Material for photoelectric conversion device and organic photoelectric conversion device

Abstract

To provide a material for photoelectric conversion devices that is capable of forming an organic layer with superior charge transport properties.SOLUTION: There is provided a material for photoelectric conversion devices, comprising a charge-transporting polymer, where the charge-transporting polymer includes a structural unit containing a triarylamine structure having a substituent represented by RCO-* (where RC represents a hydrocarbon group and * represents a bonding site with an aryl group).SELECTED DRAWING: None

Description

[Technical field]

[0001] An embodiment of the present invention relates to a material for a photoelectric conversion element, an organic layer, an organic photoelectric conversion element, an organic solar cell, and an organic image sensor. [Background technology]

[0002] Photoelectric conversion elements are elements that perform electrical functions by absorbing light and causing charge separation. In recent years, organic photoelectric conversion elements have been attracting attention as a technology that can replace conventional silicon-based inorganic semiconductors, as they are expected to offer advantages such as energy saving, low cost, and flexibility.

[0003] Examples of organic photoelectric conversion elements include organic solar cells and organic image sensors. Organic photoelectric conversion elements have an organic layer formed using an organic material. For example, Patent Document 1 discloses a charge transport material containing a hole transport polymer having an oxymethylene group (benzyl ether bond) bonded to a benzene ring and a proton donor as a polymer material for forming an organic layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 037813 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a material for a photoelectric conversion element capable of forming an organic layer having excellent charge transport properties. Another object of the present invention is to provide an organic layer having excellent charge transport properties, and an organic photoelectric conversion element, an organic solar cell, and an organic image sensor including the organic layer. [Means for solving the problem]

[0006] The present invention includes the following embodiments, but is not limited to the following embodiments. [1] A charge transporting polymer is contained, and the charge transporting polymer is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents a bonding site with an aryl group. [2] The material for a photoelectric conversion element according to the above [1], wherein the hydrocarbon group is an alkyl group having 1 to 18 carbon atoms. [3] The material for a photoelectric conversion element according to the above [1] or [2], wherein the charge transporting polymer comprises a branched polymer. [4] The material for photoelectric conversion elements according to any one of the above [1] to [3], wherein the structural unit having a triarylamine structure includes at least one selected from the group consisting of a structural unit represented by the following formula (A1) and a structural unit represented by the following formula (B1): [ka] (Ar each independently represents a substituted or unsubstituted aromatic hydrocarbon group, and at least one Ar is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents a bonding site to the aromatic hydrocarbon group. * indicates a bonding site with other structural units.) [ka] (Ar each independently represents a substituted or unsubstituted aromatic hydrocarbon group, and at least one Ar is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents a bonding site to the aromatic hydrocarbon group. * indicates a bonding site with other structural units.) [5] The material for photoelectric conversion elements according to any one of the above [1] to [4], wherein the structural unit having a triarylamine structure includes at least one selected from the group consisting of a structural unit represented by the following formula (A2) and a structural unit represented by the following formula (B2): [ka] (Each R independently represents a substituent; each n independently represents an integer of 0 or more, at least one n is an integer of 1 or more, and at least one R is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents the bonding site to the benzene ring. * indicates a bonding site with other structural units.) [ka] (Each R independently represents a substituent; each n independently represents an integer of 0 or more, at least one n is an integer of 1 or more, and at least one R is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents the bonding site to the benzene ring. * indicates a bonding site with other structural units.) [6] The material for a photoelectric conversion element according to any one of the above [1] to [5], wherein the charge transporting polymer contains a structural unit represented by the following formula (A4) and a structural unit represented by the following formula (B4): [ka] (R C represents a hydrocarbon group, and * represents a bonding site with other structural units.) [ka] (* indicates a bonding site with other structural units.) [7] An organic layer formed using the material for a photoelectric conversion element according to any one of the above [1] to [6]. [8] An organic photoelectric conversion element comprising the organic layer according to [7] above. [9] An organic solar cell comprising the organic layer according to [7] above.

[10] An organic image sensor comprising the organic layer according to [7] above. Effect of the Invention

[0007] According to an embodiment of the present invention, a material for a photoelectric conversion element capable of forming an organic layer having excellent charge transport properties can be provided. Also, according to an embodiment of the present invention, an organic layer having excellent charge transport properties, an organic photoelectric conversion element including the organic layer, an organic solar cell, and an organic image sensor can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The following describes embodiments of the present invention. The present invention is not limited to the following embodiments. The following embodiments can be implemented alone or in combination. A combination of multiple embodiments is also included in the present invention. In the present disclosure, a numerical range indicated using "~" means a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in the present disclosure, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. The upper or lower limit of a numerical range described in the present disclosure may be replaced with a value shown in the examples. A numerical range may be set in stages by selecting a numerical value from each of the upper limit and lower limit numerical values ​​described in stages in the present disclosure. The upper limit and lower limit numerical values ​​described in the present disclosure may be replaced with values ​​shown in the examples. In the present disclosure, unless otherwise specified, "including A or B" means that either one of A or B may be included, or both may be included. In the present disclosure, each component may contain multiple types of corresponding substances. When multiple types of substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, each structure in the polymer may contain multiple types of corresponding structures. When multiple types of structures corresponding to each structure exist in the polymer, the content or amount of each structure means the total content or amount of the multiple types of structures present in the polymer, unless otherwise specified. In the present disclosure, the term "layer" includes a continuous layer and a discontinuous layer. The thickness of the "layer" may be uniform or non-uniform. The outer edge of the "layer" in the planar direction and the outer edge in the thickness direction may be clear or unclear. The same applies to the "film".

[0009] <Photoelectric conversion element materials> In an embodiment of the present invention, the material for a photoelectric conversion element contains at least a charge transporting polymer. C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents a bonding site with an aryl group. The material for photoelectric conversion elements includes a structural unit containing a triarylamine structure having a aryl group. The material for photoelectric conversion elements is used in the manufacture of organic photoelectric conversion elements such as organic solar cells and organic image sensors. Hereinafter, R C A structural unit containing a triarylamine structure having a substituent represented by O-* may be referred to as a "triarylamine structural unit".

[0010] [Charge transport polymer] The charge transporting polymer is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents a bonding site with an aryl group. The charge transporting polymer contains at least a structural unit containing a triarylamine structure having a structure of . The charge transporting polymer may contain any other structural unit. The charge transporting polymer may contain only one type of triarylamine structural unit, or may contain two or more types of triarylamine structural units. The charge transporting polymer may be a linear polymer or a branched polymer.

[0011] (R C (Structural unit containing a triarylamine structure having a substituent represented by O-*) The triarylamine structure is R C O-*. C represents a hydrocarbon group, and * represents a bonding site with an aryl group contained in the triarylamine structure. The number of carbon atoms in the hydrocarbon group may be, for example, 1 to 18, 1 to 12, 2 to 8, or 4 to 6. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, and an aryl group. The hydrocarbon group may be, for example, an alkyl group. Examples of the alkyl group include linear, branched, and cyclic alkyl groups.

[0012] Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a 2-ethylhexyl group, a 3,7-dimethyloctyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, etc. The alkyl group may be, for example, a linear alkyl group, a linear alkyl group having 2 to 8 carbon atoms, or an n-butyl group.

[0013] Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a 2-methyl-1-propenyl group, a 2-methylallyl group, and a 2-butenyl group.

[0014] An aryl group is an atomic group obtained by removing one hydrogen atom from an aromatic hydrocarbon. Examples of aromatic hydrocarbons include benzene, naphthalene, anthracene, tetracene, fluorene, phenanthrene, 9,10-dihydrophenanthrene, triphenylene, pyrene, chrysene, perylene, triphenylene, pentacene, benzopyrene, biphenyl, terphenyl, and triphenylbenzene. In the present disclosure, the term "aryl group" may be referred to as an "aromatic hydrocarbon group."

[0015] The three aryl groups in the triarylamine structure may be the same as each other, or may be partially or entirely different. Examples of the aryl group are as described above. The triarylamine structure is preferably a triphenylamine structure.

[0016] In some embodiments, the triarylamine structural unit includes at least one selected from the group consisting of a structural unit represented by the following formula (A1) and a structural unit represented by the following formula (B1). [ka] (Ar each independently represents a substituted or unsubstituted aromatic hydrocarbon group, and at least one Ar is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents a bonding site to the aromatic hydrocarbon group. * indicates a bonding site with other structural units.) [ka] (Ar each independently represents a substituted or unsubstituted aromatic hydrocarbon group, and at least one Ar is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents a bonding site to the aromatic hydrocarbon group. * indicates a bonding site with other structural units.)

[0017] Examples of the aromatic hydrocarbon in the aromatic hydrocarbon group in the formula (A1) and the formula (B1) are as described above. C Examples of the hydrocarbon group represented by the formula (I) are as described above.

[0018] The aromatic hydrocarbon group may be substituted or unsubstituted. In the case of substitution, examples of the substituent include R C Substituents represented by O-*, R C The substituents represented by S-*, alkyl groups, and R CExamples of the substituent represented by 3Si-* include a halogen group, a halogen-substituted alkyl group, a nitro group, a cyano group, a sulfonic acid group, a sulfoxide group, and an amino group. C O-*, R C S-* and R C In each of the 3Si-*, R C represents a hydrocarbon group, and * represents a bonding site with an aromatic hydrocarbon group. Examples of halogen groups include fluoro and chloro groups.

[0019] The triarylamine structural unit preferably contains at least a structural unit represented by formula (A1). The structural unit represented by formula (A1) is, for example, R C The structural unit represented by formula (A1) has only one aromatic hydrocarbon group having a substituent represented by O-*. C It has only one substituent represented by O-*.

[0020] In some embodiments, the triarylamine structural unit includes at least one selected from the group consisting of a structural unit represented by the following formula (A2) and a structural unit represented by the following formula (B2). [ka] (Each R independently represents a substituent; each n independently represents an integer of 0 or more, at least one n is an integer of 1 or more, and at least one R is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents the bonding site to the benzene ring. * indicates a bonding site with other structural units.) [ka] (Each R independently represents a substituent; each n independently represents an integer of 0 or more, at least one n is an integer of 1 or more, and at least one R is R C Substituents represented by O-* (R C represents a hydrocarbon group, and * represents the bonding site to the benzene ring. * indicates a bonding site with other structural units.)

[0021] Examples of the substituents represented by R in formula (A2) and formula (B2) and R C Examples of the hydrocarbon group represented by the formula: are as described above. For example, each n may be independently an integer of 0 to 3, and may be 0 or 1.

[0022] The triarylamine structural unit preferably contains at least a structural unit represented by formula (A2). The structural unit represented by formula (A2) is, for example, R C The structural unit represented by formula (A2) has only one benzene ring having a substituent represented by O-*. C It has only one substituent represented by O-*.

[0023] In some embodiments, the triarylamine structural unit includes at least a structural unit represented by the following formula (A4): [ka] (R C represents a hydrocarbon group, and * represents a bonding site with other structural units.)

[0024] R C is, for example, an alkyl group, which may be a linear alkyl group, a linear alkyl group having 2 to 8 carbon atoms, or an ethyl group, an n-propyl group, or an n-butyl group.

[0025] R C The charge transporting polymer containing an arylamine structure having a substituent represented by O-* has a structure in which R CDue to the O-Ar-N- structure, it is believed that high current density can be obtained and that it exhibits excellent conductivity. The introduction of arylamine structural units can improve the conductivity of the charge transport polymer. Charge transport polymers are useful as materials for photoelectric conversion devices, and the use of these materials for photoelectric conversion devices can achieve high efficiency and long life for organic solar cells, organic image sensors, etc.

[0026] (any structural unit) The charge transporting polymer may further contain any structural unit other than the triarylamine structural unit (hereinafter referred to as "any structural unit").

[0027] The arbitrary structural unit may be, for example, a substituted or unsubstituted aromatic amine structure, a substituted or unsubstituted carbazole structure, a substituted or unsubstituted thiophene structure, a substituted or unsubstituted fluorene structure, a substituted or unsubstituted benzene structure, a substituted or unsubstituted biphenyl structure, a substituted or unsubstituted terphenyl structure, a substituted or unsubstituted naphthalene structure, a substituted or unsubstituted anthracene structure, a substituted or unsubstituted tetracene structure, a substituted or unsubstituted phenanthrene structure, a substituted or unsubstituted dihydrophenanthrene structure, a substituted or unsubstituted pyridine structure, a substituted or unsubstituted pyrazine structure, a substituted or unsubstituted quinoline structure, a substituted or unsubstituted isoquinoline structure, a substituted or unsubstituted quinoxaline structure, a substituted or unsubstituted phenylene ... Selected from unsubstituted acridine structure, substituted or unsubstituted diazaphenanthrene structure, substituted or unsubstituted furan structure, substituted or unsubstituted pyrrole structure, substituted or unsubstituted oxazole structure, substituted or unsubstituted oxadiazole structure, substituted or unsubstituted thiazole structure, substituted or unsubstituted thiadiazole structure, substituted or unsubstituted triazole structure, substituted or unsubstituted benzothiophene structure, substituted or unsubstituted benzoxazole structure, substituted or unsubstituted benzoxadiazole structure, substituted or unsubstituted benzothiazole structure, substituted or unsubstituted benzothiadiazole structure, substituted or unsubstituted benzotriazole structure, and structural units containing one or more of these.Preferably, any structural unit contains a substituted or unsubstituted aromatic amine structure, a substituted or unsubstituted carbazole structure, or a substituted or unsubstituted benzene structure.

[0028] Any structural unit may be monovalent or higher, preferably monovalent to hexavalent, more preferably monovalent to tetravalent, and further preferably monovalent to trivalent.

[0029] Examples of substituents that may be included in any structural unit include R C The substituents represented by S-*, alkyl groups, and R C Examples of the substituent represented by 3Si-* include a halogen group, a halogen-substituted alkyl group, a nitro group, a cyano group, a sulfonic acid group, a sulfoxide group, and an amino group. Cand * are as defined above. Examples of the halogen group include a fluoro group and a chloro group.

[0030] The charge transporting polymer preferably includes at least one selected from the group consisting of a structural unit including a substituted or unsubstituted aromatic amine structure, a structural unit including a substituted or unsubstituted carbazole structure, and a structural unit including a substituted or unsubstituted benzene structure. The charge transporting polymer more preferably includes at least one divalent or trivalent structural unit selected from the group consisting of a structural unit including a substituted or unsubstituted aromatic amine structure, and a structural unit including a substituted or unsubstituted carbazole structure, and a monovalent structural unit including a substituted or unsubstituted benzene structure. The charge transporting polymer further preferably includes a divalent or trivalent structural unit including a substituted or unsubstituted aromatic amine structure, and a monovalent structural unit including a substituted or unsubstituted benzene structure. The monovalent structural unit is located at the end of the polymer chain of the charge transporting polymer.

[0031] The divalent or trivalent structural unit containing a substituted or unsubstituted aromatic amine structure includes, for example, at least one selected from the group consisting of a structural unit represented by the following formula (A3) and a structural unit represented by the following formula (B3). [ka] (R e each independently represents a substituent, each m independently represents an integer of 0 or more, and * represents a bonding site to another structural unit. [ka] (R e each independently represents a substituent, each m independently represents an integer of 0 or more, and * represents a bonding site to another structural unit.

[0032] Examples of the substituent are the same as those given as examples of the substituent contained in the arbitrary structural unit. For example, m may be each independently 0 to 3, and may be 0 or 1.

[0033] The divalent or trivalent structural unit containing a substituted or unsubstituted aromatic amine structure includes, for example, at least a structural unit represented by the following formula (B4). [ka] (* indicates a bonding site with other structural units.)

[0034] The structural unit containing a substituted or unsubstituted benzene structure includes, for example, at least a structural unit represented by the following formula (C1). [ka] (R p represents a hydrogen atom or a substituent, and * represents a bonding site with another structural unit.

[0035] R p As an example of a substituent, R C Substituents represented by O-*, R C The substituents represented by S-*, alkyl groups, and R C Examples of the substituent include a substituent represented by 3Si-*, a halogen group, a halogen-substituted alkyl group, a nitro group, a cyano group, a sulfonic acid group, a sulfoxide group, an amino group, and a group containing a polymerizable substituent. C R is a group containing a substituent represented by O-*, an alkyl group, or a polymerizable substituent. Cand * are as described above. The alkyl group may be a linear, branched, or cyclic alkyl group, and is preferably a linear alkyl group. The number of carbon atoms in the linear alkyl group may be, for example, 2 to 16, 4 to 12, or 6 to 8. Examples of the polymerizable substituent include a group having a substituted or unsubstituted carbon-carbon multiple bond (e.g., a vinyl group, a styryl group, an allyl group, a butenyl group, an ethynyl group, an acryloyl group, an acryloyloxy group, an acryloylamino group, a methacryloyl group, a methacryloyloxy group, a methacryloylamino group, a vinyloxy group, and a vinylamino group), a substituted or unsubstituted cyclic alkyl group (e.g., a cyclopropyl group, a benzocyclobutenyl group, and a cyclobutyl group), and a group having a substituted or unsubstituted cyclic ether structure (e.g., an epoxy group (oxiranyl group), and an oxetane group (oxetanyl group)). When these groups are substituted, the substituent is not particularly limited, but examples thereof include linear, branched, or cyclic alkyl groups. The number of carbon atoms in the alkyl group is preferably 1 to 22, more preferably 1 to 10, and even more preferably 1 to 4.

[0036] (Examples of charge transport polymers) The charge transporting polymer may be a linear polymer or a branched polymer. For example, the linear polymer includes a divalent structural unit and a monovalent structural unit, and the divalent structural unit includes the triarylamine structural unit. For example, the branched polymer includes a divalent structural unit, a trivalent structural unit, and a monovalent structural unit, and at least one of the divalent structural unit and the trivalent structural unit includes the triarylamine structural unit.

[0037] In a preferred embodiment, the charge transporting polymer comprises a structural unit represented by formula (A4) and a structural unit represented by formula (B4): The charge transporting polymer may further comprise a structural unit represented by formula (C1).

[0038] The content of the triarylamine structural unit contained in the charge transporting polymer is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more based on the total structural units from the viewpoint of obtaining sufficient charge transporting properties. Also, the content of the triarylamine structural unit is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, taking into consideration the structural units that may be optionally contained.

[0039] The content of the divalent structural unit contained in the charge transporting polymer is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more based on the total structural units from the viewpoint of obtaining sufficient charge transportability. In addition, the content of the divalent structural unit is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, taking into consideration the monovalent structural unit and the trivalent or higher structural unit.

[0040] The content of the trivalent or higher structural unit contained in the charge transporting polymer is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more based on the total structural units from the viewpoint of obtaining an organic layer having excellent solvent resistance. Also, the content of the trivalent or higher structural unit is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, and particularly preferably 20 mol% or less from the viewpoint of suppressing an increase in viscosity and favorably synthesizing the charge transporting polymer, or from the viewpoint of obtaining sufficient charge transportability.

[0041] The content of the monovalent structural unit contained in the charge transport polymer is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more based on the total structural units from the viewpoint of the curability and solubility of the charge transport polymer and from the viewpoint of improving the characteristics of the organic photoelectric conversion element. Also, the content of the monovalent structural unit is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 40 mol% or less from the viewpoint of obtaining sufficient charge transportability.

[0042] The content of the structural unit can be determined by the amount of monomer used corresponding to each structural unit for synthesizing the charge transporting polymer. 1 The average value can be calculated using the integral values ​​of the spectra derived from each structural unit in the H NMR spectrum. When the amount used is clear, it is preferable to use the value calculated using the amount used, since this is simple.

[0043] (number average molecular weight) The number average molecular weight of the charge transporting polymer can be appropriately adjusted in consideration of solubility in a solvent, film-forming property, etc. From the viewpoint of excellent charge transportability, the number average molecular weight is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 5,000 or more, and particularly preferably 10,000 or more. In addition, from the viewpoint of maintaining good solubility in a solvent and facilitating preparation of a liquid composition, the number average molecular weight is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less.

[0044] (Weight average molecular weight) The weight average molecular weight of the charge transporting polymer can be appropriately adjusted in consideration of solubility in a solvent, film-forming property, etc. From the viewpoint of excellent charge transportability, the weight average molecular weight is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 40,000 or more. In addition, from the viewpoint of maintaining good solubility in a solvent and facilitating preparation of a liquid composition, the weight average molecular weight is preferably 100,000 or less, more preferably 80,000 or less, and even more preferably 60,000 or less.

[0045] The number average molecular weight and the weight average molecular weight can be measured by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. The measurement conditions include, for example, the conditions described in the Examples.

[0046] (Method of Manufacturing Charge-Transporting Polymer) The method for producing the charge transporting polymer is not particularly limited. The method for producing the charge transporting polymer includes, for example, obtaining a charge transporting polymer using a monomer containing at least a monomer having the triarylamine structural unit. The monomer may further contain a monomer having any structural unit depending on the structure of the target charge transporting polymer. The monomer has a reactive functional group that can react with each other to form a bond between the structural units. The bond is preferably a direct bond. The reactive functional group can be appropriately selected depending on the type of reaction between the monomers to obtain the charge transporting polymer.

[0047] The reaction is preferably a coupling reaction, and the coupling reaction may be, for example, a known reaction such as Suzuki-Miyaura coupling. Suzuki-Miyaura coupling is, for example, a cross-coupling reaction between an aromatic boronic acid compound or an aromatic boronic acid ester compound and an aromatic halogen compound using a Pd catalyst. According to Suzuki-Miyaura coupling, a charge transporting polymer can be easily produced by bonding desired aromatic rings together. For example, when the reaction is the Suzuki-Miyaura coupling reaction, the reactive functional group of the monomer is preferably selected from the group consisting of a boronic acid group, a boronic acid ester group, and a halogen group.

[0048] In the Suzuki-Miyaura coupling, for example, Pd compounds such as Pd(0) compounds and Pd(II) compounds, Ni compounds, Ru compounds, and the like are used as catalysts.

[0049] Examples of the solvent include water and organic solvents, and may be a mixed solvent of water and an organic solvent. Examples of the organic solvent include aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and diphenyl ether; aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, tetralin, and diphenylmethane; tetrahydrofuran, acetone, acetonitrile, and N,N-dimethylformamide. In the reaction, it is also possible to use, as a base, carbonates of alkali metals such as Na2CO3 and K2CO3; hydroxides of alkali metals such as NaOH and KOH; phosphates of alkali metals such as K3PO4; water-soluble organic bases such as triethylamine, TMAH (tetramethylammonium hydroxide), and TEAH (tetraethylammonium hydroxide). In addition, a phase transfer catalyst can be added to promote the reaction. Examples of the phase transfer catalyst include TBAB (tetrabutylammonium bromide), Aliquat 336 (registered trademark, manufactured by SIGMA-ALDRICH, a mixture of trioctylmethylammonium chloride and tricaprylmethylammonium chloride), and the like.

[0050] [Dopant] The photoelectric conversion element material may contain any additive, for example, a dopant. The dopant is not particularly limited as long as it can exhibit a doping effect by adding to the photoelectric conversion element material and improve the charge transportability. It is preferable to perform p-type doping to improve hole transportability, and n-type doping to improve electron transportability. In addition, one type of dopant may be added alone, or multiple types of dopants may be added in combination.

[0051] The dopant used in p-type doping is an electron-accepting compound, and examples thereof include Lewis acids, protonic acids, transition metal compounds, ionic compounds, halogen compounds, and π-conjugated compounds. The photoelectric conversion element material may contain an ionic compound. Among the ionic compounds, onium salts are particularly preferred. The onium salt may be a compound consisting of a cation containing an onium ion such as carbonium, sulfonium, iodonium, or ammonium, and a corresponding anion.

[0052] The dopant used in n-type doping is an electron-donating compound, and examples thereof include alkali metals such as Li and Cs; alkaline earth metals such as Mg and Ca; salts of alkali metals and / or alkaline earth metals such as LiF and Cs2CO3; metal complexes; and electron-donating organic compounds.

[0053] The material for a photoelectric conversion element contains, for example, a dopant represented by the following formula. [ka] (R a ~R c each independently represents a hydrogen atom (H), an alkyl group, or an aryl group, and A represents an anion.

[0054] The number of carbon atoms in the alkyl group is, for example, 1 to 24. The number of carbon atoms in the aryl group is, for example, 6 to 30. As a specific example, R a and R b may be an alkyl group having 1 to 4 carbon atoms, R c may be an alkyl group having 12 to 24 carbon atoms. a ~R c may be an alkyl group having 1 to 8 carbon atoms, or R a ~R c may be an aryl group having 6 to 30 carbon atoms.

[0055] As anions, tetrakis(pentafluorophenyl)borate ion, tris(trifluoromethanesulfonyl)methide ion, bis(trifluoromethanesulfonyl)imide ion, hexafluoroantimonate ion, AsF6 - (Hexafluoroarsenate ion), BF4 - (Tetrafluoroborate ion), PF6 - (hexafluorophosphate ion), etc.

[0056] In order to improve the solvent resistance of the organic layer, a compound capable of acting as a polymerization initiator for the polymerizable functional group may be used as a dopant.

[0057] [Other optional ingredients] The material for a photoelectric conversion element may further contain a charge transporting low molecular weight compound, other polymers, and the like.

[0058] [Content] From the viewpoint of obtaining good charge transportability, the content of the charge transporting polymer in the material for photoelectric conversion element is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the total mass of the material for photoelectric conversion element (excluding the mass of the solvent when the material contains a solvent). The upper limit of the content of the charge transporting polymer is not particularly limited, and it can be 100% by mass. Considering the inclusion of additives such as dopants, the content of the charge transporting polymer may be, for example, 95% by mass or less or 90% by mass or less.

[0059] When a dopant is contained, the content thereof is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, based on the total mass of the material for photoelectric conversion element (excluding the mass of the solvent when the material contains a solvent), from the viewpoint of improving the charge transportability of the material for photoelectric conversion element. Also, from the viewpoint of maintaining good film formability, the content thereof is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, based on the total mass of the material for photoelectric conversion element.

[0060] <Liquid Composition> In an embodiment of the present invention, the material for a photoelectric conversion element may be a liquid composition containing a solvent. The liquid composition containing a solvent makes it possible to easily form an organic layer by a coating method. The liquid composition can be used as an ink composition.

[0061] [solvent] The solvent may be any solvent, such as water, an organic solvent, or a mixture thereof. Examples of the organic solvent include alcohols such as methanol, ethanol, and isopropyl alcohol; alkanes such as pentane, hexane, and octane; cyclic alkanes such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, tetralin, and diphenylmethane; aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate; and aromatic hydrocarbons such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, and 2,4-dimethylanisole. Examples of the solvent include ethers, aliphatic cyclic ketones such as cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, 2-methylcyclopentanone, and 2-methylcyclohexanone, aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate, aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate, aromatic halides such as chlorobenzene, o-dichlorobenzene, and 1-chloronaphthalene, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, acetone, chloroform, and methylene chloride. The liquid composition may contain one type of solvent alone, or may contain two or more types of solvents.

[0062] [Additives] The liquid composition may further contain additives as optional components, such as polymerization inhibitors, stabilizers, thickeners, gelling agents, flame retardants, antioxidants, reduction inhibitors, oxidizing agents, reducing agents, surface modifiers, emulsifiers, antifoaming agents, dispersants, surfactants, and the like.

[0063] [Content] The content of the solvent in the liquid composition can be determined in consideration of application to various coating methods.For example, the content of the solvent is preferably such that the ratio of the charge transport polymer to the solvent is 0.1% by mass or more, more preferably such that the ratio is 0.2% by mass or more, and even more preferably such that the ratio is 0.5% by mass or more.The content of the solvent is preferably such that the ratio of the charge transport polymer to the solvent is 20% by mass or less, more preferably such that the ratio is 15% by mass or less, and even more preferably such that the ratio is 10% by mass or less.

[0064] <Organic layer> In an embodiment of the present invention, the organic layer is a layer formed using the photoelectric conversion element material or the liquid composition. The organic layer exhibits good charge transport properties. By using the liquid composition, the organic layer can be formed well and easily by a coating method. Examples of the coating method include known methods such as spin coating; casting; immersion; plate printing methods such as letterpress printing, intaglio printing, offset printing, lithographic printing, letterpress reverse offset printing, screen printing, and gravure printing; and plateless printing methods such as inkjet printing. When the organic layer is formed by a coating method, the layer of the liquid composition obtained after coating may be dried using a hot plate or an oven to remove the solvent.

[0065] The thickness of the organic layer after drying or curing is preferably 0.1 nm or more, more preferably 1 nm or more, and even more preferably 3 nm or more, from the viewpoint of improving the efficiency of charge transport, and is preferably 300 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less, from the viewpoint of reducing the electrical resistance.

[0066] <Organic photoelectric conversion element> In an embodiment of the present invention, the organic photoelectric conversion element includes at least the organic layer. The organic photoelectric conversion element includes an organic solar cell, an organic image sensor, and the like. The organic photoelectric conversion element includes, for example, a photoelectric conversion layer, an electrode, and a substrate. In addition, for the purpose of improving the conversion efficiency or the stability in air, other layers such as a buffer layer and an electron transport layer may be included. The organic photoelectric conversion element has at least the organic layer, and the organic layer can be used as a photoelectric conversion layer and a buffer layer, and is preferably used as a buffer layer. Therefore, an example of an organic photoelectric conversion element has an anode, an organic layer as a buffer layer, a photoelectric conversion layer, and a cathode in this order, and may further have any layer between these layers.

[0067] [Photoelectric conversion layer] Any material can be used for the photoelectric conversion layer as long as it absorbs light, causes charge separation, and generates an electromotive force. The material for the photoelectric conversion layer may be, for example, a mixture of a p-type organic semiconductor and an n-type organic semiconductor blended from the viewpoint of conversion efficiency. Examples of p-type organic semiconductors include polymers or oligomers such as oligothiophene, polyalkylthiophene, poly(3-hexylthiophene) (P3HT), and polyphenylenevinylene (PPV); porphyrin, phthalocyanine, copper phthalocyanine; and derivatives thereof. Examples of n-type organic semiconductors include polymers or oligomers containing -CN groups or -CF3 groups such as CN-poly(phenylene-vinylene) (CN-PPV), MEH-CN-PPV, and -CF3-substituted polymers thereof; polymers or oligomers such as poly(fluorene) derivatives and fluorene-benzothiadiazole copolymers; fullerene (C 60 ), naphthalenetetracarboxylic anhydride (NTCDA), perylenetetracarboxylic anhydride (PTCDA), quinacridone, and derivatives thereof. From the viewpoints of conversion efficiency, flexibility, productivity, and the like, the material for the photoelectric conversion layer may be a material containing a perovskite compound.

[0068] The method for forming the photoelectric conversion layer is not particularly limited, and may be formed by a deposition method or a coating method. When formed by a coating method, the organic photoelectric conversion element can be manufactured inexpensively, which is more preferable. As the method for forming by a coating method, the method described in the method for forming the light-emitting layer can be used.

[0069] [Other layers] The organic photoelectric conversion element may have the above-mentioned buffer layer in addition to the photoelectric conversion layer, and may further have layers such as an electron transport layer, etc. The buffer layer may be the organic layer, and the electron transport layer may be a layer containing LiF, TiOx, ZnOx, etc. EXAMPLES

[0070] The embodiments of the present invention will be described with reference to the following examples, but the embodiments of the present invention are not limited to the following examples.

[0071] <Synthesis of charge transporting polymer> The charge transporting polymer was synthesized by Suzuki-Miyaura coupling using the monomers listed below. The monomers were mixed in the ratios (mol percent) shown in Table 1.

[0072] [ka]

[0073] [Table 1]

[0074] (Preparation of Pd catalyst) In a glove box under a nitrogen atmosphere, at room temperature, a fluororesin-coated magnetic stirrer was placed in a glass sample vial, 73.2 mg (80 μmol) of tris(dibenzylideneacetone)dipalladium was weighed out, 15 mL of toluene was added, and the mixture was stirred for 30 minutes to obtain a solution. Similarly, a fluororesin-coated magnetic stirrer was placed in a glass sample vial, 129.6 mg (640 μmol) of tris(t-butyl)phosphine was weighed out, 5 mL of toluene was added, and the mixture was stirred for 5 minutes to obtain a solution. These solutions were mixed and stirred at 80 ° C for 2 hours, and insoluble matter was removed using a membrane filter with a pore size of 0.2 μm, and the resulting solution was used as a Pd catalyst solution. All solvents were degassed by nitrogen bubbling for more than 30 minutes.

[0075] (Synthesis of charge transporting polymer 1) In a 100mL three-necked round-bottom glass flask, each monomer was weighed out to the mixing ratio in Table 1 on a scale of 10mmol total monomer amount, and 1.2mL of 1% by mass trioctylmethylammonium chloride toluene solution, 2.2mL of 3M potassium hydroxide aqueous solution, and toluene were added so that the monomer concentration was 10% by mass. All solvents were used after degassing by nitrogen bubbling for 30 minutes or more. Next, a reflux condenser and a nitrogen gas flow tube were attached to the flask, and the flask was immersed in an oil bath heated to 120°C, and stirred for 10 minutes under solvent reflux to dissolve the monomer. Next, 0.3mL of Pd catalyst solution was added to the liquid in the flask, and the mixture was heated and refluxed for 2 hours. All reactions were carried out under a nitrogen stream.

[0076] After the reaction was completed, the flask was removed from the oil bath, and 5 mL of 0.1 mol / L sodium N,N-diethyldithiocarbamate aqueous solution was added and stirred for 5 minutes. The reaction solution was left to stand for 10 minutes, the separated aqueous layer was removed, and the organic layer was washed with water. The organic layer was filtered through a membrane filter with a pore size of 0.2 μm, and the filtrate was poured into a methanol-water (9:1) mixed solution. The resulting precipitate was filtered off and washed with methanol. The precipitate was further washed with ethyl acetate, and the remaining solid matter was suction filtered and washed with methanol. After washing, the solid matter was vacuum dried to obtain charge transporting polymer 1.

[0077] (Synthesis of charge transporting polymers 2 to 6) Each monomer was weighed out so as to have the compounding ratio shown in Table 1, and the synthesis of charge transporting polymer 1 was carried out in the same manner to obtain charge transporting polymers 2 to 6.

[0078] (Measurement of number average molecular weight, measurement of weight average molecular weight) The number average molecular weight and weight average molecular weight of the charge transporting polymer were measured by gel permeation chromatography (hereinafter, GPC) under the following conditions. Equipment: High-performance liquid chromatograph Prominence, Shimadzu Corporation Liquid delivery pump (LC-20AD) Degassing unit (DGU-20A) Autosampler (SIL-20AHT) Column oven (CTO-20A) PDA detector (SPD-M20A) Refractive index detector (RID-20A) Column: Gelpack GL-A160S (serial number: 686-1J27) GL-A150S (serial number: 685-1J27) Eluent: Tetrahydrofuran (THF) (for HPLC, contains stabilizer) Fujifilm Wako Pure Chemical Industries, Ltd. Flow rate: 1mL / min Column temperature: 40℃ Detection wavelength: 254 nm Molecular weight standard: PStQuick B / C / D Tosoh Corporation

[0079] The number average molecular weight and weight average molecular weight of the charge transporting polymer are shown in Table 2. [Table 2]

[0080] <Synthesis of ionic compounds> (Ionic Compound 1) A fluororesin-coated magnetic stirrer was placed in a 200 mL wide-mouth flask, 1.8 g of N,N-dimethyl-N-octadecylamine (Tokyo Chemical Industry Co., Ltd.) was weighed, 15 mL of acetone and 3 mL of pure water were added, and the mixture was stirred for 10 minutes. 2.2 g of 10% by mass aqueous hydrochloric acid was added dropwise while stirring the obtained solution. Then, the solvent was removed under reduced pressure using a rotary evaporator until a white precipitate was precipitated. 46.5 g of 10% by mass aqueous tetrakis(pentafluorophenylborate) sodium salt solution was added to the obtained liquid (including the precipitate) while stirring, and the mixture was stirred for 30 minutes. Then, the organic layer was washed four times with pure water, and the precipitate was separated by filtration. The obtained precipitate was washed with pure water and then dried under vacuum. The dried solid was dissolved in methanol, and insoluble matter was removed using a 0.2 μm membrane filter, and the solution was poured into pure water and the white precipitate was separated by filtration. The obtained white precipitate was dried in vacuum to obtain ionic compound 1. The chemical structure of ionic compound 1 is shown in the following formula. n is 4. [ka]

[0081] <Evaluation of materials for photoelectric conversion elements> 1. Preparation of materials for photoelectric conversion elements A charge transporting polymer (29.7 mg), ionic compound 1 (0.3 mg), and toluene (1.0 ml) were mixed to prepare a material for a photoelectric conversion element (ink composition).

[0082] 2. Fabrication of organic hole-only devices In air, the material for photoelectric conversion elements was applied to a glass substrate with a 1.6 mm wide pattern of ITO at a rotation speed of 3,000 min ー1 The glass substrate was then placed on a hot plate in a glove box substituted with a nitrogen atmosphere, and heated at 200° C. for 30 minutes to harden the layer of the photoelectric conversion element material, thereby forming an organic layer.

[0083] The organic layer was formed to a thickness of 100 nm (± 5 nm). The thickness of the organic layer was determined by forming an organic layer on a quartz substrate under the above conditions, measuring the thickness at multiple points with a contact film thickness meter, and averaging the measured values.

[0084] The glass substrate having the organic layer obtained as described above was transferred into a vacuum deposition apparatus, and an Al (100 nm) film was formed on the organic layer by deposition, followed by a sealing treatment to prepare an organic hole-only device (HOD).

[0085] 3. Evaluation of organic HOD When a voltage was applied to the organic HOD, it was found that a current flowed, and it was confirmed that the organic layer had a hole injection function. The current density of the organic HOD was measured at a driving voltage of 1.0 V. The results are shown in Table 3.

[0086] [Table 3]

Claims

1. The charge transporting polymer is R Ｃ A substituent represented by O-* (R Ｃ represents a hydrocarbon group, and * represents a bonding site with an aryl group.

2. 2. The material for a photoelectric conversion element according to claim 1, wherein the hydrocarbon group is an alkyl group having 1 to 18 carbon atoms.

3. The material for a photoelectric conversion element according to claim 1 , wherein the charge transporting polymer comprises a branched polymer.

4. The material for photoelectric conversion elements according to claim 1, wherein the structural unit including a triarylamine structure includes at least one selected from the group consisting of a structural unit represented by the following formula (A1) and a structural unit represented by the following formula (B1): 【Chemistry 1】 (Ar each independently represents a substituted or unsubstituted aromatic hydrocarbon group, and at least one Ar is R Ｃ A substituent represented by O-* (R Ｃ represents a hydrocarbon group, and * represents a bonding site to the aromatic hydrocarbon group. * indicates a bonding site with other structural units.) 【Chemistry 2】 (Ar each independently represents a substituted or unsubstituted aromatic hydrocarbon group, and at least one Ar is R Ｃ A substituent represented by O-* (R Ｃ represents a hydrocarbon group, and * represents a bonding site to the aromatic hydrocarbon group. * indicates a bonding site with other structural units.)

5. The material for photoelectric conversion elements according to claim 1, wherein the structural unit including a triarylamine structure includes at least one selected from the group consisting of a structural unit represented by the following formula (A2) and a structural unit represented by the following formula (B2): 【Chemistry 3】 (Each R independently represents a substituent; each n independently represents an integer of 0 or more; at least one n is an integer of 1 or more; and at least one R is R Ｃ A substituent represented by O-* (R Ｃ represents a hydrocarbon group, and * represents a bonding site with a benzene ring. * indicates a bonding site with other structural units.) 【Chemistry 4】 (Each R independently represents a substituent; each n independently represents an integer of 0 or more; at least one n is an integer of 1 or more; and at least one R is R Ｃ A substituent represented by O-* (R Ｃ represents a hydrocarbon group, and * represents a bonding site with a benzene ring. * indicates a bonding site with other structural units.)

6. The material for a photoelectric conversion element according to claim 1 , wherein the charge transporting polymer comprises a structural unit represented by the following formula (A4) and a structural unit represented by the following formula (B4): 【Chemistry 5】 (R Ｃ represents a hydrocarbon group, and * represents a bonding site with other structural units.) 【Chemistry 6】 (* indicates a bonding site with other structural units.)

7. An organic layer formed using the material for photoelectric conversion elements according to any one of claims 1 to 6.

8. An organic photoelectric conversion element comprising the organic layer according to claim 7 .

9. An organic solar cell comprising the organic layer according to claim 7.

10. An organic image sensor comprising the organic layer of claim 7.

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