Compound, hole transport material, and photoelectric conversion element using the same

Abstract

To provide a compound useful as a hole transport material for photoelectric conversion elements that enables efficient current extraction, as well as a photoelectric conversion element and a solar cell, including the compound in the hole transport layer, and exhibiting excellent photoelectric conversion efficiency and high thermal resistance.SOLUTION: Provided is a compound represented by the following general formula (1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a compound, a hole transport material, and a photoelectric conversion element using the same. [Background technology]

[0002] In recent years, solar power generation has been attracting attention as a clean energy source, and the development of solar cells has been actively carried out. Among them, the development of solar cells using perovskite materials in the photoelectric conversion layer (hereinafter referred to as perovskite-type solar cells) has attracted attention as a next-generation solar cell that can be manufactured at low cost by solution processing (for example, Patent Document 1, Non-Patent Documents 1-2).

[0003] In perovskite solar cells, hole transport materials are often used in the element. The purpose of using them is to (1) improve the function of selectively transporting holes to improve photoelectric conversion efficiency, and (2) protect the perovskite material, which is easily affected by moisture and oxygen, by bonding with the perovskite photoelectric conversion layer (for example, Non-Patent Document 3). Spiro-OMeTAD, a spirobifluorene organic compound, is often used as a standard hole transport material, but there are few reports of hole transport materials that contribute more to photoelectric conversion characteristics than this material. In addition, since it is expected that the photoelectric conversion element will be used outdoors under sunlight irradiation, high heat resistance is required. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 104792 [Non-patent literature]

[0005] [Non-Patent Document 1] Journal of the American Chemical Society, 2009, Vol. 131, P. 6050-6051 [Non-Patent Document 2] Science, 2012, Vol. 388, P. 643-647 [Non-Patent Document 3] Chem. Sci.,2019,10,P.6748-6769 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a compound useful as a hole transport material for a photoelectric conversion element, which is capable of efficiently extracting current, and to provide a photoelectric conversion element and a solar cell which use the compound in a hole transport layer, have good photoelectric conversion efficiency and high heat resistance. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors have conducted extensive research into improving photoelectric conversion characteristics, and as a result have discovered that a photoelectric conversion element and a perovskite solar cell exhibiting high photoelectric conversion efficiency can be obtained by designing and developing a compound having a specific structure and using the compound as a hole transport layer in a photoelectric conversion element.

[0008] 1. A compound represented by the following general formula (1):

[0009] [ka]

[0010] [In the formula, L 1 and L 2 is, independently, an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 36 ring atoms which may have a substituent, L 3 ~L 12 is, independently, Hydrogen atom, halogen atom, cyano group, nitro group, carboxyl group, trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent; a linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent; a thio group having 0 to 20 carbon atoms which may have a substituent, an amino group having 0 to 20 carbon atoms which may have a substituent; represents an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, X 1 and X 2 are independently an oxygen atom, a sulfur atom, a sulfonyl group (—S(=O)2—), or NR 1 or CR 2 R 3 represents R 1 ~R 3 is, independently, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, or It represents an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent.]

[0011] 2. L of the compound represented by the general formula (1) 1 and L 2 is an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent.

[0012] 3. L of the compound represented by the general formula (1)1 and L 2 The compound according to item 1 above, wherein the compound is represented by the following general formula (2) or (3):

[0013] [ka]

[0014] [In the formula, R 4 ~R 18 is, independently, Hydrogen atom, halogen atom, cyano group, nitro group, carboxyl group, trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent; a linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent; a thio group having 0 to 20 carbon atoms which may have a substituent, an amino group having 0 to 20 carbon atoms which may have a substituent; an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or represents a heterocyclic group having 5 to 36 ring atoms which may have a substituent, R 4 and R 5 , R 5 and R 6 , R 6 and R 7 , R 7 and R 8 , R 9 and R 10 , R 10 and R 11 , R11 and R 12 , R 12 and R 13 , R 13 and R 14 , R 14 and R 15 , R 15 and R 16 , R 16 and R 17 , and R 17 and R 18 may be bonded to each other to form a ring.

[0015] 4. In the general formula (2), R 4 ~R 8 The compound according to 3 above, wherein at least one of the above is represented by a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent.

[0016] 5. In the general formula (3), R 9 ~R 18 The compound according to 3 above, wherein at least one of the above is represented by a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent.

[0017] 6. A hole transport material represented by the compound according to any one of 1 to 5 above.

[0018] 7. A photoelectric conversion element using the hole transport material described in 6 above. Effect of the Invention

[0019] By using the compound according to the present invention and a hole transport layer using the compound, it is possible to obtain a photoelectric conversion element and a perovskite solar cell having good photoelectric conversion efficiency and high heat resistance. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic cross-sectional view illustrating the configuration of a photoelectric conversion element according to an example of the present invention and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The contents of the present invention will be described in detail below. The following description of the constituent elements may be based on representative embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In this specification, a numerical range expressed using "to" means a range including the numerical values ​​before and after "to" as the lower and upper limits. In addition, some or all of the hydrogen atoms present in the compound represented by general formula (1) and the groups represented by R1 to R29 may be replaced with deuterium atoms. In this specification, "transparent" and "translucent" refer to a transmittance of light for photoelectric conversion of 50% or more, for example, 80% or more, for example, 90% or more, for example, 99% or more. The transmittance of light can be measured by an ultraviolet-visible spectrophotometer.

[0022] The compound represented by the above general formula (1) of the present invention will be specifically explained below, but the present invention should not be construed as being limited to these specific explanations.

[0023] In general formula (1), L 1 and L 2 is, independently, an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or It represents a heterocyclic group having 5 to 36 carbon atoms which may have a substituent.

[0024] In general formula (1), L 1 and L 2The aromatic ring constituting the "aromatic hydrocarbon group having 6 to 36 carbon atoms" in the "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" represented by the formula (I) may be a single ring, a condensed ring in which two or more rings are condensed, or a linked ring in which two or more rings are linked by a single bond. In the case of a condensed ring, it becomes a "condensed polycyclic aromatic group", and the number of condensed rings is 2 to 6, for example, 2 to 4. Specific examples of the aromatic hydrocarbon group include a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group (anthryl group), a phenanthryl group, a fluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, and a triphenylenyl group.

[0025] In general formula (1), L 1 and L 2 The heterocycle constituting the "heterocyclic group having 5 to 36 ring atoms" in the "heterocyclic group having 5 to 36 ring atoms which may have a substituent" represented by the formula (I) may be a single ring or a condensed ring in which two or more rings are condensed. In the case of a condensed ring, the number of condensed rings is 2 to 6, for example, 2 to 4. In addition, the heterocycle may be an aromatic heterocycle or an aliphatic heterocycle. Examples of atoms constituting the heterocycle include a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples of the aromatic heterocyclic group include a pyridyl group, a pyrimidinyl group, a triazinyl group, a thienyl group, a furyl group (a furanyl group), a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a triazolyl group, a quinolyl group, an isoquinolyl group, a naphthyldinyl group, an acridinyl group, a phenanthrolinyl group, a benzofuranyl group, a benzothienyl group, an oxazolyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a thiazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, a carbonyl group, etc. Specific examples of the aliphatic heterocyclic group include a group bonded at a nitrogen atom such as a morpholino group, a pyrrolidino group, a piperazino group, etc., and a group bonded at a carbon atom such as a tetrahydrofuryl group, a tetrahydrothienyl group, etc.

[0026] In general formula (1), L 1 and L 2 Specific examples of the "substituent" in the "optionally substituted aromatic hydrocarbon group having 6 to 36 carbon atoms" or the "optionally substituted heterocyclic group having 5 to 36 ring atoms" represented by the above formula (I) include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a cyano group; a hydroxyl group; a nitro group; a nitroso group; a carboxyl group; a phosphate group; a thioxo group (>C=S); a trimethylsilyl group; a sulfonic acid group; a sulfonate group (-SO3X: ​​X represents an alkali metal cation other than hydrogen); Carboxylic acid ester groups such as methyl ester groups and ethyl ester groups; linear or branched alkyl groups having 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, and decyl; Straight-chain or branched alkenyl groups having 2 to 18 carbon atoms, such as ethenyl (vinyl), 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 1-pentenyl, 1-hexenyl, 2-methyl-1-propenyl, 2-methyl-2-propenyl, and 1-ethylethenyl; Alkoxy groups having 1 to 18 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, a t-butoxy group, an n-pentyloxy group, an n-hexyloxy group, a heptyloxy group, a nonyloxy group, an isopropoxy group, an isobutoxy group, an s-butoxy group, or an isooctyloxy group; aryloxy groups having 1 to 18 carbon atoms, such as a phenoxy group, a tolyloxy group, a biphenyloxy group, a terphenyloxy group, or a naphthyloxy group; Aromatic hydrocarbon groups having 6 to 30 carbon atoms, such as a phenyl group, a biphenylyl group, a naphthyl group, an anthryl group, a phenanthryl group, or a pyrenyl group; heterocyclic groups having 5 to 30 ring atoms, such as a pyridyl group, a pyrimidinyl group, a triazinyl group, a thienyl group, a furyl group (a furanyl group), a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a triazolyl group, a quinolyl group, an isoquinolyl group, a naphthyldinyl group, an acridinyl group, a phenanthrolinyl group, a benzofuranyl group, a benzothienyl group, an oxazolyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a thiazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, or a carbonylyl group; Unsubstituted amino group (-NH 2、 an amino group having 0 carbon atoms; a substituted amino group having 1 to 18 carbon atoms, which is a mono-substituted amino group such as an ethylamino group, an acetylamino group, or an arylamino group (e.g., a phenylamino group), or a di-substituted amino group such as a diethylamino group, a diphenylamino group, or an acetylphenylamino group; Unsubstituted thio groups (thiol groups: —SH); substituted thio groups having 1 to 18 carbon atoms, such as methylthio groups, ethylthio groups, propylthio groups, phenylthio groups, and biphenylthio groups; (In the present specification, these substituents are referred to as "substituent group A"). Only one of these "substituents" may be included, or multiple may be included, and when multiple substituents are included, they may be the same or different from each other, and adjacent substituents may be bonded to each other via a single bond, a bond via an oxygen atom, a sulfur atom, a selenium atom, or a bond via a nitrogen atom to form a ring. In addition, the hydrogen atom of each of the substituents constituting the substituent group A may be further substituted with a substituent selected from the substituent group A.

[0027] In general formula (1), L 3 ~L 12 is, independently, Hydrogen atom, halogen atom, cyano group, nitro group, carboxyl group, trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent; a linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent; a thio group having 0 to 20 carbon atoms which may have a substituent, an amino group having 0 to 20 carbon atoms which may have a substituent; It represents an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent.

[0028] In the present invention, the "halogen atom" includes fluorine, chlorine, bromine and iodine.

[0029] In general formula (1), L 3 ~L 12 Specific examples of the "straight-chain or branched alkyl group having 1 to 20 carbon atoms" in the "straight-chain or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by the formula (1) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a s-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, an isooctyl group, a nonyl group, and a decyl group.

[0030] In general formula (1), L 3 ~L 12Specific examples of the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms" in the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" represented by the formula (1) include an ethenyl group (vinyl group), a 1-propenyl group, a 2-propenyl group (allyl group), a 1-methylethenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 1-hexenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, a 1-ethylethenyl group, and a straight-chain or branched alkenyl group having 2 to 20 carbon atoms in which a plurality of these alkenyl groups are bonded.

[0031] In general formula (1), L 3 ~L 12 Specific examples of the "cycloalkyl group having 3 to 10 carbon atoms" in the "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent" represented by the formula (1) include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, a cyclododecyl group, a 4-methylcyclohexyl group, and a 4-ethylcyclohexyl group.

[0032] In general formula (1), L 3 ~L 12 Specific examples of the "alkoxy group having 1 to 20 carbon atoms" in the "alkoxy group having 1 to 20 carbon atoms which may have a substituent" represented by the formula (1) include a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an isopropoxy group, an isobutoxy group, a s-butoxy group, a t-butoxy group, an isooctyloxy group, and a t-octyloxy group.

[0033] In general formula (1), L 3 ~L 12For an explanation and specific examples of the aryl group bonded to the oxy group of the "aryloxy group having 6 to 30 carbon atoms" in the "aryloxy group having 6 to 30 carbon atoms which may have a substituent" represented by the following formula, the description of the "aromatic hydrocarbon group having 6 to 30 carbon atoms" below can be referred to. Specific examples of the "aryloxy group having 6 to 30 carbon atoms" include a phenoxy group, a tolyloxy group, a biphenylyloxy group, a terphenylyloxy group, a naphthyloxy group, an anthryloxy group, a phenanthryloxy group, a fluorenyloxy group, and an indenyloxy group.

[0034] In general formula (1), L 3 ~L 12 Specific examples of the "cycloalkoxy group having 3 to 10 carbon atoms" in the "cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent" represented by the following formula include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, a cyclohexyloxy group, and a 4-methylcyclohexyloxy group.

[0035] In general formula (1), L 3 ~L 12 Specific examples of the "straight-chain or branched acyl group having 1 to 20 carbon atoms, which may have a substituent" represented by the formula (1) include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a valeryl group, an isovaleryl group, a benzoylacetyl group, and a benzoyl group. In the case where the acyl group contains an alkyl chain, the hydrogen atoms are completely replaced with fluorine atoms (perfluorinated). The acyl group may also be bonded to an amino group (-CO-N<).

[0036] In general formula (1), L 3 ~L 12Specific examples of the "thio group having 0 to 20 carbon atoms" in the "thio group having 0 to 20 carbon atoms which may have a substituent" represented by the formula (1) include an unsubstituted thio group (thiol group: —SH), a methylthio group, an ethylthio group, a propylthio group, a phenylthio group, and a biphenylthio group.

[0037] In general formula (1), L 3 ~L 12 In the "amino group having 1 to 20 carbon atoms" in the "amino group having 0 to 20 carbon atoms which may have a substituent" represented by the formula (1), specific examples of the monosubstituted amino group include an alkylamino group (e.g., an ethylamino group), an acetylamino group, and an arylamino group (e.g., a phenylamino group). Specific examples of the disubstituted amino group include a dialkylamino group (e.g., a diethylamino group), a diarylamino group (e.g., a diphenylamino group), and an acetylphenylamino group.

[0038] In general formula (1), L 3 ~L 12 In the "optionally substituted aromatic hydrocarbon group having 6 to 36 carbon atoms" represented by the formula (1), the "aromatic hydrocarbon group having 6 to 36 carbon atoms" is, for example, 1 and L 2 Examples of the aromatic hydrocarbon group include the same as the "aromatic hydrocarbon group having 6 to 36 carbon atoms" in the "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0039] In general formula (1), L 3 ~L 12 In the "heterocyclic group having 5 to 36 ring atoms which may be substituted" represented by the formula (1), the "heterocyclic group having 5 to 36 ring atoms" is preferably a heterocyclic group having 5 to 36 ring atoms which may be substituted, represented by the formula (1), 1 and L 2 Examples of the heterocyclic group having 5 to 36 ring atoms include the same as the "heterocyclic group having 5 to 36 ring atoms which may be substituted" represented by the following formula:

[0040] In general formula (1), L 3 ~L 12 Examples of the "substituent" in "a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent", "a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent", "a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent", "a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent", "an aryloxy group having 6 to 30 carbon atoms which may have a substituent", "a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent", "a linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent", "a thio group having 0 to 20 carbon atoms which may have a substituent", "an amino group having 0 to 20 carbon atoms which may have a substituent", and "an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" represented by the formula (1) include, for example, L 1 and L 2 Examples of the "substituent" include the same as those in the "optionally substituted aromatic hydrocarbon group having 6 to 36 carbon atoms" represented by the following formula:

[0041] In the present invention, L in general formula (1) 1 and L 2 are each preferably an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, and L 1 and L 2 and more preferably, each of the groups is an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have the same substituent. In this case, the "substituent" is preferably selected from the above-mentioned Substituent Group A.

[0042] In the present invention, L in general formula (1) 2 and L 3 is preferably a hydrogen atom, a halogen atom, or a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent.

[0043] L in general formula (1) 3~L 12 is preferably a hydrogen atom, a halogen atom, a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an aryloxy group having 6 to 30 carbon atoms which may have a substituent. 5 ~L 8 and L 9 ~L 12 Adjacent groups may be bonded to each other via a single bond, an oxygen atom, a nitrogen atom, a sulfur atom, or a selenium atom to form a ring.

[0044] In the general formula (1), X 1 and X 2 are independently an oxygen atom, a sulfur atom, a sulfonyl group (—S(=O)2—), or NR 1 or CR 2 R 3 R 1 ~R 3 is, independently, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, or It represents an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent.

[0045] In the present invention, X 1 and X 2 is an oxygen atom, a sulfur atom, and NR 1 or CR 2 R 3 It is preferable that X is an oxygen atom or a sulfur atom, and more preferable that X is an oxygen atom or a sulfur atom. 1 and X 2 are preferably identical.

[0046] R 1 ~R 3 In the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by the formula (1), the "linear or branched alkyl group having 1 to 20 carbon atoms" is preferably, for example,3 ~L 12 Examples of the alkyl group include the same as the "linear or branched alkyl group having 1 to 20 carbon atoms" in the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by the following formula:

[0047] R 1 ~R 3 In the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" represented by the formula (1), the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms" is, for example, 3 ~L 12 Examples of the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" include the same as the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms" represented by the following formula:

[0048] R 1 ~R 3 In the "optionally substituted aromatic hydrocarbon group having 6 to 36 carbon atoms" represented by the formula (1), the "aromatic hydrocarbon group having 6 to 36 carbon atoms" is, for example, 3 ~L 12 Examples of the aromatic hydrocarbon group include the same as the "aromatic hydrocarbon group having 6 to 36 carbon atoms" in the "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0049] R 1 ~R 3 Examples of the "substituent" in the "straight-chain or branched alkyl group having 1 to 20 carbon atoms which may have a substituent", the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent", or the "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" represented by the following general formula (1) include L 1 and L 2 Examples of the "substituent" include the same as those in the "optionally substituted aromatic hydrocarbon group having 6 to 36 carbon atoms" represented by the following formula:

[0050] In the present invention, R 1 ~R 3 is preferably a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent. Also, R 1 is more preferably a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent, and R 2 and R 3 is more preferably a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent, and further preferably a methyl group.

[0051] In the present invention, L in general formula (1) 1 and L 2 can be preferably represented by the above general formula (2) or general formula (3).

[0052] In the general formula (2) or (3), R 4 ~R 18 is, independently, Hydrogen atom, halogen atom, cyano group, nitro group, carboxyl group, trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent; a linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent; a thio group having 0 to 20 carbon atoms which may have a substituent, an amino group having 0 to 20 carbon atoms which may have a substituent; an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or It represents a heterocyclic group having 5 to 36 ring atoms which may have a substituent.

[0053] In the general formula (2) or (3), R 4 ~R 18 In the "straight-chain or branched alkyl group having 1 to 20 carbon atoms which may have a substituent", the "straight-chain or branched alkyl group having 1 to 20 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the alkyl group include the same as the "linear or branched alkyl group having 1 to 20 carbon atoms" in the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by the following formula:

[0054] In the general formula (2) or (3), R 4 ~R 18 In the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent", the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" include the same as the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms" represented by the following formula:

[0055] In the general formula (2) or (3), R 4 ~R 18 In the "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent", the "cycloalkyl group having 3 to 10 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the cycloalkyl group include the same as the "cycloalkyl group having 3 to 10 carbon atoms" in the "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent" represented by the following formula:

[0056] In the general formula (2) or (3), R4 ~R 18 In the "straight-chain or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent", the "straight-chain or branched alkoxy group having 1 to 20 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the alkoxy group include the same as the "straight-chain or branched alkoxy group having 1 to 20 carbon atoms" in the "straight-chain or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent" represented by the following formula:

[0057] In the general formula (2) or (3), R 4 ~R 18 In the "aryloxy group having 6 to 30 carbon atoms which may have a substituent", the "aryloxy group having 6 to 30 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the aryloxy group include the same as the "aryloxy group having 6 to 30 carbon atoms" in the "aryloxy group having 6 to 30 carbon atoms which may have a substituent" represented by the following formula:

[0058] In the general formula (2) or (3), R 4 ~R 18 In the "cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent", the "cycloalkoxy group having 3 to 10 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the cycloalkoxy group having 3 to 10 carbon atoms include the same as the "cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent" represented by the following formula:

[0059] In the general formula (2) or (3), R 4 ~R 18 In the "straight-chain or branched acyl group having 1 to 20 carbon atoms which may have a substituent", the "straight-chain or branched acyl group having 1 to 20 carbon atoms" is, in the general formula (1), L 3 ~L 12Examples of the "straight-chain or branched acyl group having 1 to 20 carbon atoms which may have a substituent" include the same as the "straight-chain or branched acyl group having 1 to 20 carbon atoms" represented by the following formula:

[0060] In the general formula (2) or (3), R 4 ~R 18 In the "thio group having 0 to 20 carbon atoms which may have a substituent", in the general formula (1), L 3 ~L 12 Examples of the thio group having 0 to 20 carbon atoms include the same as the "thio group having 0 to 20 carbon atoms which may have a substituent" represented by the following formula:

[0061] In the general formula (2) or (3), R 4 ~R 18 In the "amino group having 0 to 20 carbon atoms which may have a substituent", the "amino group having 0 to 20 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the amino group having 0 to 20 carbon atoms include the same as the "amino group having 0 to 20 carbon atoms which may have a substituent" represented by the following formula:

[0062] In the general formula (2) or (3), R 4 ~R 18 In the "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent", the "aromatic hydrocarbon group having 6 to 36 carbon atoms" is, in the general formula (1), L 3 ~L 12 Examples of the aromatic hydrocarbon group include the same as the "aromatic hydrocarbon group having 6 to 36 carbon atoms" in the "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0063] In the general formula (2) or (3), R 4 ~R 18In the "heterocyclic group having 5 to 36 ring atoms which may be substituted", the "heterocyclic group having 5 to 36 ring atoms" is, in the general formula (1), L 3 ~L 12 Examples of the heterocyclic group include the same as the "heterocyclic group having 5 to 36 carbon atoms" in the "heterocyclic group having 5 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0064] In the general formula (2) or (3), R 4 ~R 18 Examples of the "substituent" in the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent", "linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent", "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent", "linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent", "aryloxy group having 6 to 30 carbon atoms which may have a substituent", "cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent", "linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent", "thio group having 0 to 20 carbon atoms which may have a substituent", "amino group having 0 to 20 carbon atoms which may have a substituent", "aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent" or "heterocyclic group having 5 to 36 ring atoms which may have a substituent" represented by the formula (1) include, for example, L 1 and L 2 Examples of the "substituent" include the same as those in the "optionally substituted aromatic hydrocarbon group having 6 to 36 carbon atoms" represented by the following formula:

[0065] In the general formula (2), R 4 ~R 8is preferably represented by a hydrogen atom, a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, an aryloxy group having 6 to 30 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent, and at least one of them is preferably a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent. In this case, R 6 is preferably a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent, and R 6 is an amino group having 0 to 20 carbon atoms which may have a substituent, R 6 is more preferably a diphenylamino group which may have a substituent, and has a structure as represented by general formula (3).

[0066] In the general formula (3), R 9 ~R 18 is preferably represented by a hydrogen atom, a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent, and at least one of them is preferably represented by a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent, and R 11 and R 16 is preferably a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent.

[0067] Specific examples of the compound represented by the general formula (1) of the present invention are shown below, but the present invention is not limited thereto. In addition, the following exemplary compounds are described with some hydrogen atoms, carbon atoms, etc. omitted, and are examples of isomers that may exist, and all other isomers are included. In addition, each may be a mixture of two or more isomers.

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] [ka]

[0086] The compound of the present invention represented by the above general formula (1) can be synthesized by a known method.

[0087] The compound can be synthesized by carrying out a Buchwald reaction between a 4,7-dibromo-2,1,3-benzothiadiazole derivative represented by the following formula (4) and a secondary amine compound represented by the following general formula (5) or the following general formula (6). 3 ~L 12 is L in the general formula (1). 3 ~L 12 is synonymous with.

[0088] [ka]

[0089] The compound represented by the general formula (1) of the present invention can be purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using a solvent, etc. Alternatively, it is effective to use a compound with an increased purity by using these methods in combination. In addition, these compounds can be identified by nuclear magnetic resonance analysis (NMR).

[0090] Hereinafter, the embodiment of the present invention will be described in detail. The compound represented by the general formula (1) of the present invention is useful as a hole transport material. In addition, when used as a hole transport material for a photoelectric conversion element, it can be used in a photoelectric conversion element and a perovskite type photoelectric conversion element, but is not limited thereto.

[0091] Preferred embodiments of the photoelectric conversion element of the present invention will now be described.

[0092] <Photoelectric conversion element> The photoelectric conversion element of the present invention typically has a conductive support 1, an electron transport layer 2, a photoelectric conversion layer 3, a hole transport layer 4, and a counter electrode 5, as shown in the schematic cross-sectional view of FIG.

[0093] As shown in FIG. 1, the photoelectric conversion element of the present invention preferably comprises a conductive support 1, an electron transport layer 2, a photoelectric conversion layer 3, a hole transport layer 4, and a counter electrode 5, but is not limited thereto. In addition, the photoelectric conversion element of the present invention is preferably used as a solar cell, and is more preferably a perovskite-type photoelectric conversion element, but is not limited thereto. In the present invention, the perovskite-type photoelectric conversion element preferably comprises a conductive support (electrode) 1, an electron transport layer 2, a photoelectric conversion layer (perovskite layer) 3, a hole transport layer 4, and a counter electrode 5 in this order. In addition, the conductive support, the hole transport layer, the photoelectric conversion layer (perovskite layer), the electron transport layer, and the counter electrode may be configured in this order.

[0094] <Conductive Support> In the photoelectric conversion element of the present invention, the conductive support 1 shown in FIG. 1 must have a translucency that allows light that contributes to photoelectric conversion to pass through. In addition, since the conductive support is a member that has a function of extracting current from the photoelectric conversion layer, it is preferable that it is a conductive substrate. Specific examples of conductive materials include conductive transparent oxide semiconductors such as tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), tungsten-doped indium oxide (IWO), zinc-aluminum oxide (AZO), fluorine-doped tin oxide (FTO), indium oxide (In2O3), and indium-tin composite oxide, but it is preferable to use tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), etc.

[0095] <Electron transport layer> In the photoelectric conversion element of the present invention, the electron transport layer 2 shown in Fig. 1 is a layer located between the conductive support 1 and the photoelectric conversion layer (perovskite layer) 3, and it is preferable, but not particularly limited, that the electron transport layer 2 is formed on the conductive support 1. The electron transport layer is used to improve the efficiency of electron transfer from the photoelectric conversion layer to the electrode and to block the transfer of holes.

[0096] Specific examples of the semiconductor that forms the electron transport layer include metal oxides such as tin oxide (SnO, SnO2, SnO3, etc.), titanium oxide (TiO2, etc.), 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.); metal sulfides such as titanium sulfide, zinc sulfide, zirconium sulfide, copper sulfide, tin sulfide, indium sulfide, tungsten sulfide, cadmium sulfide, and silver sulfide; metal selenides such as titanium selenide, zirconium selenide, indium selenide, and tungsten selenide; and elemental semiconductors such as silicon and germanium. It is preferable to use one or more of these semiconductors. In the present invention, it is preferable to use one or more semiconductors selected from tin oxide, titanium oxide, and zinc oxide.

[0097] To form the electron transport layer, a paste containing the semiconductor fine particles, which is a commercially available product, may be used, or a paste (electron transport layer coating liquid) prepared by dispersing commercially available semiconductor fine powder in a solvent may be used. Specific examples of the solvent used to prepare the paste include, but are not limited to, water; alcohol-based solvents such as methanol, ethanol, and isopropyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and hydrocarbon-based solvents such as n-hexane, cyclohexane, benzene, and toluene. These solvents may be used alone or in the form of a mixed solvent of two or more kinds.

[0098] The semiconductor fine powder may be dispersed in a solvent by grinding the powder in a mortar or the like, or a dispersing machine such as a ball mill, a paint conditioner, a vertical bead mill, a horizontal bead mill, an attritor, etc. When preparing a paste, it is preferable to add a surfactant or the like to prevent aggregation of the semiconductor fine particles, and it is preferable to add a thickener such as polyethylene glycol to thicken the paste.

[0099] The electron transport layer can be formed by a known film-forming method depending on the material to be formed. As a film-forming method of the electron transport layer, any coating method can be used in which a coating liquid is used for coating. After coating on a conductive substrate by a wet coating method such as spin coating, inkjet method, doctor blade method, drop casting method, squeegee method, screen printing method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire barber coating method, pipe doctor method, impregnation coating method or curtain coating method, a method of removing a solvent or additives by baking to form a film, a sputtering method, a vapor deposition method, an electrodeposition method, an electrodeposition method, a microwave irradiation method, etc. can be mentioned, but are not limited to these. In the present invention, it is preferable to form a film by a spin coating method using the coating liquid for the electron transport layer prepared by the above method, but is not limited thereto. The conditions of the spin coating can be set appropriately. The atmosphere in which the film is formed is not particularly limited, and may be in the air.

[0100] From the viewpoint of further improving the photoelectric conversion efficiency, when a dense electron transport layer is used, the thickness of the electron transport layer is usually preferably 5 nm to 100 nm, and more preferably 10 nm to 50 nm. In the present invention, when a porous (mesoporous) metal oxide is used in addition to the dense layer, the thickness is usually preferably 20 to 200 nm, and more preferably 50 to 150 nm.

[0101] <Photoelectric conversion layer> In the photoelectric conversion element of the present invention, a photoelectric conversion layer 3 is preferably formed on the electron transport layer 2 shown in FIG.

[0102] When used as a perovskite-type photoelectric conversion element, the perovskite material of the photoelectric conversion layer represents a series of materials having a structure represented by the general formula ABX3, where A, B, and X represent an organic cation or a monovalent metal cation, a metal cation, and a halide anion, respectively. For example, A=K + , Rb +, Cs + , CH3NH3 + (hereinafter, MA: methylammonium), NH=CHNH2 + (hereinafter, FA: formamidinium), CH3CH2NH3 + (hereinafter, EA: ethylammonium; B = Pb, Sn; X = I) - , Br - Examples of the perovskite material include, but are not limited to, a layer containing a perovskite material having any of the following compositions: MAPbI3, FAPbI3, EAPbI3, CsPbI3, MASnI3, FASnI3, EASnI3, MAPbBr3, FAPbBr3, EAPbBr3, MASnBr3, FASnBr3, and a perovskite material having any of the following compositions: FAMA)Pb(IBr)3, K(FAMA)Pb(IBr)3, Rb(FAMA)Pb(IBr)3, and Cs(FAMA)Pb(IBr)3 with mixed cations and mixed anions. It is preferable to use one or more of these perovskite materials. In addition, the layer may contain a light absorber other than the perovskite material.

[0103] As a method for forming the photoelectric conversion layer (perovskite layer) of the photoelectric conversion element of the present invention, any coating method for coating with a coating liquid can be used, and examples thereof include the same methods as those for forming the electron transport layer.

[0104] The perovskite precursor may be a commercially available material. In the present invention, it is preferable to use a precursor consisting of a lead halide, a methylammonium halide, a formamidine halide, or a cesium halide in any composition, but the present invention is not limited thereto.

[0105] From the viewpoint of solubility of the precursor, the solvent of the perovskite precursor solution of the present invention may be, but is not limited to, N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), γ-butyrolactone, etc. These solvents may be used alone or in combination of two or more, and it is preferable to use a mixed solution of N,N-dimethylformamide and dimethylsulfoxide. It is also preferable to use a dehydrated solvent with a water content of 10 ppm or less.

[0106] In the present invention, the atmosphere during deposition of the photoelectric conversion layer (perovskite layer) is preferably a dry atmosphere, more preferably a dry inert gas atmosphere such as a glove box, from the viewpoint of being able to reproducibly produce a highly efficient perovskite solar cell by preventing the incorporation of moisture. It is also preferable to use a solvent with a low moisture content by dehydrating with a molecular sieve or the like.

[0107] In the present invention, from the viewpoint of generating a perovskite material from a precursor, the temperature when the photoelectric conversion layer (perovskite layer) is heated by a hot plate or the like is preferably 50 to 200° C., more preferably 70 to 150° C. The heating time is preferably about 10 to 90 minutes, more preferably about 10 to 60 minutes.

[0108] The film thickness of the photoelectric conversion layer (perovskite layer) of the present invention is preferably 50 to 1000 nm, and more preferably 300 to 700 nm, from the viewpoint of further suppressing performance deterioration due to defects or peeling, and in order that the photoelectric conversion layer has sufficient light absorptivity and does not become too high in element resistance.

[0109] The efficiency of charge transfer between layers of the photoelectric conversion layer (perovskite layer) can be increased by covering the surface defects and passivating it. Passivation can be performed using any coating method that uses a coating liquid, and examples of the method include the same method as the film formation method for the electron transport layer.

[0110] For passivation, it is preferable to use a compound having a quaternary ammonium salt structure, but this is not limiting, and multiple compounds may be used in combination.Specific examples include phenylethylammonium bromide, n-hexylammonium bromide, and n-hexyltrimethylammonium bromide.

[0111] The passivation is preferably performed in a dry atmosphere. The method for removing the solvent from the coating solution is preferably a reduced pressure method. The coating thickness is not particularly limited as long as it has an effect of increasing the efficiency of charge transfer, but is preferably 10 nm or less, more preferably 5 nm or less.

[0112] <Hole transport layer> In the photoelectric conversion element of the present invention, the hole transport layer 4 shown in FIG. 1 is a layer having a function of transporting holes, and is a layer located between the photoelectric conversion layer (perovskite layer) 3 and the counter electrode 5. The hole transport layer is used to improve the efficiency of hole transfer from the photoelectric conversion layer to the electrode and to block the transfer of electrons. For example, a conductor, a semiconductor, an organic hole transport material, etc. can be used for the hole transport layer, and an additive may be included for the purpose of further improving the hole transport property.

[0113] The hole transport layer of the present invention is a layer containing the compound represented by the general formula (1) as a hole transport material. The hole transport layer of the present invention may contain one or more compounds represented by the general formula (1) in combination, and may also be used in combination with other hole transport materials not belonging to the present invention.

[0114] Specific examples of other hole transport materials not belonging to the hole transport material of the present invention include, for example, compound semiconductors containing monovalent copper, such as CuI, CuInSe2, and CuS; and compounds containing metals other than copper, such as GaP, NiO, CoO, FeO, Bi2O3, MoO2, and Cr2O3. These metal oxides may be mixed in the hole transport layer or may be laminated on the hole transport material. Examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyethylenedioxythiophene (PEDOT); fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD); carbazole derivatives such as polyvinylcarbazole; triphenylamine derivatives such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA); diphenylamine derivatives; polysilane derivatives; and polyaniline derivatives.

[0115] The hole transport layer of the photoelectric conversion element can be formed by any coating method using a coating liquid, and the same methods as those for forming the electron transport layer can be used.

[0116] In the film formation, the solvents used in the coating solution for the hole transport layer are aromatic organic solvents such as benzene, toluene, xylene, mesitylene, tetralin (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, and nitrobenzene; alkyl halide organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, and dichloromethane; nitrile solvents such as benzonitrile and acetonitrile; tetrahydrofuran, dioxane, and diisopropyl ether. Examples of the solvent include, but are not limited to, ether solvents such as isopropyl ether, c-pentyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate and propylene glycol monomethyl ether acetate; and alcohol solvents such as methanol, isopropanol, n-butanol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, cyclohexanol, and 2-n-butoxyethanol. In addition, the above solvents may be used alone or in combination of two or more, and the solvent to be used can be selected depending on the structure. In particular, it is preferable to use an aromatic organic solvent and an alkyl halide organic solvent.

[0117] In the present invention, the thickness of the hole transport layer is preferably from 5 to 500 nm, and more preferably from 10 to 250 nm, from the viewpoint of further improving the photoelectric conversion efficiency. The atmosphere during film formation of the hole transport layer is preferably a dry atmosphere from the viewpoint of reproducibly producing a highly efficient perovskite solar cell by preventing moisture from being mixed in. It is also preferable to use a dehydrated solvent with a moisture content of 10 ppm or less.

[0118] Additives In the present invention, the hole transport layer may contain a dopant (or an oxidizing agent) or a basic compound (or a basic additive) as an additive. Incorporating an additive into the hole transport layer and increasing the carrier concentration of the hole transport material in the hole transport layer (doping) leads to an improvement in the photoelectric conversion efficiency of the photoelectric conversion element. In the present invention, when the hole transport layer contains a dopant and a basic additive as additives, the amount of the additive is preferably 4 equivalents or less per equivalent of the hole transport material.

[0119] In the present invention, when a dopant is contained, specific examples of the dopant include lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), silver bis(trifluoromethanesulfonyl)imide, zinc bis(trifluoromethanesulfonyl)imide (II), copper bis(trifluoromethanesulfonyl)imide (II), magnesium bis(trifluoromethanesulfonyl)imide (II), calcium bis(trifluoromethanesulfonyl)imide (II), tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide] (FK209), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ), tris(pentafluorophenyl)borane (BCF), NOSbF6, SbCl5, SbF5, and the like. In the present invention, it is preferable to use lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), but the present invention is not limited thereto.

[0120] When a dopant is used, it is preferably 2.0 equivalents or less, more preferably 0.5 equivalents or less, relative to 1 equivalent of the hole transport material contained in the hole transport layer. While the inclusion of an additive in the hole transport layer leads to an improvement in the photoelectric conversion efficiency of the photoelectric conversion element, the use of a dopant as an additive is concerned to reduce the durability of a photoelectric conversion element using an organic compound and shorten the life of the entire element (for example, Non-Patent Document 3). For this reason, there is a demand for the development of a photoelectric conversion element having a hole transport layer with a reduced content of dopant. In addition, if the content can be reduced, it is possible to reduce the cost of additives and the manufacturing process cost.

[0121] In the present invention, a basic compound (basic additive) may be contained as an additive to the hole transport layer. When a basic compound is contained, specific examples include 4-tert-butylpyridine (tBP), 2-picoline, and 2,6-lutidine. A basic compound is often used in combination with a dopant. In the present invention, it is also desirable to use a basic compound in combination with a dopant, and it is preferable to use 4-tert-butylpyridine.

[0122] In the present invention, when a basic compound is used, the amount of the basic compound is preferably 5 equivalents or less, and more preferably 3.5 equivalents or less, relative to 1 equivalent of the hole transport material of the present invention.

[0123] Opposite 1 is disposed opposite the conductive support 1 and formed on the hole transport layer 4, thereby enabling exchange of charges with the hole transport layer. In the photoelectric conversion element of the present invention, it is preferable to provide a metal electrode as a counter electrode on the hole transport layer 4, but an electron blocking layer made of an organic material or an inorganic compound semiconductor can also be added between the hole transport layer 4 and the counter electrode 5.

[0124] Specific examples of materials used for the counter electrode include metals such as platinum, titanium, stainless steel, aluminum, gold, silver, nickel, magnesium, chromium, cobalt, and copper, or alloys thereof. Among these, it is preferable to use gold, silver, or a silver alloy, since it exhibits high electrical conductivity even in a thin film. Examples of silver alloys include silver-gold alloys, silver-copper alloys, silver-palladium alloys, silver-copper-palladium alloys, and silver-platinum alloys, which are less susceptible to sulfurization or chlorination and improve the stability of the thin film.

[0125] In the present invention, the counter electrode is preferably made of a material that can be formed by a method such as vapor deposition. When a metal electrode is used as the counter electrode, the thickness thereof is preferably 10 nm or more, and more preferably 50 nm or more, in order to obtain good electrical conductivity.

[0126] In the photoelectric conversion element of the present invention, the conductive support serves as the cathode, and the counter electrode serves as the anode. It is preferable to irradiate light such as sunlight from the conductive support side. When irradiated with sunlight, the photoelectric conversion layer (perovskite layer) absorbs the light and becomes excited, generating electrons and holes. The electrons move to the electrode via the electron transport layer, and the holes move to the electrode via the hole transport layer, causing a current to flow, and the element functions as a photoelectric conversion element.

[0127] When evaluating the performance (characteristics) of the photoelectric conversion element of the present invention, the short-circuit current density, open-circuit voltage, fill factor (FF), and photoelectric conversion efficiency are measured. The short-circuit current density is the current flowing between the output terminals when the output terminals are short-circuited. 2 The open circuit voltage is the voltage between the output terminals when they are open. The fill factor is the maximum output (product of current and voltage) divided by the product of the short circuit current density and the open circuit voltage, and is mainly dependent on the internal resistance. The photoelectric conversion efficiency is the ratio of maximum output (W) to 1 cm 2The initial photoelectric conversion efficiency of the photoelectric conversion element having the element configuration of the present invention is determined as a percentage by dividing the efficiency by the light intensity (W) per unit area and multiplying the result by 100. If the initial photoelectric conversion efficiency of the photoelectric conversion element having the element configuration of the present invention is 10% or more, it can be determined that the efficiency is good.

[0128] The photoelectric conversion element of the present invention can be applied to solar cells, various photosensors, etc. The solar cell of the present invention is preferably a perovskite solar cell, and the perovskite solar cell can be obtained by arranging a required number of such cells into a module and providing predetermined electrical wiring, the module being a photoelectric conversion element that contains a hole transport material containing the compound represented by the general formula (1) as a hole transport layer, as a cell.

[0129] The hole transport material of the present invention can be applied not only to single-junction solar cells consisting of only perovskite solar cells, but also to multi-junction (tandem) solar cells. Examples of multi-junction solar cells include, but are not limited to, perovskite-perovskite and perovskite-silicon solar cells.

[0130] Although the preferred embodiment has been described above, the present invention is not limited to this, and may be modified as appropriate without departing from the scope of the present invention. EXAMPLES

[0131] The present invention will be specifically described below with reference to the drawings using examples, but the present invention is not limited to the following examples. In addition, the identification of the compounds obtained in the synthesis examples was carried out by 1 This was performed using H-NMR (JNM-ECZ400S / L1 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd.).

[0132] [Synthesis Example 1] Synthesis of compound (A-1) 4,7-Dibromo-2,1,3-benzothiadiazole (0.40 g, Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (7) (1.08 g), sodium tert-butoxide (1.16 g, Fuji Film Wako Pure Chemical Industries, Ltd.), and dehydrated toluene (20 mL) were charged into a reaction vessel, and degassed under reduced pressure. Palladium (II) acetate (0.018 g, Kishida Chemical Industry Co., Ltd.) and tri-tert-butylphosphine (0.028 g, Fuji Film Wako Pure Chemical Industries, Ltd.) were charged under argon atmosphere, and stirred under heating and reflux for 5 hours. After the reaction was completed, the mixture was poured into water (250 mL) and extracted with toluene (100 mL). The separated organic layer was dehydrated with magnesium sulfate, and the filtrate obtained by filtering it was concentrated under reduced pressure. The crude product was purified using a silica gel column (toluene), and the purified fraction was concentrated under reduced pressure. The obtained solid was dried under reduced pressure to obtain a compound of the following formula (A-1) as a purple solid (yield: 0.75 g, yield: 72%).

[0133] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 7.62 (4H), 7.43 (2H), 7.09-7.27 (10H), 6.97 (2H), 6.90 (4H), 6.79 (2H), 3.71 (6H) 1.26 (12H).

[0134] [ka]

[0135] [Synthesis Example 2] Synthesis of compound (A-2) 4,7-Dibromo-2,1,3-benzothiadiazole (0.45 g, Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (8) (1.14 g), sodium tert-butoxide (1.15 g, Fuji Film Wako Pure Chemical Industries, Ltd.), and dehydrated toluene (15 mL) were added to a reaction vessel, and degassed under reduced pressure. Palladium (II) acetate (0.018 g, Kishida Chemical Industry Co., Ltd.) and tri-tert-butylphosphine (0.031 g, Fuji Film Wako Pure Chemical Industries, Ltd.) were added under argon atmosphere, and the mixture was stirred under heating and reflux for 5 hours. After the reaction was completed, the mixture was added to water (200 mL) and extracted with chloroform (300 mL). The separated organic layer was dehydrated with magnesium sulfate, and the filtrate obtained by filtering the organic layer was concentrated under reduced pressure. The crude product was purified using a silica gel column (toluene:hexane = 1:2), and the purified fraction was concentrated under reduced pressure. The obtained solid was dried under reduced pressure to obtain a compound of the following formula (A-2) as a purple solid (yield: 0.48 g, yield: 41%).

[0136] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=8.01(2H), 7.83(2H), 7.52(4H), 7.36-7.40(2H), 7.1 7(2H), 7.07(2H), 6.95(2H), 6.89(4H), 6.79-6.82(4H), 4.37(4H), 3.68(6H), 1.28(6H).

[0137] [ka]

[0138] [Synthesis Example 3] Synthesis of compound (A-3) 4,7-Dibromo-2,1,3-benzothiadiazole (0.35 g, Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (9) (0.88 g), sodium tert-butoxide (0.343 g, Fuji Film Wako Pure Chemical Industries, Ltd.), and dehydrated toluene (10 mL) were added to a reaction vessel, and argon was bubbled for 20 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.056 g, Tokyo Chemical Industry Co., Ltd.) and tri-tert-butylphosphine (0.0.090 g, Fuji Film Wako Pure Chemical Industries, Ltd.) were added under an argon atmosphere, and the mixture was stirred under heating and reflux for 3 hours. After the reaction was completed, the reaction solution was filtered through Celite, and the filtrate obtained was concentrated under reduced pressure. The crude product was purified using a silica gel column (toluene:hexane = 1:1 to 3:1), and the purified fraction was concentrated under reduced pressure. The obtained solid was dried under reduced pressure to obtain a compound of the following formula (A-3) as a purple solid (yield: 0.54 g, yield: 58%).

[0139] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=7.95(4H), 7.48(2H), 7.30-7.34(2H), 7.0 7-7.16(8H), 7.01(2H), 6.88(2H), 6.77(2H), 4.19(4H), 3.72(6H), 1.08(6H).

[0140] [ka]

[0141] [Synthesis Example 4] Synthesis of compound (A-4) 4,7-Dibromo-2,1,3-benzothiadiazole (0.40 g, manufactured by Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (10) (0.87 g), sodium tert-butoxide (0.392 g, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), and dehydrated toluene (15 mL) were added to a reaction vessel, and argon was bubbled for 20 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.085 g, manufactured by Tokyo Chemical Industry Co., Ltd.) and tri-tert-butylphosphine (0.0.090 g, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were added under an argon atmosphere, and the mixture was stirred under heating and reflux for 5 hours. After the reaction was completed, the reaction solution was filtered through Celite, and the filtrate obtained was concentrated under reduced pressure. The crude product was purified using a silica gel column (toluene:hexane = 1:1 to toluene), and the purified fraction was concentrated under reduced pressure. The obtained solid was dried under reduced pressure to obtain a compound of the following formula (A-4) as a purple solid (yield: 0.61 g, 63%).

[0142] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=8.04(2H), 7.74(2H), 7.63(2H), 7.54-7.58(2H), 7. 44-7.48(2H), 7.29(2H), 7.09-7.13(2H), 7.00-7.05(6H), 6.84-6.91(4H), 3.70(6H).

[0143] [ka]

[0144] [Synthesis Example 5] Synthesis of compound (A-5) 4,7-Dibromo-2,1,3-benzothiadiazole (0.40 g, manufactured by Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (11) (0.87 g), sodium tert-butoxide (0.392 g, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), and dehydrated toluene (15 mL) were added to a reaction vessel, and argon was bubbled for 20 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.056 g, manufactured by Tokyo Chemical Industry Co., Ltd.) and tri-tert-butylphosphine (0.0.030 g, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) were added under an argon atmosphere, and the mixture was stirred under heating and reflux for 5 hours. After the reaction was completed, the reaction solution was filtered through Celite, and the filtrate obtained was concentrated under reduced pressure. The crude product was purified using a silica gel column (toluene:hexane = 1:1 to toluene), and the purified fraction was concentrated under reduced pressure. The obtained solid was dried under reduced pressure to obtain a compound of the following formula (A-5) as a purple solid (yield: 447 g, yield: 51%).

[0145] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=8.13(2H), 7.95(2H), 7.86(2H), 7.83(2 H), 7.42-7.46(2H), 7.35-7.39(2H), 7.09-7.13(8H), 6.90(4H), 3.72(6H).

[0146] [ka]

[0147] [Synthesis Example 6] Synthesis of compound (A-37) 4,7-Dibromo-2,1,3-benzothiadiazole (0.30 g, Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (12) (0.68 g), sodium tert-butoxide (0.295 g, Fuji Film Wako Pure Chemical Industries, Ltd.), and dehydrated toluene (15 mL) were added to a reaction vessel, and argon was bubbled for 20 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.049 g, Tokyo Chemical Industry Co., Ltd.) and tri-tert-butylphosphine (0.060 g, Fuji Film Wako Pure Chemical Industries, Ltd.) were added under argon atmosphere, and the mixture was stirred under heating and reflux for 4 hours. After the reaction was completed, the reaction solution was filtered through Celite, and the filtrate obtained was concentrated under reduced pressure. The crude product was purified with an NH-modified silica gel column (toluene:hexane = 1:4 to 1:1), and the purified fraction was concentrated under reduced pressure. The obtained solid was dried under reduced pressure to obtain a compound of the following formula (A-37) as a purple solid (yield: 0.61 g, yield: 50%).

[0148] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=8.01(2H), 7.58-7.64(4H), 7.42-7.54(4H), 7.26-7.30(2H), 6.97-7.06(8H), 6.66-6.70(4H), 2.84(12H).

[0149] [ka]

[0150] [Synthesis Example 7] Synthesis of compound (A-50) 4,7-Dibromo-2,1,3-benzothiadiazole (0.25 g, Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (13) (1.02 g), sodium tert-butoxide (0.246 g, Fuji Film Wako Pure Chemical Industries, Ltd.), and dehydrated toluene (10 mL) were added to a reaction vessel, and argon was bubbled for 20 minutes. Tris(dibenzylideneacetone)dipalladium(0) (0.080 g, Tokyo Chemical Industry Co., Ltd.) and tri-tert-butylphosphine (0.120 g, Fuji Film Wako Pure Chemical Industries, Ltd.) were added in two portions every 5 hours, and the mixture was stirred under heating and reflux for 10 hours. After the reaction was completed, the reaction solution was filtered through Celite, and the filtrate obtained was concentrated under reduced pressure. The crude product was purified using a silica gel column (toluene:hexane = 2:1 to toluene), and the purified fraction was concentrated under reduced pressure. The obtained solid was dried under reduced pressure to obtain a compound of the following formula (A-50) as a purple solid (yield: 0.42 g, yield: 43%).

[0151] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=8.01(2H), 7.89(2H), 7.50-7.57(4H), 7.36-7.40(2H), 7.21-7.25(2H), 7. 06(4H), 6.89-6.94(8H), 6.79-6.84(8H), 6.76(4H), 6.68-6.71(4H), 4.36(4H), 3.62-3.66(12H), 1.27(6H).

[0152] [ka]

[0153] [Example 1] Fabrication of photoelectric conversion element and evaluation of current-voltage characteristics A flat ITO-coated glass (conductive support 1, manufactured by Geomatec Co., Ltd.) was ultrasonically cleaned with isopropyl alcohol and then subjected to a UV ozone treatment. In a dry atmosphere with a relative humidity of 10% or less, a tin(IV) oxide, 15% in H2O colloidal dispersion (manufactured by Alfa Aesar) was spin-coated onto the ITO film as a coating liquid for the electron transport layer. Then, the coating liquid was heated on a hot plate at 150°C for 30 minutes to form a tin oxide layer (electron transport layer 2) with a thickness of about 20 nm.

[0154] In a dry atmosphere with a relative humidity of 10% or less, formamidine hydroiodide (1M, Tokyo Chemical Industry Co., Ltd.), lead(II) iodide (1.1M, Tokyo Chemical Industry Co., Ltd.), methylamine hydrobromide (0.2M, Tokyo Chemical Industry Co., Ltd.), and lead(II) bromide (0.2M, Tokyo Chemical Industry Co., Ltd.) were dissolved in a mixed solvent of dimethylformamide and dimethylsulfoxide in a volume ratio of 4:1. A dimethylsulfoxide solution of cesium iodide (1.5M, Tokyo Chemical Industry Co., Ltd.) was added to the mixture so that the amount of cesium charged was 5% in the composition ratio, to prepare a perovskite precursor solution. In a dry atmosphere with a relative humidity of 10% or less, the prepared perovskite precursor solution was dropped onto the tin oxide layer, spin-coated, and 0.35 mL of chlorobenzene was dropped during the spin-coating to form a perovskite precursor film. After that, the film was heated at 100°C for 1 hour using a hot plate to form a Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) with a thickness of approximately 500 nm.

[0155] In a dry atmosphere with a relative humidity of 10% or less, lithium bis(trifluoromethanesulfonyl)imide as a dopant was dissolved in acetonitrile at a concentration of 1.8 M to prepare a dopant solution. Compound (A-2), which is a hole transport material obtained in Synthesis Example 2, was dissolved in chlorobenzene at room temperature at a concentration of 59 mM. 4-tert-butylpyridine was added thereto so that the amount was 3.3 equivalents relative to compound (A-2). Furthermore, the dopant solution was added so that lithium bis(trifluoromethanesulfonyl)imide was 0.5 equivalents relative to compound (A-2) to prepare a hole transport layer coating solution. In a dry atmosphere with a relative humidity of 10% RH or less, the hole transport layer coating solution was spin-coated onto the Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) to form a hole transport layer 4 with a thickness of about 100 nm.

[0156] On the hole transport layer, a vacuum of 1×10 was applied by vacuum deposition. -4 A gold film of about 80 nm was formed at about Pa to form a gold electrode (counter electrode 5), and a photoelectric conversion element was fabricated.

[0157] A white light irradiation device (Otento-Sun SH model, manufactured by Bunkoukeiki Co., Ltd.) was used to generate simulated sunlight (AM1.5, 1000 W / m 2 ) was irradiated from the conductive support side of the photoelectric conversion element, and the current-voltage characteristics were measured using a source meter (KEITHLEY, Model 2400 Series SourceMeter), to obtain the short-circuit current J sc [mA / cm 2 ], open circuit voltage V oc [V], the fill factor, and the initial photoelectric conversion efficiency were obtained. The short-circuit current J sc [mA / cm 2 ], open circuit voltage V oc [V], fill factor, and initial photoelectric conversion efficiency were normalized based on those of Comparative Example 1, and the results are shown in Table 1.

[0158] [Example 2] A photoelectric conversion element was prepared in the same manner as in Example 1, except that compound (A-50) was dissolved at a concentration of 39 mM instead of compound (A-2), and the initial photoelectric conversion efficiency was obtained in the same manner as in Example 1. The results of normalizing the obtained photoelectric conversion characteristics such as the initial photoelectric conversion efficiency based on Comparative Example 1 are shown in Table 1.

[0159] After obtaining the initial photoelectric conversion efficiency, the photoelectric conversion element was sealed in a laminated bag with a zipper (AL-8, Seizo Nippon Co., Ltd.) in a glove box under a nitrogen atmosphere. The sealed photoelectric conversion element was placed in a vacuum constant temperature dryer (VOS-310C, Tokyo Rikakikai Co., Ltd.) and stored at 85°C for 1,000 hours. The current-voltage characteristics were measured again under simulated solar irradiation to obtain the photoelectric conversion efficiency after 1,000 hours of heating. The retention rate (%) calculated from the initial photoelectric conversion efficiency and the obtained photoelectric conversion efficiency after 1,000 hours of heating using the following formula (a-1) is shown in Table 2.

[0160]

number

[0161] [Comparative Example 1] A photoelectric conversion element was prepared in the same manner as in Example 1, except that a standard hole transport material Spiro-OMeTAD (manufactured by Sigma-Aldrich) represented by the above formula (B-1) was dissolved in chlorobenzene at room temperature at a concentration of 70 mM instead of compound (A-2). The initial photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics in the same manner as in Example 1. The obtained initial photoelectric conversion efficiency is shown in Table 1.

[0162] [ka]

[0163] After obtaining the initial photoelectric conversion efficiency, the photoelectric conversion efficiency after 1,000 hours of heating was obtained in the same manner as in Example 2. Table 2 shows the retention rate (%) calculated from the initial photoelectric conversion efficiency and the obtained photoelectric conversion efficiency after 1,000 hours of heating according to formula (a-1).

[0164] [Table 1]

[0165] The results in Table 1 show that the photoelectric conversion element using the compound represented by general formula (1) as a hole transport material exhibits superior photoelectric conversion efficiency compared to the photoelectric conversion element using the comparative compound (B-1), which is a standard hole transport material.

[0166] [Table 2]

[0167] The results in Table 2 show that the photoelectric conversion element using the compound corresponding to general formula (1) as a hole transport material maintains a high photoelectric conversion efficiency even after 1,000 hours of heating, as compared with the photoelectric conversion element of Comparative Example 2 using Comparative Compound (B-1), which is a conventional standard hole transport material, and exhibits excellent heat resistance. [Industrial Applicability]

[0168] By using the compound represented by the general formula (1) according to the present invention as a hole transport material for a photoelectric conversion element, the photoelectric conversion element has good photoelectric conversion efficiency and excellent heat resistance, and can efficiently convert solar energy into electric energy, and can provide clean energy as a solar cell. Therefore, the present invention has a high industrial applicability. [Explanation of symbols]

[0169] 1. Conductive support 2 Electron transport layer 3 Photoelectric conversion layer 4. Hole transport layer 5. Opposite

Claims

1. A compound represented by the following general formula (1): 【Chemistry 1】 [In the formula, L １ and L ２ is, independently, an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 36 ring atoms which may have a substituent, L ３ ~L １２ is, independently, Hydrogen atom, halogen atom, cyano group, nitro group, carboxyl group, trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent; a linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent; a thio group having 0 to 20 carbon atoms which may have a substituent; an amino group having 0 to 20 carbon atoms which may have a substituent, or represents an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, X １ and X ２ are independently an oxygen atom, a sulfur atom, a sulfonyl group, NR １ or CR ２ R ３ represents R １ ~R ３ is, independently, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, or It represents an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent.]

2. In the general formula (1), L １ and L ２ The compound according to claim 1, wherein is an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent.

3. In the general formula (1), L １ and L ２ The compound according to claim 1, wherein the compound is represented by the following general formula (2) or the following general formula (3): 【Chemistry 2】 [In the formula, R ４ ~R １８ is, independently, Hydrogen atom, halogen atom, cyano group, nitro group, carboxyl group, trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent; a linear or branched acyl group having 1 to 20 carbon atoms which may have a substituent; a thio group having 0 to 20 carbon atoms which may have a substituent; an amino group having 0 to 20 carbon atoms which may have a substituent; an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have a substituent, or represents a heterocyclic group having 5 to 36 ring atoms which may have a substituent, R ４ and R ５ , R ５ and R ６ , R ６ and R ７ , R ７ and R ８ , R ９ and R １０ , R １０ and R １１ , R １１ and R １２ , R １２ and R １３ , R １３ and R １４ , R １４ and R １５ , R １５ and R １６ , R １６ and R １７ , and R １７ and R １８ may be bonded to each other to form a ring.

4. In the general formula (2), R ４ ~R ８ The compound according to claim 3, wherein at least one of the following is represented by a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent.

5. In the general formula (3), R ９ ~R １８ The compound according to claim 3, wherein at least one of the following is represented by a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent.

6. A hole transport material represented by the compound according to any one of claims 1 to 5.

7. A photoelectric conversion element using the hole transport material according to claim 6.

8. A solar cell using the photoelectric conversion element according to claim 7.

Images