Compound having sulfonate group and photoelectric conversion element using the same

Abstract

A compound represented by the following general formula (1) is provided as a hole transport material useful as a photoelectric conversion element, and a photoelectric conversion element using the compound in a hole transport layer is provided.

Description

Compounds with sulfonate groups and photoelectric conversion elements using these compounds Technical Field

[0001] This invention relates to a compound having a sulfonate group, a photoelectric conversion element using the compound, and a perovskite solar cell. Background Technology

[0002] In recent years, solar power generation, as a clean energy source, has attracted much attention, and the development of solar cells is booming. Among them, the development of perovskite solar cells (hereinafter referred to as perovskite solar cells), which are low-cost and can be manufactured using solution processes, has attracted much attention (e.g., Patent Document 1, Non-Patent Documents 1-2).

[0003] In perovskite solar cells, hole transport materials are mostly used in the elements. Examples of their use include (1) improving photoelectric conversion efficiency and (2) protecting perovskite materials susceptible to moisture or oxygen (e.g., non-patent literature 3). Spiro-OMe TAD is the standard hole transport material, and there are fewer reports of hole transport materials that contribute significantly to photoelectric conversion characteristics compared to this material.

[0004] When hole transport materials are used in elements of perovskite solar cells, in conventional methods that use organic compounds to fabricate elements, a dopant is added to the hole transport material as an additive. This dopant is used to reduce the resistance of the hole transport material (e.g., non-patent literature 3-4).

[0005] However, using dopants as additives not only complicates the manufacturing process but also increases manufacturing costs. Furthermore, reports indicate that dopants promote moisture absorption, corrode the photoelectric conversion layer, and degrade the hole transport layer due to volatilization, all of which degrade device characteristics (e.g., Non-Patent Literature 5). Therefore, it is desirable to develop photoelectric conversion devices with a dopant-free hole transport layer that exhibit high photoelectric conversion characteristics and durability. On the other hand, dopants are sometimes necessary to achieve good photoelectric conversion efficiency. Therefore, it is also desirable to develop photoelectric conversion devices whose characteristics degrade less over time even when dopants are present.

[0006] Patent Document 1: International Publication No. 2017 / 104792

[0007] Non-patent literature 1: J. Am. Chem. Soc., 2009, Vol. 131, pp. 6050-6051 Non-patent literature 2: Science, 2012, Vol. 388, pp. 643-647

[0008] Non-patent literature 3: Chem. Sci., 2019, 10, pp. 6748-6769.

[0009] Non-patent literature 4: Adv. Funct. Mater., 29, 24, 2019, 1901-296

[0010] Non-patent literature 5: J. Am. Chem. Soc., 2018, 140, 48, 16720-16730 Summary of the Invention

[0011] 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 that does not contain additives, i.e., dopants; a photoelectric conversion element with good photoelectric conversion characteristics when the compound is used in a hole transport layer; and a perovskite solar cell. Furthermore, the problem to be solved by the present invention is also to provide a compound useful as a hole transport material for a photoelectric conversion element whose characteristics degrade over time even when dopants are present.

[0012] To address the aforementioned problems, the inventors conducted in-depth research on improving photoelectric conversion characteristics. They discovered that by using compounds with specific structures as hole transport layers, high-efficiency photoelectric conversion elements and perovskite solar cells can be obtained. In other words, the main points of this invention are as follows.

[0013] 1. A compound represented by the following general formula (1).

[0014] [Chemistry 1]

[0015]

[0016] [In the formula, R] 1 It can be a straight-chain or branched alkyl group with 1 to 18 carbon atoms that can have a substituent, a straight-chain or branched alkenyl group with 2 to 20 carbon atoms that can have a substituent, a straight-chain or branched alkynyl group with 2 to 20 carbon atoms that can have a substituent, a cycloalkyl group with 3 to 12 carbon atoms that can have a substituent, an aromatic hydrocarbon group with 6 to 36 carbon atoms that can have a substituent, or a heterocyclic group with 5 to 36 cyclic atoms that can have a substituent, where X represents a monovalent cation other than hydrogen ions.

[0017] R 2 ~R 9Each of the following can independently represent a hydrogen atom, a straight-chain or branched alkyl group having 1 to 18 carbon atoms that can have substituents, a straight-chain or branched alkenyl group having 2 to 20 carbon atoms that can have substituents, a straight-chain or branched alkynyl group having 2 to 20 carbon atoms that can have substituents, a cycloalkyl group having 3 to 12 carbon atoms that can have substituents, a straight-chain or branched alkoxy group having 1 to 20 carbon atoms that can have substituents, a cycloalkoxy group having 3 to 10 carbon atoms that can have substituents, a straight-chain or branched alkoxycarbonyl group having 1 to 18 carbon atoms that can have substituents, a mercapto group having 1 to 18 carbon atoms that can have substituents, an amino group having 1 to 20 carbon atoms that can have substituents, an aromatic hydrocarbon group having 6 to 36 carbon atoms that can have substituents, or a heterocyclic group having 5 to 36 cyclic atoms that can have substituents.

[0018] 2. The compound according to 1 above, wherein, in the general formula (1), R 1 It is a straight-chain or branched alkyl group that can have 1 to 18 carbon atoms and can have substituents.

[0019] 3. The compound according to 1 or 2 above, wherein, in the general formula (1), R 2 ~R 9 At least one of them is an aromatic hydrocarbon group with 6 to 36 carbon atoms that can have a substituent or an amino group with 1 to 20 carbon atoms that can have a substituent.

[0020] 4. The compound according to any one of 1 to 3 above, wherein in the general formula (1), X is an alkali metal ion or an ammonium ion capable of having substituents.

[0021] 5. The compound according to 4 above, wherein, in the general formula (1), the alkali metal ion is selected from at least one of the group consisting of sodium ion, potassium ion, rubidium ion and cesium ion.

[0022] 6. A hole transport material comprising any one of the compounds described in 1 to 5 above.

[0023] 7. A hole transport material composition for a photoelectric conversion element, comprising the hole transport material described in 6 above.

[0024] 8. A photoelectric conversion element using the hole transport material composition for photoelectric conversion described in 7 above.

[0025] According to the sulfonate-based compound of the present invention and the hole transport layer using the compound, by using the compound between the photoelectric conversion layer and the electrode, a photoelectric conversion element with good photoelectric conversion efficiency and a perovskite solar cell can be obtained. Attached Figure Description

[0026] Figure 1 is a schematic cross-sectional view showing the structure of the photoelectric conversion element of the present invention and a comparative example. Detailed Implementation

[0027] The embodiments of the present invention will be described in detail below. The hole transport layer of the present invention is used in photoelectric conversion elements and perovskite photoelectric conversion elements.

[0028] Hereinafter, compounds represented by general formula (1) will be specifically described, but the present invention is not limited to these.

[0029] In general formula (1), R 1 This refers to a straight-chain or branched alkyl group that can have a substituent with 1 to 18 carbon atoms, a straight-chain or branched alkenyl group that can have a substituent with 2 to 20 carbon atoms, a straight-chain or branched alkynyl group that can have a substituent with 2 to 20 carbon atoms, a cycloalkyl group that can have a substituent with 3 to 12 carbon atoms, an aromatic hydrocarbon group that can have a substituent with 6 to 36 carbon atoms, or a heterocyclic group that can have a substituent with 5 to 36 cyclic atoms.

[0030] In general formula (1), as R 1 The phrase "a straight-chain or branched alkyl group having 1 to 18 carbon atoms capable of having substituents" specifically includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, decyl, etc., in R 1 In the example, one of the hydrogen atoms of the substituent is replaced by a sulfonate group (-SO3X).

[0031] In general formula (1), as R 1 The phrase "a straight-chain or branched alkenyl group with 2 to 20 carbon atoms capable of having substituents" specifically includes vinyl, 1-propenyl, allyl, 1-butenyl, 2-butenyl, 1-pentenyl, 1-hexenyl, isopropenyl, isobutenyl, or alkenyl groups of these with multiple carbon atoms bonded together, forming a straight-chain or branched alkenyl group with 2 to 20 carbon atoms. (In R...) 1 In the example, one of the hydrogen atoms of the substituent is replaced by a sulfonate group (-SO3X).

[0032] In general formula (1), as R 1The phrase "a straight-chain or branched alkynyl group with 2 to 20 carbon atoms capable of having substituents" specifically includes ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 1-methyl-2-propynyl, 1-pentynyl, 2-pentynyl, 1-methyl-n-butynyl, 2-methyl-n-butynyl, 3-methyl-n-butynyl, 1-hexynyl, etc., in R 1 In the example, one of the hydrogen atoms of the substituent is replaced by a sulfonate group (-SO3X).

[0033] In general formula (1), as R 1 The phrase "cycloalkyl groups with 3 to 12 carbon atoms" in the definition of "cycloalkyl groups capable of having substituents" can specifically include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, cyclododecyl, etc., in R 1 In the example, one of the hydrogen atoms of the substituent is replaced by a sulfonate group (-SO3X).

[0034] In general formula (1), as R 1 The phrase "aromatic hydrocarbon groups with 6 to 36 carbon atoms capable of having substituents" specifically includes phenyl, biphenyl, terphenyl, naphthyl, anthraceneyl, phenanthryl, fluorenyl, indene, pyrene, perylene, fluoranyl, and triphenylene, among others. 1 In this invention, one of the hydrogen atoms of the substituents is replaced by a sulfonate group (-SO3X). Furthermore, in this invention, the aromatic hydrocarbon group includes a "fused polycyclic aromatic group".

[0035] In general formula (1), as R 1 The phrase "heterocyclic groups with 5 to 36 cyclic atoms capable of having substituents" specifically includes pyridyl, pyrimidinyl, triazine, thiophene, furanyl, pyrroleyl, imidazolyl, pyrazolyl, triazolyl, quinolinyl, isoquinolinyl, naphthidyl, acridineyl, phenanthrolinel, benzofuranyl, benzothiophene, oxazolyl, indoleyl, carbazoleyl, benzooxazolyl, thiazolyl, benzothiazolyl, quinoxolinyl, benzoimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiophene, carbolinyl, etc., in R 1 In the example, one of the hydrogen atoms of the substituent is replaced by a sulfonate group (-SO3X).

[0036] In general formula (1), as R 1The term "substituent" in the following categories refers to "a straight-chain or branched alkyl group having 1 to 18 carbon atoms that can have a substituent," "a straight-chain or branched alkenyl group having 2 to 20 carbon atoms that can have a substituent," "a straight-chain or branched alkynyl group having 2 to 20 carbon atoms that can have a substituent," "a cycloalkyl group having 3 to 12 carbon atoms that can have a substituent," "an aromatic hydrocarbon group having 6 to 36 carbon atoms that can have a substituent," or "a heterocyclic group having 5 to 36 cyclic atoms that can have a substituent." Specific examples of substituents include fluorine, chlorine, and bromine atoms. Halogen atoms such as iodine; cyano; hydroxyl; nitro; nitroso; carboxyl; phosphate; carboxylic acid esters such as methyl ester and ethyl ester; straight-chain or branched alkyl groups with 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, decyl; and straight-chain or branched alkyl groups with 2 to 20 carbon atoms, such as vinyl, 1-propenyl, allyl, 1-butenyl, 2-butenyl, 1-pentenyl, 1-hexenyl, isopropenyl, isobutylenyl. Alkenyl groups with 1-18 carbon atoms, including methoxy, ethoxy, propoxy, tert-butoxy, pentoxy, and hexoxy groups; aromatic hydrocarbon groups with 6-30 carbon atoms, including phenyl, naphthyl, anthraceneyl, phenanthryl, and pyrene groups; and pyridyl, pyrimidinyl, triazine, thiopheneyl, furanyl, pyrroleyl, imidazolyl, pyrazolyl, triazolyl, quinolinyl, isoquinolinyl, naphthidyl, acridineyl, phenanthrene-rholineyl, benzofuranyl, benzothiopheneyl, oxazolyl, indoleyl, carbazoleyl, and benzoxazolyl. Heterocyclic groups with 5 to 30 ring atoms, such as thiazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiophene, and carbolinyl; amino groups with 0 to 18 carbon atoms, such as unsubstituted amino groups (-NH2), ethylamino, acetylamino, and phenylamino, or disubstituted amino groups (such as diethylamino, diphenylamino, and acetylphenylamino); mercapto groups with 0 to 18 carbon atoms, such as unsubstituted mercapto groups (thiol groups: -SH), methylmercapto, ethmercapto, propiconazole, hex-5-en-3-mercapto, phenylmercapto, and biphenylmercapto; etc. These "substituents" may include only one or more, and when multiple are included, they may be the same or different from each other. Furthermore, these "substituents" may further have the substituents exemplified above.

[0037] In general formula (1), R 1 In the sulfonate group (-SO3X), X represents a monovalent cation other than a hydrogen ion. Specifically, the monovalent cation is preferably an alkali metal ion, an ammonium ion capable of having a substituent, or a phosphonium ion capable of having a substituent, more preferably an alkali metal ion or an ammonium ion capable of having a substituent, particularly preferably an alkali metal ion, but not limited to these.

[0038] Examples of alkali metals include lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, and francium ions, with a preference for at least one selected from the group consisting of sodium ions, potassium ions, rubidium ions, and cesium ions.

[0039] In addition, specific examples of ammonium ions that can have substituents include methylammonium ion, monofluorinated methylammonium ion, difluorinated methylammonium ion, trifluorinated methylammonium ion, ethylammonium ion, isopropylammonium ion, n-propylammonium ion, isobutylammonium ion, n-butylammonium ion, tert-butylammonium ion, dimethylammonium ion, diethylammonium ion, phenylammonium ion, benzylammonium ion, phenethylammonium ion, guanidinium ion, formamidinium ion, acetamipridium ion, imidazolium ion, tri-n-butylammonium ion, and tetra-n-butylammonium ion.

[0040] In general formula (1), R 1 Preferably, it is a straight-chain or branched alkyl group with 1 to 18 carbon atoms capable of having substituents. 1 More preferably, the alkyl group containing the substituent has 18 or fewer carbon atoms in its entirety; even more preferably, the alkyl group containing the substituent has 10 or fewer carbon atoms in its entirety; and particularly preferably, the alkyl group containing the substituent has 6 or fewer carbon atoms in its entirety.

[0041] In general formula (1), R 2 ~R 9 Each of the following can be independently represented: a hydrogen atom; a straight-chain or branched alkyl group having 1 to 18 carbon atoms that can have substituents; a straight-chain or branched alkenyl group having 2 to 20 carbon atoms that can have substituents; a straight-chain or branched alkynyl group having 2 to 20 carbon atoms that can have substituents; a cycloalkyl group having 3 to 12 carbon atoms that can have substituents; a straight-chain or branched alkoxy group having 1 to 20 carbon atoms that can have substituents; a cycloalkoxy group having 3 to 10 carbon atoms that can have substituents; a straight-chain or branched alkoxycarbonyl group having 1 to 18 carbon atoms that can have substituents; a mercapto group having 1 to 18 carbon atoms that can have substituents; an amino group having 1 to 20 carbon atoms that can have substituents; an aromatic hydrocarbon group having 6 to 36 carbon atoms that can have substituents; or a heterocyclic group having 5 to 36 cyclic atoms that can have substituents.

[0042] In general formula (1), as R 2 ~R 9 The phrase "a straight-chain or branched alkyl group having 1 to 18 carbon atoms capable of having substituents" can be exemplified by the alkyl group consisting of R in general formula (1). 1 The same group as "a straight-chain or branched alkyl group that can have 1 to 18 carbon atoms that can have substituents".

[0043] In general formula (1), as R 2 ~R 9 The phrase "a straight-chain or branched alkenyl group with 2 to 20 carbon atoms capable of having substituents" can be exemplified by the alkenyl group represented by R in general formula (1). 1 The same group as the "alkenyl group with 2 to 20 carbon atoms in a straight or branched form".

[0044] In general formula (1), as R 2 ~R 9 The phrase "a straight-chain or branched alkynyl group with 2 to 20 carbon atoms capable of having substituents" can be exemplified by the alkynyl group represented by R in general formula (1). 1 It refers to the same group as "a straight-chain or branched alkynyl group with 2 to 20 carbon atoms".

[0045] In general formula (1), as R 2 ~R 9 The "cycloalkyl group with 3 to 12 carbon atoms" in the phrase "cycloalkyl group capable of having substituents" can be exemplified by R in general formula (1). 1 The same group as "cycloalkyl group with 3 to 12 carbon atoms".

[0046] In general formula (1), as R 2 ~R 9 The phrase "a straight-chain or branched alkoxy group with 1 to 20 carbon atoms that can have substituents" includes, specifically, methoxy, ethoxy, propoxy, n-butoxy, n-pentoxy, n-hexoxy, heptoxy, octoxy, nonoxy, decoxy, isopropoxy, isobutoxy, sec-butoxy, tert-butoxy, isooctoxy, tert-octoxy, phenoxy, tolyloxy, biphenyloxy, terphenyloxy, naphthoxy, anthraquinoneoxy, phenanthroxy, fluorenoxy, and fluorenoxy.

[0047] In general formula (1), as R 2 ~R 9 The phrase "a straight-chain or branched cycloalkoxy group with 3 to 10 carbon atoms that can have substituents" can specifically include cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexoxy, etc.

[0048] In general formula (1), as R 2 ~R 9The phrase "alkoxycarbonyl with 1 to 18 carbon atoms" in the definition of "a straight-chain or branched alkoxycarbonyl that can have substituents" can specifically include methoxycarbonyl, ethoxycarbonyl, etc.

[0049] In general formula (1), as R 2 ~R 9 The phrase "thiol group with 1 to 18 carbon atoms that can have substituents" can specifically include methylthiol, ethimyl, propanyl, phenylthiol, biphenylthiol, etc.

[0050] In general formula (1), as R 2 ~R 9 The phrase "amino group with 1 to 20 carbon atoms that can have substituents" can specifically include ethylamino, acetylamino, phenylamino, etc., as monosubstituted amino groups, and diethylamino, diphenylamino, acetylphenylamino, etc., as disubstituted amino groups.

[0051] In general formula (1), as R 2 ~R 9 The "aromatic hydrocarbon group with 6 to 36 carbon atoms" in the expression "aromatic hydrocarbon group capable of having substituents" can be exemplified by the group represented by R in general formula (1). 1 The same group is referred to as "an aromatic hydrocarbon group that can have 6 to 36 carbon atoms as a substituent".

[0052] In general formula (1), as R 2 ~R 9 The "heterocyclic group with 5 to 36 cyclic atoms" in the expression "a heterocyclic group capable of having substituents" can be exemplified by R in general formula (1). 1 The same group as "a heterocyclic group with 5 to 36 cyclic atoms capable of having substituents".

[0053] In general formula (1), as R 2 ~R 9The "substituent" in the following expressions, namely "a straight-chain or branched alkyl group having 1 to 18 carbon atoms that can have a substituent", "a straight-chain or branched alkenyl group having 2 to 20 carbon atoms that can have a substituent", "a straight-chain or branched alkynyl group having 2 to 20 carbon atoms that can have a substituent", "a cycloalkyl group having 3 to 12 carbon atoms that can have a substituent", "a straight-chain or branched alkoxy group having 1 to 20 carbon atoms that can have a substituent", "a cycloalkoxy group having 3 to 10 carbon atoms that can have a substituent", "a straight-chain or branched alkoxycarbonyl group having 1 to 18 carbon atoms that can have a substituent", "a mercapto group having 1 to 18 carbon atoms that can have a substituent", "an amino group having 1 to 20 carbon atoms that can have a substituent", "an aromatic hydrocarbon group having 6 to 36 carbon atoms that can have a substituent", or "a heterocyclic group having 5 to 36 cyclic atoms that can have a substituent", can be exemplified by R in general formula (1). 1 The same group as "a straight-chain or branched alkyl group that can have 1 to 18 carbon atoms and have substituents".

[0054] In general formula (1), R is preferred. 2 ~R 9 At least one of them is an aromatic hydrocarbon group having 6 to 36 carbon atoms capable of having a substituent, or an amino group having 1 to 20 carbon atoms capable of having a substituent. In general formula (1), R is more preferably preferred. 2 ~R 9 At least two of them are aromatic hydrocarbon groups with 6 to 36 carbon atoms that can have substituents or amino groups with 1 to 20 carbon atoms that can have substituents.

[0055] In general formula (1), R is more preferably preferred. 3 and R 8 These are, respectively, aromatic hydrocarbon groups with 6 to 36 carbon atoms that can have substituents, or amino groups with 1 to 20 carbon atoms that can have substituents, or R... 4 and R 7 These are either aromatic hydrocarbon groups with 6 to 36 carbon atoms that can have substituents, or amino groups with 1 to 20 carbon atoms that can have substituents. In this case, the remaining R is preferred. 2 R 4 ~R 7 and R 9 Or the remaining R 2 R 3 R 5 R 6 R 8 and R 9 It is a hydrogen atom.

[0056] In general formula (1), R is more preferably preferred. 3and R 8 These are either diphenylamino groups capable of having substituents, or aromatic hydrocarbon groups with 6 to 36 carbon atoms substituted by a carbazole group, or R... 4 and R 7 These are either diphenylamino groups capable of having substituents, or diphenylamino groups capable of having substituents, or aromatic hydrocarbon groups with 6 to 36 carbon atoms substituted by a carbazole group. In this case, the remaining R is preferred. 2 R 4 ~R 7 and R 9 Or the remaining R 2 R 3 R 5 R 6 R 8 and R 9 It is a hydrogen atom. In this case, R is preferred. 3 and R 8 Or R 4 and R 7 The number of carbon atoms in the whole containing the substituents is 50 or less, more preferably 40 or less, and even more preferably 30 or less.

[0057] 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, showing one example of possible isomers, and include all other isomers. Additionally, mixtures of two or more isomers may also be present.

[0058] [Chemistry 2]

[0059]

[0060] [Chemistry 3]

[0061]

[0062] [Chemistry 4]

[0063]

[0064] [Chemistry 5]

[0065]

[0066] [Chemistry 6]

[0067]

[0068] [Chemistry 7]

[0069]

[0070] [Chemistry 8]

[0071]

[0072] [Chemistry 9]

[0073]

[0074] The compounds of the present invention represented by the general formula (1) can be synthesized by methods known such as Japanese Patent Application 2018-135255. As an example, the synthesis of compound (A-1) will be described. Compound (A-1) can be obtained by introducing the corresponding substituent into 3,6-dibromocarbazole via a Suzuki-Miyaura coupling reaction or a Buchwald reaction, followed by a reaction of the corresponding sulfonyl lactone. Similarly, the compounds represented by the general formula (1) can be obtained by known methods using a halogenated carbazole derivative as a precursor.

[0075] As a purification method for the compounds represented by the general formula (1) of the present invention, purification can be carried out by column chromatography, adsorption purification based on silica gel, activated carbon, activated clay, etc., and solvent-based recrystallization or crystallization. Alternatively, it is effective to use compounds whose purity is improved by combining these methods. In addition, the identification of these compounds can be performed by nuclear magnetic resonance (NMR) analysis.

[0076] The compound represented by the general formula (1) of the present invention can be used as a hole transport material contained in the hole transport layer of organic electronic devices such as photoelectric conversion elements and organic EL elements.

[0077] The preferred embodiment of the photoelectric conversion element of the present invention will be described below.

[0078] <Photoelectric conversion element>

[0079] The photoelectric conversion element of the present invention, typically as shown in the schematic cross-sectional view of FIG1, 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.

[0080] In addition, to prevent the diffusion of dopants between the photoelectric conversion layer 3 and the hole transport layer 4, a multilayer structure with an inserted hole transport layer can also be constructed.

[0081] As shown in Figure 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. Furthermore, the photoelectric conversion element of the present invention is preferably used as a solar cell, and more preferably as a perovskite photoelectric conversion element, but is not limited thereto. In the present invention, the perovskite photoelectric conversion element preferably comprises, in sequence, 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. 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.

[0082] <Conductive support>

[0083] In the photoelectric conversion element of the present invention, the conductive support 1 shown in FIG1 needs to have light transmittance that allows light that facilitates photoelectric conversion to pass through. Furthermore, the conductive support is a component that functions to extract current from the photoelectric conversion layer; therefore, a conductive substrate is preferred. 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 and aluminum oxide (AZO), fluorine-doped tin oxide (FTO), indium oxide (In2O3), and indium-tin composite oxides; however, tin-doped indium oxide (ITO) and fluorine-doped tin oxide (FTO) are preferred.

[0084] <Electron transport layer>

[0085] In the photoelectric conversion element of the present invention, the electron transport layer 2 shown in FIG1 is a layer located between the conductive support 1 and the photoelectric conversion layer (perovskite layer) 3. Preferably, the electron transport layer 2 is formed on the conductive support 1, but is not particularly limited thereto. The electron transport layer is used to improve the efficiency of electron movement from the photoelectric conversion layer to the electrode and to block the movement of holes.

[0086] In this invention, specific examples of semiconductors forming 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 single-element semiconductors such as silicon and germanium. Preferably, one or more of these semiconductors are used. In this invention, one or more semiconductors selected from tin oxide, titanium oxide, and zinc oxide are preferred.

[0087] In this invention, the paste containing the semiconductor microparticles can be a commercially available product, or a paste (electron transport layer coating liquid) prepared by dispersing commercially available semiconductor microparticles in a solvent. Specific examples of solvents used in preparing the paste include water; alcohol-based solvents such as methanol, ethanol, and isopropanol; 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, but are not limited to these. Furthermore, these solvents can be used as one or a mixture of two or more solvents.

[0088] In this invention, as a method for dispersing semiconductor micropowder in a solvent, the powder can be ground using a mortar and pestle, or dispersed using a ball mill, paint conditioner, vertical bead mill, horizontal bead mill, grinder, or other dispersing machine. When preparing the paste, to prevent the agglomeration of semiconductor particles, it is preferable to add surfactants, and to increase viscosity, it is preferable to add thickeners such as polyethylene glycol.

[0089] In this invention, the electron transport layer can be obtained using known film-forming methods based on the material being formed. As a film-forming method for the electron transport layer, any coating method utilizing a coating solution can be used. Examples include wet coating methods such as spin coating, inkjet coating, doctor blade coating, drop casting, doctor blade coating, screen printing, reverse roller coating, gravure coating, kiss coating, roller brush coating, spray coating, air knife coating, wire rod coating, tube doctor blade coating, dip coating, or curtain coating, followed by firing to remove solvents or additives, sputtering, vapor deposition, electroplating, electrodeposition, microwave irradiation, etc., but not limited to these. In this invention, it is preferable to use an electron transport layer coating solution prepared by the aforementioned methods for film formation via spin coating, but this is not a limitation. Furthermore, the spin coating conditions can be appropriately set. The film-forming environment is not particularly limited and can be atmospheric.

[0090] Regarding the thickness of the electron transport layer, 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 generally preferably 5 nm to 100 nm, and more preferably 10 nm to 50 nm. In this invention, when a porous (mesoporous) metal oxide is used in addition to a dense layer, its thickness is generally preferably 20 nm to 200 nm or less, and more preferably 50 nm to 150 nm.

[0091] <Photoconversion layer>

[0092] In the photoelectric conversion element of the present invention, it is preferable to form a photoelectric conversion layer (perovskite layer) 3 on the electron transport layer 2 shown in FIG1.

[0093] In this invention, when used as a perovskite-type photoelectric conversion element, the perovskite material serving as the photoelectric conversion layer refers to a series of materials having a structure represented by the general formula ABX3. Here, A, B, and X represent organic cations or monovalent metal cations, metal cations, and halide anions, respectively. For example, A = K... + 、Rb + Cs + CH3NH3 + (Hereinafter, MA: methylammonium), NH=CHNH2 + (FA: formamidinium) CH3CH2NH3 + (Hereinafter, EA: ethylammonium); B = Pb, Sn; X = I - ,Br - Furthermore, the perovskite material can be specifically represented by any combination of MAPbI3, FAPbI3, EAPbI3, CsPbI3, MASnI3, FASnI3, EASnI3, MAPbBr3, FAPbBr3, EAPbBr3, MASnBr3, FASnBr3, and EASnBr3, as well as a layer of perovskite material containing mixed cations or mixed anions represented by any combination of (FAMA)Pb(IBr)3, K(FAMA)Pb(IBr)3, Rb(FAMA)Pb(IBr)3, and Cs(FAMA)Pb(IBr)3, but is not limited to these. It is preferred to use one or more of these perovskite materials. Additionally, light absorbers other than perovskite materials may also be included.

[0094] As a method for coating the photoelectric conversion layer (perovskite layer) of the photoelectric conversion element of the present invention with a coating liquid, any coating method can be used, and methods similar to those for forming electron transport layers can be cited.

[0095] The perovskite precursor can be a commercially available material. In this invention, it is preferred to use a precursor composed of lead halide, methylammonium halide, formamidinium halide, and cesium halide in any combination, but not limited thereto.

[0096] From the viewpoint of the solubility of the precursor, the solvent for the perovskite precursor solution of the present invention can include N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone, etc., but is not limited to these. Furthermore, one or more of these solvents can be used, and a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide is preferred.

[0097] In this invention, the environment during the film formation of the photoelectric conversion layer (perovskite layer) is preferably in a dry environment, and more preferably in a dry, inert gas environment such as a glove box, from the viewpoint of reproducing high-efficiency perovskite solar cells by preventing the introduction of moisture. Furthermore, it is preferable to use a solvent with low water content by dehydration using molecular sieves or the like.

[0098] In this invention, from the viewpoint of generating perovskite material from a precursor, the temperature at which the photoelectric conversion layer (perovskite layer) is heated by a hot plate or the like is preferably 50°C to 200°C, and more preferably 70°C to 150°C. Furthermore, the heating time is preferably about 10 to 90 minutes, and more preferably about 10 to 60 minutes.

[0099] Regarding the thickness of the photoelectric conversion layer (perovskite layer) of the present invention, from the viewpoint of further suppressing performance degradation caused by defects or peeling, and in order to ensure that the photoelectric conversion layer has sufficient light absorption while preventing the element resistance from becoming too high, it is preferably 50 nm to 1000 nm, and more preferably 300 nm to 700 nm.

[0100] Hole transport layer

[0101] In the photoelectric conversion element of the present invention, the hole transport layer 4 shown in FIG1 is a layer that functions to transport 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 the movement of electrons. For example, a conductor, semiconductor, or organic hole transport material can be used in the hole transport layer to further improve the hole transport characteristics, and additives may also be included. It is desirable to reduce the amount of additives used in the hole transport layer, and the photoelectric conversion element of the present invention exhibits high performance even without the additives in the hole transport layer.

[0102] 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. In the hole transport layer of the present invention, one or more compounds represented by the general formula (1) may be used, or other hole transport materials not belonging to the present invention may be used. For the purpose of preventing dopant diffusion between the photoelectric conversion layer and the hole transport layer, even in the case of constructing a multilayer structure using an intercalated hole transport layer (hereinafter also referred to as an intermediate layer), the intermediate layer may contain a compound represented by the general formula (1), or a hole transport material not belonging to the present invention may be used as the hole transport layer.

[0103] Specific examples of hole transport materials that are not part of the hole transport materials 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 oxide metals can be mixed in the hole transport layer or stacked on top of the hole transport material. Examples of organic hole transport materials include, for example, polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyethylene dioxythiophene (PEDOT); fluorene derivatives such as 2,2',7,7'-tetra-(N,N-di-p-methoxyaniline)-9,9'-spirodifluorene (Spiro-OMe TAD); 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.

[0104] As a method for coating the hole transport layer of the photoelectric conversion element of the present invention with a coating liquid, any coating method can be used, and methods similar to those for forming electron transport layers can be cited.

[0105] In this invention, during film formation, the solvent used for the coating liquid in the hole transport layer can include aromatic organic solvents such as benzene, toluene, xylene, mesitylene, tetrahydronaphthalene (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, and nitrobenzene; halogenated alkyl organic solvents such as dichloromethane, trichloromethane, 1,2-dichloroethane, 1,1,2-trichloroethane, and dichloromethane; and benzene. Nitrile solvents such as nitrile and acetonitrile; ether solvents such as tetrahydrofuran, dioxane, diisopropyl ether, C-pentylmethyl 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, etc., but not limited to these. Furthermore, one or more of the above solvents can be used, and the solvent used can be selected according to the structure. In particular, aromatic organic solvents and halogenated alkyl organic solvents are preferred.

[0106] In this invention, regarding the thickness of the hole transport layer, from the viewpoint of further improving photoelectric conversion efficiency, it is preferably 5 nm to 500 nm, and more preferably 10 nm to 250 nm. To prevent dopant diffusion between the photoelectric conversion layer 4 and the hole transport layer 5, even when the hole transport layer is configured as a multilayer structure with an inserted hole transport layer, the total film thickness is preferably the same.

[0107] In this invention, regarding the environment during the fabrication of the hole transport layer, from the viewpoint of reproducing high-efficiency perovskite solar cells by preventing the incorporation of moisture, a dry environment is preferred. Furthermore, a dehydrated solvent with a moisture content of 10 ppm or less is preferably used.

[0108] <additive>

[0109] In this invention, the additive used as the hole transport layer may contain a dopant (or oxidant) or an alkaline compound (or alkaline additive). The presence of the additive in the hole transport layer increases the carrier concentration of the hole transport material (doping), leading to improved conversion efficiency of the photoelectric conversion element. In this invention, when the hole transport layer contains both a dopant and an alkaline additive, the amount of additive is preferably 3.5 equivalents or less relative to 1 equivalent of the hole transport material. On the other hand, the use of both dopant and alkaline additives raises concerns about increased manufacturing complexity, higher costs, reduced durability, and shortened lifespan of the photoelectric conversion element. Therefore, reducing the amount used is desirable; however, the photoelectric conversion element of this invention exhibits high performance even without the additive.

[0110] In this invention, when a dopant is included, specific examples of dopant include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), silver bis(trifluoromethanesulfonyl)imide, tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III)tris[bis(trifluoromethanesulfonyl)imide](FK209), NOSbF6, SbCl5, SbF5, etc. In this invention, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is preferred, but it is not limited thereto.

[0111] In this invention, when a dopant is used, it is preferably 2.0 equivalents or less, and more preferably 0.5 equivalents or less, relative to the amount of hole transport material contained in the hole transport layer.

[0112] Furthermore, in this invention, a basic compound (basic additive) may be included as an additive for the hole transport layer. Specific examples of basic compounds included in this invention are 4-tert-butylpyridine (tBP), 2-methylpyridine, and 2,6-dimethylpyridine. Basic compounds are mostly used in conjunction with dopants. Even in this invention, it is desirable to use them in conjunction with dopants, and tert-butylpyridine is preferred.

[0113] In this invention, when using an alkaline compound, the amount is preferably 5 equivalents or less, and more preferably 3 equivalents or less, relative to 1 equivalent of the hole transport material of this invention.

[0114] <Counter electrode>

[0115] In this invention, the counter electrode 5 shown in FIG1 can exchange charge with the hole transport layer by being disposed opposite to the conductive support 1 and formed on the hole transport layer 4. In the photoelectric conversion element of this invention, it is preferable to have a metal electrode as the counter electrode on the hole transport layer 4; however, an electron blocking layer made of organic material or inorganic compound semiconductor may also be added between the hole transport layer 4 and the counter electrode 5.

[0116] In this invention, specific materials used for the counter electrode include platinum, titanium, stainless steel, aluminum, gold, silver, nickel, magnesium, chromium, cobalt, copper, and other metals or alloys thereof. Among these, gold, silver, or silver alloys are preferred for exhibiting high conductivity even in the thin film. Furthermore, as a silver alloy, to improve the stability of the thin film by reducing sulphurization or chlorination, alloys of silver and gold, silver and copper, silver and palladium, silver, copper, and palladium, and silver and platinum are examples of such alloys.

[0117] In this invention, the counter electrode is preferably made of a material that can be formed by methods such as vapor deposition.

[0118] When a metal electrode is used as the counter electrode, in order to obtain good conductivity, the film thickness is preferably 10 nm or more, and more preferably 50 nm or more.

[0119] In the photoelectric conversion element of the present invention, the conductive support body serves as the cathode, and the counter electrode serves as the anode. Sunlight or other light preferably irradiates from the conductive support side. Upon irradiation by sunlight or other light, the photoelectric conversion layer (perovskite layer) absorbs the light and becomes excited, generating electrons and holes. These electrons move towards the electrode via the electron transport layer, and the holes move via the hole transport layer, thereby allowing current to flow and enabling the element to function as a photoelectric conversion element.

[0120] When evaluating the performance (characteristics) of the photoelectric conversion element of the present invention, short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency are measured. Short-circuit current density represents the current flowing between the two terminals per 1 cm when the output terminals are short-circuited. 2 The current and open-circuit voltage represent the voltage between the two terminals when the output terminals are open. Additionally, 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 internal resistance. The photoelectric conversion efficiency is calculated by dividing the maximum output (W) by the product of the short-circuit current density and the open-circuit voltage per 1cm². 2 The value of light intensity (W) is obtained by multiplying it by 100 and expressing it as a percentage.

[0121] The photoelectric conversion element of the present invention can be applied to perovskite solar cells or various photosensors. The perovskite solar cell of the present invention is obtained by modularizing the photoelectric conversion element, which contains a hole transport material containing a compound represented by the general formula (1) as a hole transport layer, by arranging the required number of units, and by setting a predetermined electrical wiring.

[0122] The preferred embodiments have been described above, but the present invention is not limited thereto, and appropriate modifications can be made without departing from the scope of the present invention.

[0123] Example

[0124] The present invention will be specifically described below through examples, but the present invention is not limited to the following examples. Furthermore, the compounds obtained in the synthetic examples were identified through… 1 The 1H-NMR (1H-NMR (Nuclear Magnetic Resonance Device manufactured by NEC Corporation, JNM-ECZ400S / L1 type)) was performed.

[0125] [Synthetic Example 1] Synthesis of Compound (A-1)

[0126] 3,6-Dibromocarbazole (0.65 g, TCI), [4-[bis(4-methoxyphenyl)amino]phenyl]boronic acid (1.68 g, TCI), 2M potassium carbonate aqueous solution (10 mL), tetra(triphenylphosphine)palladium (0.06 g, Kanto Chemical), and THF (30 mL) were added to the reaction vessel and degassed under reduced pressure. The mixture was heated under reflux for 6 hours. After the reaction was completed, the reaction solution was transferred to a beaker containing water (150 mL). Toluene (30 mL) was added to the solution, and the mixture was separated. The organic layer was dried with magnesium sulfate and then concentrated. The crude product was purified by silica gel column chromatography (toluene:ethyl acetate = 50:1 (v / v)) to give the compound represented by the following formula (2) as a white solid (yield: 0.85 g, 55%).

[0127] 1 H-NMR (400MHz, THF-d8): δ (ppm) = 3.73 (12H), 6.81 (8H), 6.96 (4H), 7.01 (8H), 7.40 (2H), 7.51 (4H), 7.56 (2H), 8.30 (2H), 10.3 (1H).

[0128] [Chemistry 10]

[0129]

[0130] The compound of formula (2) above (0.40 g), sodium hydride (0.03 g, manufactured by Kanto Chemical Co., Ltd.), and THF (15 mL) were added to the reaction vessel and stirred at room temperature for 3 hours. 2,4-Butanesulfonyl lactone (0.08 mL, manufactured by TCI) was added, and the mixture was heated under reflux for 4 hours. The reaction solution was concentrated, dissolved in toluene (60 mL), filtered, and the filtrate was concentrated. After purification of the crude product by silica gel column chromatography (ethyl acetate), recrystallization (acetone: methanol) yielded the compound represented by formula (A-1) as a pale green solid (yield: 0.40 g, 86%).

[0131] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.76 (1H), 2.22 (1H), 2.47 (1H), 3. 73(12H), 4.57(2H), 6.88-6.95(12H), 7.04(8H), 7.63(4H), 7.70(4H), 8.48(2H)

[0132] [Chemistry 11]

[0133]

[0134] [Synthetic Example 2] Synthesis of Compound (A-2)

[0135] The compound of formula (2) above (0.20 g), potassium tert-butoxide (0.06 g, manufactured by Kanto Chemical Co., Ltd.), and THF (7 mL) were added to a reaction vessel and stirred at room temperature for 3 hours. 2,4-Butanesulfonyl lactone (0.04 mL, manufactured by TCI) was added, and the mixture was heated under reflux for 4 hours. The reaction solution was concentrated, dissolved in toluene (30 mL), filtered, and the filtrate was concentrated. The crude product was recrystallized (acetone: methanol) to obtain the compound represented by formula (A-2) as a milky white solid (yield: 0.15 g, 60%).

[0136] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.76 (1H), 2.22 (1H), 2.40 (1H), 3. 75(12H), 4.58(2H), 6.89-6.95(12H), 7.05(8H), 7.63(4H), 7.70(4H), 8.47(2H)

[0137] [Chemistry 12]

[0138]

[0139] [Synthetic Example 3] Synthesis of Compound (A-3)

[0140] The compound of formula (2) above (0.20 g), cesium carbonate (0.19 g, manufactured by Kanto Chemical Co., Ltd.), and THF (7 mL) were added to a reaction vessel and stirred at room temperature for 3 hours. 2,4-Butanesulfonyl lactone (0.04 mL, manufactured by TCI) was added, and the mixture was heated under reflux for 4 hours. The reaction solution was filtered, washed with THF (20 mL), and concentrated. It was dissolved in methanol, filtered, and the filtrate was concentrated. The crude product was recrystallized (acetone: ethanol) to give the compound represented by formula (A-3) as a pale green solid (yield: 0.09 g, 33%).

[0141] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.15 (3H), 1.32 (1H), 1.87 (1H), 2.32 (1H), 3. 77(12H), 4.57(2H), 6.88-6.95(12H), 7.03(8H), 7.63(4H), 7.69(4H), 8.46(2H)

[0142] [Chemistry 13]

[0143]

[0144] [Synthetic Example 4] Synthesis of Compound (A-4)

[0145] The compound of formula (2) above (0.20 g), rubidium carbonate (0.13 g, manufactured by Kanto Chemical Co., Ltd.), and THF (7 mL) were added to a reaction vessel and stirred at room temperature for 3 hours. 2,4-Butanesulfonyl lactone (0.04 mL, manufactured by TCI) was added, and the mixture was heated under reflux for 4 hours. The reaction solution was filtered, washed with THF (20 mL), and concentrated. It was dissolved in methanol, filtered, and the filtrate was concentrated. The crude product was recrystallized (acetone: ethanol) to give the compound represented by formula (A-4) as a pale green solid (yield: 0.07 g, 27%).

[0146] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.44 (1H), 2.15 (1H), 2.33 (1H), 3. 73(12H), 4.57(2H), 6.88-6.95(12H), 7.04(8H), 7.63(4H), 7.70(4H), 8.47(2H)

[0147] [Chemistry 14]

[0148]

[0149] [Synthetic Example 5] Synthesis of Compound (A-5)

[0150] Except for changing the compound represented by formula (2) above to the compound represented by formula (3) below, the compound represented by formula (A-5) below was obtained as a pale green solid (yield: 0.25 g, yield: 81%) by the same method as in synthesis example 1.

[0151] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.79 (1H), 2.23 (1H), 2.46 (1H) ,3.65(12H),4.57(2H),6.81(8H),6.85(8H),7.10(2H),7.50(2H),7.79(2H)

[0152] [Chemistry 15]

[0153]

[0154] [Synthetic Example 6] Synthesis of Compound (A-6)

[0155] Except for changing the compound represented by formula (2) above to the compound represented by formula (3) above, the compound represented by formula (A-6) below was obtained as a milky white solid (yield: 0.13 g, yield: 63%) by the same method as in synthesis example 2.

[0156] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.79 (1H), 2.23 (1H), 2.40 (1H) ,3.63(12H),4.57(2H),6.81(8H),6.85(8H),7.10(2H),7.50(2H),7.78(2H)

[0157] [Chemistry 16]

[0158]

[0159] [Synthetic Example 7] Synthesis of Compound (A-7)

[0160] Except for changing the compound represented by formula (2) above to the compound represented by formula (3) above, the compound represented by formula (A-7) below was obtained in the form of a pale green solid (yield: 0.09 g, yield: 39%) by the same method as in synthesis example 3.

[0161] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.17 (3H), 1.35 (1H), 1.88 (1H), 2.32 (1H) ,3.65(12H),4.57(2H),6.81(8H),6.85(8H),7.09(2H),7.49(2H),7.77(2H)

[0162] [Chemistry 17]

[0163]

[0164] [Synthetic Example 8] Synthesis of Compound (A-8)

[0165] Except for changing the compound represented by formula (2) above to the compound represented by formula (3) above, the compound represented by formula (A-8) below was obtained in the form of a pale green solid (yield: 0.06 g, yield: 28%) by the same method as in synthesis example 4.

[0166] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.48 (1H), 2.18 (1H), 2.33 (1H) ,3.65(12H),4.57(2H),6.81(8H),6.85(8H),7.10(2H),7.50(2H),7.79(2H)

[0167] [Chemistry 18]

[0168]

[0169] [Synthetic Example 9] Synthesis of Compound (A-23)

[0170] Except for changing the compound represented by formula (2) above to the compound represented by formula (4) below, the compound represented by formula (A-23) below was obtained in the form of a pale green solid (yield: 0.38 g, yield: 81%) by the same method as in synthesis example 1.

[0171] 1H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.76 (1H), 2.22 (1H), 2.47 (1H), 3.73 (1 2H), 4.57(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0172] [Chemistry 19]

[0173]

[0174] [Synthetic Example 10] Synthesis of Compound (A-24)

[0175] Except for changing the compound represented by formula (2) above to the compound represented by formula (4) above, the compound represented by formula (A-24) below was obtained as a milky white solid (yield: 0.16 g, yield: 65%) by the same method as in synthesis example 2.

[0176] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.76 (1H), 2.22 (1H), 2.40 (1H), 3.75 (1 2H), 4.58(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0177] [Chemistry 20]

[0178]

[0179] [Synthetic Example 11] Synthesis of Compound (A-25)

[0180] Except for changing the compound represented by formula (2) above to the compound represented by formula (4) above, the compound represented by formula (A-25) below was obtained in the form of a pale green solid (yield: 0.11 g, yield: 40%) by the same method as in synthesis example 3.

[0181] 1H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.76 (1H), 2.22 (1H), 2.40 (1H), 3.75 (1 2H), 4.58(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0182] [Chemistry 21]

[0183]

[0184] [Synthetic Example 12] Synthesis of Compound (A-26)

[0185] Except for changing the compound represented by formula (2) above to the compound represented by formula (4) above, the compound represented by formula (A-26) below was obtained in the form of a pale green solid (yield: 0.08 g, yield: 31%) by the same method as in synthesis example 4.

[0186] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.76 (1H), 2.22 (1H), 2.40 (1H), 3.75 (1 2H), 4.58(2H), 6.88-6.95(12H), 7.00(8H), 7.49(2H), 7.60(4H), 7.85(2H), 7.96(2H)

[0187] [Chemistry 22]

[0188]

[0189] [Synthetic Example 13] Synthesis of Compound (A-27)

[0190] Except for changing the compound represented by formula (2) above to the compound represented by formula (5) below, the compound represented by formula (A-27) below was obtained in the form of a pale green solid (yield: 0.28 g, yield: 72%) by the same method as in synthesis example 1.

[0191] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.79 (1H), 2.23 (1H), 2.46 (1H) ,3.65(12H),4.57(2H),6.84(8H),6.89(8H),6.95(2H),7.20(2H),7.25(2H)

[0192] [Chemistry 23]

[0193]

[0194] [Synthetic Example 14] Synthesis of Compound (A-28)

[0195] Except for changing the compound represented by formula (2) above to the compound represented by formula (5) above, the compound represented by formula (A-28) below was obtained as a milky white solid (yield: 0.12 g, yield: 58%) by the same method as in synthesis example 2.

[0196] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.79 (1H), 2.23 (1H), 2.40 (1H) ,3.63(12H),4.57(2H),6.84(8H),6.89(8H),6.95(2H),7.20(2H),7.25(2H)

[0197] [Chemistry 24]

[0198]

[0199] [Synthetic Example 15] Synthesis of Compound (A-29)

[0200] Except for changing the compound represented by formula (2) above to the compound represented by formula (5) above, the compound represented by formula (A-29) below was obtained in the form of a pale green solid (yield: 0.06 g, yield: 26%) by the same method as in synthesis example 3.

[0201] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.17 (3H), 1.35 (1H), 1.88 (1H), 2.32 (1H) ,3.65(12H),4.57(2H),6.84(8H),6.89(8H),6.95(2H),7.20(2H),7.25(2H)

[0202] [Chemistry 25]

[0203]

[0204] [Synthetic Example 16] Synthesis of Compound (A-30)

[0205] Except for changing the compound represented by formula (2) above to the compound represented by formula (5) above, the compound represented by formula (A-30) below was obtained in the form of a pale green solid (yield: 0.07 g, yield: 32%) by the same method as in synthesis example 4.

[0206] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.48 (1H), 2.18 (1H), 2.33 (1H) ,3.65(12H),4.57(2H),6.84(8H),6.89(8H),6.95(2H),7.20(2H),7.25(2H)

[0207] [Chemistry 26]

[0208]

[0209] [Synthetic Example 17] Synthesis of Compound (A-73)

[0210] Except for changing the compound represented by formula (2) above to the compound represented by formula (6) below, the compound represented by formula (A-73) below was obtained in the form of a pale green solid (yield: 0.29 g, yield: 79%) by the same method as in synthesis example 1.

[0211] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.84 (1H), 2.28 (1H), 2.53 (1H), 3.70 (24H), 4.67 (2H) , 6.83(16H), 6.89(16H), 7.12(4H), 7.40(4H), 7.73(6H), 7.75(2H), 7.94(2H), 8.10(6H), 8.79(2H)

[0212] [Chemistry 27]

[0213]

[0214] [Synthetic Example 18] Synthesis of Compound (A-74)

[0215] Except for changing the compound represented by formula (2) above to the compound represented by formula (6) above, the compound represented by formula (A-74) below was obtained in the form of a pale green solid (yield: 0.22 g, yield: 56%) by the same method as in synthesis example 3.

[0216] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.84 (1H), 2.28 (1H), 2.53 (1H), 3.70 (24H), 4.67 (2H) , 6.83(16H), 6.90(16H), 7.11(4H), 7.40(4H), 7.73(6H), 7.75(2H), 7.94(2H), 8.10(6H), 8.79(2H)

[0217] [Chemistry 28]

[0218]

[0219] [Synthetic Example 19] Synthesis of Compound (A-75)

[0220] Except for changing the compound represented by formula (2) above to the compound represented by formula (7) below, the compound represented by formula (A-75) was obtained as a pale green solid (yield: 0.21 g, yield: 48%) by the same method as in synthesis example 1.

[0221] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.18 (3H), 1.89 (1H), 2.31 (1H), 2.56 (1H), 3.70 (24H), 4.8 1(2H), 6.84(16H), 6.90(16H), 7.12(4H), 7.42(4H), 7.62(2H), 7.74(8H), 8.17(6H), 8.31(2H)

[0222] [Chemistry 29]

[0223]

[0224] [Synthetic Example 20] Synthesis of Compound (A-76)

[0225] Except for changing the compound represented by formula (2) above to the compound represented by formula (7) above, the compound represented by formula (A-76) below was obtained in the form of a pale green solid (yield: 0.22 g, yield: 60%) by the same method as in synthesis example 3.

[0226] 1H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.19 (3H), 1.89 (1H), 2.30 (1H), 2.53 (1H), 3.73 (24H), 4.8 1(2H), 6.82(16H), 6.90(16H), 7.11(4H), 7.41(4H), 7.63(2H), 7.73(8H), 8.15(6H), 8.28(2H)

[0227] [Chemistry 30]

[0228]

[0229] [Comparative Compound 1] Synthesis of Compound (B-1)

[0230] The compound represented by the above formula (A-1) (0.10 g) was given as a green solid (yield: 0.07 g, yield: 71%) by an ion exchange reaction based on an ion exchange resin (manufactured by Sigma-Aldrich) to give the compound represented by the following formula (B-1).

[0231] 1 H-NMR (400MHz, DMSO-d6): δ (ppm) = 1.16 (3H), 1.76 (1H), 2.22 (1H), 3.73 (1 2H), 4.57(2H), 6.88-6.95(12H), 7.04(8H), 7.63(4H), 7.70(4H), 8.48(2H)

[0232] [Chemistry 31]

[0233]

[0234] [Example 1] Fabrication of photoelectric conversion element and evaluation of photoelectric conversion characteristics

[0235] The glass substrate (conductive support 1, manufactured by Solarionix) that has been etched and coated with a fluorine-doped tin oxide (FTO) film was ultrasonically cleaned with isopropanol and then subjected to UV ozone treatment.

[0236] A 15% aqueous colloidal dispersion of tin(IV) oxide (manufactured by Alfa Aesar) and purified water in a volume ratio of 1:3 were spin-coated onto the substrate. Subsequently, a tin oxide layer (electron transport layer 2) with a thickness of approximately 40 nm was formed by heating at 150°C for 30 minutes using a hot plate.

[0237] In a glove box under nitrogen flow, formamidinium hydroiodate (1M, manufactured by Tokyo Chemical Company), lead(II) iodide (1.1M, manufactured by Tokyo Chemical Company), methylamine hydrobromide (0.2M, manufactured by Tokyo Chemical Company), and lead(II) bromide (0.2M, manufactured by Tokyo Chemical Company) 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 Company) was added to prepare a perovskite precursor solution, such that the amount of cesium added was 5% by composition.

[0238] In a glove box under nitrogen conditions, a prepared perovskite precursor solution was dropped onto a tin oxide layer and spin-coated. A perovskite precursor film was then formed by dropping 0.3 mL of chlorobenzene during the spin-coating process. 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.

[0239] In a glove box under nitrogen flow, compound (A-1), the hole transport material obtained in Example 1, was dissolved in chlorobenzene at 50 mM and used as a coating solution for the hole transport layer. In a glove box under nitrogen environment, the coating solution for the hole transport layer was spin-coated onto a Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) to form a hole transport layer 4 with a film thickness of approximately 200 nm.

[0240] On hole transport layer 4, vacuum evaporation is performed at a vacuum level of 1×10⁻⁶. -4 Gold is filmed at a thickness of 80 nm to 100 nm at approximately 100 nm to form a gold electrode (counter electrode 5) and a photoelectric conversion element is fabricated.

[0241] Simulated sunlight (AM1.5, 100mW / cm²) generated by a white light irradiation device (OTENTO-SUN SH type, manufactured by Spectrometer Co., Ltd.) is irradiated from the conductive support 1 side of the photoelectric conversion element. 2 The current-voltage characteristics were measured using a digital source meter (KEITHLEY, Model 2400 Series SourceMeter), from which the photoelectric conversion efficiency was obtained. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0242] [Comparative Example 1]

[0243] A chlorobenzene solution containing 25 mM lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, 0.5 equivalent) as a dopant and 150 mM 4-tert-butylpyridine as an additive basic compound was prepared as the doping solution. A 50 mM chlorobenzene solution was prepared using the prepared doping solution and Spiro-OMe TAD (Sigma-Aldrich), a standard hole transport material represented by the following formula (B-2), as the coating solution for the hole transport layer. A photoelectric conversion element was prepared in the same manner as in Example 1, except that the hole transport layer coating solution was used, and the current-voltage characteristics were measured to obtain the photoelectric conversion efficiency. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0244] [Chemistry 32]

[0245]

[0246] [Comparative Example 2]

[0247] Except for using the non-salt-forming compound with a sulfonic acid group represented by formula (B-1) above as the hole transport material, the photoelectric conversion element was prepared in the same manner as in Example 1, and the current-voltage characteristics were measured to obtain the photoelectric conversion efficiency. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0248] [Table 1]

[0249]

[0250] The results in Table 1 show that a photoelectric conversion element with higher performance than that using a compound (B-1) containing both dopants and basic additives can be prepared by using a hole transport layer containing the compound of the present invention without using dopants or basic additives. Therefore, the photoelectric conversion element containing the compound of the present invention can reduce manufacturing costs by eliminating the need for additives and can be prepared using a simple process that requires no additives. Furthermore, it was determined that a photoelectric conversion element with higher performance than that using a compound (B-2) which is a hole transport material that does not form salts and has sulfonic acid groups can be prepared by using a hole transport layer containing the compound of the present invention. Therefore, it can be seen that hole transport materials that form salts exhibit superior performance as photoelectric conversion elements compared to hole transport materials that do not form salts.

[0251] [Example 2] Fabrication of photoelectric conversion element and evaluation of its current-voltage characteristics

[0252] The glass with a FLAT ITO film (conductive support 1, manufactured by GEOMATEC) was ultrasonically cleaned with isopropanol and then subjected to UV ozone treatment.

[0253] A 15% aqueous colloidal dispersion of tin(IV) oxide (manufactured by Alfa Aesar) and purified water in a volume ratio of 1:9 were spin-coated onto the ITO film (coating solution for the electron transport layer). Subsequently, a tin oxide layer (electron transport layer 2) with a thickness of approximately 20 nm was formed by heating at 150°C for 30 minutes using a hot plate.

[0254] In a glove box under nitrogen flow, formamidinium hydroiodate (1M, manufactured by Tokyo Chemical Industries), lead(II) iodide (1.1M, manufactured by Tokyo Chemical Industries), methylamine hydrobromide (0.2M, manufactured by Tokyo Chemical Industries), and lead(II) bromide (0.2M, manufactured by Tokyo Chemical Industries) 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 Industries) was added to prepare a perovskite precursor solution, such that the amount of cesium added was 5% by composition.

[0255] In a glove box under nitrogen conditions, a prepared perovskite precursor solution was dropped onto a tin oxide layer and spin-coated. The perovskite precursor film was prepared by dropping 0.3 mL of chlorobenzene during the spin-coating process. 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.

[0256] In a glove box under nitrogen flow, the compound (A-5) obtained in Example 5 as a hole transport material was dissolved in chlorobenzene at 50 mM and used as a coating solution for the hole transport layer.

[0257] In a glove box under nitrogen environment, a hole transport layer coating solution was spin-coated onto a Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) to form a hole transport layer 4 with a film thickness of about 200 nm.

[0258] On the hole transport layer, vacuum evaporation is performed at a vacuum level of 1×10⁻⁶. -4 Gold is deposited at a thickness of about 80 nm to form a gold electrode (counter electrode 5), thereby preparing a photoelectric conversion element.

[0259] Simulated sunlight (AM1.5, 100mW / cm²) generated by a white light irradiation device (OTENTO-SUN SH type, manufactured by Spectrometer Co., Ltd.) is irradiated from the conductive support side of the photoelectric conversion element. 2 The initial photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics using a digital source meter (KEITHLEY, Model 2400 Series SourceMeter).

[0260] After measuring the current-voltage characteristics, the photoelectric conversion element was stored in a desiccator containing silica gel for 28 days. The current-voltage characteristics were then measured again under simulated sunlight irradiation to obtain the photoelectric conversion efficiency after 28 days. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 2.

[0261] The rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days, calculated using the following formula (a-1), is shown in Table 2.

[0262] [Mathematical Expression 1]

[0263]

[0264] [Example 3]

[0265] Except that compound (A-5) was dissolved in chlorobenzene instead of compound (A-7) to achieve a concentration of 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 2, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 2. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated using the above formula (a-1) is shown in Table 2.

[0266] [Example 4]

[0267] Except that compound (A-5) was dissolved in chlorobenzene instead of compound (A-73) to achieve a concentration of 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 2, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 2. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated using the above formula (a-1) is shown in Table 2.

[0268] [Example 5]

[0269] Except that compound (A-5) was dissolved in chlorobenzene instead of compound (A-74) to achieve a concentration of 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 2, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 2. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated using the above formula (a-1) is shown in Table 2.

[0270] [Example 6]

[0271] Except that compound (A-5) was used instead of compound (A-5) to dissolve in chlorobenzene at 120°C to achieve 30 mM, the photoelectric conversion element was prepared in the same manner as in Example 2, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 2. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated using the above formula (a-1) is shown in Table 2.

[0272] [Example 7]

[0273] Except that compound (A-5) was used instead of compound (A-5) to dissolve in chlorobenzene at 120°C to achieve 30 mM, the photoelectric conversion element was prepared in the same manner as in Example 2, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 2. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated using the above formula (a-1) is shown in Table 2.

[0274] [Comparative Example 3]

[0275] In a glove box under nitrogen flow, 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide were dissolved in chlorobenzene as dopants. Spiro-OMe TAD (manufactured by Sigma-Aldrich), a standard hole transport material represented by formula (B-2) above, was dissolved at 50 mM in this chlorobenzene solution to prepare a coating solution for the hole transport layer, with 3 equivalents of 4-tert-butylpyridine and 0.5 equivalents of lithium bis(trifluoromethanesulfonyl)imide relative to (B-2). The photoelectric conversion element was prepared in the same manner as in Example 2, except as described above, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiency after 28 days is shown in Tables 2 and 3. Furthermore, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated using formula (a-1) above is shown in Tables 2 and 3.

[0276] [Table 2]

[0277]

[0278] As can be seen from the results in Table 2, compared with the photoelectric conversion device using compound (B-2) as the standard hole transport material, the photoelectric conversion device using compounds (A-5), (A-7), (A-27), (A-29), (A-73), and (A-74) of the present invention as hole transport materials exhibits sufficient photoelectric conversion efficiency and less degradation of device characteristics, even when the hole transport layer does not contain dopants.

[0279] [Example 8]

[0280] In a glove box under nitrogen flow, 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide were dissolved in chlorobenzene as dopants. Compound (A-5), the hole transport material obtained in Example 5, was synthesized by dissolving it in this chlorobenzene solution at 50 mM. A coating solution was prepared with 3 equivalents of 4-tert-butylpyridine and 0.5 equivalents of lithium bis(trifluoromethanesulfonyl)imide relative to (A-5) as the hole transport layer coating solution. Photoelectric conversion elements were prepared in the same manner as in Example 2, except as described above, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 2. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 3. Furthermore, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days, calculated using the above formula (a-1), is shown in Table 3.

[0281] [Example 9]

[0282] Except that compound (A-5) was used instead of compound (A-5) dissolved in the chlorobenzene solution of the above-mentioned dopant to achieve 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 8, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The photoelectric conversion efficiency after 28 days is shown in Table 3. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated by the above formula (a-1) is shown in Table 3.

[0283] [Example 10]

[0284] Except that compound (A-5) was dissolved in the chlorobenzene solution of the above-mentioned dopant to achieve 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 8, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The photoelectric conversion efficiency after 28 days is shown in Table 3. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated by the above formula (a-1) is shown in Table 3.

[0285] [Example 11]

[0286] Except that compound (A-5) was dissolved in the chlorobenzene solution of the above-mentioned dopant at 60°C with compound (A-27) to achieve 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 8, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiency after 28 days is shown in Table 3. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated by the above formula (a-1) is shown in Table 3.

[0287] [Example 12]

[0288] Except that compound (A-5) was used instead of compound (A-5) dissolved in the chlorobenzene solution of the above-mentioned dopant to achieve 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 8, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 3. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated by the above formula (a-1) is shown in Table 3.

[0289] [Example 13]

[0290] Except that compound (A-5) was used instead of compound (A-5) dissolved in the chlorobenzene solution of the above-mentioned dopant to achieve 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 8, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 3. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated by the above formula (a-1) is shown in Table 3.

[0291] [Example 14]

[0292] Except that compound (A-5) was dissolved in the chlorobenzene solution of the above-mentioned dopant to achieve 50 mM, the photoelectric conversion element was prepared in the same manner as in Example 8, and the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days were obtained in the same manner as in Example 8. The obtained photoelectric conversion efficiencies after 28 days are shown in Table 3. In addition, the rate of change (%) of the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 28 days calculated by the above formula (a-1) is shown in Table 3.

[0293] [Table 3]

[0294]

[0295] As can be seen from the results in Table 3, compared with the photoelectric conversion element using compound (B-2) as the standard hole transport material, the photoelectric conversion elements using compounds (A-5), (A-27), (A-29), (A-73), (A-74), (A-75), and (A-76) of the present invention as hole transport materials exhibit sufficient photoelectric conversion efficiency, and their characteristics are not degraded even when the hole transport layer does not contain dopants.

[0296] The present invention will be described in detail with reference to specific methods, but various changes and modifications can be made without departing from the concept and scope of the present invention, which will be obvious to those skilled in the art.

[0297] Furthermore, this application is based on Japanese Patent Application No. 2021-057864, filed on March 30, 2021, the entire contents of which are incorporated herein by reference. All references cited herein are also incorporated in their entirety into this description.

[0298] The sulfonate-based compounds of the present invention are useful as photoelectric conversion elements with good photoelectric conversion efficiency by using the compounds as hole transport layers. They can provide clean energy as solar cells that can efficiently convert solar energy into electrical energy, and can also be applied to other organic EL or image sensors, etc.

[0299] (Explanation of reference numerals in the attached diagram)

[0300] 1: Conductive support

[0301] 2: Electron transport layer

[0302] 3: Photoelectric conversion layer

[0303] 4: Hole transport layer

[0304] 5: Counter electrode

Claims

1. A compound represented by the following general formula (1), [Chemical 1] In the formula, R 1 It is a straight-chain or branched alkyl group with 1 to 18 carbon atoms that can have substituents, where X represents a sodium ion or a cesium ion, and R... 3 and R 8 These are either diphenylamino groups capable of having substituents, or aromatic hydrocarbon groups with 6 to 36 carbon atoms substituted by diphenylamino or carbazole groups capable of having substituents, or R 4 and R 7 These are either diphenylamino groups capable of having substituents, or aromatic hydrocarbon groups with 6 to 36 carbon atoms substituted by diphenylamino or carbazole groups capable of having substituents. In this case, the remaining R... 2 R 4 ~R 7 and R 9 It is a hydrogen atom, or the remaining R. 2 R 3 R 5 R 6 R 8 and R 9 It is a hydrogen atom, and the substituent is a straight-chain or branched alkoxy group having 1 to 18 carbon atoms or an amino group having 0 to 18 carbon atoms.

2. A hole transport material comprising the compound of claim 1.

3. A hole transport material composition for a photoelectric conversion element, comprising the hole transport material of claim 2.

4. A photoelectric conversion element using the hole transport material composition for photoelectric conversion as described in claim 3.

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