Organic thin film for photoelectric conversion element, photoelectric conversion element, imaging element, optical sensor, solid-state imaging device, and solar cell

Abstract

This organic thin film for a photoelectric conversion element contains a compound represented by formula (1), where the content of the compound represented by formula (1) is 60 mass % or more based on the total mass of the organic thin film for a photoelectric conversion element. In formula (1), Ar1 and Ar2 are aryl groups different from each other, and Ar1 is a group represented by formula (2). In formula (2), R1, R2, R3, R4, and R5 are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having a Hammett substituent constant σp of 0 or more. One or more of R1, R2, R3, R4, and R5 are a halogen atom or a monovalent organic group having a Hammett substituent constant σp of 0.230 or more. Any adjacent R1, R2, R3, R4, or R5 may be a part of a condensed aliphatic ring or a condensed aromatic ring. The condensed aliphatic ring and the condensed aromatic ring may contain one or a plurality of atoms other than carbon.

Description

Organic thin films for photoelectric conversion elements, photoelectric conversion elements, image sensors, light sensors, solid-state imaging devices, and solar cells

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

[0002] Conventionally, a technology has been known for converting visible light into electrical signals via photoelectric conversion, and this technology is used, for example, in image sensors. Such image sensors are incorporated into solid-state imaging devices such as CCD (Charge Coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors.

[0003] For example, Patent Document 1 describes an electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer in that order on a conductive support, wherein the charge transport layer contains a hole-carrying material, and the universal hardness of the surface layer of the electrophotographic photoreceptor is 230 N / mm². ２ The present invention describes an electrophotographic photoreceptor characterized by having the above characteristics and containing a charge generating material and an electron transporting material in the charge generating layer, a process cartridge having the electrophotographic photoreceptor, and an electrophotographic apparatus. Patent Document 2 describes an electrophotographic photoreceptor having a support, an undercoat layer formed on the support, a charge generating layer formed on the undercoat layer, and a charge transport layer formed on the charge generating layer, wherein the undercoat layer contains a cured product of a composition comprising a compound represented by a specific structural formula and a crosslinking agent. Patent Document 3 describes an electrophotographic photoreceptor having a laminate and a hole transport layer formed on the laminate, wherein the laminate comprises a support, an electron transport layer formed on the support with a thickness d1 (μm), and a charge generating layer formed on the electron transport layer with a thickness d2 (μm), the laminate satisfies a specific formula, and the electron transport layer contains a polymer obtained by polymerizing a composition of an electron transport substance having polymerizable functional groups, a thermoplastic resin having polymerizable functional groups, and a crosslinking agent, and the content of the electron transport substance having polymerizable functional groups is 30% by mass or more and 70% by mass or less of the total mass of the composition.

[0004] Japanese Patent Application Laid-Open No. 2005-189721, Japanese Patent Application Laid-Open No. 2014-215477, Patent No. 5981887

[0005] In the technical field of photoelectric conversion elements, the creation of new materials that have never existed before is desired. That is, as materials for photoelectric conversion elements, particularly materials contained in the electron transport layer and hole blocking layer of photoelectric conversion elements, the provision of new options different from the conventional ones is required.

[0006] The problem to be solved by the present invention is to provide an organic thin film for a photoelectric conversion element, a photoelectric conversion element, an imaging element, an optical sensor, a solid-state imaging device, and a solar cell that can suppress dark current.

[0007] The present invention is as follows. [1] An organic thin film for a photoelectric conversion element, which contains a compound represented by the following formula (1), and the content of the compound represented by the formula (1) is 60% by mass or more based on the total mass of the organic thin film for a photoelectric conversion element.

[0008]

[0009] (In formula (1), Ar １ and Ar ２ are different aryl groups from each other, and Ar １ is a group represented by the following formula (2).)

[0010]

[0011] (In formula (2), R １ , R ２ , R ３ , R ４ and R ５ are each independently a hydrogen atom, a halogen atom having a Hammett substituent constant σp of 0 or more, or a monovalent organic group, and one or more of R １ , R ２ , R ３ , R ４ and R ５ are a halogen atom or a monovalent organic group having a Hammett substituent constant σp of 0.230 or more, and any adjacent R １ , R ２ , R ３ , R ４ and R ５R may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) [2] In formula (2), R １ , R ２ , R ３ , R ４ and R ５ An organic thin film for a photoelectric conversion element according to [1], wherein one or more of the members are a bromine atom, an iodine atom, a cyano group, a nitro group, a trifluoromethyl group, or a sulfonyl group. [3] In formula (2), R １ , R ２ , R ３ , R ４ and R ５ One or more of these is a halogen atom or monovalent organic group with a Hammett substituent constant σp of 0.600 or more, as described in [1] or [2], an organic thin film for a photoelectric conversion element. [4] In formula (1), Ar ２ The organic thin film for photoelectric conversion elements described in any one of [1] to [3] is a group represented by the following formula (3).

[0012]

[0013] (In formula (3), R ６ , R ７ , R ８ , R ９ and R １０ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, and any adjacent R ６ , R ７ , R ８ , R ９ and R １０ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) [5-1] An organic thin film for a photoelectric device comprising a compound represented by the following formula (4).

[0014]

[0015] (In equation (4), He １ It is a heteroaryl group, Ar ３ It is an aryl group, He １(This is a base represented by one of the following equations (5-1) to (5-6).)

[0016]

[0017] (In formulas (5-1) to (5-6), R １１ ~R ２９ Each of these is independently a hydrogen atom, a halogen atom with Hammett substituent constant σp of 0 or greater, or a monovalent organic group, and any adjacent R １１ ~R １６ , R １８ ~R ２４ , R ２６ , R ２８ ~R ３１ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) [5-2] An organic thin film for a photoelectric device comprising a compound represented by the following formula (4).

[0018]

[0019] (In equation (4), He １ It is a heteroaryl group, Ar ３ It is an aryl group, He １ (This is a base represented by one of the following equations (5-1) to (5-8).)

[0020]

[0021]

[0022] (In formulas (5-1) to (5-8), R １１ ~R ２９ and R １１ｈ ~R １６ｈ Each of these is independently a hydrogen atom, a halogen atom with Hammett substituent constant σp of 0 or greater, or a monovalent organic group, and any adjacent R １１ ~R １６ , R １８ ~R ２４ , R ２６ , R ２８ ~R ３１ and R １１ｈ ~R １６ｈAr may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) [6] In formula (4), Ar ３ The organic thin film for photoelectric conversion elements described in [5] is a group represented by the following formula (6).

[0023]

[0024] (In formula (6), R ２９ , R ３０ , R ３１ , R ３２ and R ３３ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, and any adjacent R ２９ , R ３０ , R ３１ , R ３２ and R ３３(This may be a part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) [7] An organic thin film for a photoelectric device according to any one of [1] to [6], wherein the energy level of the lowest unoccupied orbital obtained by density functional theory of the compound is -6.00 eV or more and -3.20 eV or less. [8] An organic thin film for a photoelectric device according to any one of [1] to [7], 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 of the compound is 3.00 eV or more and 4.00 eV or less. [9] An organic thin film for a photoelectric device according to any one of [1] to [8], wherein the maximum absorption wavelength of the light absorption band is 450 nm or less.

[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 an organic thin film for photoelectric conversion elements according to any one of [1] to [9].

[11] The photoelectric conversion element according to

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

[12] 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 comprises a photoelectric conversion layer and two auxiliary layers located between the photoelectric conversion layer and the second electrode film, and the auxiliary layer closest to the second electrode film of the two auxiliary layers includes an organic thin film for photoelectric conversion elements according to any one of [1] to [9].

[13] The photoelectric conversion element according to

[12] , wherein the auxiliary layer closest to the second electrode film among the two auxiliary layers is a buffer layer.

[14] 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the electron transport layer includes an organic thin film for photoelectric conversion elements according to any one of [1] to [9].

[15] 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the photoelectric conversion layer includes an organic thin film for photoelectric conversion elements as described in any one of [1] to [9].

[16] 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the buffer layer includes an organic thin film for photoelectric conversion elements as described in any one of [1] to [9].

[17] An image sensor comprising a photoelectric conversion element as described in any one of

[10] to

[16] .

[18] The image sensor according to

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

[19] An image sensor comprising a photoelectric conversion element according to any one of

[10] to

[16] and a light-emitting element stacked on top of each other.

[20] An image sensor comprising a photoelectric conversion element according to any one of

[10] to

[16] and a light-emitting element arranged in parallel.

[21] An image sensor comprising a plurality of photoelectric conversion elements according to any one of

[10] to

[16] arranged in an array.

[22] A light sensor comprising an image sensor according to any one of

[17] to

[21] .

[23] A solid-state imaging device comprising an image sensor according to any one of

[17] to

[21] .

[24] A solar cell comprising a photoelectric conversion element according to any one of

[10] to

[16] .

[0025] According to the present invention, it is possible to provide an organic thin film for a photoelectric conversion element that can suppress dark current, a photoelectric conversion element, an image sensor, a light sensor, a solid-state imaging device, and a solar cell.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In this specification, examples of halogen atoms include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0030] In this specification, the 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, a cyano group, and an optionally substituted alkyl group, and may also 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.

[0031] As the organic thin film for a photoelectric conversion element of the present embodiment (also simply referred to as an organic thin film in this specification), the following First Embodiment to Second Embodiment can be mentioned.

[0032] The organic thin films of the First Embodiment to Second Embodiment can suppress the leakage current in the dark. The reason is not clear, but it is speculated as follows. That is, the specific compounds (that is, the compound represented by Formula (1) and the compound represented by Formula (4)) contained in the organic thin film for a photoelectric conversion element of the present embodiment have a structure in which the π-conjugated system is extended. Thereby, the energy level of the lowest unoccupied molecular orbital in the specific compound is lowered, and the leakage current in the dark can be suppressed. Note that the reason is not limited to the above.

[0033] [First Embodiment] The organic thin film for a photoelectric conversion element of the First Embodiment contains a compound represented by the following formula (1), and the content of the compound represented by the formula (1) is 60% by mass or more with respect to the total mass of the organic thin film for a photoelectric conversion element.

[0034]

[0035] (In Formula (1), Ar １ and Ar ２ are different aryl groups from each other, and Ar １ is a group represented by the following formula (2).)

[0036]

[0037] (In Formula (2), R １ , R ２ , R ３ , R ４ and R ５ are each independently a hydrogen atom, a halogen atom having a Hammett substituent constant σp of 0 or more, or a monovalent organic group, and one or more of R １ , R ２ , R ３ , R ４ and R ５ are a halogen atom having a Hammett substituent constant σp of 0.230 or more or a monovalent organic group, and any adjacent R １ , R ２ , R ３ , R ４ and R ５(This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.)

[0038] In formula (1), Ar １ and Ar ２ These are different aryl groups, and the compound represented by formula (1) has an asymmetric structure.

[0039] In the first embodiment, in formula (1), Ar １ is a group represented by formula (2). In formula (2), examples of halogen atoms with Hammett substituent constant σp of 0 or more include fluorine (σp: 0.062), chlorine (σp: 0.227), bromine (σp: 0.232), and iodine (σp: 0.180). Among the above, bromine is preferred as the halogen atom with Hammett substituent constant σp of 0 or more.

[0040] 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 International Publication No. 2019 / 189134. In this embodiment, the atoms and organic groups identified by the Hammett substituent constants σp are not limited to atoms and organic groups whose substituent constants σp are known as described in the above-mentioned literature, but also include atoms and organic groups whose substituent constants σp are not known, but whose substituent constants σp measured based on Hammett's rule fall within the range shown in this embodiment.

[0041] In formula (2), examples of monovalent organic groups with Hammett substituent constant σp of 0 or more include cyano group (σp: 0.660), nitro group (σp: 0.778), trifluoromethyl group (σp: 0.540), sulfonylmethyl group (σp: 0.728), sulfonylamino group (σp: 0.570), carboxyl group (σp: 0.450), and the like. Among the above, cyano group, nitro group, trifluoromethyl group, and sulfonyl group are preferred as monovalent organic groups with Hammett substituent constant σp of 0 or more.

[0042] In formula (2), R １ , R ２ , R ３ , R ４ and R ５ Preferably, one or more of these is a halogen atom or monovalent organic group with a Hammett substituent constant σp of 0.230 or higher, and a halogen atom or monovalent organic group with a Hammett substituent constant σp of 0.600 or higher.

[0043] In the first embodiment, in formula (2), R １ , R ２ , R ３ , R ４ and R ５ Preferably, one or more of these is a bromine atom, an iodine atom, a cyano group, a nitro group, a trifluoromethyl group, or a sulfonyl group, and more preferably a cyano group.

[0044] In formula (1), Ar ２ Ar １ These are aryl groups that are different from each other, and the aryl groups may have substituents. Examples of substituents include halogen atoms, cyano groups, nitro groups, trifluoromethyl groups, and sulfonyl groups. Among these, cyano groups and trifluoromethyl groups are preferred substituents.

[0045] In the first embodiment, in formula (1), Ar ２ Preferably, the group is represented by the following formula (3).

[0046] (In formula (3), R ６ , R ７ , R ８ , R ９ and R １０ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, and any adjacent R ６ , R ７ , R ８ , R ９ and R １０ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.)

[0047] In formula (3), R ６ , R ７ , R ８ , R ９ and R １０ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, preferably selected from the group consisting of a hydrogen atom, a cyano group, and a trifluoromethyl group. In formula (3), R ６ , R ７ , R ８ , R ９ and R １０ It is also preferable that at least one of these groups is a cyano group and a trifluoromethyl group.

[0048] The content of the compound represented by formula (1) is 60% by mass or more, relative to the total mass of the organic thin film for the photoelectric conversion element. This makes it possible for the organic thin film of the first embodiment to avoid trapping carriers in impurity levels caused by unintended impurities when used in a photoelectric conversion element or image sensor. As a result, it is possible to obtain a photoelectric conversion element or image sensor that can suppress carrier recombination and effectively suppress dark current. From the same viewpoint as above, the content of the compound represented by formula (1) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, relative to the total mass of the organic thin film for the photoelectric conversion element. From the viewpoint of designing the organic thin film, the content of the compound represented by formula (1) may be 100% by mass or less, 99.9% by mass or less, 99.5% by mass or less, or 99% by mass or less, relative to the total mass of the organic thin film for the photoelectric conversion element.

[0049] The content of the compound represented by formula (1) relative to the total mass of the organic thin film is measured by methods such as high-performance liquid chromatography (HPLC). When using HPLC, for example, the measurement can be performed under the following conditions: (Measurement conditions) Column: Inertsil ODS-3V (GL Sciences Co., Ltd.) Detector: UV Mobile phase: Acetonitrile / 0.1 vol% formic acid aqueous solution = 70 / 30 (v / v) Temperature: 40°C Detection wavelength: 254 nm Flow rate: 0.5 ml / min

[0050] [Second Embodiment] The organic thin film for the photoelectric conversion element of the second embodiment contains a compound represented by the following formula (4).

[0051]

[0052] (In equation (4), He １ It is a heteroaryl group, Ar ３ It is an aryl group, He １ (This refers to a group represented by any one of the following formulas (5-1) to (5-8), preferably a group represented by any one of the following formulas (5-1) to (5-6).)

[0053]

[0054]

[0055] (In formulas (5-1) to (5-8), R １１ ~R ２９ and R １１ｈ ~R １６ｈ Each of these is independently a hydrogen atom, a halogen atom with Hammett substituent constant σp of 0 or greater, or a monovalent organic group, and any adjacent R １１ ~R １６ , R １８ ~R ２４ , R ２６ , R ２８ ~R ３１ and R １１ｈ ~R １６ｈ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.)

[0056] In equation (4), He １is a heteroaryl group, Ar ３ The group is an aryl group, and the compound represented by formula (4) has an asymmetric structure.

[0057] In formulas (5-1) to (5-8), specific examples of halogen atoms with Hammett substituent constant σp of 0 or more, and monovalent organic groups with Hammett substituent constant σp of 0 or more are the same as the specific examples of halogen atoms with Hammett substituent constant σp of 0 or more, and monovalent organic groups with Hammett substituent constant σp of 0 or more in the first embodiment. In formulas (5-1) to (5-8), chlorine atoms, bromine atoms, and iodine atoms are preferred as halogen atoms with Hammett substituent constant σp of 0 or more. In formulas (5-1) to (5-8), cyano groups, nitro groups, trifluoromethyl groups, and sulfonyl groups are preferred as monovalent organic groups with Hammett substituent constant σp of 0 or more.

[0058] In formula (4), Ar ３ The group is an aryl group, and the aryl group may have substituents. Examples of substituents include halogen atoms, cyano groups, nitro groups, trifluoromethyl groups, and sulfonyl groups. Among these, cyano groups and trifluoromethyl groups are preferred substituents.

[0059] In formula (4), Ar ３ Preferably, the group is represented by the following formula (6).

[0060]

[0061] (In formula (6), R ２９ , R ３０ , R ３１ , R ３２ and R ３３ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, and any adjacent R ２９ , R ３０ , R ３１ , R ３２ and R ３３ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.)

[0062] In formula (6), R ２９ , R ３０ , R ３１ , R ３２ and R ３３ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, and is preferably a hydrogen atom, a cyano group, and a trifluoromethyl group.

[0063] The content of the compound represented by formula (2) may be 60% by mass or more based on the total mass of the organic thin film for the photoelectric conversion element. This makes it possible for the organic thin film of the first embodiment to avoid trapping carriers in impurity levels caused by unintended impurities when used in a photoelectric conversion element or image sensor. As a result, it is possible to obtain a photoelectric conversion element or image sensor that can suppress dark current well by suppressing carrier recombination. From the same viewpoint as above, the content of the compound represented by formula (2) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on the total mass of the organic thin film for the photoelectric conversion element. From the viewpoint of designing the organic thin film, the content of the compound represented by formula (2) may be 100% by mass or less, 99.9% by mass or less, 99.5% by mass or less, or 99% by mass or less, based on the total mass of the organic thin film for the photoelectric conversion element.

[0064] The compounds of this embodiment (i.e., the compounds represented by formula (1) and the compounds represented by formula (4)) preferably have an energy level of the lowest unoccupied molecular orbital (LUMO) obtained by density functional theory that is between -6.00 eV and -3.20 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.

[0065] In this embodiment, the compound preferably has a difference between the energy level of the lowest unoccupied orbital and the energy level of the highest occupied orbital obtained by density functional theory of 3.00 eV or more and 4.00 eV or less, more preferably 3.20 eV or more and 3.95 eV or less, and even more preferably 3.40 eV or more and 3.90 eV or less.

[0066] For the compound 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.), and the energy levels of the lowest unoccupied orbital and the highest occupied orbital can be determined. Furthermore, the energy levels of the lowest unoccupied orbital and the highest occupied orbital obtained by density functional theory for the compound of this embodiment are not particularly limited, but Ar １ Ar ２ Ar ３ , and He １ This may be adjusted by changing the setting.

[0067] There are no particular limitations on the method for producing the compounds of this embodiment. For example, the compound represented by formula (1) in this embodiment can be synthesized by the following scheme.

[0068]

[0069] The mixture obtained by adding 1,4,5,8-naphthalenetetracarboxylic dianhydride (1) and aniline (1.0 molar equivalent relative to anhydride (1)) to N,N-dimethylformamide is stirred. The solvent is then removed by distillation, and acetone is added to the resulting solid. Water is gradually added while stirring, and the precipitate is filtered. After dissolving the precipitate with chloroform, sodium sulfate is added and the mixture is allowed to stand for 30 minutes. After filtering out the sodium sulfate, the solvent is removed by distillation under reduced pressure. Compound (2) is obtained by size exclusion chromatography.

[0070]

[0071] Compound (2) and 4-aminobenzonitrile (1.5 molar equivalents relative to compound (2)) are added to pyridine, and the resulting mixture is heated. Then, after cooling to room temperature, methanol is added, the precipitated mixture is filtered, and washed with water and methanol to obtain compound (3).

[0072] For example, in the product (100% by mass) obtained by the above synthesis, the compound content is preferably 90% by mass or more, more preferably 93% by mass, and even more preferably 97% by mass or more. The content can be measured by known methods, such as liquid chromatography, gas chromatography, and elemental analysis.

[0073] (Materials for Photoelectric Conversion Elements) The compounds of this embodiment are preferably materials for photoelectric conversion elements. More specifically, the photoelectric conversion element materials of the compounds of this embodiment can be suitably used as materials included in each layer of a photoelectric conversion element. In particular, from the viewpoint of achieving the effects of the compounds of this embodiment more effectively and reliably, the compounds of this embodiment are preferably included in the photoelectric conversion film, more preferably in the auxiliary layer, and even more preferably in at least one of the electron transport layer and the hole blocking layer. Furthermore, the compounds of this embodiment can be used alone as photosensitive materials.

[0074] A composition containing the compound of this embodiment can be used as a material for a photoelectric conversion element. The composition of this embodiment contains the compound of this embodiment. The composition of this embodiment may be a product obtained by the above-described synthesis, or it may be a composition obtained by adding any component other than the compound of this embodiment to the product obtained by the above-described synthesis. The above-mentioned arbitrary component may be a component contained in a normal photosensitive composition, and is not particularly limited. Examples include n-type semiconductor materials, p-type semiconductor materials, light-absorbing materials, etc. These can be used individually or in combination of two or more.

[0075] The composition of this embodiment can be used to form an organic thin film. In this case, the composition of this embodiment may contain a resin, but it is not necessarily required to contain a resin. The composition of this embodiment can form an organic thin film even if it does not contain a resin or contains only a small amount of resin. In this case, the content of the compound of this embodiment will be relatively high in the composition of this embodiment.

[0076] The compound content of this embodiment may be 50% by mass or more relative to the total amount of the composition of this embodiment. Alternatively, the content may be 95% by mass or less, 90% by mass or less, or 80% by mass or less.

[0077] The organic thin film of this embodiment can be fabricated by general dry or wet deposition methods. Specifically, examples include vacuum processes such as resistance heating evaporation, electron beam evaporation, 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, for photoelectric conversion elements, it is preferable to use a process in which the compound is applied in a solution state, from the viewpoint of ease of processing. However, in the case of photoelectric conversion elements in which organic thin films are stacked, dry deposition methods such as resistance heating evaporation are preferred because the coating solution may damage the underlying film.

[0078] For example, in a dry deposition method, an organic thin film can be obtained by mixing the photoelectric conversion element material of this embodiment with other materials as needed, depending on the application of the photoelectric conversion element, to form a composition, and then depositing it onto a substrate or other film under vacuum. Alternatively, in a wet deposition method, an organic thin film can be obtained by mixing the photoelectric conversion film of this embodiment with other materials as needed, depending on the application of the photoelectric conversion element, with a solvent to form a liquid composition, coating it onto a substrate or other film, printing it, and then drying it.

[0079] The thickness of the organic thin film cannot be limited as it depends on the resistance and charge mobility of each material, but it may be between 0.5 nm and 5000 nm, between 1 nm and 1000 nm, or between 5 nm and 500 nm.

[0080] 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.

[0081] (Photoelectric Conversion Element) 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 includes the organic thin film of this embodiment.

[0082] The photoelectric conversion element of this embodiment generates an electric charge corresponding to the amount of incident light and outputs the generated charge to the outside of the photoelectric conversion element via a capacitor for storing the generated charge (also called a "storage unit") and a transistor circuit for reading it out (also called a "readout unit"). Here, the photoelectric conversion element is defined as having 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 an "infrared photoelectric conversion element"). Here, the infrared photoelectric conversion element is defined as having a photoelectric conversion film that absorbs infrared light (also referred to as an "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. Furthermore, the infrared photoelectric conversion film is a photosensitive thin film containing a material that absorbs at least a portion of incident light in the infrared region (hereinafter also referred to as "infrared absorbing material"), and generates holes and electrons as a result of the incidence of light.

[0083] In this embodiment, the photoelectric conversion element preferably comprises a photoelectric conversion film including a photoelectric conversion layer and an auxiliary layer, wherein the auxiliary layer consists solely of the organic thin film, or of a plurality of films including the organic thin film.

[0084] 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.

[0085] 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.

[0086] 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, and examples include tin oxide (SnO2)-based materials with dopants, and zinc oxide-based materials with dopants added to zinc oxide (ZnO). Examples of zinc oxide-based materials include aluminum zinc oxide (AZO) with aluminum (Al) as a dopant, gallium zinc oxide (GZO) with gallium (Ga) as a dopant, and indium zinc oxide (IZO) with indium (In) as a dopant. Alternatively, examples of materials constituting the lower electrode 102 include CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, and ZnSnO3. The thickness of the lower electrode 102 is, for example, 5 nm to 3000 nm, and may be 5 nm to 500 nm, or 10 nm to 300 nm.

[0087] 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.

[0088] 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, it is preferable that the conductivity be as high as possible from the viewpoint of the signal strength and power consumption of the photoelectric conversion element. For example, as a transparent electrode, an ITO film with a sheet resistance of 300 Ω / or less is sufficient to function as an electrode. However, commercially available substrates equipped with ITO films with conductivity of several Ω / (e.g., 5 to 9 Ω / ) are also available, and substrates with such high conductivity are desirable.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] As electrode materials that satisfy these conditions, transparent conductive oxides (TCOs) with high transmittance to visible and infrared light and low resistance are preferred. Metal thin films such as gold can also be used as electrodes, but the resistance increases drastically when trying to achieve a transmittance of 90% or more. Therefore, TCOs are preferred as electrodes. Among TCOs, ITO, IZO, AZO, FTO, SnO2, TiO2, and ZnO2 are particularly preferred.

[0093] 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.

[0094] Furthermore, the photoelectric conversion element of this embodiment is 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, from the viewpoint of more effectively and reliably achieving the effects of the present invention, 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 the organic thin film of this embodiment. It is even more preferable that the auxiliary layer closer to the second electrode film is a buffer layer.

[0095] The exact factors that enable such photoelectric conversion elements to suppress leakage current in the dark are unclear, but the inventors believe the following. The photoelectric conversion element of this embodiment preferably comprises two auxiliary layers between the photoelectric conversion layer and the second electrode film, with the auxiliary layer closer to the second electrode film containing the compound of this embodiment. This provides a rectifying effect that suppresses the movement of electrons generated in the photoelectric conversion layer to the second electrode film due to the relatively low HOMO level of the compound of this embodiment, and as a result, 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 the compound of this embodiment, 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.

[0096] 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.

[0097] 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.

[0098] 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. In the photoelectric conversion layer 110, these organic semiconductor films and organic thin films may be one or more layers. If there is one layer, a p-type organic semiconductor film, an n-type organic semiconductor film, or a mixed film thereof (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 may be a stack of either a p-type organic semiconductor film, an n-type organic semiconductor film, or a mixed film thereof (bulk heterostructure), with buffer layers inserted between the layers.

[0099] 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. In particular, it is preferable to include at least one of organic p-type semiconductors, organic n-type semiconductors, and light-absorbing materials, as this allows for more efficient conversion of incident light energy of a desired wavelength into an electrical signal. In particular, 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.

[0100] 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.

[0101] 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.

[0102] The photoelectric conversion element of this embodiment may also be the following embodiments. Embodiment a is 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the electron transport layer includes the organic thin film for the photoelectric conversion element of this embodiment. Embodiment b is 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the photoelectric conversion layer includes the organic thin film for the photoelectric conversion element of this embodiment. The photoelectric conversion element of embodiment c is 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the buffer layer includes the organic thin film for the photoelectric conversion element of this embodiment.

[0103] The following provides a detailed explanation of organic semiconductors. Organic p-type semiconductors are donor organic semiconductors (hereinafter also called "donor organic compounds"), and are mainly represented by hole-transporting organic compounds, which are organic compounds that readily donate electrons. More specifically, they are organic compounds that have a lower ionization potential when two organic materials are brought into contact. Therefore, any organic compound that is electron-donating can be used as a donor organic compound.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] The light-absorbing material may be a compound having a maximum light absorption wavelength in the visible light range, particularly in the range of 450 nm to 650 nm. Preferably, 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.

[0108] 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 with an absorption intensity greater than that of the donor organic compound or acceptor organic compound at its 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] In one aspect of this embodiment, the compound of this embodiment is included in at least the third auxiliary layer 107 of these auxiliary layers. The third auxiliary layer 107 may contain materials other than the compound of this embodiment. The content of the compound of this embodiment 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.

[0114] The following describes the compounds of this embodiment that may be included in each layer of the auxiliary layer, as well as materials other than the photoelectric conversion element material.

[0115] 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.

[0116] More specifically, materials that constitute the hole transport layer include selenium, iodides such as copper iodide (CuI), cobalt complexes such as layered cobalt oxide, CuSCN, molybdenum oxide (MoO3, etc.), nickel oxide (NiO, etc.), 4CuBr·3S(C4H9), and organic hole transporters. Among these, copper iodide (CuI) is an example of an iodide. An example of a layered cobalt oxide is AxCoO2 (where 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) and 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, examples of materials for the hole transport layer include compound semiconductors having monovalent copper such as CuInSe2 and copper sulfide (CuS), gallium phosphide (GaP), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (FeO), bismuth oxide (Bi2O3), molybdenum oxide (MoO2), and chromium oxide (Cr2O3).

[0117] 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.

[0118] 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.

[0119] From the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency, the thickness of the hole transport layer is preferably 10 nm to 300 nm, more preferably 30 nm to 250 nm, and even more preferably 50 nm to 200 nm.

[0120] The method for forming the hole transport layer and electron 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.

[0121] The materials constituting the electron transport layer are not particularly limited as long as they are known as electron transport layers in photoelectric conversion elements such as solid-state image sensors. Examples include octa-azaporphyrin and perfluoro compounds of p-type semiconductors (such as perfluoropentacene and perfluorophthalocyanine), fullerenes, fullerene derivatives (e.g., [6,6]-Phenyl-C61-Butyric Acid Methyl Ester; PCBM), perylene, indenoindene and indenoindene derivatives, and other organic compounds. Inorganic oxides such as titanium dioxide (TiO2, etc.), nickel oxide (NiO), tin oxide (SnO2), tungsten oxide (WO2, WO3, W2O3, etc.), zinc oxide (ZnO), niobium oxide (Nb2O5, etc.), tantalum oxide (Ta2O5, etc.), yttrium oxide (Y2O3, etc.), and strontium titanate (SrTiO3, etc.) are also included. The electron transport layer may be porous or dense, and when stacking them, it is preferable to stack the porous electron transport layer and the dense electron transport layer in that order from the photoelectric conversion film side.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] (Image Sensor) The image sensor of this embodiment includes the photoelectric conversion element of this embodiment. The image sensor of this embodiment may have the same configuration as a conventional image sensor, except for the photoelectric conversion element of this embodiment. The image sensor of this embodiment may consist of the photoelectric conversion element of this embodiment and a light-emitting element stacked on top of each other. Alternatively, the image sensor of this embodiment may consist of the photoelectric conversion element of this embodiment and a light-emitting element arranged in parallel.

[0134] In this embodiment, it is preferable that multiple photoelectric conversion elements of this embodiment are arranged in an array. That is, by arranging a large number of photoelectric conversion elements in an array, a solid-state image sensor can be constructed that indicates not only the amount of incident light but also the incident position information.

[0135] The image sensor of this embodiment may comprise one photoelectric conversion element of this embodiment, or it may be a laminate containing two or more photoelectric conversion elements of this embodiment. 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.

[0136] In an image sensor, if a photoelectric conversion element positioned closer to the light source does not block (transmits) the absorption wavelength of another photoelectric conversion element positioned behind it as viewed from the light source, then a device having multiple photoelectric conversion elements or silicon photodiodes may be stacked.

[0137] 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.

[0138] 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.

[0139] (Optical Sensor) The optical sensor of this embodiment includes the image sensor of this embodiment. The optical sensor of this embodiment may have the same configuration as a conventional optical sensor, except for the image sensor of this embodiment. This optical sensor can receive light with the image sensor of this embodiment and output an electrical signal corresponding to the amount of light received.

[0140] (Solid-State Imaging Device) The solid-state imaging device of this embodiment includes the image sensor of this embodiment. The solid-state imaging device of this embodiment may have the same configuration as a conventional solid-state imaging device, except for the image sensor of this embodiment. The solid-state imaging device of this embodiment may be, for example, a CMOS image sensor, and may have a pixel section as an imaging area on a semiconductor substrate, and further may have 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.

[0141] 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 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.

[0142] (Solar Cell) The solar cell of this embodiment is equipped with the photoelectric conversion element of this embodiment. The photoelectric conversion element of this embodiment can be suitably used as a solar cell.

[0143] 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.

[0144] <Synthesis Example 1>

[0145] 6.0 g of 1,4,5,8-naphthalenetetracarboxylic dianhydride (1) (hereinafter referred to as "compound (1)" (manufactured by Tokyo Chemical Industry Co., Ltd.)) and 2.1 g of aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) (1.0 molar equivalent relative to anhydride (1)) were added to 90 mL of N,N-dimethylformamide (manufactured by Tokyo Chemical Industry Co., Ltd.), and the resulting mixture was stirred at 150°C for 8 hours. After that, it was cooled to room temperature and the solvent was removed under reduced pressure. Acetone was added to the solid obtained by solvent removal, and water was gradually added while stirring, and the precipitate was filtered. After dissolving the precipitate with chloroform, sodium sulfate was added and it was allowed to stand for 30 minutes. Next, the sodium sulfate was filtered, and the solvent was removed under reduced pressure. Compound (2), a pale yellow solid, was obtained by size exclusion chromatography using chloroform as the eluent.

[0146]

[0147] 3.0 g of compound (2) and 1.5 g of 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) (1.5 molar equivalents relative to compound (2)) were added to 90 mL of pyridine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the resulting mixture was heated at 120°C for 6 hours. After cooling to room temperature, methanol was added, and the precipitated mixture was filtered. Further washing with water and methanol yielded compound (3), an orange solid. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.74 (s, 4H), 8.08 (d, 2H), 7.74 (d, 2H), 7.56 (dm, 2H), 7.51 (dm, 1H), 7.45 (d, 2H)

[0148] <Synthesis Example 2>

[0149] Compound (4) was obtained in the same manner as in Synthesis Example 1, except that 4-aminophthalonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.75 (d, 4H), 8.40 (d, 1H), 8.37 (d, 1H), 8.13 (dd, 1H), 7.56 (dm, 2H), 7.51 (dm, 1H), 7.47 (d, 2H)

[0150] <Synthesis Example 3>

[0151] Compound (5) was obtained in the same manner as in Synthesis Example 1, except that 3,5-bis(trifluoromethyl)aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of aniline. Compound (6) was also obtained in the same manner as in Synthesis Example 1, except that 4-aminophthalonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of the NMR measurements are shown below. １ HNMR (500MHz, DMSO-d6): 8.78 (s, 4H), 8.41 (d, 1H), 8.36 (s, 2H), 8.35 (s, 1H), 8.34 (d, 1H), 8.12 (dd, 1H)

[0152] <Synthesis Example 4>

[0153] 2.0 g of compound (1) and 1.5 g of aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.2 molar equivalents relative to compound (1)) 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 filtration and washing with methanol, compound (7), a white solid, was obtained by sublimation purification. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.73 (s, 4H), 7.58-7.45 (m, 10H)

[0154] <Synthesis Example 5>

[0155] Compound (8) was obtained in the same manner as in Synthesis Example 4, except that 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of aniline. The results of its NMR measurement are shown below. １ HNMR (500MHz, HFIP-d2): 8.93 (s, 4H), 8.77 (dm, 4H), 7.55 (dm, 4H)

[0156] <Synthesis Example 6>

[0157] Compound (9) was obtained in the same manner as in Synthesis Example 4, except that 3,5-bis(trifluoromethyl)aniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of aniline. The results of its NMR measurement are shown below. １ HNMR (500MHz, HFIP-d2): 8.54 (s, 4H), 7.81 (s, 2H), 7.52 (s, 4H)

[0158] <Synthesis Example 7>

[0159] Compound (10) was obtained in the same manner as in Synthesis Example 1, except that 3-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.75 (d, 4H), 8.04 (s, 1H), 8.02 (d, 1H), 7.88 (dm, 1H), 7.81 (dm, 1H), 7.56 (dm, 2H), 7.51 (dm, 1H), 7.45 (d, 2H)

[0160] <Synthesis Example 8>

[0161] Compound (11) was obtained in the same manner as in Synthesis Example 1, except that 2-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.79 (dd, 4H), 8.14 (dd, 1H), 7.99 (dd, 1H), 7.85 (d, 1H), 7.78 (dd, 1H), 7.56 (dm, 2H), 7.51 (dm, 1H), 7.47 (d, 2H)

[0162] <Synthesis Example 9>

[0163] Compound (12) was obtained in the same manner as in Synthesis Example 1, except that 2-aminopyrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.99 (d, 1H), 8.89-8.86 (m, 2H), 8.77 (q, 4H), 7.59-7.47 (m, 5H)

[0164] <Synthesis Example 10>

[0165] Compound (13) was obtained in the same manner as in Synthesis Example 1, except that 2-aminopyrazine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of aniline. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.99 (d, 1H), 8.89-8.86 (m, 2H), 8.78 (q, 4H), 8.09 (dm, 2H), 7.74 (dm, 2H)

[0166] <Synthesis Example 11>

[0167] Compound (14) was obtained in the same manner as in Synthesis Example 1, except that 4-aminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.82 (dm, 2H), 8.75 (q, 4H), 7.59-7.47 (m, 7H)

[0168] <Synthesis Example 12>

[0169] Compound (15) was obtained in the same manner as in Synthesis Example 1, except that 4-aminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of aniline. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.82 (dm, 2H), 8.75 (q, 4H), 8.09 (dm, 2H), 7.75 (dm, 2H), 7.59 (dm, 2H)

[0170] <Synthesis Example 13>

[0171] Compound (16) was obtained in the same manner as in Synthesis Example 1, except that ammonium acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of 4-aminobenzonitrile. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 12.17 (s, 1H), 8.69 (d, 2H), 8.66 (d, 2H), 7.56 (dm, 2H), 7.51 (dm, 1H), 7.45 (d, 2H)

[0172] <Synthesis Example 14>

[0173] Compound (17) was obtained in place of compound (2) in the same manner as in Synthesis Example 1, except that 4-aminobenzonitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of aniline.

[0174]

[0175] Compound (18) was obtained in the same manner as in Synthesis Example 13, except that compound (17) was used instead of compound (2). The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 12.17 (s, 1H), 8.69 (d, 2H), 8.66 (d, 2H), 8.07 (d, 2H), 7.71 (d, 2H)

[0176] <Synthesis Example 15>

[0177] Compound (19) was obtained in the same manner as in Synthesis Example 1, except that compound (17) was used instead of compound (2) and 4-aminopyrimidine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminobenzonitrile. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 9.42 (s, 1H), 9.17 (d, 1H), 8.78 (d, 2H), 8.75 (d, 2H), 8.05 (d, 2H), 7.90 (d, 1H), 7.74 (d, 2H)

[0178] <Synthesis Example 16>

[0179] Compound (20) was obtained in the same manner as in Synthesis Example 15, except that 5-aminopyrimidine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminopyrimidine. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 9.33 (s, 1H), 9.00 (s, 2H), 8.78 (d, 2H), 8.76 (d, 2H), 8.08 (d, 2H), 7.74 (d, 2H)

[0180] <Synthesis Example 17>

[0181] Compound (21) was obtained in the same manner as in Synthesis Example 15, except that 2-aminopyrimidine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminopyrimidine. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 9.13 (d, 2H), 8.79 (d, 2H), 8.76 (d, 2H), 8.08 (d, 2H), 7.80 (t, 1H), 7.73 (d, 2H)

[0182] <Synthesis Example 18>

[0183] Compound (22) was obtained in the same manner as in Synthesis Example 15, except that 3-aminopyridazine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 4-aminopyrimidine. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 9.45 (dd, 2H), 8.79 (d, 2H), 8.76 (d, 2H), 8.08 (d, 2H), 8.06 (dm, 2H), 7.73 (d, 2H)

[0184] <Synthesis Example 19>

[0185] Compound (23) was obtained in the same manner as in Synthesis Example 1, except that 4-nitroaniline (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of 4-aminopyrimidine. The results of its NMR measurement are shown below. １ HNMR (500MHz, DMSO-d6): 8.75 (s, 4H), 8.45 (d, 2H), 8.09 (d, 2H), 7.82 (d, 2H), 7.74 (d, 2H)

[0186] (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 (ITO) (manufactured by Tokyo Chemical Industry Co., Ltd.) was deposited to a thickness of 25 nm by resistance heating vacuum deposition, and then compound (3) was deposited as auxiliary layer 2 to a thickness of 25 nm by resistance heating vacuum deposition (organic thin film, maximum absorption wavelength: 365 nm). 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. The content of the compound represented by formula (1) or formula (4) relative to the total mass of the organic thin film was measured by high-performance liquid chromatography. For the obtained photoelectric conversion element, a voltage of 3 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 1.

[0187] (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 (4) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0188] (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 (6) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0189] (Example 4) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (10) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0190] (Example 5) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (12) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0191] (Example 6) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (13) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0192] (Example 7) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (19) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0193] (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 (1) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0194] (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 (7) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0195] (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 (8) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0196] (Comparative Example 4) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (9) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0197] (Comparative Example 5) A single-layer organic thin film and a photoelectric conversion element were fabricated in the same manner as in Example 1, except that compound (14) was used instead of compound (3). The obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0198]

[0199] As shown in Table 1, the organic thin film containing the compound represented by formula (1), wherein the content of the compound represented by formula (1) is 60% by mass or more of the total mass of the organic thin film for the photoelectric conversion element, and the photoelectric conversion element using the organic thin film containing the compound represented by formula (4) exhibited low dark current values, indicating excellent leakage prevention (in the dark). Furthermore, the examples also showed a high light-dark ratio, indicating even better leakage prevention. From the above, it was found that the organic thin film of this embodiment is suitable as a material for photoelectric conversion elements, in particular as a material included in the electron transport layer and hole blocking layer of the photoelectric conversion element.

[0200] The disclosure of Japanese Patent Application No. 2024-196653, filed on November 11, 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.

[0201] The photoelectric conversion elements, image sensors, etc., including the organic thin film of this embodiment exhibit excellent leakage prevention. Therefore, the organic thin film, photoelectric conversion element material, photoelectric conversion element, and image sensor of this embodiment have industrial applicability in fields where such characteristics are required. Specifically, as a solid-state image sensor, it has 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 light sensors in bio and chemical sensors. Furthermore, as a display utilizing electroluminescence, it has industrial applicability in television monitors, touch monitors, digital signage, wearable displays, electronic paper, and head-up displays for mobility applications.

[0202] 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. An organic thin film for a photoelectric conversion element, comprising a compound represented by the following formula (1), wherein the content of the compound represented by the formula (1) is 60% by mass or more based on the total mass of the organic thin film for a photoelectric conversion element. (In formula (1), Ar ５ , ４ and Ar ２ are different aryl groups from each other, and Ar １ is a group represented by the following formula (2).) (In formula (2), R １ , R ２ , R ３ , R ４ and R ５ are each independently a hydrogen atom, a halogen atom having a Hammett substituent constant σp of 0 or more, or a monovalent organic group, and one or more of R １ , R ２ , R ３ , R ４ and R ５ are a halogen atom or a monovalent organic group having a Hammett substituent constant σp of 0.230 or more, and any adjacent R １ , R ２ , R ３ , R ４ and R ５ may be a part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) 2. In formula (2), R １ , R ２ , R ３ , R ４ and R ５ The organic thin film for a photoelectric conversion element according to claim 1, wherein one or more of the members are a bromine atom, an iodine atom, a cyano group, a nitro group, a trifluoromethyl group, or a sulfonyl group.

3. In formula (2), R １ , R ２ , R ３ , R ４ and R ５ The organic thin film for a photoelectric conversion element according to claim 1, wherein one or more of them are halogen atoms or monovalent organic groups with a Hammett substituent constant σp of 0.600 or more.

4. In formula (1), Ar ２ The organic thin film for a photoelectric conversion element according to claim 1, wherein is a group represented by the following formula (3). (In formula (3), R ６ , R ７ , R ８ , R ９ and R １０ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, and any adjacent R ６ , R ７ , R ８ , R ９ and R １０ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) 5. An organic thin film for a photoelectric device, comprising a compound represented by the following formula (4). (In equation (4), He １ It is a heteroaryl group, Ar ３ It is an aryl group, He １ (This is a base represented by one of the following equations (5-1) to (5-8).) (In formulas (5-1) to (5-8), R １１ ~R ２９ and R １１ｈ ~R １６ｈ Each of these is independently a hydrogen atom, a halogen atom with Hammett substituent constant σp of 0 or greater, or a monovalent organic group, and any adjacent R １１ ~R １６ , R １８ ~R ２４ , R ２６ , R ２８ ~R ３１ and R １１ｈ ~R １６ｈ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) 6. In formula (4), Ar ３ The organic thin film for a photoelectric conversion element according to claim 5, wherein is a group represented by the following formula (6). (In formula (6), R ２９ , R ３０ , R ３１ , R ３２ and R ３３ Each of these is independently selected from the group consisting of a hydrogen atom, a halogen atom, a cyano group, a nitro group, a trifluoromethyl group, and a sulfonyl group, and any adjacent R ２９ , R ３０ , R ３１ , R ３２ and R ３３ (This may be part of a condensed aliphatic ring or a condensed aromatic ring, and the condensed aliphatic ring and the condensed aromatic ring may contain one or more atoms other than carbon.) 7. The organic thin film for a photoelectric conversion element according to any one of claims 1 to 6, wherein the energy level of the lowest unoccupied orbital obtained by density functional theory of the compound is -6.00 eV or more and -3.20 eV or less.

8. The organic thin film for a photoelectric conversion element according to any one of claims 1 to 6, 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 of the compound is 3.00 eV or more and 4.00 eV or less.

9. An organic thin film for a photoelectric conversion element according to any one of claims 1 to 6, wherein the maximum absorption wavelength of the light absorption band is 450 nm or less.

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 an organic thin film for photoelectric conversion elements according to any one of claims 1 to 6.

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 only of the organic thin film or consists of a plurality of films including the organic thin film.

12. 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 comprises a photoelectric conversion layer and two auxiliary layers located between the photoelectric conversion layer and the second electrode film, and the auxiliary layer closest to the second electrode film contains the organic thin film for photoelectric conversion element described in any one of claims 1 to 6.

13. The photoelectric conversion element according to claim 12, wherein the auxiliary layer closest to the second electrode film among the two auxiliary layers is a buffer layer.

14. 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the electron transport layer includes an organic thin film for a photoelectric conversion element according to any one of claims 1 to 9.

15. 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the photoelectric conversion layer includes an organic thin film for a photoelectric conversion element according to any one of claims 1 to 9.

16. 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 an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a buffer layer, and the buffer layer includes an organic thin film for a photoelectric conversion element according to any one of claims 1 to 9.

17. An image sensor comprising the photoelectric conversion element described in claim 10.

18. The image sensor according to claim 17, which is a laminate comprising two or more of the photoelectric conversion elements.

19. An image sensor comprising a photoelectric conversion element according to claim 10 and a light-emitting element stacked on top of each other.

20. An imaging sensor comprising a photoelectric conversion element according to claim 10 and a light-emitting element arranged in parallel.

21. An image sensor in which a plurality of photoelectric conversion elements according to claim 10 are arranged in an array.

22. A light sensor comprising the image sensor described in claim 17.

23. A solid-state imaging device comprising the image sensor described in claim 17.

24. A solar cell comprising the photoelectric conversion element described in claim 10.

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