Compounds, hole transport materials, and photoelectric conversion elements using the same

Abstract

To provide: a compound useful as a hole transport material for a photoelectric conversion element capable of efficiently extracting electric current; and a photoelectric conversion element and a solar cell with good photoelectric conversion characteristics using the compound in a hole transport layer.SOLUTION: The compound is represented by the general formula (1) in the figure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This 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 attracted attention as a clean energy source, and the development of solar cells is progressing rapidly. Among these, the development of solar cells using perovskite materials in the photoelectric conversion layer (hereinafter referred to as perovskite solar cells) is attracting attention as a next-generation solar cell that is low-cost and can be manufactured using a solution process (for example, Patent Document 1, Non-Patent Documents 1-2).

[0003] Perovskite solar cells often use hole transport materials within the device. The purposes of using them include (1) improving photoelectric conversion efficiency by enhancing the function of selectively transporting holes, and (2) protecting the perovskite material, which is susceptible to the effects of moisture and oxygen, by bonding with the perovskite photoelectric conversion layer (for example, Non-Patent Document 3). Spiro-OMeTAD, a spirobifluorene-based 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. [Prior art documents] [Patent Documents]

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

[0005] [Non-Patent Document 1] J. Am. Chem. Soc., 2009, Vol. 131, pp. 6050-6051 [Non-Patent Document 2] Science, 2012, Vol. 388, pp. 643-647 [Non-Patent Document 3] Chem. Sci.,2019,10,P.6748-6769 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The problem that this invention aims to solve is to provide a compound useful as a hole transport material for a photoelectric conversion element that can efficiently extract electric current, and a photoelectric conversion element and a solar cell that use the compound in the hole transport layer and have good photoelectric conversion characteristics. [Means for solving the problem]

[0007] To solve the above problems, the inventors diligently studied ways to improve photoelectric conversion characteristics and, as a result, designed and developed a compound having a specific structure. By using this compound as a hole transport layer in a photoelectric conversion element, they found that a photoelectric conversion element and a perovskite-type solar cell exhibiting sufficient photoelectric conversion efficiency and high durability can be obtained. In other words, the gist of the present invention is as follows.

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

[0009] [ka]

[0010] [In the formula, R 1 ~R 20 Each of them operates independently. Hydrogen atom, halogen atom, carboxyl group, trimethylsilyl group, Linear or branched alkyl groups having 1 to 20 carbon atoms, which may have substituents. A linear or branched alkenyl group having 2 to 20 carbon atoms, which may have substituents. Cycloalkyl groups having 3 to 12 carbon atoms, which may have substituents. A linear or branched alkoxy group having 1 to 20 carbon atoms, which may have substituents. 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 1 to 18 carbon atoms which may have a substituent, An amino group having 1 to 20 carbon atoms which may have a substituent, An aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent, R 1 ~R 5 、R 6 ~R 10 、R 11 ~R 15 、R 16 ~R 20 may be bonded to each other to form a ring, and R 5 and R 6 and R 15 and R 16 may be bonded to each other to form a ring. X 1 and X 2 represent divalent groups and may be the same or different. Y 1 represents an oxygen atom, a sulfur atom or CR 21 R 22 and, R 21 and R 22 each independently represent a nitrile group, a linear or branched acyl group having 1 to 10 carbon atoms which may have a substituent, or a linear or branched alkoxycarbonyl group having 1 to 10 carbon atoms which may have a substituent, and R 21 and R 22 may be bonded to each other to form a ring.]

[0011] 2. In the general formula (1), compounds in which X 1 and X 2 are represented by the following general formula (2).

[0012]

Chemical formula

[0013] [In the formula, R 23 ~R 28 Each of them operates independently. hydrogen atom, Linear or branched alkyl groups having 1 to 10 carbon atoms, which may have substituents. A linear or branched alkenyl group having 2 to 10 carbon atoms, which may have substituents. Cycloalkyl groups having 3 to 12 carbon atoms, which may have substituents. Aromatic hydrocarbon groups having 6 to 18 carbon atoms, which may have substituents. Alternatively, it represents a heterocyclic group having 5 to 18 ring-forming atoms, which may have substituents. R 24 and R 25 , R 26 and R 27 and R 28 and R 29 They may be joined to each other to form a ring. Z represents an oxygen atom, a sulfur atom, or a selenium atom, and m and n each represent an integer between 0 and 2. However, either m or n is either 1 or 2.

[0014] 3. A compound in which m in the general formula (2) is 1.

[0015] 4. In the above general formula (1), R 1 ~R 20 However, the compound is a hydrogen atom, an alkoxy group having 1 to 20 carbon atoms which may have substituents, or an amino group having 1 to 20 carbon atoms which may have substituents.

[0016] 5. In the above general formula (1), Y 1 A compound in which the atom is an oxygen atom.

[0017] 6. A hole transport material represented by the compound described above.

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

[0019] The compound according to the present invention, and the hole transport layer using the compound, make it possible to obtain a photoelectric conversion element and a perovskite solar cell having sufficient photoelectric conversion efficiency and high durability. [Brief explanation of the drawing]

[0020] [Figure 1] This is a schematic cross-sectional view showing the configuration of the photoelectric conversion element in the embodiments and comparative examples of the present invention. [Modes for carrying out the invention]

[0021] Embodiments of the present invention will be described in detail below. The hole transport material of the present invention is used in photoelectric conversion elements and perovskite-type photoelectric conversion elements.

[0022] The compounds represented by the general formula (1) of the present invention will be described in detail below, but the present invention is not limited to these.

[0023] In general formula (1), R 1 ~R 20 Each is independent of the others. Hydrogen atom, halogen atom, carboxyl group, trimethylsilyl group, Linear or branched alkyl groups having 1 to 20 carbon atoms, which may have substituents. A linear or branched alkenyl group having 2 to 20 carbon atoms, which may have substituents. Cycloalkyl groups having 3 to 12 carbon atoms, which may have substituents. A linear or branched alkoxy group having 1 to 20 carbon atoms, which may have substituents. A cycloalkoxy group having 3 to 10 carbon atoms, which may have substituents. A linear or branched acyl group having 1 to 20 carbon atoms, which may have substituents. A thio group having 1 to 18 carbon atoms, which may have substituents. An amino group having 1 to 20 carbon atoms, which may have substituents. A substituted aromatic hydrocarbon group having 6 to 36 carbon atoms, or This represents a heterocyclic group having 5 to 36 ring-forming atoms, which may have substituents.

[0024] In general formula (1), R 1 ~R 20 Examples of "halogen atoms" represented by this formula include fluorine, chlorine, bromine, and iodine.

[0025] In general formula (1), R 1 ~R 20 In the expression "linear or branched alkyl group having 1 to 20 carbon atoms which may have substituents," specific examples of "linear or branched alkyl group having 1 to 20 carbon atoms" include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, n-hexyl group, 2-ethylhexyl group, heptyl group, octyl group, isooctyl group, nonyl group, decyl group, and the like.

[0026] In general formula (1), R 1 ~R 20 In the expression "linear or branched alkenyl group having 2 to 20 carbon atoms which may have substituents," examples of "linear or branched alkenyl group having 2 to 20 carbon atoms" include ethenyl group (vinyl group), 1-propenyl group, 2-propenyl group (allyl group), 1-methylethenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 1-hexenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, or linear or branched alkenyl group having 2 to 20 carbon atoms formed by the bonding of multiple of these alkenyl groups.

[0027] In general formula (1), R 1 ~R 20In the "cycloalkyl group having 3 to 12 carbon atoms that may have substituents" represented by , specific examples of "cycloalkyl group having 3 to 12 carbon atoms" include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecyl group, cyclododecyl group, 4-methylcyclohexyl group, and 4-ethylcyclohexyl group.

[0028] In general formula (1), R 1 ~R 20 In the expression "linear or branched alkoxy groups having 1 to 20 carbon atoms that may have substituents," examples of "linear or branched alkoxy groups having 1 to 20 carbon atoms" include methoxy, ethoxy, propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, isopropoxy, isobutoxy, s-butoxy, t-butoxy, isooctyloxy, t-octyloxy, phenoxy, tolyloxy, biphenylyloxy, terphenylyloxy, naphthyloxy, anthryloxy, phenanthryloxy, fluorenyloxy, and indenyloxy groups.

[0029] In general formula (1), R 1 ~R 20 In the "cycloalkoxy group having 3 to 10 carbon atoms that may have substituents" represented by , specific examples of "linear or branched cycloalkoxy group having 3 to 10 carbon atoms" include cyclopropoxy group, cyclobutoxy group, cyclopentyloxy group, cyclohexyloxy group, and 4-methylcyclohexyloxy group.

[0030] In general formula (1), R 1 ~R 20In the expression "linear or branched acyl group having 1 to 20 carbon atoms which may have substituents," specific examples of "linear or branched acyl group having 1 to 20 carbon atoms" include acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, benzoylacetyl group, benzoyl group, etc. If an alkyl chain is included, it includes those in which all hydrogen atoms are replaced by fluorine atoms (perfluorinated). It may also be a group bonded to an amino group (-CO-N<).

[0031] In general formula (1), R 1 ~R 20 In the expression "thio group having 1 to 18 carbon atoms which may have substituents," specific examples of "thio group having 1 to 18 carbon atoms" include methylthio group, ethylthio group, propylthio group, phenylthio group, biphenylthio group, and so on.

[0032] In general formula (1), R 1 ~R 20 In the expression "amino group having 1 to 20 carbon atoms which may have substituents," specific examples of "amino group having 1 to 20 carbon atoms" include monosubstituted amino groups such as ethylamino group, acetylamino group, and phenylamino group, and disubstituted amino groups such as diethylamino group, diphenylamino group, and acetylphenylamino group.

[0033] In general formula (1), R 1 ~R 20 In the "aromatic hydrocarbon group having 6 to 36 carbon atoms that may have substituents" represented by , specific examples of "aromatic hydrocarbon groups having 6 to 36 carbon atoms" include phenyl group, biphenyl group, terphenyl group, naphthyl group, biphenyl group, anthracenyl group (anthryl group), phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, perilenyl group, fluoranthenyl group, triphenylenyl group, and the like. In this invention, the aromatic hydrocarbon group includes "condensed polycyclic aromatic groups".

[0034] In general formula (1), R 1 ~R 20 In the expression "heterocyclic groups having 5 to 36 ring-forming atoms which may have substituents," examples of "heterocyclic groups having 5 to 36 ring-forming atoms" include pyridyl group, pyrimidinyl group, triazinyl group, thienyl group, furyl group (furanyl group), pyrrolyl group, imidazolyl group, pyrazolyl group, triazolyl group, quinolyl group, isoquinolyl group, naphthilidinyl group, acridinyl group, phenanthrolinyl group, benzofuranyl group, benzothienyl group, oxazolyl group, indolyl group, carbazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, and carbonillyl group.

[0035] In general formula (1), R 1 ~R 20 In the following expressions, "a linear or branched alkyl group having 1 to 18 carbon atoms which may have substituents," "a linear or branched alkenyl group having 2 to 20 carbon atoms which may have substituents," "a cycloalkyl group having 3 to 12 carbon atoms which may have substituents," "a linear or branched alkoxy group having 1 to 20 carbon atoms which may have substituents," "a cycloalkoxy group having 3 to 10 carbon atoms which may have substituents," "a linear or branched acyl group having 1 to 20 carbon atoms which may have substituents," "a thio group having 1 to 18 carbon atoms which may have substituents," "an amino group having 1 to 20 carbon atoms which may have substituents," "a substituted aromatic hydrocarbon group having 6 to 36 carbon atoms," or "a heterocyclic group having 5 to 36 ring-forming atoms which may have substituents," the "substituents" specifically include halogen atoms such as fluorine, chlorine, bromine, and iodine; cyano groups; hydroxyl groups; nitro groups; nitroso groups; carboxyl groups; phosphate groups; thioxo groups (>C=S); trimethylsilyl groups; 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 group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, n-hexyl group, 2-ethylhexyl group, heptyl group, octyl group, isooctyl group, nonyl group, and decyl group; Linear or branched alkenyl groups having 2 to 18 carbon atoms, such as ethenyl group (vinyl group), 1-propenyl group, 2-propenyl group (allyl group), 1-butenyl group, 2-butenyl group, 1-pentenyl group, 1-hexenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, etc. Alkoxy groups with 1 to 18 carbon atoms, such as methoxy, ethoxy, propoxy, t-butoxy, pentyloxy, and hexyloxy groups; Aromatic hydrocarbon groups with 6 to 30 carbon atoms, such as phenyl, naphthyl, anthryl, phenanthryl, and pyrenyl groups; Heterocyclic groups with 5 to 30 ring-forming atoms, such as pyridyl, pyrimidinyl, triazinyl, thienyl, furyl (furanyl), pyrrolyl, imidazolyl, pyrazolyl, triazolyl, quinolyl, isoquinolyl, naphthylidinyl, acridinyl, phenanthrolinyl, benzofuranyl, benzothienyl, oxazolyl, indolyl, carbazolyl, benzoxazolyl, thiazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothienyl, and carbonillyl groups; Amino groups having 0 to 18 carbon atoms, including unsubstituted amino groups (-NH2), monosubstituted amino groups such as ethylamino groups, acetylamino groups, and phenylamino groups, or disubstituted amino groups such as diethylamino groups, diphenylamino groups, and acetylphenylamino groups; Thio groups with 0 to 18 carbon atoms, such as unsubstituted thio groups (thiol groups: -SH), methylthio groups, ethylthio groups, propylthio groups, phenylthio groups, and biphenylthio groups; Examples include the above. These "substituents" may consist of only one or more, and if there are multiple substituents, they may be identical or different from each other. Furthermore, these "substituents" may have further substituents as exemplified above.

[0036] In general formula (1), R 1 ~R 20 Preferably, is a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have substituents, a linear or branched alkoxy group having 1 to 20 carbon atoms which may have substituents, a thio group having 1 to 18 carbon atoms which may have substituents, an amino group having 1 to 20 carbon atoms which may have substituents, or an aromatic hydrocarbon group having 6 to 36 carbon atoms which may have substituents; more preferably, is a linear or branched alkoxy group having 1 to 20 carbon atoms which may have substituents, a thio group having 1 to 18 carbon atoms which may have substituents, or an amino group having 1 to 20 carbon atoms which may have substituents.

[0037] In general formula (1), R 1 ~R 5 , R 6 ~R 10 , R 11 ~R 15 , R 16 ~R 20 The adjacent groups may be bonded to each other by single bonds, bonds via oxygen atoms, sulfur atoms, selenium atoms, or bonds via nitrogen atoms to form a ring, R 5 and R 6 and R 15 and R 16 They may also be bonded to each other by single bonds, bonds via oxygen atoms, sulfur atoms, selenium atoms, or bonds via nitrogen atoms to form a ring. 5 and R 6 and R 15 and R 16 When forming a ring, it is preferable that the atoms are bonded to each other by single bonds, oxygen atoms, and sulfur atoms to form the ring.

[0038] In general formula (1), Y 1 represents an oxygen atom, a sulfur atom or CR 21 R 22 and, R 21 and R 22 each independently represent a nitrile group, an acyl group having from 1 to 10 carbon atoms which may have a substituent, or an alkoxycarbonyl group having from 1 to 10 carbon atoms which may have a substituent, and is preferably electron-withdrawing.

[0039] In general formula (1), the “linear or branched acyl group having from 1 to 10 carbon atoms which may have a substituent” represented by R 21 and R 22 may be the same as the “linear or branched acyl group having from 1 to 10 carbon atoms which may have a substituent” among the “acyl groups having from 1 to 20 carbon atoms which may have a substituent” represented by R 1 to R 20 in general formula (1).

[0040] In general formula (1), specific examples of the “linear or branched alkoxycarbonyl group having from 1 to 10 carbon atoms” represented by R 21 and R 22 include a methoxycarbonyl group, an ethoxycarbonyl group, etc., and when including an alkyl chain, include those in which a hydrogen atom is completely substituted with a fluorine atom (perfluorinated).

[0041] In general formula (1), R 21 and R 22 may be bonded to each other via a single bond, an oxygen atom, a sulfur atom, a selenium atom or a nitrogen atom to form a ring. When forming a ring, it is preferably an acidic heterocyclic ring such as a barbituric acid type, a thiobarbituric acid type, an indandione type, etc.

[0042] In general formula (1), Y 1 is preferably an oxygen atom.

[0043] In general formula (2), R 23 ~R 28 each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 10 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 12 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 18 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 18 ring-forming atoms which may have a substituent.

[0044] In general formula (2), R 23 ~R 28 Examples of the "linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent" represented by R 1 ~R 20 in the "linear or branched alkyl group having 1 to ́10 carbon atoms which may have a substituent" are the same as those of the "linear or branched alkyl group having 1 to 10 carbon atoms" among the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by R

[0045] In general formula (2), R 23 ~R 28 Examples of the "linear or branched alkenyl group having z to 10 carbon atoms which may have a substituent" represented by R 1 ~R 20Among the "linear or branched alkenyl groups having 2 to 20 carbon atoms that may have substituents" represented by , those that are the same as "linear or branched alkenyl groups having 2 to 10 carbon atoms" can be listed.

[0046] In general formula (2), R 23 ~R 28 In the "cycloalkyl group having 3 to 12 carbon atoms that may have substituents" represented by , the "cycloalkyl group having 3 to 10 carbon atoms" is, in general formula (1), R 1 ~R 20 Examples of the same thing as the "cycloalkyl group having 3 to 12 carbon atoms that may have substituents" represented by can be given.

[0047] In general formula (2), R 23 ~R 28 In the "aromatic hydrocarbon group having 6 to 18 carbon atoms that may have substituents" represented by , the "aromatic hydrocarbon group having 6 to 18 carbon atoms" is, in general formula (1), R 1 ~R 20 Among the "aromatic hydrocarbon groups having 6 to 36 carbon atoms that may have substituents" represented by , those that are the same as "aromatic hydrocarbon groups having 6 to 18 carbon atoms" can be listed.

[0048] In general formula (2), R 23 ~R 28 In the "heterocyclic group with 5 to 18 ring-forming atoms that may have substituents" represented by , the "heterocyclic group with 5 to 18 ring-forming atoms" is, in general formula (1), R 1 ~R 20 Among the "heterocyclic groups with 5 to 36 ring-forming atoms that may have substituents" represented by , those that are the same as "heterocyclic groups with 5 to 18 ring-forming atoms" can be listed.

[0049] In general formula (2), R 23 ~R 28In the expressions "a linear or branched alkyl group having 1 to 10 carbon atoms which may have substituents", "a linear or branched alkenyl group having 2 to 10 carbon atoms which may have substituents", "a cycloalkyl group having 3 to 12 carbon atoms which may have substituents", "an aromatic hydrocarbon group having 6 to 18 carbon atoms which may have substituents", or "a heterocyclic group having 5 to 18 ring-forming atoms which may have substituents", the "substituents" in general formula (1) are, 1 ~R 20 In the "linear or branched alkyl group having 1 to 18 carbon atoms that may have substituents" represented by the formula, the same substituents can be listed within the range of carbon atoms and ring-forming atoms.

[0050] In general formula (2), R 23 and R 24 , R 25 and R 26 and R 27 and R 28 These atoms may be bonded to each other by single bonds, bonds via oxygen atoms, sulfur atoms, selenium atoms, or nitrogen atoms, forming a ring.

[0051] In general formula (2), Z 1 represents an oxygen atom, a sulfur atom, or a selenium atom, Z 1 It is preferable that it be a sulfur atom.

[0052] In general formula (2), m and n each represent integers from 0 to 2. When m is 0, n is 1 or 2. When n is 0, m is 1 or 2. Cases where either m or n is 1 or greater and both are 0 are not included. It is preferable that m is 1. Also, the thioxanthone derivative (Y) is the central skeleton of general formula (1). 1 CR 21 R 22 (Including the case where) means that either the phenyl group represented by general formula (2) or the five-membered heterocyclic group may be bonded first.

[0053] In general formula (2), it is preferable that m is 1 and n is 0 or 1. In general formula (2), when m is 1 and n is 1, it is preferable that a 5-membered heterocyclic group is bonded to the thioxanthone derivative portion, which is the central skeleton of general formula (1).

[0054] Specific examples of compounds represented by the general formula (1) of the present invention are shown below, but the present invention is not limited to these. Furthermore, the following exemplary compounds are described with some hydrogen atoms, carbon atoms, etc. omitted, and represent only one example of possible isomers, encompassing all other isomers. In addition, each compound may be a mixture of two or more isomers.

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[0088] The hole transport material of the present invention, represented by the general formula (1) above, can be synthesized by known methods.

[0089] A Suzuki-Miyaura cross-coupling reaction is carried out between a 2,7-dibromothioxanthone represented by the following formula (3) and a boronic acid compound represented by the following general formulas (4) and (5) or a boronic acid ester compound represented by the following general formulas (6) and (7). Furthermore, a Kneefengel condensation reaction is carried out with the compound represented by the following general formula (8), resulting in the above general formula (1) where Y is replaced with CR. 21 R 22 It is possible to perform synthesis using a type that incorporates [this technology].

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[0094] The hole transport material 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., or by recrystallization or crystallization with a solvent. Alternatively, it is effective to use a compound with increased purity obtained by using a combination of these methods. Furthermore, these compounds can be identified by nuclear magnetic resonance analysis (NMR).

[0095] Preferred embodiments of the photoelectric conversion element of the present invention will be described below.

[0096] <Photoelectric conversion element> The photoelectric conversion element of the present invention typically 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, as shown in the schematic cross-sectional view of Figure 1.

[0097] 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, as shown in Figure 1, but is not limited thereto. Furthermore, 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. Alternatively, it may be configured in the order of conductive support, hole transport layer, photoelectric conversion layer (perovskite layer), electron transport layer, and counter electrode.

[0098] <Conductive support> In the photoelectric conversion element of the present invention, the conductive support 1 shown in Figure 1 needs to be translucent, capable of transmitting light that contributes to photoelectric conversion. Furthermore, since the conductive support is a component that has the function of extracting current from the photoelectric conversion layer, it is preferable that it be 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) or fluorine-doped tin oxide (FTO).

[0099] <Electron transport layer> In the photoelectric conversion element of the present invention, the electron transport layer 2 shown in Figure 1 is a layer located between the conductive support 1 and the photoelectric conversion layer (perovskite layer) 3. It is preferable, but not limited to, that the electron transport layer 2 be 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 movement of holes.

[0100] In the present invention, specific examples of semiconductors that form 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.

[0101] In the present invention, the paste containing the semiconductor fine particles may be a commercially available product, or a paste prepared by dispersing commercially available semiconductor fine powder in a solvent (a coating solution for electron transport layers) may be used. Specific examples of solvents used when preparing 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. Furthermore, these solvents can be used individually or as a mixture of two or more solvents.

[0102] In the present invention, the method for dispersing semiconductor fine powder in a solvent may involve grinding the powder in a mortar and pestle, or using a disperser such as a ball mill, paint conditioner, vertical bead mill, horizontal bead mill, or attritor. When preparing the paste, it is preferable to add a surfactant or the like to prevent aggregation of semiconductor fine particles, and it is preferable to add a thickener such as polyethylene glycol to increase the viscosity.

[0103] In the present invention, the electron transport layer can be obtained using a known film-forming method depending on the material to be formed. Any coating method using a coating solution can be used to form the electron transport layer. Examples include, but are not limited to, a wet coating method such as spin coating, inkjet coating, doctor blade coating, drop casting, squeegee coating, screen printing, reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, wire barber coating, pipe doctor coating, impregnation coating, or curtain coating, which is applied to a conductive substrate and then the solvent and additives are removed by firing; or sputtering, vapor deposition, electrodeposition, photodeposition, microwave irradiation, etc. In the present invention, it is preferable to form the film by spin coating using a coating solution for the electron transport layer prepared by the above method, but is not limited to this. The conditions for spin coating can be set as appropriate. The atmosphere in which the film is formed is not particularly limited and may be in the atmosphere.

[0104] From the viewpoint of further improving 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 of the electron transport layer is usually preferably 20 to 200 nm or less, and more preferably 50 to 150 nm.

[0105] <Photoelectric conversion layer> In the photoelectric conversion element of the present invention, it is preferable that a photoelectric conversion layer (perovskite layer) 3 is formed on the electron transport layer 2 shown in Figure 1.

[0106] In the present invention, when used as a perovskite-type photoelectric conversion element, the perovskite material which is the photoelectric conversion layer represents a series of materials having a structure represented by the general formula ABX3. Here, A, B, and X represent an organic cation or a monovalent metal cation, a metal cation, and a halide anion, respectively, and as an example, A=K+ , Rb + , Cs + CH3NH3 + (Hereafter, MA: methylammonium), NH=CHNH2 + (Hereafter, FA: Formamidinium), CH3CH2NH3 + (Hereafter, EA: ethylammonium; B=Pb, Sn; X=I) - , Br - Examples include the following. More specifically, layers containing perovskite materials represented by any composition of MAPbI3, FAPbI3, EAPbI3, CsPbI3, MASnI3, FASnI3, EASnI3, MAPbBr3, FAPbBr3, EAPbBr3, MASnBr3, FASnBr3, EASnBr3, and perovskite materials of mixed cations and mixed anions represented by any composition of FAMA)Pb(IBr)3, K(FAMA)Pb(IBr)3, Rb(FAMA)Pb(IBr)3, and Cs(FAMA)Pb(IBr)3 can be used, but are not limited to these. It is preferable to use one or more of these perovskite materials. In addition, light absorbers other than perovskite materials may be included.

[0107] Any coating method can be used to coat the photoelectric conversion layer (perovskite layer) of the photoelectric conversion element of the present invention using a coating solution, and the same method as the method for forming the electron transport layer can be used.

[0108] The perovskite precursor may be a commercially available material, and in the present invention, it is preferable to use a precursor consisting of lead halide, methylammonium halide, formamidine halide, and cesium halide in any composition, but is not limited thereto.

[0109] From the viewpoint of precursor solubility, the solvent for the perovskite precursor solution of the present invention can be N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone, etc., but is not limited to these. Furthermore, one or more of these solvents may be used, and a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide is preferred.

[0110] In the present invention, the atmosphere during film formation of the photoelectric conversion layer (perovskite layer) is preferably a dry atmosphere, and more preferably a dry inert gas atmosphere such as a glove box, from the viewpoint of being able to reproducibly manufacture highly efficient perovskite solar cells by preventing the inclusion of moisture. Furthermore, it is preferable to dehydrate the solvent using molecular sieves or the like and use a solvent with a low moisture content.

[0111] In the present invention, the temperature at which the photoelectric conversion layer (perovskite layer) is heated using a hot plate or the like is preferably 50 to 200°C, and more preferably 70 to 150°C, from the viewpoint of generating perovskite material from the precursor. The heating time is preferably about 10 to 90 minutes, and more preferably about 10 to 60 minutes.

[0112] The 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 degradation due to defects and delamination, and in order to ensure that the photoelectric conversion layer has a sufficient light absorption rate while preventing the element resistance from becoming too high.

[0113] <Hole transport layer> In the photoelectric conversion element of the present invention, the hole transport layer 4 shown in Figure 1 is a layer that has the function of transporting holes and is 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 movement from the photoelectric conversion layer to the electrode and to block electron movement. For example, a conductor, semiconductor, or organic hole transport material can be used for the hole transport layer, and additives may be included for the purpose of further improving the hole transport characteristics.

[0114] The hole transport layer of the present invention is a layer containing a 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), and may also be used in combination with other hole transport materials not belonging to the present invention.

[0115] Specific examples of other hole transport materials not belonging to 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 oxide metals may be mixed in the hole transport layer or laminated on top of 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.

[0116] Any coating method can be used to coat the hole transport layer of the photoelectric conversion element of the present invention using a coating solution, and the same method as the method for forming the electron transport layer can be used.

[0117] In the present invention, the solvents used in the coating solution for the hole transport layer during film formation 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 halogenated organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, and dichloromethane; nitrile solvents such as benzonitrile and acetonitrile; and tetrahydrofuran and dioxa. Examples of suitable solvents include ether-based solvents such as diisopropyl ether, c-pentyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol monomethyl ether; ester-based solvents such as ethyl acetate and propylene glycol monomethyl ether acetate; and alcohol-based solvents such as methanol, isopropanol, n-butanol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, cyclohexanol, and 2-n-butoxyethanol, but are not limited to these. Furthermore, one or more of the above solvents may be used, and the solvent to be used can be selected depending on the structure. In particular, the use of aromatic organic solvents and alkyl halogenated organic solvents is preferred.

[0118] In the present invention, the thickness of the hole transport layer is preferably 5 to 500 nm, and more preferably 10 nm to 250 nm, from the viewpoint of further improving the photoelectric conversion efficiency.

[0119] In the present invention, a dry atmosphere is preferred during the deposition of the hole transport layer, from the viewpoint of being able to reproducibly manufacture highly efficient perovskite solar cells by preventing the inclusion of moisture. Furthermore, it is preferable to use a dehydrated solvent with a moisture content of 10 ppm or less.

[0120] <Additives> In the present invention, the hole transport layer may contain dopants (or oxidizing agents) or basic compounds (or basic additives) as additives. Including additives in the hole transport layer and improving 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 dopants and basic additives as additives, it is preferable that the amount of additive is 3.5 equivalents or less per equivalent of the hole transport material.

[0121] In the present invention, when a dopant is included, specific examples of dopants include bis(trifluoromethylsulfonyl)imide lithium (LiTFSI), bis(trifluoromethanesulfonyl)imide silver, tris(2-(1H-pyrazole-1-yl)-4-tert-butylpyridine)cobalt(III)tri[bis(trifluoromethane)sulfonimide](FK209), NOSbF6, SbCl5, SbF5, etc. In the present invention, it is preferable to use bis(trifluoromethylsulfonyl)imide lithium (LiTFSI), but the invention is not limited thereto.

[0122] In the present invention, when using a dopant, the amount of dopant is preferably 2.0 equivalents or less, and more preferably 0.5 equivalents or less, relative to 1 equivalent of the hole transport material contained in the hole transport layer. While including additives in the hole transport layer leads to an improvement in the photoelectric conversion efficiency of the photoelectric conversion element, there are concerns that using dopants, which are additives, will reduce the durability of photoelectric conversion elements using organic compounds and shorten the overall lifespan of the element (for example, Non-Patent Literature 3). For this reason, there is a need for the development of a photoelectric conversion element having a hole transport layer with reduced dopant content. Furthermore, if the content can be reduced, it will be possible to reduce the cost of additives and the manufacturing process cost.

[0123] Furthermore, the present invention may contain a basic compound (basic additive) as an additive to the hole transport layer. Specific examples of basic compounds included in the present invention include 4-tert-butylpyridine (tBP), 2-picoline, and 2,6-lutidine. Basic compounds are often used in combination with dopants. In the present invention, it is desirable to use a basic compound in combination with a dopant, and tert-butylpyridine is preferred.

[0124] In the present invention, when a basic compound is used, it is preferable that the amount is 5 equivalents or less, and more preferably 3 equivalents or less, relative to 1 equivalent of the hole transport material of the present invention.

[0125] <Opposite> In the present invention, the counter electrode 5 shown in Figure 1 is positioned opposite the conductive support 1 and formed on the hole transport layer 4, thereby enabling charge exchange with the hole transport layer. In the photoelectric conversion element of the present invention, it is preferable to have 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.

[0126] In the present invention, specific 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, gold, silver, or silver alloys are preferred because they exhibit high electrical conductivity even in thin films. As for silver alloys, silver-gold alloys, silver-copper alloys, silver-palladium alloys, silver-copper-palladium alloys, and silver-platinum alloys are used to improve the stability of the thin film by making them less susceptible to sulfidation or chlorination.

[0127] In the present invention, the counter electrode is preferably made of a material that can be formed by methods such as vapor deposition.

[0128] When a metal electrode is used as the counter electrode, its film thickness is preferably 10 nm or more, and more preferably 50 nm or more, in order to obtain good conductivity.

[0129] In the photoelectric conversion element of the present invention, the conductive support acts as the cathode and the counter electrode acts as the anode. It is preferable to irradiate the conductive support with light, such as sunlight, from the conductive support side. Upon irradiation with sunlight or other light, the photoelectric conversion layer (perovskite layer) absorbs the light and enters an excited state, generating electrons and holes. These electrons move through the electron transport layer and the holes move through the hole transport layer to the electrodes, causing an electric current to flow and enabling the element to function as a photoelectric conversion element.

[0130] When evaluating the performance (characteristics) of the photoelectric conversion element of the present invention, the short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency are measured. Short-circuit current density is the current that flows between the two terminals when the output terminals are short-circuited. 2 The current per watt is expressed, and the open-circuit voltage is the voltage between the two terminals when the output terminals are open-circuited. The fill factor is the value obtained by dividing the maximum output (product of current and voltage) by the product of the short-circuit current density and the open-circuit voltage, and is mainly affected by the internal resistance. The photoelectric conversion efficiency is calculated by multiplying the maximum output (W) by 1 cm². 2 It can be calculated by dividing the value by the light intensity (W) per unit area, multiplying the result by 100, and expressing it as a percentage.

[0131] The photoelectric conversion element of the present invention can be applied to solar cells, various light sensors, and the like. The solar cell of the present invention is preferably a perovskite solar cell. A perovskite solar cell is obtained by arranging the required number of photoelectric conversion elements, each containing a hole transport material containing the compound represented by the general formula (1) as a hole transport layer, to form a module, and providing predetermined electrical wiring.

[0132] Although preferred embodiments have been described above, the present invention is not limited thereto, and may be modified as appropriate without departing from the scope of the present invention. [Examples]

[0133] The present invention will be described in detail below with reference to the drawings and examples, but the present invention is not limited to the following examples. The identification of the compounds obtained in the synthesis examples is as follows: 1 The analysis was performed using ¹H-NMR (¹H-NMR (JEOL Ltd. nuclear magnetic resonance spectrometer, JNM-ECZ400S / L1 model)).

[0134] [Synthesis Example 1] Synthesis of Compound (A-1) 2,7-Dibromothioxanthone (0.20 g), [4-[bis(4-methoxyphenyl)amino]phenyl]boronic acid (0.46 g, Tokyo Chemical Co., Ltd.), tetrakis(triphenylphosphine)palladium (0) (0.05 g, Kanto Chemical Co., Ltd.), potassium carbonate (0.69 g, Kanto Chemical Co., Ltd.), toluene (20 mL), and water (5.0 mL) were added to a reaction vessel, and degassing was carried out under reduced pressure. The mixture was heated and stirred under reflux under an argon atmosphere for 8 hours. After the reaction was complete, water (50 mL) and toluene (50 mL) were added, and the mixture was separated. The organic layer was dehydrated with magnesium sulfate, filtered, and the filtrate was concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (toluene:ethyl acetate = 100:1), and reprecipitation (ethyl acetate / methanol) was performed to obtain the compound represented by the following formula (A-1) as a yellow solid (yield: 0.36 g, yield: 81%).

[0135] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 8.64 (2H), 8.04 (2H), 7.91 (2H), 7.63 (4H), 7.09 (8H), 6.95 (8H), 6.87 (4H), 3.76 (12H).

[0136] [ka]

[0137] [Synthesis Example 2] Synthesis of compound (A-21) 2,7-dibromothioxanthone (0.20 g), the compound of formula (10) below (1.1 g), tetrakis(triphenylphosphine)palladium (0) (0.03 g, manufactured by Kanto Chemical Co., Ltd.), potassium carbonate (0.69 g, manufactured by Kanto Chemical Co., Ltd.), toluene (50 mL), ethanol (10 mL), and water (5 mL) were added to a reaction vessel, and degassing was carried out under reduced pressure. The mixture was heated under reflux and stirred under an argon atmosphere for 5 hours. After the reaction was complete, water (200 mL) and methanol (100 mL) were added. This was separated, the organic layer was dried over magnesium sulfate, and then concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (toluene:ethyl acetate = 30:1 to 20:1 (volume ratio)) to obtain the compound represented by formula (A-21) below as a yellow powder (yield: 0.59 g, yield: 67%).

[0138] 1 H-NMR (400MHz, DMSO-d6): δ(ppm)=8.84(2H), 8.25(2H), 8.08(6H), 7.80-7.75(8H), 7.40(4H), 7.12-7.09(4H), 6.90(16H), 6.83(16H), 3.70(24H).

[0139] [ka]

[0140] [Example 1] Fabrication of a photoelectric conversion element and evaluation of its current-voltage characteristics A glass coated with a flat ITO film (conductive support 1, manufactured by Geomatec) was ultrasonically cleaned with isopropyl alcohol and then treated with UV ozone. A tin(IV) oxide dispersion (coating solution for electron transport layer) consisting of 15% in H2O colloidal dispersion (manufactured by Alfa Aesar) and purified water in a volume ratio of 1:9 was applied to this ITO film by spin coating. Subsequently, a tin oxide layer (electron transport layer 2) with a thickness of approximately 20 nm was formed by heating on a hot plate at 150°C for 30 minutes.

[0141] Under a nitrogen atmosphere in a glove box, formamidine hydroiodide (1M, manufactured by Tokyo Chemical Industry Co., Ltd.), lead(II) iodide (1.1M, manufactured by Tokyo Chemical Industry Co., Ltd.), methylamine hydrobromide (0.2M, manufactured by Tokyo Chemical Industry Co., Ltd.), and lead(II) bromide (0.2M, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in a mixed solvent of dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. A dimethyl sulfoxide solution of cesium iodide (1.5M, manufactured by Tokyo Chemical Industry Co., Ltd.) was then added to prepare a perovskite precursor solution, with the amount of cesium added reaching 5% of the composition ratio. In a glove box under a nitrogen atmosphere, the prepared perovskite precursor solution was dropped onto a tin oxide layer and spin-coated. During the spin-coating process, 0.3 mL of chlorobenzene was added to form a perovskite precursor film. Subsequently, a Cs(MAFA)Pb(IBr) 3-layer (photoelectric conversion layer 3) with a thickness of approximately 500 nm was formed by heating at 100°C for 1 hour using a hot plate.

[0142] Under a nitrogen atmosphere in a glove box, 4-tert-butylpyridine and bis(trifluoromethanesulfonyl)imide lithium were dissolved in chlorobenzene as dopants. Compound (A-1), which is a hole transport material obtained in Synthesis Example 1, was dissolved in this chlorobenzene solution at 50 mM. The solution was prepared so that 3 equivalents of 4-tert-butylpyridine and 0.5 equivalents of bis(trifluoromethanesulfonyl)imide lithium were added to (A-1), and this was used as the coating solution for the hole transport layer. In a glove box under a nitrogen atmosphere, a hole transport layer coating solution was spin-coated onto three layers of Cs(MAFA)Pb(IBr) (photoelectric conversion layer 3) to form a hole transport layer 4 with a thickness of approximately 200 nm.

[0143] On the hole transport layer, a vacuum deposition method is used to create a vacuum of 1 × 10⁻⁶. -4 A gold electrode (counter electrode 5) was formed by depositing a gold film of approximately 80 nm in thickness at a temperature of around Pa, and a photoelectric conversion element was fabricated.

[0144] Simulated sunlight (AM1.5, 100mW / cm²) generated by a white light irradiation device (OTENTO-SUN SH model, manufactured by Spectrometer Co., Ltd.) 2 The initial photoelectric conversion efficiency was obtained by irradiating the photoelectric conversion element with a light source from the conductive support side and measuring the current-voltage characteristics using a source meter (KEITHLEY Model 2400 Series SourceMeter).

[0145] After measuring the current-voltage characteristics, the photoelectric conversion element was stored in a desiccator containing silica gel for 30 days, and the current-voltage characteristics were measured again under simulated sunlight irradiation to obtain the photoelectric conversion efficiency after 30 days. The photoelectric conversion efficiency over time, which is the photoelectric conversion efficiency after 30 days, is shown in Table 1.

[0146] Table 1 shows the rate of change (%) calculated using the following formula (a-1) with respect to the initial photoelectric conversion efficiency obtained and the photoelectric conversion efficiency after 30 days.

[0147]

number

[0148] [Comparative Example 1] A photoelectric conversion element was fabricated in the same manner as in Example 1, except that Spiro-OMeTAD (manufactured by Sigma-Aldrich), a standard hole transport material represented by the above formula (B-1), was dissolved in a chlorobenzene solution of the above dopant to a concentration of 50 mM and used instead of compound (A-1). The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 1. The rate of change (%) calculated using the obtained initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days, as shown in Table 1, is calculated using the following formula (a-1).

[0149] [ka]

[0150] [Table 1]

[0151] The results in Table 1 show that the photoelectric conversion element using the compound (A-1) having a thioxanthone skeleton of the present invention as a hole transport material exhibits sufficient photoelectric conversion efficiency and high durability compared to photoelectric conversion elements using standard hole transport materials. [Industrial applicability]

[0152] The photoelectric conversion element using the hole transport material according to the present invention exhibits good photoelectric conversion efficiency and can provide clean energy as a solar cell that can efficiently convert solar energy into electrical energy, and can also be applied to other applications such as organic EL and image sensors. [Explanation of Symbols]

[0153] 1. Conductive support 2 Electron transport layer 3. Photoelectric conversion layer 4. Hole transport layer 5 Opposites

Claims

1. A compound represented by the following general formula (1). 【Chemistry 1】 [In the formula, R1, R2, R4, R5, R6, R7, R9, R10, R11, R12, R14, R15, R16, R17, R19, and R20 are hydrogen atoms, and R3, R8, R13, and R18 represent diphenylamino groups substituted with alkoxy groups having 1 to 18 carbon atoms.] R ５ and R ６ and R １５ and R １６ They may be joined to each other to form a ring. X １ and X ２ This is expressed by the following general formula (2). Y １ This represents an oxygen atom. 【Chemistry 2】 [wherein, R ２３ to R ２８ is a hydrogen atom. Z １ [where m represents an oxygen atom, sulfur atom, or selenium atom, and n represents an integer of 1 and 0.]

2. A hole transport material represented by the compound described in claim 1.

3. A photoelectric conversion element using the hole transport material described in claim 2.

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