

[0100] As a method for forming the hole transport layer and the electron blocking layer, a conventionally known method may be used, and either a dry film forming method such as a vacuum evaporation method or a wet film forming method such as a solution coating method may be used. From the viewpoint of leveling the coating surface, a wet film forming method is preferably used. Examples of the dry film forming method include a vapor deposition method such as a vacuum evaporation method and a sputtering method. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum evaporation is preferred. Examples of the wet film forming method include 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 roll coating method, a bar coating method, and a gravure coating method.

[0101] 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 device. For example, octaazaporphyrin and a perfluoro body of a p-type semiconductor (for example, perfluoropentacene, perfluorophthalocyanine, etc.), fullerene, a fullerene derivative (for example, [6,6]-Phenyl-C61-Butyric Acid Methyl Ester; PCBM, etc.), perylene, indenoindene, and an organic compound such as an indenoindene derivative, titanium oxide (TiO ２ etc.), nickel oxide (NiO), tin oxide (SnO ２ ), tungsten oxide (WO ２ ), WO ３ ), W ２ O ３ etc.), zinc oxide (ZnO), niobium oxide (Nb ２ O ５ etc.), tantalum oxide (Ta ２ O ５ etc.), yttrium oxide (Y ２ O ３ etc.), and strontium titanate (SrTiO ３Examples of inorganic oxides include those such as (etc.). The electron transport layer may be porous or dense, and when they are laminated, it is preferable that the porous electron transport layer and the dense electron transport layer be laminated in that order from the photoelectric conversion film side.

[0102] Furthermore, it is preferable that the electron transport layer has a HOMO level lower than the HOMO level of the photoelectric conversion film, as this provides a hole blocking function that has a rectifying effect that suppresses the movement of holes generated in the photoelectric conversion film toward the opposing electrode. Such an electron transport layer is also called a hole blocking layer.

[0103] Materials that constitute the hole blocking layer include, for example, oxadiazole derivatives such as 1,3-bis(4-tert-butylphenyl-1,3,4-oxadiazolyl)phenylene (OXD-7), anthraquinodimethane derivatives, diphenylquinone derivatives, vasocuproin, vasophenanthroline, and their derivatives, triazine compounds, triazole compounds, tris(8-hydroxyquinolinate)aluminum complexes, bis(4-methyl-8-quinolinate)aluminum complexes, silole compounds, and porphyrins. Examples include styrene compounds, styryl compounds such as DCM (4-dicyanomethylene-2-methyl-6-(4-(dimethylaminostyryl))-4Hpyran), n-type semiconductor materials such as naphthalenetetracarboxylic anhydride (NTCDA), naphthalenetetracarboxylic diimide, perylenetetracarboxylic anhydride (PTCDA), and perylenetetracarboxylic diimide, n-type inorganic oxides such as titanium dioxide, zinc oxide, and gallium oxide, and alkali metal fluorides such as lithium fluoride, sodium fluoride, and cesium fluoride. Furthermore, alkali metal compounds doped into organic semiconductor molecules are also preferred because they have the function of improving the electrical junction with the counter electrode. These can be used individually or in combination of two or more.

[0104] 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.

[0105] The method for forming the electron transport layer and hole blocking layer may be any conventionally known method, and may be either a dry film formation method such as vacuum deposition or a wet film formation method such as solution coating. However, from the viewpoint of being able to level the coated surface, a wet film formation method is preferred. Examples of dry film formation methods include vapor deposition methods such as vacuum deposition and sputtering. Vacuum deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum deposition is preferred. Examples of wet film formation methods include inkjet, spray, nozzle print, spin coat, dip coat, cast, die coat, roll coat, bar coat, and gravure coat.

[0106] The photoelectric conversion element of this embodiment may include a single or two or more auxiliary layers between the first auxiliary layer 103 and the lower electrode 102, separate from the first auxiliary layer 103. Examples of such auxiliary layers include hole injection layers that improve hole injection from the lower electrode 102 to the first auxiliary layer 103. Examples of materials constituting the hole injection layer include 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 polymeric materials such as polyvinylcarbazole derivatives. The thickness of this auxiliary layer may be the same as that of the first auxiliary layer 103.

[0107] In this embodiment, the photoelectric conversion element may include a single or multi-layer auxiliary layer between the second auxiliary layer 105 and the upper electrode 106, separate from the second auxiliary layer 105. Examples of such auxiliary layers include an electron injection layer that improves electron injection from the upper electrode 106 to the second auxiliary layer 105, and an electron transport layer. Examples of materials constituting the electron injection layer include metals such as cesium, lithium, and strontium, as well as lithium fluoride. The 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.

[0108] In this embodiment, the photoelectric conversion element may include a single or two or more auxiliary layers between the third auxiliary layer 107 and the upper electrode 106, separate from the second auxiliary layer 105 and the third auxiliary layer 107. Examples of such auxiliary layers include an electron injection layer that improves the electron injection from the upper electrode 106 to the third auxiliary layer 107, and an electron transport layer. Examples of materials constituting the electron injection layer include metals such as cesium, lithium, and strontium, as well as lithium fluoride. The material constituting the electron transport layer may be the same as described above. Furthermore, the thickness of this auxiliary layer may be the same as that of the second auxiliary layer 105.

[0109] In addition to the layers described above, the photoelectric conversion element of this embodiment may also include at least one of the interlayer contact improvement layer and crystallization prevention layer located between those layers.

[0110] The interlayer contact improvement layer serves to reduce damage to the immediately below the upper electrode 106, such as the photoelectric conversion film 110, during film formation of the upper electrode 106. In particular, high-energy particles present in the apparatus used for film formation of the upper electrode 106, such as sputtered particles, secondary electrons, Ar particles, and oxygen negative ions in the sputtering method, collide with the immediately below film, causing alteration and potentially leading to performance degradation such as increased leakage current and decreased sensitivity. One way to prevent this is to provide an interlayer contact improvement layer on top of the immediately below film. Preferably, the interlayer contact improvement layer is made of organic substances such as copper phthalocyanine, NTCDA, PTCDA, [dipyradino[2,3-F:2',3'-H]quinoxaline-2,3,6,7,10,11-hexacarbonitride] (HATCN), acetylacetonate complexes, BCP, organometallic compounds, or inorganic substances such as MgAg and MgO. The appropriate thickness of the interlayer contact improvement layer varies depending on the composition of the photoelectric conversion film and the thickness of the electrodes, but it is preferable that it be between 2 nm and 500 nm, particularly from the viewpoint of selecting a material that does not absorb in the visible range or from the viewpoint of using a thin thickness.

[0111] As described above, the photoelectric conversion element of this embodiment is connected to a storage unit, which is a capacitor for storing the generated charge, and a readout unit, which is a transistor circuit for reading the charge, via a connection part made of a conductive material. In addition, the photoelectric conversion element may include a protective structure from the outside air, such as a protective film, a substrate for maintaining strength, and microlenses for focusing light, if necessary.

[0112] The readout unit is provided to read out a signal corresponding to the charge generated in the photoelectric conversion film. The readout unit is composed of, for example, a CCD, CMOS circuit, or TFT circuit, and is preferably shielded from light by a light-shielding layer placed within the insulating layer. The readout circuit is electrically connected to the corresponding electrode via a connector. In addition, to secure the amount of charge necessary for reading, a storage unit composed of a capacitor or the like may be interposed between the electrode and the connector. The connector is embedded in the insulating layer and is a plug or the like for electrically connecting the electrode (for example, a transparent electrode or a counter electrode) and the readout unit. When the component configured in this way is a solid-state image sensor, when light is incident, this light is incident on the photoelectric conversion film, and charge is generated there. Electrons of the generated charge are collected (and stored) by one electrode, and holes are collected by the other electrode. A voltage signal corresponding to the amount is output to the outside of the solid-state image sensor by the readout unit.

[0113] (Image Sensor) In one aspect of this embodiment, the image sensor of this embodiment may have the same configuration as a conventional image sensor, as long as it is equipped with the photoelectric conversion elements of this embodiment. For example, the image sensor of this embodiment is equipped with a large number of the photoelectric conversion elements of this embodiment arranged in an array. That is, by arranging a large number of photoelectric conversion elements in an array, a solid-state image sensor is constructed that indicates not only the amount of incident light but also the incident position information.

[0114] The image sensor of this embodiment may consist of one photoelectric conversion element of this embodiment, or it may consist of two or more stacked elements. When two or more photoelectric conversion elements of this embodiment are stacked, each photoelectric conversion element may selectively detect light in different wavelength bands and perform photoelectric conversion. For example, when three or more photoelectric conversion elements of this embodiment are stacked, at least one may acquire a green color signal, another at least one may acquire a blue color signal, another at least one may acquire a red color signal, and yet another at least one may acquire an infrared color signal. As a result, the image sensor can acquire multiple types of color signals in a single pixel without using a color filter. In addition, color signals other than those detected by the photoelectric conversion elements of this embodiment may be sensed by a conventionally known device having a silicon photodiode.

[0115] In an image sensor, if a photoelectric conversion element positioned closer to the light source does not block (i.e., transmit) the absorption wavelength of another photoelectric conversion element positioned behind it as viewed from the light source side, then a device having multiple photoelectric conversion elements or silicon photodiodes may be stacked.

[0116] In an image sensor, from the viewpoint of ease of molding, some of the photoelectric conversion elements may be configured as thin films on the same plane without structural separations between adjacent photoelectric conversion elements.

[0117] The image sensor of this embodiment may further include a substrate. The substrate may be used to manufacture the image sensor by laminating each layer thereon, or to increase the mechanical strength of the image sensor. The type of substrate is not particularly limited, and examples include semiconductor substrates, glass substrates, and plastic substrates.

[0118] In this embodiment, by including compound (1) or (2) in the image sensor, it is possible to provide an image sensor that can suppress leakage current in the dark and has excellent wavelength selectivity. Therefore, compound (1) or (2) can suppress noise and charge separation due to light of other wavelengths, and is suitable for image sensors that require high resolution. Furthermore, compound (1) or (2) is not particularly limited, but from the viewpoint of more effectively and reliably achieving the effects of the present invention, it is preferable that it be included in the photoelectric conversion film in the image sensor, and more preferably in the auxiliary layer close to the second electrode film. Here, the photoelectric conversion film and the auxiliary layer close to the second electrode film are as described above.

[0119] (Optical Sensor) The optical sensor of this embodiment may be any optical sensor equipped with the image sensor of this embodiment, and other configurations may be the same as those of a conventional optical sensor. This optical sensor can receive light in the image sensor of this embodiment and output an electrical signal corresponding to the amount of light received.

[0120] (Solid-State Imaging Device) The solid-state imaging device of this embodiment may be any device equipped with the image sensor of this embodiment, and other configurations may be the same as those of a conventional solid-state imaging device. The solid-state imaging device of this embodiment may be, for example, a CMOS image sensor, and may be equipped with a pixel section as an imaging area on a semiconductor substrate, and further equipped with a peripheral circuit section having a row scanning section, a horizontal selection section, a column scanning section, and a system control section in the peripheral region or vertically below the pixel section. The pixel section has the image sensor of this embodiment.

[0121] The photoelectric conversion element of this embodiment has the following advantages by using the photoelectric conversion element material of this embodiment. Specifically, the photoelectric conversion element of this embodiment is less prone to short circuits and pinhole formation, resulting in a lower dark current value. As a result, the photoelectric conversion element of this embodiment has excellent leakage prevention properties (especially in the dark). Furthermore, the photoelectric conversion element of this embodiment tends to exhibit a high light-dark ratio, in which case it has even better leakage prevention properties. In addition, the photoelectric conversion element of this embodiment has excellent hole and electron transport properties despite the photoelectric conversion element material being less prone to aggregation, resulting in higher photoelectric conversion efficiency. Furthermore, by using the photoelectric conversion element material of this embodiment, the photoelectric conversion element of this embodiment also has good heat resistance, improving durability in the manufacturing process and in practical environments.

[0122] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The synthesized compounds were further purified by sublimation as needed.

[0123] <Synthesis Example 1> 6.0 g of 1,4,5,8-naphthalenetetracarboxylic anhydride (hereinafter referred to as "compound (A1)") (manufactured by Tokyo Chemical Industry Co., Ltd.) and 3.7 g of 5,6-diamino-2,3-dicyanopyrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) (1.0 molar equivalent relative to compound (A1)) were added to 90 mL of pyridine (manufactured by Tokyo Chemical Industry Co., Ltd.) and the resulting mixture was stirred at 120°C for 8 hours. After that, it was cooled to room temperature and the solvent was removed under reduced pressure. Methanol was added to the solid obtained by solvent removal and stirred, and the solid was filtered. After filtering the solid, the solvent was removed under reduced pressure. Compound (A2), a yellowish-brown solid, was obtained by size exclusion chromatography using chloroform as the eluent.

[0124] 3.0 g of compound (A2) was heated at 300°C for 1 hour under vacuum. After cooling to room temperature, methanol was added, and the solid was filtered. Compound (A3), a yellowish-brown solid, was obtained by size exclusion chromatography using chloroform as the eluent.

[0125] The results of the NMR measurement of compound (A3) are shown below. １ HNMR (500MHz, DMSO-d6): 9.20 (d, 1H), 9.00 (d, 1H), 8.84 (d, 2H)

[0126] <Synthesis Example 2> Compound (A4) was obtained in the same manner as in Synthesis Example 1, except that 5,6-diamino-2,3-dicyanopyrazine was replaced with 5,6-diamino-2,3-pyrazinedicarimide (manufactured by Aurora Fine Chemicals LLC). Compound (A5) was obtained in the same manner as in Synthesis Example 1, except that compound (A4) was replaced with compound (A2).

[0127] The results of the NMR measurement of compound (A5) are shown below. １ HNMR (500MHz, DMSO-d6): 12.09 (s, 1H), 9.16 (d, 1H), 8.99 (d, 1H), 8.83 (d, 2H)

[0128] <Synthesis Example 3> Compound (A6) was obtained in the same manner as in Synthesis Example 1, except that diaminomaleonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 5,6-diamino-2,3-dicyanopyrazine. Compound (A7) was obtained in the same manner as in Synthesis Example 1, except that compound (A6) was used instead of compound (A2).

[0129] The results of the NMR measurement of compound (A7) are shown below. １ HNMR (500MHz, DMSO-d6): 8.98 (d, 1H), 8.90 (d, 1H), 8.80 (d, 1H), 8.76 (d, 1H)

[0130] <Synthesis Example 4> 2.0 g of compound (A1) and 1.5 g of aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.2 molar equivalents relative to compound (A1)) were added to 15 mL of acetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and the resulting mixture was stirred at 125°C under reflux for 8 hours. After cooling to room temperature, methanol was added, and the precipitated mixture was filtered. After further washing with methanol, pyridine was added and the mixture was stirred for 5 minutes. Subsequently, after filtering and washing with methanol, compound (A8), a white solid, was obtained by sublimation purification.

[0131] The results of the NMR measurement of compound (A8) are shown below. １ HNMR (500MHz, DMSO-d6): 8.73 (s, 4H), 7.58-7.45 (m, 10H)

[0132] <Synthesis Example 5> Compound (A9) was obtained in the same manner as in Synthesis Example 1, except that 1,2-phenylenediamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 5,6-diamino-2,3-dicyanopyrazine. Compound (A10) was obtained in the same manner as in Synthesis Example 1, except that compound (A9) was used instead of compound (A2).

[0133] The results of the NMR measurement of compound (A10) are shown below. １ HNMR (500MHz, DMSO-d6): 8.93 (d, 1H), 8.88 (d, 1H), 8.78 (d, 1H), 8.75 (d, 1H), 8.45 (d, 1H), 7.96 (d, 1H), 7.61-7.54 (m, 2H)

[0134] Table 3 shows the difference (eV) between the energy level of the lowest unoccupied orbital and the energy level of the highest occupied molecular orbital (HOMO) obtained by density functional theory for compounds (A3), (A5), and (A7) ([energy level of the highest occupied orbital] - [energy level of the lowest unoccupied orbital]).

[0135]

[0136] (Example 1) A 100 nm thick vacuum-deposited boron subphthalocyanine chloride (refined product from Sigma-Aldrich, purity >99%) was formed as a photoelectric conversion layer on an ITO transparent conductive glass (ITO manufactured by Geomatec Co., Ltd., 100 nm thick), and on top of that, a tris(8-quinolinolato)aluminum (Alq) was formed as auxiliary layer 1. ３A sublimation product of (manufactured by Tokyo Chemical Industry Co., Ltd.) was deposited to a thickness of 25 nm by resistance heating vacuum deposition, and then compound (A3) was deposited as auxiliary layer 2 to a thickness of 25 nm by resistance heating vacuum deposition (organic thin film, maximum absorption wavelength: 435 nm). The maximum absorption wavelength of the obtained organic thin film was measured using a Hitachi U-4100 spectrophotometer. Next, aluminum was fabricated as an electrode to a thickness of 100 nm by vacuum deposition on auxiliary layer 2 to obtain a photoelectric conversion element. For the obtained photoelectric conversion element, a voltage of 5 V was applied using ITO and aluminum as electrodes, and the current value in the dark and the current value when irradiated with light were measured. The light-dark ratio was calculated from the measurement results. The dark current value was evaluated as a relative value with the value in Comparative Example 1 described later set to 1, with less than 0.01 being A, 0.01 or more and less than 1.0 being B, and 1.0 or more being C. Similarly, the brightness-dark ratio was evaluated as a relative value, with the value in Comparative Example 1 set to 1. Values ​​of 100 or more were rated A, values ​​between 10 and 100 were rated B, and values ​​below 10 were rated C. The results are shown in Table 4.

[0137] (Example 2) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (A7) was used instead of compound (A3). The maximum absorption wavelength of the obtained organic thin film was 417 nm. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0138] (Comparative Example 1) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (A1) was used instead of compound (A3). The maximum absorption wavelength of the obtained organic thin film was 400 nm. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0139] (Comparative Example 2) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (A8) was used instead of compound (A3). The maximum absorption wavelength of the obtained organic thin film was 375 nm. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0140] (Comparative Example 3) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (A10) was used instead of compound (A3). The maximum absorption wavelength of the obtained organic thin film was 467 nm. The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0141]

[0142] The disclosure of Japanese Patent Application No. 2024-230958, filed on 26 December 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

[0143] Photoelectric conversion elements, image sensors, etc., containing the above-mentioned compound (1) or (2) exhibit excellent leakage prevention and wavelength selectivity. Therefore, the compounds, photoelectric conversion element materials, organic thin films, photoelectric conversion elements, and image sensors of the present invention have industrial applicability in fields where such properties are required. Specifically, as solid-state image sensors, they have industrial applicability in security cameras, automotive cameras, unmanned aerial vehicle cameras, agricultural cameras, industrial cameras, medical cameras such as endoscope cameras, game console cameras, digital still cameras, digital video cameras, mobile phone cameras, and other mobile device cameras; image reading elements in facsimile machines, scanners, and copiers; and optical sensors in bio and chemical sensors. Furthermore, as displays utilizing electroluminescence, they have industrial applicability in television monitors, touch monitors, digital signage, wearable displays, electronic paper, and head-up displays for mobility applications.

[0144] 100, 200... Photoelectric conversion element, 101... Substrate, 102... Lower electrode, 103... First auxiliary layer, 104... Photoelectric conversion layer, 105... Second auxiliary layer, 106... Upper electrode, 107... Third auxiliary layer, 110... Photoelectric conversion film.

Claims

1. A compound represented by the following formula (1). (In formula (1), X １ and X ２ Each is independently selected from the group consisting of a methine group and a nitrogen atom, n is an integer between 0 and 3, and R １ and R ２ Each of these is independently a hydrogen atom, a halogen atom, or a monovalent organic group, and R １ and R ２ At least one of them is a monovalent organic group with Hammett substituent constant σp of 0.50 or greater, and adjacent R １ and R ２ (This may be part of a fused ring, and the fused ring may contain one or more atoms other than carbon.) 2. In formula (1), R １ and R ２ The compound according to claim 1, wherein at least one of them is a cyano group, a nitro group, a trifluoromethyl group, or a sulfonyl group.

3. A compound represented by the following formula (2). (In formula (2), X ３ and X ４ Each is independently selected from the group consisting of a methine group and a nitrogen atom, X ５ is an oxygen atom or NR ３ And n is an integer between 0 and 3, and R ３ This is selected from the group consisting of hydrogen atoms, halogen atoms, hydroxyl groups, thiol groups, amino groups, cyano groups, carboxyl groups, nitro groups, and optionally substituted linear, branched, or cyclic alkyl groups, thioalkyl groups, thioaryl groups, arylsulfonyl groups, aryloxy groups, alkylsulfonyl groups, alkylamino groups, arylamino groups, alkoxy groups, acylamino groups, acyloxy groups, aryl groups, carboxyamide groups, carboalkoxy groups, carboaryloxy groups, acyl groups, and monovalent heterocyclic groups.

4. The compound according to any one of claims 1 to 3, wherein the energy level of the lowest unoccupied orbital obtained by density functional theory is -6.00 eV or higher and -3.80 eV or lower.

5. The compound according to any one of claims 1 to 3, wherein the difference between the energy level of the lowest unoccupied orbital and the energy level of the highest occupied orbital obtained by density functional theory is 3.0 eV or more and 4.0 eV or less.

6. A compound according to any one of claims 1 to 3, which is a material for a photoelectric conversion element.

7. An organic thin film comprising the compound described in any one of claims 1 to 3.

8. The organic thin film according to claim 7, wherein the maximum absorption wavelength of the light absorption band is 450 nm or less.

9. A photoelectric conversion element comprising a first electrode film, a second electrode film, and a photoelectric conversion film positioned between the first electrode film and the second electrode film, wherein the photoelectric conversion film contains the material for a photoelectric conversion element described in claim 6.

10. 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, wherein the photoelectric conversion film includes the organic thin film described in claim 7.

11. The photoelectric conversion element according to claim 10, wherein the photoelectric conversion film comprises a photoelectric conversion layer and an auxiliary layer, and the auxiliary layer consists solely of the organic thin film or a plurality of films including the organic thin film.

12. An image sensor comprising the photoelectric conversion element described in claim 9.

13. The image sensor according to claim 12, wherein the image sensor is a laminate containing two or more photoelectric conversion elements.

14. An image sensor in which a plurality of photoelectric conversion elements according to claim 9 are arranged in an array.

15. A light sensor comprising the image sensor described in claim 12.

16. A solid-state imaging device comprising the image sensor described in claim 12.

Images