Compound having diazatruxene derivative and photoelectric conversion element using the compound

Abstract

An object of the present invention is to provide a compound useful as a hole transport material for a photoelectric conversion element, and a photoelectric conversion element and a solar cell having good photoelectric conversion characteristics using the compound in a hole transport layer for a photoelectric conversion element.SOLUTION: The compound is represented by general formula (I).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a compound having a diazatruxene derivative and a photoelectric conversion element using the compound. [Background technology]

[0002] In recent years, solar power generation has attracted attention as a clean energy source, and the development of solar cells has been actively pursued. Among these, the development of solar cells using perovskite materials in the photoelectric conversion layer (hereinafter referred to as perovskite solar cells) has attracted attention as a next-generation solar cell that can be manufactured at low cost using a solution process (e.g., Non-Patent Documents 1 and 2).

[0003] Perovskite solar cells often use hole transport materials in their devices. One of the purposes of using them is to improve photoelectric conversion efficiency (for example, Non-Patent Document 3). Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (hereinafter referred to as PTAA) is often used as a standard hole transport material, but there have been few reports of hole transport materials that contribute more significantly to photoelectric conversion properties than this material. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Journal of the American Chemical Society, 2009, Vol. 131, pp. 6050-6051 [Non-patent document 2] Science, 2012, Vol. 388, P. 643-647 [Non-patent document 3] Chem. Sci.,2019,10,P.6748-6769 [Non-patent document 4] Journal of Heterocyclic Chemistry(2017),54(2),1077-1083 Summary of the Invention [Problem to be solved by the invention]

[0005] 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, and a photoelectric conversion element and a solar cell which use the compound in a hole transport layer for the photoelectric conversion element and have good photoelectric conversion characteristics. [Means for solving the problem]

[0006] In order to solve the above problems, the inventors have conducted extensive research into improving photoelectric conversion properties and have found that by using a compound having a diazatruxenone structure as a hole transport layer, a photoelectric conversion element and a solar cell with high photoelectric conversion efficiency can be obtained.

[0007] 1) A compound represented by the following general formula (I):

[0008] [ka]

[0009] [In formula (I), A represents a phosphonic acid group, a carboxy group, a sulfo group, a cyanoacrylate group, or a group corresponding to a salt thereof, X represents an oxygen atom or a sulfur atom; L1 and L2 may be the same or different. single bond, a linear or branched alkylene group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkenylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkynylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkoxysilane group having 1 to 20 carbon atoms which may have a substituent; a cycloalkylene group having 3 to 12 carbon atoms which may have a substituent; an arylene group having 6 to 36 carbon atoms which may have a substituent, or represents an optionally substituted heteroarylene group having 5 to 36 ring atoms, R1~R 12 may be the same or different from each other, Hydrogen atoms, deuterium atoms, halogen atoms, a linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkynyl group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 12 carbon atoms which may have a substituent; an aryl group having 6 to 36 carbon atoms which may have a substituent; a heteroaryl group having 5 to 36 ring atoms which may have a substituent; a thio group having 0 to 18 carbon atoms which may have a substituent, or represents an amino group having 0 to 20 carbon atoms which may have a substituent, m and n represent integers of 1 to 2. However, when m or n is an integer 2, the corresponding L1 or L2 may be the same or different.

[0010] 2) The compound according to 1), wherein X in the general formula (I) is an oxygen atom.

[0011] 3) The compound according to 1), wherein the integers m and n in the general formula (I) are 1.

[0012] 4) In the general formula (I), L1 and L2 are single bond, a linear or branched alkylene group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkenylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkynylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkoxysilane group having 1 to 20 carbon atoms which may have a substituent, or The compound according to 1), wherein the cycloalkylene group has 3 to 12 carbon atoms and may have a substituent.

[0013] 5) The compound according to 1), wherein A in the general formula (I) is a phosphonic acid group, a carboxy group, a sulfo group, or a cyanoacrylate group.

[0014] 6) The compound according to 5), wherein A in the general formula (I) is a phosphonic acid group.

[0015] 7) R1 to R2 in the general formula (I) 12 but, Hydrogen atoms, deuterium atoms, halogen atoms, a linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryl group having 6 to 36 carbon atoms which may have a substituent; a heteroaryl group having 5 to 36 ring atoms which may have a substituent; a thio group having 0 to 18 carbon atoms which may have a substituent, or 1) The compound according to 1), wherein the amino group is an amino group having 0 to 20 carbon atoms which may have a substituent.

[0016] 8) A photoelectric conversion element comprising the compound according to any one of 1) to 7).

[0017] 9) A perovskite solar cell comprising the photoelectric conversion element according to 8), which contains a compound represented by general formula (I).

[0018] 10) The perovskite solar cell according to 9), wherein the compound represented by general formula (I) is used as a hole transport material.

[0019] 11) An electronic device or electronic element having a pair of electrodes and at least one organic layer sandwiched between them, the electronic device or electronic element containing the compound according to any one of 1) to 7). [Effects of the Invention]

[0020] According to the compound represented by general formula (I) of the present invention and the hole transport layer using the compound, by using the compound between the photoelectric conversion layer and the electrode, it is possible to obtain a photoelectric conversion element and a solar cell having good photoelectric conversion efficiency. [Brief explanation of the drawings]

[0021] [Figure 1] 1A and 1B are schematic cross-sectional views illustrating the configurations of photoelectric conversion elements according to examples of the present invention and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail. The hole transport layer of the present invention is used in a photoelectric conversion element and a perovskite-type photoelectric conversion element, but the present invention is not limited to such embodiments or specific examples. In this specification, a numerical range expressed using "to" means a range including the numerical values ​​written before and after "to" as the lower and upper limits. In addition, the isotope species of hydrogen atoms present in the molecule of the compound used in the present invention are not particularly limited, and for example, all hydrogen atoms in the molecule may be 1 H, or part or all of 2 It may also be H (deuterium: D). In this specification, "organic layer" refers to a layer containing 70% by weight or more of an organic compound, and "organic compound" refers to a compound containing one or more carbon atoms. The organic compound may be composed only of atoms selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, sulfur, boron, phosphorus, and halogen atoms.

[0023] The compounds represented by general formula (I) will be specifically explained below, but the present invention is not limited to these.

[0024] In general formula (I), A represents a phosphonic acid group (-P(=O)(OH)2), a carboxy group (-COOH), a sulfo group (-SO2(OH)), a cyanoacrylate group (-CHC(CN)COOH), or a group equivalent to a salt thereof. In the case of a salt, M in the phosphonic acid group salt (-P(=O)(OM)2), the carboxy group salt (-COOM), or the sulfo group salt (-SO2(OM)) represents a monovalent cation other than a hydrogen ion. Specific examples of monovalent cations include alkali metal ions. In the present invention, A in general formula (I) is preferably a phosphonic acid group, a carboxy group, a sulfo group, or a cyanoacrylate group, more preferably a phosphonic acid group or a sulfo group, and even more preferably a phosphonic acid group.

[0025] In general formula (I), R to R 12 The "halogen atom" represented by the formula (I) includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0026] In general formula (I), R to R 12 is expressed as Specific examples of the "straight-chain or branched alkyl group having 1 to 18 carbon atoms" in the "straight-chain or branched alkyl group having 1 to 18 carbon atoms which may have a substituent" include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, an isooctyl group, a nonyl group, and a decyl group.

[0027] In general formula (I), R to R 12 is expressed as Specific examples of the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms" in the "straight-chain or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" include vinyl group, 1-propenyl group, allyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 1-hexenyl group, isopropenyl group, isobutenyl group, and straight-chain or branched alkenyl groups having 2 to 20 carbon atoms in which a plurality of these alkenyl groups are bonded.

[0028] In general formula (I), R to R 12 is expressed as Specific examples of the "straight-chain or branched alkynyl group having 2 to 20 carbon atoms" in the "straight-chain or branched alkynyl group having 2 to 20 carbon atoms which may have a substituent" include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 1-methyl-2-propynyl group, a 1-pentynyl group, a 2-pentynyl group, a 1-methyl-n-butynyl group, a 2-methyl-n-butynyl group, a 3-methyl-n-butynyl group, and a 1-hexynyl group.

[0029] In general formula (I), R to R 12 is expressed as Specific examples of the "straight-chain or branched alkoxy group having 1 to 20 carbon atoms" in the "straight-chain or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent" include a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, a pentyloxy group, and a hexyloxy group.

[0030] In general formula (I), R to R 12 is expressed as Specific examples of the "aryloxy group having 6 to 30 carbon atoms" in the "aryloxy group having 6 to 30 carbon atoms which may have a substituent" include a phenyloxy group, a tolyloxy group, a biphenylyloxy group, and a naphthyloxy group.

[0031] In general formula (I), R to R 12 is expressed as Specific examples of the "cycloalkyl group having 3 to 12 carbon atoms" in the "cycloalkyl group having 3 to 12 carbon atoms which may have a substituent" include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, and a cyclododecyl group.

[0032] In general formula (I), R to R 12 is expressed as The aromatic ring constituting the "aryl group having 6 to 36 carbon atoms" in the "aryl group having 6 to 36 carbon atoms which may have a substituent" may be a monocyclic ring, a fused ring in which two or more rings are fused, or a linked ring in which two or more rings are linked by a single bond. Specific examples include a phenyl group, a biphenylyl group, a terphenylyl group, a naphthyl group, an anthracenyl group (anthryl group), a phenanthryl group, a fluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, and a triphenylenyl group.

[0033] In general formula (I), R to R 12 is expressed as Specific examples of the "heteroaryl group having 5 to 36 ring atoms" in the "heteroaryl group having 5 to 36 ring atoms which may have a substituent" include a pyridyl group, a pyrimidinyl group, a triazinyl group, a thienyl group, a furyl group (a furanyl group), a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a triazolyl group, a quinolyl group, an isoquinolyl group, a naphthyldinyl group, an acridinyl group, a phenanthrolinyl group, a benzofuranyl group, a benzothienyl group, an oxazolyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a thiazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, and a carbonyl group.

[0034] In general formula (I), R to R 12 is expressed as Specific examples of the "thio group having 0 to 18 carbon atoms" in the "thio group having 0 to 18 carbon atoms which may have a substituent" include an unsubstituted thio group (thiol group: -SH), an alkylthio group (for example, a methylthio group, an ethylthio group, a propylthio group), an arylthio group (for example, a phenylthio group, a biphenylthio group), etc.

[0035] In general formula (I), R to R 12 is expressed as The "amino group having 0 to 20 carbon atoms" in the "amino group having 0 to 20 carbon atoms which may have a substituent" may be an unsubstituted amino group, or a mono- or di-substituted amino group. Specific examples of the "amino group having 0 to 20 carbon atoms" include an unsubstituted amino group (-NH2), mono-substituted amino groups such as ethylamino, acetylamino, phenylamino, and pyridylamino, and di-substituted amino groups such as diethylamino, diphenylamino, acetylphenylamino, and phenylpyridylamino.

[0036] In general formula (I), R to R 12and the like. Examples of the "substituent" in the "optionally substituted linear or branched alkyl group of 1 to 18 carbon atoms," "optionally substituted linear or branched alkenyl group of 2 to 20 carbon atoms," "optionally substituted linear or branched alkynyl group of 2 to 20 carbon atoms," "optionally substituted linear or branched alkoxy group of 1 to 20 carbon atoms," "optionally substituted aryloxy group of 6 to 30 carbon atoms," "optionally substituted cycloalkyl group of 3 to 12 carbon atoms," "optionally substituted aryl group of 6 to 36 carbon atoms," "optionally substituted heteroaryl group of 5 to 36 ring atoms," "optionally substituted thio group of 0 to 18 carbon atoms," or "optionally substituted amino group of 0 to 20 carbon atoms," represented by the above formula, specifically include a deuterium atom, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a cyano group; a hydroxyl group; a nitro group; a nitroso group; a carboxy group; a phosphonic acid (phosphoric acid) group; a sulfo group; Carboxylic acid ester groups such as methyl ester groups and ethyl ester groups; linear or branched alkyl groups having 1 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, isopentyl, n-hexyl, 2-ethylhexyl, heptyl, octyl, isooctyl, nonyl, and decyl; linear or branched alkenyl groups having 2 to 20 carbon atoms, such as vinyl, 1-propenyl, allyl, 1-butenyl, 2-butenyl, 1-pentenyl, 1-hexenyl, isopropenyl, and isobutenyl; linear or branched alkynyl groups having 2 to 20 carbon atoms, such as ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 1-methyl-2-propynyl, 1-pentynyl, 2-pentynyl, and 1-hexynyl; linear or branched alkoxy groups having 1 to 18 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, a pentyloxy group, or a hexyloxy group; Aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a biphenylyl group, a naphthyl group, an anthryl group, a phenanthryl group, or a pyrenyl group; heteroaryl groups having 5 to 30 ring atoms, such as a pyridyl group, a pyrimidinyl group, a triazinyl group, a thienyl group, a furyl group (a furanyl group), a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a triazolyl group, a quinolyl group, an isoquinolyl group, a naphthyldinyl group, an acridinyl group, a phenanthrolinyl group, a benzofuranyl group, a benzothienyl group, an oxazolyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a thiazolyl group, a benzothiazolyl group, a quinoxalinyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, or a carbonylyl group; an amino group having 0 to 18 carbon atoms, which may be an unsubstituted amino group (-NH2), a monosubstituted amino group such as an ethylamino group, an acetylamino group, or a phenylamino group, or a disubstituted amino group such as a diethylamino group, a diphenylamino group, or an acetylphenylamino group; Examples include unsubstituted thio groups (thiol groups: —SH), methylthio groups, ethylthio groups, propylthio groups, hex-5-ene-3-thio groups, phenylthio groups, biphenylthio groups, and other thio groups having 0 to 18 carbon atoms. These "substituents" may be present in only one or more groups, and when present in more than one group, they may be the same or different. Furthermore, these "substituents" may further have the substituents exemplified above.

[0037] In the general formula (I), the "alkylene group", "alkenylene group", "alkynylene group", "alkoxylene group", "cycloalkylene group", "arylene group", or "heteroarylene group" in the "linear or branched alkylene group of 1 to 18 carbon atoms which may have a substituent", "linear or branched alkenylene group of 2 to 20 carbon atoms which may have a substituent", "linear or branched alkynylene group of 2 to 20 carbon atoms which may have a substituent", "linear or branched alkoxylene group of 1 to 20 carbon atoms which may have a substituent", "cycloalkylene group of 3 to 12 carbon atoms which may have a substituent", "arylene group of 6 to 36 carbon atoms which may have a substituent", or "heteroarylene group of 5 to 36 ring atoms which may have a substituent" represented by L1 and L2 specifically includes: In general formula (I), R to R 12 It is a divalent group obtained by removing one hydrogen atom from an "alkyl group," "alkenyl group," "alkynyl group," "alkoxy group," "cycloalkyl group," "aryl group," or "heteroaryl group" represented by the following formula: and examples thereof include divalent groups obtained by removing one hydrogen atom from the above specific groups.

[0038] In the general formula (I), the "substituent" in the "linear or branched alkylene group having 1 to 18 carbon atoms which may have a substituent", "linear or branched alkenylene group having 2 to 20 carbon atoms which may have a substituent", "linear or branched alkynylene group having 2 to 20 carbon atoms which may have a substituent", "linear or branched alkoxylene group having 1 to 20 carbon atoms which may have a substituent", "cycloalkylene group having 3 to 12 carbon atoms which may have a substituent", "arylene group having 6 to 36 carbon atoms which may have a substituent", or "heteroarylene group having 5 to 36 ring atoms which may have a substituent" represented by L1 and L2 specifically includes R1 to R 12Examples of the "substituent" include the same as "a linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent" represented by the following formula:

[0039] In general formula (I), it is preferable that L1 and L2 are a single bond, a linear or branched alkylene group of 1 to 18 carbon atoms which may have a substituent, a linear or branched alkenylene group of 2 to 20 carbon atoms which may have a substituent, a linear or branched alkynylene group of 2 to 20 carbon atoms which may have a substituent, a linear or branched alkoxylene group of 1 to 20 carbon atoms which may have a substituent, or a cycloalkylene group of 3 to 12 carbon atoms which may have a substituent.

[0040] In general formula (I), at least one of L1 and L2 is preferably a linear or branched alkylene group having 1 to 18 carbon atoms which may have a substituent, more preferably a linear or branched alkylene group having 1 to 6 carbon atoms which may have a substituent, and even more preferably a linear alkylene group having 1 to 6 carbon atoms which may have a substituent.

[0041] In general formula (I), R to R 12 is preferably a hydrogen atom, a deuterium atom, a halogen atom, a linear or branched alkyl group of 1 to 18 carbon atoms which may have a substituent, a linear or branched alkoxy group of 1 to 20 carbon atoms which may have a substituent, an aryl group of 6 to 36 carbon atoms which may have a substituent, a heteroaryl group of 5 to 36 ring atoms which may have a substituent, a thio group of 0 to 18 carbon atoms which may have a substituent, or an amino group of 0 to 20 carbon atoms which may have a substituent.

[0042] In addition, in the general formula (I), R to R 12At least one of R5 to R8 is preferably a hydrogen atom or a deuterium atom, more preferably at least one of R5 to R8 is a hydrogen atom or a deuterium atom, and even more preferably R5 to R8 are hydrogen atoms or deuterium atoms.

[0043] Specific examples of the compound represented by the general formula (I) of the present invention are shown below, but the present invention is not limited to these. Furthermore, the following exemplary compounds are shown with some hydrogen atoms, carbon atoms, etc. omitted, and are examples of possible isomers, but all other isomers are included. Furthermore, each may be a mixture of two or more isomers.

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] The diazatruxene derivative, which is the compound represented by the general formula (I) of the present invention, can be synthesized from ninhydrin and indole in an acetic acid solvent (Non-Patent Document 4). Then, a phosphonic acid group or a sulfo group can be introduced by a known method to obtain the compound.

[0050] The compound of the present invention represented by the general formula (I) can be purified by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using a solvent, etc. Alternatively, it is effective to use a compound with increased purity by combining these methods. Furthermore, these compounds can be identified by nuclear magnetic resonance analysis (NMR).

[0051] The compound of the present invention represented by the general formula (I) can be used as a hole transport material contained in a hole transport layer for organic electronic devices such as photoelectric conversion elements and organic EL elements.

[0052] Preferred embodiments of the photoelectric conversion element of the present invention will be described below.

[0053] <Photoelectric conversion element> The photoelectric conversion element of the present invention typically includes a conductive support 1, a hole transport layer 2, a photoelectric conversion layer 3, an electron transport layer 4, a buffer layer 5, and a counter electrode 6, as shown in the schematic cross-sectional view of FIG.

[0054] 1, the photoelectric conversion element of the present invention preferably comprises a conductive support 1, a hole transport layer 2, a photoelectric conversion layer (perovskite layer) 3, an electron transport layer 4, a buffer layer 5, and a counter electrode 6, but is not limited thereto. 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 photoelectric conversion element preferably has an inverted structure including, in this order, a conductive support (electrode) 1, a hole transport layer 2, a photoelectric conversion layer (perovskite layer) 3, an electron transport layer 4, a buffer layer 5, and a counter electrode 6. Alternatively, the perovskite photoelectric conversion element may have a normal structure including, in this order, a conductive support, an electron transport layer, a photoelectric conversion layer (perovskite layer), a hole transport layer, and a counter electrode.

[0055] <Conductive Support> In the photoelectric conversion element of the present invention, the conductive support 1 shown in FIG. 1 must be translucent enough to transmit light that contributes to photoelectric conversion. Furthermore, since the conductive support is a member that functions to extract current from the photoelectric conversion layer, it is preferably 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. However, tin-doped indium oxide (ITO) and fluorine-doped tin oxide (FTO) are preferred.

[0056] <Hole transport layer> In the photoelectric conversion element of the present invention, the hole transport layer 2 shown in FIG. 1 is a layer having a function of transporting holes, and is a layer located between the conductive support 1 and the photoelectric conversion layer (perovskite layer) 3. The hole transport layer is used to improve the efficiency of hole transfer from the photoelectric conversion layer to the counter electrode and to block (prevent) the transfer of electrons. For example, a conductor, a semiconductor, an organic hole transport material, etc. can be used for the hole transport layer, and an additive may be included for the purpose of further improving the hole transport properties.

[0057] The hole transport layer of the present invention is a layer containing the compound represented by the general formula (I) as a hole transport material. The hole transport layer of the present invention may contain one or more compounds represented by the general formula (I) in combination, and may also contain other hole transport materials not belonging to the present invention.

[0058] Specific examples of other hole transport materials that do not belong to the hole transport material of the present invention include, for example, compound semiconductors containing nickel such as NiO; compound semiconductors containing monovalent copper such as CuI, CuInSe2, and CuS; and compounds containing metals other than those mentioned above, such as GaP, CoO, FeO, Bi2O3, MoO2, and Cr2O3. These metal oxides may be mixed in the hole transport layer or may be laminated on the hole transport material. Examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyethylenedioxythiophene (PEDOT); triphenylamine derivatives such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA); fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD); polyvinylcarbazole, [2-(9H-carbazol-9-yl)ethyl] ]phosphonic acid (2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [[5H-diindolo[3,2-a:3',2'-c]carbazole-5,10,15-triyl]tris(propane-3,1-diyl)]tris(phosphonic acid) (3PATAT-C3), and other carbazole derivatives; diphenylamine derivatives; acridine derivatives; phenothiazine derivatives; phenoxazine derivatives; phenoselenazine derivatives; polyaniline derivatives; polysilane derivatives, and the like.

[0059] In the present invention, the hole transport layer can be obtained using a known film-forming method depending on the material to be formed. The hole transport layer can be formed by any coating method using a coating liquid. Examples of methods include, but are not limited to, wet coating methods such as spin coating, inkjet printing, doctor blade printing, drop casting, squeegee printing, screen printing, reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, wire barber coating, pipe doctor printing, impregnation coating, or curtain coating, followed by baking to remove solvents and additives to form a film; sputtering, vapor deposition, electrodeposition, electrodeposition, and microwave irradiation. In the present invention, it is preferable to form a film by spin coating using the hole transport layer coating liquid prepared by the above method, but this is not limiting. The spin coating conditions can be set appropriately.

[0060] In the present invention, the solvent used in the coating solution for the hole transport layer during film formation is selected from the group consisting of aromatic organic solvents such as benzene, toluene, xylene, mesitylene, tetralin (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, and nitrobenzene; alkyl halide organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, and dichloromethane; nitrile solvents such as benzonitrile and acetonitrile; tetrahydrofuran, dioxane, diisopropyl ether, and c-pentylmethyl ether. Examples of suitable solvents include, but are not limited to, ether solvents such as ethyl acetate, propylene glycol monomethyl 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; alcohol solvents such as methanol, isopropanol, n-butanol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, cyclohexanol, and 2-n-butoxyethanol; and N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone. These solvents may be used alone or in combination, and the solvent to be used can be selected based on the solvent structure. It is preferable to use DMF, aromatic organic solvents, and alcohol solvents.

[0061] In the present invention, the thickness of the hole transport layer is not particularly limited, but from the viewpoint of further improving the photoelectric conversion efficiency, it is preferably 100 nm or less, and more preferably 10 nm or less.

[0062] In the present invention, the atmosphere during film formation of the hole transport layer is not particularly limited, but a dry atmosphere is preferred from the viewpoint of enabling highly efficient and reproducible production of perovskite solar cells by preventing moisture contamination. It is also preferable to use a dehydrated solvent with a moisture content of 10 ppm or less.

[0063] The hole transport layer of the present invention can be surface-modified to improve the efficiency of interlayer charge transfer and the quality of the photoelectric conversion layer formed on the hole transport layer. The surface modification can be performed using any coating method that uses a coating liquid, including the same methods as the film-forming method for the hole transport layer. Alternatively, the hole transport layer can be formed by a dry film-forming method such as vacuum deposition.

[0064] For surface modification, it is preferable to use a compound having a quaternary ammonium salt structure, but this is not limiting, and multiple compounds may be used in combination. Specific examples include phenylethylammonium bromide, n-hexylammonium bromide, n-hexyltrimethylammonium bromide, and poly[(9,9-bis(3'-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] dibromide (PFN-Br).

[0065] The coating thickness is not particularly limited as long as it is effective in improving the efficiency of charge transfer and the quality of the photoelectric conversion layer formed on the hole transport layer, but is preferably 10 nm or less. The atmosphere in which the surface modification is performed is not particularly limited, but a dry atmosphere is preferred. It is also preferable to use a dehydrated solvent with a water content of 10 ppm or less.

[0066] <Additives> In the present invention, the hole transport layer may contain a dopant (or an oxidizing agent) or a basic compound (or a basic additive) as an additive. Incorporating an additive into the hole transport layer to increase 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.

[0067] In the present invention, when a dopant is contained as an additive in the hole transport layer, specific examples of the dopant include bis(trifluoromethylsulfonyl)imide lithium (LiTFSI), bis(trifluoromethanesulfonyl)imide silver, bis(trifluoromethanesulfonyl)imide zinc(II), bis(trifluoromethanesulfonyl)imide copper(II), bis(trifluoromethanesulfonyl)imide magnesium(II), bis(trifluoromethanesulfonyl)imide calcium(II), tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III), tri[bis(trifluoromethane)sulfonimide] (FK209), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ), tris(pentafluorophenyl)borane (BCF), NOSbF6, SbCl5, SbF5, and the like.

[0068] In the present invention, a basic compound (basic additive) may be contained as an additive in the hole transport layer. Specific examples of the basic compound that can be contained in the present invention include 4-tert-butylpyridine (tBP), 2-picoline, and 2,6-lutidine. The basic compound is often used in combination with a dopant.

[0069] <Photoelectric conversion layer> In the photoelectric conversion element of the present invention, the photoelectric conversion layer (perovskite layer) 3 shown in FIG. 1 is a layer located between the hole transport layer 2 and the electron transport layer 4, and it is preferable that the photoelectric conversion layer (perovskite layer) 3 is formed on the hole transport layer 2, but this is not particularly limited.

[0070] In the present invention, when used as a perovskite photoelectric conversion element, the perovskite material of the photoelectric conversion layer represents a series of materials having a structure represented by the general formula ABX3, where A, B, and X represent an organic cation or a monovalent metal cation, a metal cation, and a halide anion, respectively. For example, A=K + , Rb + , Cs+ , CH3NH3 + (hereinafter, MA: methylammonium), NH=CHNH2 + (hereinafter FA: formamidinium), CH3CH2NH3 + (hereinafter, EA: ethylammonium; B = Pb, Sn; X = I) - , Br - Examples of suitable perovskite materials include, but are not limited to, perovskite materials having any of the following compositions: MAPbI3, FAPbI3, EAPbI3, CsPbI3, MASnI3, FASnI3, EASnI3, MAPbBr3, FAPbBr3, EAPbBr3, MASnBr3, FASnBr3, and EASnBr3; and mixed-cation, mixed-anion perovskite materials having any of the following compositions: (MAFA)Pb(IBr)3, K(MAFA)Pb(IBr)3, Rb(MAFA)Pb(IBr)3, and Cs(MAFA)Pb(IBr)3. It is preferable to use one or more of these perovskite materials. Furthermore, the perovskite material may contain a light-absorbing agent other than the perovskite material.

[0071] The method for forming the photoelectric conversion layer (perovskite layer) of the photoelectric conversion element of the present invention is not limited and can be selected according to the characteristics of the material. For example, any coating method using a coating liquid can be used, including the same method as the method for forming the hole transport layer. Alternatively, the layer can be formed by a dry film formation method such as vacuum deposition.

[0072] 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, or cesium halide in any composition, but the present invention is not limited to this.

[0073] From the viewpoint of precursor solubility, examples of solvents for the perovskite precursor solution of the present invention include, but are not limited to, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone. These solvents may be used alone or in combination, and a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide is preferably used. It is also preferable to use a dehydrated solvent with a water content of 10 ppm or less.

[0074] In the present invention, the atmosphere during deposition of the photoelectric conversion layer (perovskite layer) is preferably a dry atmosphere, more preferably a dry inert gas atmosphere such as a glove box, from the viewpoint of preventing moisture contamination and enabling highly efficient production of perovskite solar cells with good reproducibility. It is also preferable to use a solvent with a low moisture content after dehydration using a molecular sieve or the like.

[0075] 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., more preferably 70 to 150° C., from the viewpoint of producing a perovskite material from the precursor. The heating time is preferably about 10 to 90 minutes, more preferably about 10 to 60 minutes.

[0076] The film thickness of the photoelectric conversion layer (perovskite layer) of the present invention is preferably 50 to 1000 nm, more preferably 300 to 700 nm, from the viewpoint of further suppressing performance degradation due to defects and peeling, and in order to ensure that the photoelectric conversion layer has sufficient light absorption rate and does not cause the device resistance to become too high.

[0077] The photoelectric conversion layer (perovskite layer) of the present invention can increase the efficiency of interlayer charge transfer by covering surface defects and passivating them. Passivation can be achieved by any coating method using a coating liquid, including the same methods as those used to form the hole transport layer. It can also be formed by a dry film-forming method such as vacuum deposition.

[0078] For passivation, it is preferable to use a compound having a quaternary ammonium salt structure, but this is not limitative and multiple compounds may be used in combination.Specific examples include phenylethylammonium bromide, n-hexylammonium bromide, and n-hexyltrimethylammonium bromide.

[0079] The coating thickness is not particularly limited as long as it has the effect of increasing the efficiency of charge transfer, but is preferably 10 nm or less, more preferably 5 nm or less. The passivation is preferably performed in a dry atmosphere. The method for removing the solvent from the coating solution is preferably a reduced pressure method.

[0080] <Electron transport layer> 1 is a layer located between the photoelectric conversion layer (perovskite layer) 3 and the buffer layer 5, and is preferably, but not particularly limited to, formed on the photoelectric conversion layer (perovskite layer) 3. The electron transport layer is used to improve the efficiency of electron migration from the photoelectric conversion layer to the counter electrode and to block (prevent) the migration of holes.

[0081] In the present invention, specific examples of the semiconductor that forms the electron transport layer include organic semiconductors such as fullerene derivatives; 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 (YO3, 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 an organic semiconductor such as a fullerene derivative.

[0082] The method for forming the electron transport layer of the photoelectric conversion element of the present invention is not limited and can be selected according to the characteristics of the material. For example, any coating method for coating with a coating liquid can be used, including the same method as the method for forming the hole transport layer. Alternatively, the electron transport layer can be formed by a dry film formation method such as vacuum deposition.

[0083] In the present invention, a commercially available paste containing the semiconductor fine particles may be used to form the electron transport layer, or a paste (electron transport layer coating solution) prepared by dispersing commercially available semiconductor fine powder in a solvent may be used. Specific examples of solvents used in preparing the paste include, but are not limited to, water; alcoholic solvents such as methanol, ethanol, and isopropyl alcohol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and hydrocarbon solvents such as n-hexane, cyclohexane, benzene, and toluene. These solvents may be used alone or in combination.

[0084] In the present invention, the semiconductor fine powder may be dispersed in a solvent after grinding the powder in a mortar or the like, or a dispersing machine such as a ball mill, a paint conditioner, a vertical bead mill, a horizontal bead mill, or an attritor may be used. When preparing a paste, it is preferable to add a surfactant or the like to prevent aggregation of the semiconductor fine particles, and it is also preferable to add a thickener such as polyethylene glycol to increase the viscosity.

[0085] In the present invention, the solvent used in the coating solution for the electron transport layer during film formation may be an aromatic organic solvent such as benzene, toluene, xylene, mesitylene, tetralin (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, or nitrobenzene; an alkyl halide organic solvent such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, or dichloromethane; a nitrile solvent such as benzonitrile or acetonitrile; or a tetrahydrofuran or dioxane. Examples of suitable solvents include, but are not limited to, ether solvents such as ethanol, diisopropyl ether, c-pentyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate and propylene glycol monomethyl ether acetate; and alcohol solvents such as methanol, isopropanol, n-butanol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, cyclohexanol, and 2-n-butoxyethanol. These solvents may be used alone or in combination, and the solvent to be used can be selected based on the solvent's structure. Aromatic organic solvents are particularly preferred.

[0086] In the present invention, the thickness of the electron transport layer is not particularly limited, but from the viewpoint of further improving the photoelectric conversion efficiency, it is preferably 10 to 300 nm, and more preferably 10 nm to 100 nm.

[0087] In the present invention, the atmosphere during film formation of the electron transport layer is not particularly limited, but a dry atmosphere is preferred from the viewpoint of enabling highly efficient and reproducible production of perovskite solar cells by preventing moisture contamination. It is also preferable to use a dehydrated solvent with a moisture content of 10 ppm or less.

[0088] <Buffer layer> 1 is a layer located between the electron transport layer 4 and the counter electrode 6, and is preferably, but not particularly limited to, formed on the electron transport layer 4. The buffer layer is used to improve the efficiency of electron transfer from the electron transport layer to the counter electrode.

[0089] Specific examples of materials for forming the buffer layer in the present invention include inorganic compounds such as salts of alkali metals such as lithium, sodium, potassium, and cesium, and metal oxides such as zinc oxide, titanium oxide, aluminum oxide, and indium oxide. Organic compounds include bathocuproine (BCP), bathophenanthrene (Bphen), tris(8-hydroxyquinolinato)aluminum (Alq), boron compounds, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic anhydride (NTCDA), 2,2',2"-(1,3,5-benzenetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), perylenetetracarboxylic anhydride (PTCDA), fullerene compounds, and phosphine compounds. In the present invention, organic compounds such as bathocuproine are preferred.

[0090] The method for forming the buffer layer of the photoelectric conversion element of the present invention is not limited and can be selected according to the characteristics of the material. For example, any coating method for coating with a coating liquid can be used, including the same method as the method for forming the hole transport layer. Alternatively, the buffer layer can be formed by a dry film formation method such as vacuum deposition.

[0091] In the present invention, the solvent used in the coating solution for the buffer layer during film formation may be an aromatic organic solvent such as benzene, toluene, xylene, mesitylene, tetralin (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, or nitrobenzene; an alkyl halide organic solvent such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, or dichloromethane; a nitrile solvent such as benzonitrile or acetonitrile; or a tetrahydrofuran or dioxane. Examples of suitable solvents include, but are not limited to, ether solvents such as ethanol, diisopropyl ether, c-pentyl methyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate and propylene glycol monomethyl ether acetate; and alcohol solvents such as methanol, isopropanol, n-butanol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, cyclohexanol, and 2-n-butoxyethanol. These solvents may be used alone or in combination, and the solvent to be used can be selected depending on the structure. The use of alcohol solvents is particularly preferred.

[0092] In the present invention, the thickness of the buffer layer is not particularly limited, but from the viewpoint of further improving the photoelectric conversion efficiency, it is preferably 1 to 50 nm, and more preferably 1 to 20 nm.

[0093] In the present invention, the atmosphere during the deposition of the buffer layer is not particularly limited, but a dry atmosphere is preferred from the viewpoint of enabling the reproducible and highly efficient production of perovskite solar cells by preventing moisture contamination. It is also preferable to use a dehydrated solvent with a moisture content of 10 ppm or less.

[0094] Opposite In the present invention, the counter electrode 6 shown in FIG. 1 is disposed opposite the conductive support 1 and formed on the buffer layer 5, thereby enabling charge exchange with the buffer layer. It is preferable that the counter electrode 6 be formed on the buffer layer 5, but there is no particular limitation thereto.

[0095] In the present invention, specific examples of materials used for the counter electrode include metals such as platinum, titanium, stainless steel, aluminum, gold, silver, nickel, magnesium, chromium, cobalt, and copper, or alloys thereof. Among these, it is preferable to use gold, silver, or a silver alloy, as it exhibits high electrical conductivity even in a thin film. Examples of silver alloys include silver-gold alloys, silver-copper alloys, silver-palladium alloys, silver-copper-palladium alloys, and silver-platinum alloys, which are less susceptible to sulfidation or chlorination and improve the stability of the thin film.

[0096] In the present invention, the counter electrode is preferably made of a material that can be formed by a method such as vapor deposition, but is not particularly limited thereto.

[0097] When a metal electrode is used as the counter electrode, the thickness thereof is preferably 10 nm or more, more preferably 50 nm or more, in order to obtain good conductivity.

[0098] In the photoelectric conversion element of the present invention, the conductive support serves as the anode, and the counter electrode serves as the cathode. It is preferable to irradiate light such as sunlight from the conductive support side. When irradiated with sunlight, the photoelectric conversion layer (perovskite layer) absorbs the light and becomes excited, generating electrons and holes. These electrons move through the electron transport layer, and the holes move through the hole transport layer to the electrode, causing a current to flow, and the element functions as a photoelectric conversion element.

[0099] 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. The short-circuit current density is the current flowing between the output terminals when the output terminals are short-circuited. 2The open-circuit voltage is the voltage between the output terminals when they are open. The fill factor is the maximum output (product of current and voltage) divided by the product of the short-circuit current density and the open-circuit voltage, and is mainly affected by the internal resistance. The photoelectric conversion efficiency is the ratio of maximum output (W) to 1cm 2 The initial photoelectric conversion efficiency of the photoelectric conversion element having the element configuration of the present invention can be determined as a good photoelectric conversion efficiency if it shows 10% or more.

[0100] The photoelectric conversion element of the present invention can be applied to solar cells, various optical sensors, etc. The solar cell of the present invention is preferably a perovskite solar cell, and the perovskite solar cell can be obtained by arranging a required number of photoelectric conversion elements each containing a hole transport material containing the compound represented by general formula (I) as a hole transport layer to form a module and providing predetermined electrical wiring.

[0101] The hole transport material of the present invention can be applied not only to single-junction solar cells consisting of only perovskite solar cells, but also to multi-junction (tandem) solar cells, such as, but not limited to, perovskite-perovskite and perovskite-silicon solar cells.

[0102] Although the preferred embodiment has been described above, the present invention is not limited to this, and may be modified as appropriate within the scope of the present invention. [Example]

[0103] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. 1 This was measured by H-NMR (JNM-ECZ400S / L1 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd.).

[0104] [Synthesis Example 1] Synthesis of compound (7) 4.2 g of ninhydrin, 5.6 g of indole, and 180 ml of acetic acid were added to a reaction vessel, and the mixture was stirred under heating and reflux for 10 hours. After confirming the completion of the reaction, the reaction solution was concentrated to obtain a crude product, which was then dispersed and washed with chloroform, and the solid was filtered to obtain 5,10-dihydro-15H-indeno[1,2-α]indolo[3,2-c]carbazol-15-one (intermediate 1): 5.5 g (brown solid, yield: 63.7%).

[0105] The structure of the resulting brown solid was identified using NMR. 1 The following 14 hydrogen signals were detected by H-NMR (DMSO-d6). δ(ppm)=11.95(1H), 11.75(1H), 9.05-9.04(1H), 8.74-8.72(1H), 8.16-8.14(1H), 7.72-7. 70(1H), 7.64-7.63(1H), 7.59-7.52(3H), 7.45-7.42(1H), 7.38-7.35(1H), 7.25-7.23(2H).

[0106] [ka]

[0107] To a reaction vessel were added 0.4 g of Intermediate 1, 8 ml of 1,2-dibromoethane, 80 mg of tetrabutylammonium bromide, and 4 ml of a 48% aqueous potassium hydroxide solution, and the mixture was stirred at 90° C. for 6 hours. After confirming the completion of the reaction, HO / ethyl acetate and toluene solvents were added at room temperature for liquid separation and extraction, and the resulting organic layer was concentrated. The concentrate was dispersed and washed with n-hexane, and the solid was filtered to obtain 5,10-bis(2-bromoethyl)-5,10-dihydro-15H-indeno[1,2-α]indolo[3,2-c]carbazol-15-one (Intermediate 2): 0.6 g (brown solid, yield: 94.0%).

[0108] The structure of the resulting brown solid was identified using NMR. 1The following 20 hydrogen signals were detected by H-NMR (DMSO-d6). δ(ppm)=9.26-9.25(1H), 8.34-8.32(1H), 7.92-7.91(1H), 7.67-7.52(4H), 7.42-7.40(1H), 7.34-7.31( 1H), 7.30-7.29(1H), 5.30-5.27(2H), 5.15-5.13(2H), 3.86-3.81(2H), 3.86-3.31(2H), 3.73-3.71(2H).

[0109] [ka]

[0110] 1.5 g of Intermediate 2 and 15 ml of triethyl phosphite were added to a reaction vessel and stirred at 145° C. for 12 hours. After confirming the completion of the reaction, the crude product obtained by concentration was separated by column chromatography (carrier: silica gel, eluent: ethyl acetate / acetone) to obtain 1.1 g of compound (7) precursor (black liquid, yield: 64.0%).

[0111] The structure of the resulting black liquid was identified using NMR. 1 The following 40 hydrogen signals were detected by H-NMR (DMSO-d6). δ(ppm)=8.40(1H), 8.36(1H), 8.01-7.99(2H), 7.56-7.54(4H), 7.21-7.19 (2H), 7.00-6.98(2H), 6.82-6.79(8H), 6.72-6.70(8H), 3.67-3.63(12H).

[0112] [ka]

[0113] 0.3 g of the precursor of compound (7), 1.8 ml of bromotrimethylsilane, and 10 ml of chloroform were added to a reaction vessel, and the mixture was stirred under reflux for 30 hours. After confirming the completion of the reaction, the reaction solution was concentrated. The concentrate was crystallized from chloroform / methanol to obtain 0.1 g of compound (7) (black solid, yield: 64.2%).

[0114] The structure of the obtained black solid was identified using NMR. 1 The following 20 hydrogen signals were detected by H-NMR (DMSO-d6). δ(ppm)=9.29-9.23(1H), 8.55-8.49(1H), 7.73-7.52(7H), 7.36-7.24(3H), 5.00(2H), 4.86-4.83(2H), 2.16-2.12(2H), 1.81-1.76(2H).

[0115] [ka]

[0116] [Example 1] Fabrication of photoelectric conversion element and evaluation of current-voltage characteristics A flat ITO-coated glass (conductive support 1, manufactured by Geomatec Co., Ltd.) was ultrasonically cleaned with isopropyl alcohol and then treated with UV ozone.

[0117] In a dry atmosphere with a relative humidity of 10% RH or less, compound (7), which is the hole transport material obtained in Synthesis Example 1, was dissolved in N,N-dimethylformamide at room temperature to a concentration of 0.5 mM to prepare a coating solution for the hole transport layer. The hole transport layer coating solution was spin-coated on the ITO film and heated at 110° C. for 5 minutes using a hot plate, thereby forming a hole transport layer 2.

[0118] In a dry atmosphere with a relative humidity of 10% or less, formamidine hydroiodide (1 M, manufactured by Tokyo Chemical Industry Co., Ltd.), lead(II) iodide (1.1 M, manufactured by Tokyo Chemical Industry Co., Ltd.), methylamine hydrobromide (0.2 M, manufactured by Tokyo Chemical Industry Co., Ltd.), and lead(II) bromide (0.2 M, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1. A dimethyl sulfoxide solution of cesium iodide (1.5 M, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the solution so that the cesium content was 5% to prepare a perovskite precursor solution. The prepared perovskite precursor solution was dropped onto the hole transport layer and spin-coated. 0.35 mL of chlorobenzene was added dropwise during spin-coating to form a perovskite precursor film. The resulting film was then heated at 100°C for 1 hour on a hot plate to form a Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) with a thickness of approximately 500 nm.

[0119] In a dry atmosphere with a relative humidity of 10% or less, PCBM (phenyl C61 butyric acid methyl ester, manufactured by Lumtec) was dissolved in chlorobenzene at room temperature to a concentration of 20 mg / mL to prepare a coating solution for the electron transport layer. The electron transport layer coating solution was spin-coated onto the Cs(MAFA)Pb(IBr) 3 layer and heated at 100° C. for 10 minutes using a hot plate, thereby forming an electron transport layer 4.

[0120] Bathocuproine was dissolved in isopropyl alcohol at 70° C. to a concentration of 0.5 mg / mL in a dry atmosphere with a relative humidity of 10% RH or less to prepare a coating solution for the buffer layer. A buffer layer coating solution was spin-coated onto the electron transport layer to form a buffer layer 5.

[0121] On the buffer layer, a vacuum of 1×10 was applied by vacuum deposition. -4 A silver electrode (counter electrode 6) was formed by depositing a silver film of about 100 nm at about Pa, and a photoelectric conversion element was fabricated.

[0122] A simulated sunlight (AM1.5, 1000 W / m ) was generated using a white light irradiation device (Otento-Sun SH type, manufactured by Bunkoukeiki Co., Ltd.). 2 The photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics using a source meter (KEITHLEY, Model 2400 Series Source Meter). The obtained photoelectric conversion efficiency is shown in Table 1.

[0123] [Comparative Example 1] A photoelectric conversion element was fabricated in the same manner as in Example 1, except that PTAA (poly(triarylamine), manufactured by Sigma-Aldrich), a standard hole transport material represented by the following formula (A-1), was dissolved in toluene at room temperature at a concentration of 2 mg / mL instead of compound (7), and the element was heated at 100°C for 10 minutes using a hot plate after spin coating. The photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics in the same manner as in Example 1. The obtained photoelectric conversion efficiency is shown in Table 1.

[0124] [ka]

[0125] [Table 1]

[0126] The results in Table 1 show that the photoelectric conversion element using the compound (7) having a diazatruxenone skeleton of the present invention as a hole transport material exhibits superior photoelectric conversion efficiency compared to the photoelectric conversion element using a standard hole transport material.

[0127] [Example 2] Water contact angle measurement A droplet of 5 to 6 μL was dropped onto the coating film of compound (7), and the contact angle immediately after dropping was measured using a water contact angle measuring device (Phoenix-300 Touch, SEO).

[0128] Water contact angle measurement result for compound (7): Water contact angle 59°

[0129] The compound (7) of the present invention has a low water contact angle of 59°, which allows a perovskite layer to be uniformly coated on a coating of compound (7) without repelling water. This is thought to result in a high-quality perovskite layer being formed on a hole transport layer using compound (7), leading to high photoelectric conversion efficiency. On the other hand, the water contact angle of PTAA, the comparative compound of the present application, is 90°, making it difficult to uniformly apply perovskite onto PTAA. However, it has been reported that improving wettability and reducing the water contact angle makes uniform application possible, while at the same time creating a high-quality perovskite layer and achieving high photoelectric conversion efficiency (Reference: Sol. RRL, 2022, 6, 2200234). Therefore, it was found that the compound represented by general formula (I) of the present invention can improve the water contact angle more significantly than the conventionally known compounds, and can also obtain high photoelectric conversion efficiency. [Industrial Applicability]

[0130] By using the compound having a diazatruxenone skeleton represented by general formula (I) of the present invention as a hole transport material, it is possible to provide a photoelectric conversion element having good photoelectric conversion efficiency, which can efficiently convert solar energy into electrical energy, and to provide clean energy as a solar cell. [Explanation of symbols]

[0131] 1. Conductive support 2. Hole transport layer 3 Photoelectric conversion layer 4 Electron transport layer 5. Buffer layer 6. Opposite

Claims

1. A compound represented by the following general formula (I): 【Chemistry 1】 In formula (I), A represents a phosphonic acid group, a carboxy group, a sulfo group, a cyanoacrylate group, or a group corresponding to a salt thereof; X represents an oxygen atom or a sulfur atom; L １ , L ２ may be the same or different from each other, single bond, a linear or branched alkylene group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkenylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkynylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkoxysilane group having 1 to 20 carbon atoms which may have a substituent; a cycloalkylene group having 3 to 12 carbon atoms which may have a substituent; an arylene group having 6 to 36 carbon atoms which may have a substituent; represents an optionally substituted heteroarylene group having 5 to 36 ring atoms, R １ ~R １２ may be the same or different from each other, Hydrogen atoms, deuterium atoms, halogen atoms, a linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkynyl group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryloxy group having 6 to 30 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 12 carbon atoms which may have a substituent; an aryl group having 6 to 36 carbon atoms which may have a substituent, or a heteroaryl group having 5 to 36 ring atoms which may have a substituent; a thio group having 0 to 18 carbon atoms which may have a substituent; or an amino group having 0 to 20 carbon atoms which may have a substituent, m and n each represent an integer of 1 or 2. However, when m or n is an integer 2, the corresponding L １ or L ２ may be the same or different.]

2. The compound according to claim 1, wherein X in the general formula (I) is an oxygen atom.

3. The compound according to claim 1, wherein the integers m and n in the general formula (I) are 1.

4. L in the general formula (I) １ , L ２ but single bond, a linear or branched alkylene group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkenylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkynylene group having 2 to 20 carbon atoms which may have a substituent; a linear or branched alkoxysilane group having 1 to 20 carbon atoms which may have a substituent, or 2. The compound according to claim 1, wherein the cycloalkylene group is an optionally substituted cycloalkylene group having 3 to 12 carbon atoms.

5. The compound according to claim 1, wherein A in the general formula (I) is a phosphonic acid group, a carboxy group, a sulfo group, or a cyanoacrylate group.

6. The compound according to claim 1, wherein A in the general formula (I) is a phosphonic acid group.

7. R in the general formula (I) １ ~R １２ but, Hydrogen atoms, deuterium atoms, halogen atoms, a linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent; an aryl group having 6 to 36 carbon atoms which may have a substituent; a heteroaryl group having 5 to 36 ring atoms which may have a substituent; a thio group having 0 to 18 carbon atoms which may have a substituent; Alternatively, the compound according to claim 1 is an amino group having 0 to 20 carbon atoms which may have a substituent.

8. A photoelectric conversion element comprising the compound according to any one of claims 1 to 7.

9. A perovskite solar cell comprising the photoelectric conversion element according to claim 8.

10. The perovskite solar cell according to claim 9, wherein the compound represented by general formula (I) is used as a hole transport material.

11. An electronic device or electronic element having a pair of electrodes and at least one organic layer sandwiched between them, the electronic device or electronic element containing the compound according to any one of claims 1 to 7.

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