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

Abstract

The problem to be solved by the present invention is to provide: a compound useful as a hole transport material for photoelectric conversion elements whereby electric current can be efficiently taken out; and a photoelectric conversion element and a solar cell which have satisfactory photoelectric conversion characteristics and include a hole transport layer comprising the compound.　This compound is represented by general formula (1).　In the formula, R1 to R20 each represent a hydrogen atom, a C1-C20 alkoxy group, etc., and Y represents an oxygen atom or CR21R22 (R21 and R22 each represent a nitryl group, a C1-C10 acyl group, etc.).

Description

Technical Field

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

Background Art

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

[0003] In perovskite solar cells, a hole transport material is often used in the device. The purposes of use include (1) enhancing the function of selectively transporting holes to improve the photoelectric conversion efficiency, and (2) protecting the perovskite material that is easily affected by moisture and oxygen by bonding with the perovskite photoelectric conversion layer (for example, Non-Patent Document 3). Spiro-OMeTAD, a spirobifluorene-based organic compound, is often used as a standard hole transport material, but there are few reports of hole transport materials that contribute more highly to the photoelectric conversion characteristics than this material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a compound useful as a hole transport material for a photoelectric conversion element capable of efficiently extracting current, a photoelectric conversion element having good photoelectric conversion characteristics using the compound in a hole transport layer, and a solar cell.

[0007] To solve the above problems, as a result of intensive studies on improving photoelectric conversion characteristics, the inventors have designed and developed a compound having a specific structure, and by using it in a photoelectric conversion element as a hole transport layer, they have found that a photoelectric conversion element and a perovskite solar cell showing high photoelectric conversion efficiency can be obtained. That is, the present invention has the following gist.

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

[0009]

Chemical formula

[0010] In the formula, R 1 ~R 20 each independently represents a hydrogen atom, a halogen atom, a carboxyl group, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an acyl group having 1 to 20 carbon atoms which may have a substituent, a thio group having 1 to 18 carbon atoms which may have a substituent, an amino group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent, R 1 and R 2 、R 2 and R 3 、R 3 and R 4 、R 4 and R 5 、R 6 and R 7 、R 7 and R 8 、R 8 and R 9 、R 9 and R 10 、R 11 and R 12 、R 12 and R 13 、R 13 and R 14 、R 14 and R 15 、R 16 and R 17 、R 17 and R 18 、R 18 and R 19 and R 19 and R 20 may be bonded to each other to form a ring, and R 5 and R 6 and R 15 and R 16 may be bonded to each other to form a ring. X 1 and X 2 represent a divalent group, Y is an oxygen atom or CR 21 R 22 represents, R 21 and R 22 each independently represent a nitrile group, an acyl group having 1 to 10 carbon atoms which may have a substituent, or an alkoxycarbonyl group having 1 to 10 carbon atoms which may have a substituent, and R 21 and R 22 may be bonded to each other to form a ring.

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

[0012]

Chem.

[0013] In the formula, R 23 ~R 28 each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 10 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 18 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 18 ring-forming atoms which may have a substituent, R 23 and R 24 , R 25 and R 26 and R 27 and R 28 may be bonded to each other to form a ring, Z represents an oxygen atom, a sulfur atom or a selenium atom, m and n represent integers from 0 to 2, and both m and n do not become 0.

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

[0015] 4. In the general formula (1), the compound in which R 1 ~R 20 each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a thio group having 1 to 18 carbon atoms which may have a substituent, or an amino group having 1 to 20 carbon atoms which may have a substituent.

[0016] 5. A hole transport material comprising the compound.

[0017] 6. A photoelectric conversion element using the hole transport material.

[0018] According to the compound of the present invention and the hole transport layer using the compound, a photoelectric conversion element and a perovskite solar cell having good photoelectric conversion efficiency can be obtained.

Brief Description of the Drawings

[0019]

Figure 1

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail. The hole transport material of the present invention is suitably used for photoelectric conversion elements and perovskite solar cells.

[0021] 〈Photoelectric Conversion Element〉 The photoelectric conversion element of the present invention typically has a conductive support 1, an electron transport layer 2, a photoelectric conversion layer 3, a hole transport layer 4, and a counter electrode 5 as shown in the schematic cross-sectional view of FIG. 1.

[0022] Hereinafter, the compound represented by the general formula (1), which is a hole transport material used for the hole transport layer of the photoelectric conversion element of the present invention, will be specifically described, but the present invention is not limited thereto.

[0023] R in the general formula (1) 1 ~R 20Each independently represents a hydrogen atom, a halogen atom, a carboxyl group, a trimethylsilyl group, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent, an acyl group having 1 to 20 carbon atoms which may have a substituent, a thio group having 1 to 18 carbon atoms which may have a substituent, an amino group having 1 to 20 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent, or a heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent.

[0024] R 1 ~R 20 Examples of the "halogen atom" represented by 1 ~ 20 include fluorine, chlorine, bromine, and iodine.

[0025] R 1 ~R 20 Examples of the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" in 1 ~ 20 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.

[0026] R 1 ~R 20Examples of the "linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" represented by include ethenyl group (vinyl group), 1-propenyl group, 2-propenyl group (allyl group), 1-methylethenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 1-hexenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, and 1-ethylethenyl group, and linear or branched alkenyl groups having 2 to 20 carbon atoms in which a plurality of these alkenyl groups are bonded, etc.

[0027] R 1 ~R 20 Examples of the "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent" represented by include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecyl group, cyclododecyl group, 4-methylcyclohexyl group, and 4-ethylcyclohexyl group, etc.

[0028] R 1 ~R 20 Examples of the "alkoxy group having 1 to 20 carbon atoms which may have a substituent" represented by include methoxy group, ethoxy group, propoxy group, n-butoxy group, n-pentyloxy group, n-hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, isopropoxy group, isobutoxy group, s-butoxy group, t-butoxy group, isooctyloxy group, t-octyloxy group, phenoxy group, tolyloxy group, biphenylyloxy group, terphenylyloxy group, naphthyloxy group, anthryloxy group, phenanthryloxy group, fluorenyloxy group, and indenyl oxy group, etc.

[0029] R 1 ~R 20Examples of the "linear or branched cycloalkoxy group having 3 to 10 carbon atoms" in the "optionally substituted cycloalkoxy group having 3 to 10 carbon atoms" represented by include cyclopropoxy group, cyclobutoxy group, cyclopentyloxy group, cyclohexyloxy group, 4-methylcyclohexyloxy group, and the like.

[0030] R 1 ~R 20 Examples of the "acyl group having 1 to 20 carbon atoms" in the "optionally substituted acyl group having 1 to 20 carbon atoms" represented by include acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, benzoylacetyl group, benzoyl group, and the like. The hydrogen atom of the alkyl group in the acyl group may be partially substituted with a fluorine atom or may be entirely substituted with a fluorine atom (perfluorinated). Further, it may be a group bonded to an amino group (-CO-N<).

[0031] R 1 ~R 20 Examples of the "thio group having 1 to 18 carbon atoms" in the "optionally substituted thio group having 1 to 18 carbon atoms" represented by include methylthio group, ethylthio group, propylthio group, phenylthio group, biphenylthio group, and the like.

[0032] R 1 ~R 20 Examples of the "amino group having 1 to 20 carbon atoms" in the "optionally substituted amino group having 1 to 20 carbon atoms" represented by include ethylamino group, acetylamino group, phenylamino group, etc. as monosubstituted amino groups, and diethylamino group, diphenylamino group, acetylphenylamino group, etc. as disubstituted amino groups.

[0033] R 1 ~R 20Examples of the "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by [0] include phenyl group, biphenyl group, terphenyl group, naphthyl group, biphenyl group, anthracenyl group (anthryl group), phenanthryl group, fluorenyl group, indenyl group, pyrenyl group, perylenyl group, fluoranthenyl group, triphenylenyl group, etc. In the present invention, the aryl group includes a "condensed polycyclic aryl group".

[0034] R 1 ~R 20 Examples of the "heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent" represented by [8] include pyridyl group, pyrimidyl group, triazinyl group, thienyl group, furyl group (furanyl group), pyrrolyl group, imidazolyl group, pyrazolyl group, triazolyl group, quinolyl group, isoquinolyl group, naphthyldinyl group, acridinyl group, phenanthrolinyl group, benzofuranyl group, benzothienyl group, oxazolyl group, indolyl group, carbazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group, carbonyl group, etc.

[0035] R 1 ~R 20The "substituent" in the "linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent", "linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent", "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent", "alkoxy group having 1 to 20 carbon atoms which may have a substituent", "cycloalkoxy group having 3 to 10 carbon atoms which may have a substituent", "acyl group having 1 to 20 carbon atoms which may have a substituent", "thio group having 1 to 18 carbon atoms which may have a substituent", "amino group having 1 to 20 carbon atoms which may have a substituent", "aromatic hydrocarbon group having 6 to 36 carbon atoms having a substituent", or "heterocyclic group having 5 to 36 ring-forming atoms which may have a substituent" includes halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; cyano group; hydroxyl group; nitro group; nitroso group; carboxyl group; phosphoric acid group; thioxo group (>C=S); trimethylsilyl group; carboxylic acid ester groups such as methyl ester group and ethyl ester group; linear or branched alkyl groups having 1 to 18 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, n-hexyl group, 2-ethylhexyl group, heptyl group, octyl group, isooctyl group, nonyl group and decyl group; linear or branched alkenyl groups having 2 to 18 carbon atoms such as ethenyl group (vinyl group), 1-propenyl group, 2-propenyl group (allyl group), 1-butenyl group, 2-butenyl group, 1-pentenyl group, 1-hexenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group and 1-ethyl ethenyl group; alkoxy groups having 1 to 18 carbon atoms such as methoxy group, ethoxy group, propoxy group, t-butoxy group, pentyloxy group and hexyloxy group; aromatic hydrocarbon groups having 6 to 30 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group and pyrenyl group;Heterocyclic groups with 5 to 30 ring-forming atoms such as pyridyl group, pyrimidinyl group, triazinyl group, thienyl group, furyl group (furanyl group), pyrrolyl group, imidazolyl group, pyrazolyl group, triazolyl group, quinolyl group, isoquinolyl group, naphthyldinyl group, acridinyl group, phenanthrolinyl group, benzofuranyl group, benzothienyl group, oxazolyl group, indolyl group, carbazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group, quinoxalinyl group, benzimidazolyl group, pyrazolyl group, dibenzofuranyl group, dibenzothienyl group and carbonyl group; Amino groups with 0 to 18 carbon atoms such as unsubstituted amino group (-NH2), mono-substituted amino groups such as ethylamino group, acetylamino group and phenylamino group, and di-substituted amino groups such as diethylamino group, diphenylamino group and acetylphenylamino group; Thio groups with 0 to 18 carbon atoms such as unsubstituted thio group (thiol group: -SH), methylthio group, ethylthio group, propylthio group, phenylthio group and biphenylthio group; etc. can be mentioned. These "substituents" may be contained in plural, and when contained in plural, they may be the same or different from each other. Further, these "substituents" may further have the substituents exemplified above.;

[0036] In the present invention, R 1 ~R 20 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a thio group having 1 to 18 carbon atoms which may have a substituent, or an amino group having 1 to 20 carbon atoms which may have a substituent, preferably a hydrogen atom or an alkoxy group having 1 to 10 carbon atoms. In particular, since the photoelectric conversion efficiency is good when used in a photoelectric conversion element as a hole transport material, R 1 、R 2 、R 4 、R 5 、R 6 、R 7 、R 9 、R 10 、R 11 、R 12 、R14 and R 15 and R 16 and R 17 and R 19 and R 20 are hydrogen atoms, and R 3 and R 8 and R 13 and R 18 are preferably alkoxy groups having 1 to 10 carbon atoms.

[0037] In the present invention, R 1 and R 2 and R 2 and R 3 and R 3 and R 4 and R 4 and R 5 and R 6 and R 7 and R 7 and R 8 and R 8 and R 9 and R 9 and R 10 and R 11 and R 12 and R 12 and R 13 and R 13 and R 14 and R 14 and R 15 and R 16 and R 17 and R 17 and R 18 and R 18 and R 19 and R 19 and R 20 may be bonded to each other via a single bond, an oxygen atom, a sulfur atom, a selenium atom or a nitrogen atom to form a ring, and R 5 and R 6 and R 15 and R 16 may also be bonded to each other via a single bond, an oxygen atom, a sulfur atom, a selenium atom or a nitrogen atom to form a ring. Further, R 5 and R 6 and R 15 and R 16When forming a ring, they are preferably bonded to each other via a single bond, an oxygen atom or a sulfur atom to form a ring, and more preferably bonded to each other via a single bond to form a ring.

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

[0039] R 21 and R 22 Examples of the "acyl group having 1 to 10 carbon atoms which may have a substituent" represented by include those having 1 to 10 carbon atoms among the "acyl group having 1 to 20 carbon atoms which may have a substituent" represented by the above R 1 ~R 20 .

[0040] R 21 and R 22 Examples of the "alkoxycarbonyl group having 1 to 10 carbon atoms" in the "alkoxycarbonyl group having 1 to 10 carbon atoms which may have a substituent" represented by include a methoxycarbonyl group and an ethoxycarbonyl group. A part or all of the hydrogen atoms of the alkyl group in the alkoxycarbonyl group may be substituted with fluorine atoms (perfluorinated).

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

[0042] In the present invention, X in the general formula (1)1 and X 2 Since the photoelectric conversion efficiency is good when used as a hole transport material in a photoelectric conversion element, it is preferably a divalent group represented by the general formula (2).

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

[0044] R 23 ~R 28 Examples of the "linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent" represented by R 1 ~R 20 include those having 1 to 10 carbon atoms among the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by R

[0045] R 23 ~R 28 Examples of the "linear or branched alkenyl group having 2 to 10 carbon atoms which may have a substituent" represented by R 1 ~R 20 include those having 2 to 10 carbon atoms among the "linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" represented by R

[0046] R 23 ~R 28 Examples of the "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent" represented by R 1 ~R 20 include the same ones as the "cycloalkyl group having 3 to 10 carbon atoms which may have a substituent" represented by R

[0047] R 23 ~R 28 Examples of the "optionally substituted aromatic hydrocarbon group having 6 to 18 carbon atoms" represented by are the above R 1 ~R 20 Among the "optionally substituted aromatic hydrocarbon groups having 6 to 36 carbon atoms" represented by, those having 6 to 18 carbon atoms can be mentioned.

[0048] R 23 ~R 28 Examples of the "optionally substituted heterocyclic group having 5 to 18 ring-forming atoms" represented by are the above R 1 ~R 20 Among the "optionally substituted heterocyclic groups having 5 to 36 ring-forming atoms" represented by, those having 5 to 18 ring-forming atoms can be mentioned.

[0049] R 23 and R 24 、R 25 and R 26 and R 27 and R 28 are bonded to each other via a single bond, an oxygen atom, a sulfur atom, a selenium atom or a nitrogen atom, and may form a ring.

[0050] Z in the general formula (2) represents an oxygen atom, a sulfur atom or a selenium atom. In the present invention, Z is preferably a sulfur atom.

[0051] In the general formula (2), m and n represent integers of 0 to 2. When m is 0, n is 1 to 2, and when n is 0, m is 1 to 2. That is, it is assumed that m and n do not both become 0 at the same time. m is preferably 1, and n is preferably 0 or 1. Further, the fluorenone moiety which is the central skeleton of the general formula (1) and the group represented by the general formula (2) may be bonded at the phenyl group portion or at the 5-membered heterocyclic group portion.

[0052] Specific examples of the compound represented by the general formula (1) of the present invention are shown below, but the present invention is not limited thereto. Further, the following exemplified compounds are described with some hydrogen atoms, carbon atoms, etc. omitted, and an example of the possible isomers is shown, and all other isomers are included. Also, it may be a mixture of two or more isomers respectively.

[0053]

Chem.

[0054]

Chem.

[0055]

Chem.

[0056]

Chem.

[0057]

Chem.

[0058]

Chem.

[0059]

Chem.

[0060]

Chem.

[0061]

Chem.

[0062]

Chem.

[0063]

Chem.

[0064]

Chem.

[0065]

Chem.

[0066]

Chem.

[0067]

Chem.

[0068] The compound represented by the general formula (1) can be synthesized by a known method.

[0069] For example, it can be synthesized by performing a Suzuki-Miyaura cross-coupling reaction between 2,7-dibromofluorenone represented by the following formula (3) and a boronic acid compound represented by the following general formulas (4) and (5) or a boronic acid ester compound represented by the following general formulas (6) and (7), and further performing a Knoevenagel condensation reaction with a compound represented by the following general formula (8).

[0070]

Chem.

[0071]

Chem.

[0072]

Chem.

[0073]

Chem.

[0074] As a method for purifying the compound represented by the general formula (1), purification by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., purification by recrystallization or crystallization using a solvent, etc. can be mentioned. Alternatively, it is effective to use a compound with increased purity by using these methods in combination. In addition, these compounds can be identified by nuclear magnetic resonance analysis (NMR).

[0075] Hereinafter, preferred embodiments of the photoelectric conversion element of the present invention will be described.

[0076] The photoelectric conversion element of the present invention preferably includes a conductive support 1, an electron transport layer 2, a photoelectric conversion layer 3, a hole transport layer 4, and a counter electrode 5, as shown in FIG. 1, but is not limited thereto. Further, the photoelectric conversion element of the present invention can be suitably used as a solar cell, and is more preferably a perovskite-type photoelectric conversion element, but is not limited thereto. In the present invention, the perovskite-type photoelectric conversion element preferably includes a conductive support (electrode) 1, an electron transport layer 2, a photoelectric conversion layer (perovskite layer) 3, a hole transport layer 4, and a counter electrode 5 in this order. Further, the perovskite-type photoelectric conversion element may be composed in the order of a conductive support, a hole transport layer, a photoelectric conversion layer (perovskite layer), an electron transport layer, and a counter electrode.

[0077] <Conductive support> In the photoelectric conversion element of the present invention, the conductive support 1 shown in FIG. 1 needs to have translucency that allows light contributing to photoelectric conversion to pass through. Further, since the conductive support is a member having a function of extracting current from the photoelectric conversion layer, it is preferably a conductive substrate. Specific examples of the conductive material include tin-doped indium oxide (ITO), indium oxide doped with zinc (IZO), indium oxide doped with tungsten (IWO), oxides of zinc and aluminum (AZO), fluorine-doped tin oxide (FTO), indium oxide (In2O3), and conductive transparent oxide semiconductors such as indium-tin composite oxide. However, it is preferable to use tin-doped indium oxide (ITO) or fluorine-doped tin oxide (FTO).

[0078] <Electron transport layer> In the photoelectric conversion element of the present invention, the electron transport layer 2 shown in FIG. 1 is a layer located between the conductive support 1 and the photoelectric conversion layer (perovskite layer) 3, and it is preferable that the electron transport layer 2 is formed on the conductive support 1, but it is not particularly limited. The electron transport layer is used to improve the electron transfer efficiency from the photoelectric conversion layer to the electrode and to block the hole transfer.

[0079] Specific examples of the semiconductor 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; elemental semiconductors such as silicon and germanium, etc. Two or more of these semiconductors can also be used. In the present invention, it is preferable to use one or more selected from tin oxide, titanium oxide, and zinc oxide as the semiconductor.

[0080] For forming the electron transport layer, a commercially available paste (coating solution for electron transport layer) containing fine particles of the semiconductor may be used, or a paste prepared by dispersing commercially available semiconductor fine powder in a solvent may also be used. Specific examples of the solvent used when preparing the paste include water; alcohol solvents such as methanol, ethanol, and isopropyl alcohol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; hydrocarbon solvents such as n-hexane, cyclohexane, benzene, and toluene, but are not limited thereto. Also, these solvents can be used as a mixed solvent of two or more.

[0081] Examples of the method for dispersing the semiconductor fine powder in the solvent include methods using a disperser such as a ball mill, a paint conditioner, a vertical bead mill, a horizontal bead mill, and an attritor, and the powder may be ground in a mortar or the like in advance and then used. When preparing the paste, it is preferable to add a surfactant or the like to prevent aggregation of the semiconductor fine particles, and it is preferable to add a thickener such as polyethylene glycol to thicken it.

[0082] The electron transport layer can be formed by known film formation methods according to the materials used. Examples of the film formation method for the electron transport layer include wet coating methods such as spin coating method, inkjet method, doctor blade method, drop casting method, squeegee method, screen printing method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, impregnation coating method, and curtain coating method. After forming a coating film on a conductive substrate, a method of removing a solvent and additives by firing to form a film, and methods of forming a film such as sputtering method, vapor deposition method, electrodeposition method, electrodialysis method, and microwave irradiation method can be mentioned, but it is not limited thereto. In the present invention, it is preferable to form a film by spin coating using the coating solution for the electron transport layer prepared by the above method, but it is not limited thereto. Note that the conditions for spin coating can be set as appropriate. The atmosphere for film formation is not particularly limited, and it may be in the air.

[0083] From the viewpoint of further improving the photoelectric conversion efficiency, when a dense electron transport layer is used, the thickness of the electron transport layer is usually preferably 5 nm to 100 nm, and more preferably 10 nm to 50 nm. In the present invention, when a porous (mesoporous) metal oxide is used in addition to the dense layer, its film thickness is usually preferably 20 to 200 nm or less, and more preferably 50 to 150 nm.

[0084] 〈Photoelectric conversion layer〉 In the photoelectric conversion element of the present invention, it is preferable that a photoelectric conversion layer (perovskite layer) 3 is formed on the electron transport layer 2 shown in FIG. 1.

[0085] When the photoelectric conversion element of the present invention is of the perovskite type, examples of the perovskite material used for the photoelectric conversion layer include a series of materials having a structure represented by the general formula ABX3. Here, A, B, and X represent an organic cation or a monovalent metal cation, a metal cation, and a halide anion, respectively. As an example, A = K + 、Rb+ 、Cs + 、CH3NH3 + (hereinafter, MA: methylammonium), NH=CHNH2 + (hereinafter, FA: formamidinium) or CH3CH2NH3 + (hereinafter, EA: ethylammonium); B = Pb 2+ or Sn 2+ ; X = I - or Br - Combinations thereof can be given. Further, specifically, perovskite materials represented by the compositions of MAPbI3, FAPbI3, EAPbI3, CsPbI3, MASnI3, FASnI3, EASnI3, MAPbBr3, FAPbBr3, EAPbBr3, MASnBr3, FASnBr3, and EASnBr3, and perovskite materials composed of mixed cations and mixed anions represented by the compositions of K(FAMA)Pb(IBr)3, Rb(FAMA)Pb(IBr)3, and Cs(FAMA)Pb(IBr)3 can be given, but are not limited thereto. These perovskite materials can also be used in combination of two or more. Further, the photoelectric conversion layer may contain a light absorber other than the perovskite material.

[0086] As a method for forming the photoelectric conversion layer (perovskite layer) of the photoelectric conversion element of the present invention using a coating solution, any coating method can be used, and the same method as the film formation method of the electron transport layer can be given. The perovskite layer can be manufactured by forming a coating film using a precursor solution of a perovskite material and heating this.

[0087] Commercially available perovskite precursors may be used. In the present invention, it is preferable to use a precursor obtained by mixing lead halides, methylammonium halides, formamidine halides, and cesium halides so as to have a desired composition, but is not limited thereto.

[0088] As the solvent for the perovskite precursor solution, from the perspective of the solubility of the precursor, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone, etc. can be mentioned, but it is not limited thereto. Further, these solvents may be used by mixing two or more kinds, and it is preferable to use a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide.

[0089] From the perspective of being able to manufacture a highly efficient photoelectric conversion element with good reproducibility by preventing the incorporation of moisture, the atmosphere during the film formation of the photoelectric conversion layer (perovskite layer) is preferably a dry atmosphere, and more preferably a dry inert gas atmosphere such as a glove box. Further, it is preferable to perform dehydration with a molecular sieve or the like and use a solvent with a low water content.

[0090] From the perspective of more efficiently generating the perovskite material than the precursor, the temperature when heating the photoelectric conversion layer (perovskite layer) with a hot plate or the like is preferably 50 to 200 °C, and more preferably 70 to 150 °C. Further, the heating time is preferably 10 to 90 minutes, and more preferably 10 to 60 minutes.

[0091] From the perspective of further suppressing performance deterioration due to defects and peeling, and ensuring that the photoelectric conversion layer has a sufficient light absorption rate and the device resistance does not become too high, the film thickness of the photoelectric conversion layer (perovskite layer) is preferably 50 to 1000 nm, and more preferably 300 to 700 nm.

[0092] 〈Hole transport layer〉 In the photoelectric conversion element of the present invention, the hole transport layer 4 shown in FIG. 1 is a layer having a function of transporting holes, and is a layer located between the photoelectric conversion layer (perovskite layer) 3 and the counter electrode 5. The hole transport layer is used to improve the hole transfer efficiency from the photoelectric conversion layer to the electrode and block the movement of electrons. For the hole transport layer, for example, a conductor, a semiconductor, an organic hole transport material, etc. can be used, and an additive may be included for the purpose of further improving the hole transport characteristics.

[0093] In the hole transport layer of the photoelectric conversion element of the present invention, it is a layer containing a compound represented by the general formula (1) as a hole transport material. In the hole transport layer, two or more kinds of the compounds represented by the general formula (1) may be used in combination, and it can also be used in combination with other hole transport materials not belonging to the present invention.

[0094] Specific examples of other hole transport materials not belonging to the hole transport material of the present invention include, for example, compound semiconductors containing monovalent copper such as CuI, CuInSe2, and CuS; compounds containing metals other than copper such as GaP, NiO, CoO, FeO, Bi2O3, MoO2, and Cr2O3. These metal oxides may be mixed in the hole transport layer or laminated on the hole transport material. Examples of organic hole transport materials include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyethylenedioxythiophene (PEDOT); fluorene derivatives such as 2,2’,7,7’-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9’-spirobifluorene (Spiro-OMeTAD); carbazole derivatives such as polyvinylcarbazole; triphenylamine derivatives such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA); diphenylamine derivatives; polysilane derivatives; polyaniline derivatives and the like.

[0095] As a method for forming the hole transport layer of the photoelectric conversion element of the present invention using a coating solution, any coating method can be used, and the same method as the film formation method of the electron transport layer can be mentioned.

[0096] As solvents used in the coating liquid for the hole transport layer, there are aromatic organic solvents such as benzene, toluene, xylene, mesitylene, tetralin (1,2,3,4-tetrahydronaphthalene), monochlorobenzene (chlorobenzene), o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, and nitrobenzene; halogenated alkyl organic solvents such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, and dichloromethane; nitrile solvents such as benzonitrile and acetonitrile; ether solvents such as tetrahydrofuran, dioxane, 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; 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 are not limited thereto. Further, the above solvents may be used by mixing two or more kinds, and the solvent to be used can be selected according to the hole transport material to be used. In particular, it is preferable to use aromatic organic solvents and halogenated alkyl organic solvents.

[0097] In the photoelectric conversion element of the present invention, from the viewpoint of further improving the photoelectric conversion efficiency, the film thickness of the hole transport layer is preferably 5 to 500 nm, and more preferably 10 nm to 250 nm.

[0098] From the viewpoint that a highly efficient photoelectric conversion element can be manufactured with good reproducibility by preventing the mixing of moisture, the atmosphere during the film formation of the hole transport layer is preferably a dry atmosphere. Further, it is preferable to use a dehydrated solvent having a moisture content of 10 ppm or less.

[0099] 〈Additive〉 In the photoelectric conversion element of the present invention, as an additive for the hole transport layer, a dopant (or an oxidizing agent) or a basic compound (or a basic additive) may be contained. Incorporating an additive into the hole transport layer to improve the carrier concentration of the hole transport material in the hole transport layer (doping) leads to an improvement in the conversion efficiency of the photoelectric conversion element. In the present invention, when the hole transport layer contains a dopant and a basic additive as additives, it is preferably 3.5 equivalents or less of the additive with respect to 1 equivalent of the hole transport material.

[0100] When incorporating a dopant into the hole transport layer, specific examples of the dopant include lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), silver bis(trifluoromethanesulfonyl)imide, tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)cobalt(III) tris[bis(trifluoromethane)sulfonimide] (FK209), NOSbF6, SbCl5, and SbF5, etc. In the present invention, it is preferable to use lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), but it is not limited thereto.

[0101] When using a dopant, it is preferably 2.0 equivalents or less, and more preferably 0.5 equivalents or less with respect to 1 equivalent of the hole transport material contained in the hole transport layer.

[0102] When incorporating a basic compound into the hole transport layer, specific examples include 4-tert-butylpyridine (tBP), 2-picoline, and 2,6-lutidine, etc. The basic compound is often used in combination when using a dopant. Also in the present invention, it is desirable to use it in combination when using a dopant, and it is preferable to use 4-tert-butylpyridine.

[0103] When using a basic compound, it is preferably 5 equivalents or less, and more preferably 3 equivalents or less with respect to 1 equivalent of the hole transport material contained in the hole transport layer.

[0104] 〈Counter Electrode〉 In the photoelectric conversion element of the present invention, the counter electrode 5 shown in FIG. 1 is a layer that is disposed opposite to the conductive support 1 and formed on the hole transport layer 4, and is used for the exchange of charges with the hole transport layer. In the photoelectric conversion element of the present invention, it is preferable to provide a metal electrode as the counter electrode on the hole transport layer 4, but it is also possible to add an electron blocking layer made of an organic material or an inorganic compound semiconductor between the hole transport layer 4 and the counter electrode 5.

[0105] Specific examples of the material used for the counter electrode include metals such as platinum, titanium, stainless steel, aluminum, gold, silver, nickel, magnesium, chromium, cobalt, and copper, and alloys made of these metals. Among these, it is preferable to use gold, silver, or an alloy of silver in terms of exhibiting high electrical conductivity even in a thin film. As the alloy of silver, an alloy of silver and gold, an alloy of silver and copper, an alloy of silver and palladium, an alloy of silver, copper, and palladium, and an alloy of silver and platinum are preferable in order to be less affected by sulfidation and chlorination and improve the stability as a thin film.

[0106] The counter electrode is preferably a material that can be formed by a method such as vapor deposition.

[0107] When a metal electrode is used as the counter electrode, its film thickness is preferably 10 nm or more, more preferably 50 nm or more, in order to obtain good conductivity.

[0108] In the photoelectric conversion element of the present invention, the conductive support serves as the cathode and the counter electrode serves as the anode. Light such as sunlight is preferably irradiated from the side of the conductive support. By irradiation with light such as sunlight, the photoelectric conversion layer (perovskite layer) absorbs the light and becomes excited, generating electrons and holes. The current flows when these electrons pass through the electron transport layer and the holes pass through the hole transport layer to the electrodes, and the photoelectric conversion element functions.

[0109] When evaluating the performance (characteristics) of the photoelectric conversion element of the present invention, measurements of short-circuit current density, open-circuit voltage, fill factor, and photoelectric conversion efficiency are performed. The short-circuit current density represents the current per 1 cm flowing between both terminals when the output terminals are short-circuited, and the open-circuit voltage represents the voltage between both terminals when the output terminals are open. Also, the fill factor is a 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 influenced by the internal resistance. The photoelectric conversion efficiency is obtained as a value expressed as a percentage by multiplying the value obtained by dividing the maximum output (W) by the light intensity (W) per 1 cm by 100. 2 The photoelectric conversion element of the present invention can be applied to perovskite solar cells, various optical sensors, etc. A perovskite solar cell is obtained by using a photoelectric conversion element containing a hole transport material containing the compound represented by the general formula (1) as a hole transport layer as a cell, arranging a necessary number of such cells to form a module, and providing predetermined electrical wiring. 2 The above describes the preferred embodiments, but the present invention is not limited thereto, and may be appropriately modified without departing from the scope of the present invention.

[0110] The photoelectric conversion element of the present invention can be applied to perovskite solar cells, various optical sensors, etc. A perovskite solar cell is obtained by using a photoelectric conversion element containing a hole transport material containing the compound represented by the general formula (1) as a hole transport layer as a cell, arranging a necessary number of such cells to form a module, and providing predetermined electrical wiring.

[0111] The above describes the preferred embodiments, but the present invention is not limited thereto, and may be appropriately modified without departing from the scope of the present invention.

Example

[0112] Hereinafter, the present invention will be specifically described with reference to the drawings by way of examples, but the present invention is not limited to the following examples. In the synthesis examples, the identification of the compounds obtained was performed by 1 H-NMR (nuclear magnetic resonance apparatus manufactured by JEOL Ltd., JNM-ECZ400S / L1 type).

[0113] [Synthesis Example 1] Synthesis of Compound (A-2) Into a reaction vessel, 2,7-dibromofluorenone (0.63 g, manufactured by Tokyo Chemical Industry Co., Ltd.), [4-[bis(4-methoxyphenyl)amino]phenyl]boronic acid (1.50 g, manufactured by TCI), tetrakis(triphenylphosphine)palladium(0) (0.09 g, manufactured by Kanto Chemical Co., Inc.), potassium carbonate (0.68 g, manufactured by Kanto Chemical Co., Inc.), toluene (10 mL), ethanol (3.5 mL), and water (3.5 mL) were charged, and degassing was performed under reduced pressure. Under an argon atmosphere, the mixture was stirred under heating and reflux for 6 hours. After completion of the reaction, toluene (10 mL) and water (20 mL) were added. This was separated by liquid separation, and the organic layer was washed twice with water (30 mL). The organic layer was concentrated, and the crude product was purified by a silica gel column (toluene) to obtain the compound represented by the following formula (A-2) as a red-violet powder (yield: 1.44 g, yield: 98%).

[0114] 1 1H-NMR (400 MHz, CDCl3): δ (ppm) = 3.81 (12H), 6.85 (8H), 6.98 (4H), 7.10 (8H), 7.43 (4H), 7.53 (2H), 7.67 (2H), 7.86 (2H).

[0115]

Chemical formula

[0116] [Synthesis Example 2] Synthesis of Compound (A-15) Into a reaction vessel, the compound of the above formula (A-2) (0.60 g), malononitrile (0.20 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and 25 mL of THF were charged, and the mixture was stirred under an argon atmosphere. Acetic acid (2.4 mL, manufactured by Kanto Chemical Co., Inc.) and pyridine (2.4 mL, manufactured by Nacalai Tesque Inc.) were added thereto, and the mixture was stirred under heating and reflux for 16 hours. After completion of the reaction, the reaction solution was poured into a beaker containing 300 mL of water. This was filtered and washed with 30 mL of water and 20 mL of methanol. The crude product was purified by a silica gel column (toluene:chloroform = 4:1) to obtain the compound represented by the following formula (A-15) as a black-green powder (yield: 0.54 g, yield: 84%).

[0117] 11H-NMR (400 MHz, CDCl3): δ (ppm) = 3.81 (12H), 6.86 (8H), 6.98 (4H), 7.10 (8H), 7.43 (4H), 7.53 (2H), 7.65 (2H), 8.57 (2H).

[0118] [Chemical formula]

[0119] [Synthesis Example 3] Synthesis of Compound (A-28) Into a reaction vessel, the compound of the above formula (A-2) (0.6 g), diethyl malonate (0.37 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (14 mL) were charged and stirred under an argon atmosphere. It was cooled to 5 °C or lower in an ice bath, and pyridine (1 mL) was added. It was cooled again to 5 °C or lower, and titanium tetrachloride (0.5 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Then, the temperature was raised to room temperature and stirred at room temperature for 17 hours. After completion of the reaction, the reaction solution was poured into a beaker containing 200 mL of water, and toluene (30 mL) was added thereto. This was separated, and the organic layer was dried over magnesium sulfate and then concentrated. The crude product was purified by a silica gel column (toluene) to obtain a compound represented by the following formula (A-28) as a red-violet powder (yield: 0.50 g, yield: 71%).

[0120] 1 1H-NMR (400 MHz, CDCl3): δ (ppm) = 1.37 (6H), 3.81 (12H), 4.43 (4H), 6.86 (8H), 6.99 (4H), 7.11 (8H), 7.40 (4H), 7.56 (2H), 7.60 (2H), 8.04 (2H).

[0121] [Chemical formula]

[0122] [Synthesis Example 4] Synthesis of Compound (A-41) The compound of the above formula (A-2) (0.65 g), methyl cyanoacetate (0.33 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (25 mL) were charged into a reaction vessel and stirred under an argon atmosphere. It was cooled to 5°C or lower in an ice bath, and pyridine (1 mL) was added. It was cooled again to 5°C or lower, and titanium tetrachloride (0.55 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Then, the temperature was raised to room temperature, and after stirring at room temperature for 8 hours, it was stirred under heating under reflux for 2 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (200 mL), and toluene (30 mL) was added thereto. This was separated, and the organic layer was dried over magnesium sulfate and then concentrated. The crude product was purified by a silica gel column (toluene), and the compound represented by the following formula (A-41) was obtained as a blackish green powder (yield: 0.65 g, yield: 90%).

[0123] 1 1H-NMR (400 MHz, CDCl3): δ (ppm) = 3.81 (12H), 4.10 (3H), 6.86 (8H), 6.99 (4H), 7.11 (8H), 7.40 (2H), 7.46 (2H), 7.50 (2H), 7.60 (2H), 8.26 (1H), 8.78 (1H).

[0124] [Chemical Formula]

[0125] [Synthesis Example 5] Synthesis of Compound (A-1) 2,7-Dibromofluorenone (0.75 g, manufactured by Tokyo Chemical Industry Co., Ltd.), 4-(diphenylamino)phenylboronic acid (1.48 g, manufactured by Sigma-Aldrich Co., LLC.), tetrakis(triphenylphosphine)palladium(0) (0.10 g, manufactured by Kanto Chemical Co., Inc.), potassium carbonate (0.80 g, manufactured by Kanto Chemical Co., Inc.), toluene (12 mL), ethanol (4.0 mL), and water (4.0 mL) were charged into a reaction vessel, and degassing was performed under reduced pressure. The mixture was stirred under heating under reflux for 4 hours in an argon atmosphere. After completion of the reaction, the reaction solution was poured into a beaker containing water (100 mL), and toluene (30 mL) was added thereto. This was separated by liquid separation, the organic layer was dried over magnesium sulfate, and then concentrated. The crude product was purified by a silica gel column (toluene). Thereafter, recrystallization was performed with toluene to obtain the compound represented by the following formula (A-1) as a red powder (yield: 1.48 g, yield: 100%).

[0126] 1 1H-NMR (400 MHz, DMSO-d6): δ (ppm) = 7.0 - 7.1 (16H), 7.35 (8H), 7.71 (4H), 7.85 (2H), 7.92 (4H).

[0127]

Chemical formula

[0128] [Synthesis Example 6] Synthesis of Compound (A-27) The compound of the above formula (A-1) (0.6 g), diethyl malonate (0.82 g, manufactured by TCI), and THF (27 mL) were charged into a reaction vessel and stirred in an argon atmosphere. The mixture was cooled to 5°C or lower in an ice bath, and pyridine (1.1 mL) was added. It was cooled again to 5°C or lower, and titanium tetrachloride (0.6 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Thereafter, the temperature was raised to room temperature, and the mixture was stirred at room temperature for 17 hours. After completion of the reaction, the reaction solution was poured into a beaker containing 200 mL of water, and toluene (30 mL) was added thereto. This was separated by liquid separation, the organic layer was dried over magnesium sulfate, and then concentrated. The crude product was purified by a silica gel column (toluene) to obtain the compound represented by the following formula (A-27) as a red powder (yield: 0.52 g, yield: 71%).

[0129] 1 H-NMR (400 MHz, DMSO-d6): δ (ppm) = 1.38 (6H), 4.45 (4H), 7.06 (4H), 7.13 - 7.16 (12H), 7.29 (8H), 7.46 (4H), 7.61 (4H), 7.07 (2H).

[0130]

Chem.

[0131] [Synthesis Example 7] Synthesis of Compound (A-14) The compound of the above formula (A-1) (0.60 g), malononitrile (0.23 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (50 mL) were charged into a reaction vessel and stirred under an argon atmosphere. Acetic acid (2.8 mL, manufactured by Kanto Chemical Co., Inc.) and pyridine (2.8 mL, manufactured by Nacalai Tesque, Inc.) were added thereto, and the mixture was stirred under reflux heating for 6 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (200 mL). This was filtered and washed with water (20 mL) and methanol (20 mL). The crude product was recrystallized (chloroform) to obtain the compound represented by the following formula (A-14) as a blackish green powder (yield: 0.58 g, yield: 91%).

[0132] 1 H-NMR (400 MHz, THF-d8): δ (ppm) = 7.0 - 7.1 (16H), 7.35 (8H), 7.71 (4H), 7.92 (4H), 8.56 (2H).

[0133]

Chem.

[0134] [Synthesis Example 8] Synthesis of Compound (A-67) 2,7-Dibromofluorenone (0.47 g, manufactured by Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (9) (2.71 g), tetrakis(triphenylphosphine)palladium(0) (0.065 g, manufactured by Kanto Chemical Co., Inc.), potassium carbonate (0.51 g, manufactured by Kanto Chemical Co., Inc.), toluene (7.5 mL), ethanol (2.5 mL), and water (2.5 mL) were charged into a reaction vessel, and degassing was performed under reduced pressure. The mixture was stirred under heating and reflux in an argon atmosphere for 13 hours. After completion of the reaction, toluene (20 mL) and water (10 mL) were added. This was separated by liquid separation, the aqueous layer was extracted twice with toluene (20 mL), and the organic layer was concentrated. The crude product was purified by a silica gel column (toluene / ethyl acetate = 50 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-67) as a red powder (yield: 1.76 g, yield: 80%).

[0135] 1 1H-NMR (400 MHz, DMSO-d6): δ (ppm) = 3.65 (24H), 6.75 (16H), 6.83 (16H), 7.02 (4H), 7.19 (4H), 7.58 (4H), 7.63 (4H), 7.88 (4H), 7.95 (6H).

[0136]

Chemical formula

[0137] [Synthesis Example 9] Synthesis of Compound (A-82) The compound of the above formula (A-67) (0.70 g), malononitrile (0.12 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (18 mL) were charged into a reaction vessel and stirred under an argon atmosphere. Acetic acid (1.6 mL, manufactured by Kanto Chemical Co., Inc.) and pyridine (1.6 mL, manufactured by Nacalai Tesque Inc.) were added thereto. The mixture was stirred under heating and reflux for 14 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (200 mL). This was filtered and washed with water (30 mL) and methanol (20 mL). The crude product was recrystallized (chloroform / acetone) to obtain the compound represented by the following formula (A-82) as a blackish green powder (yield: 0.67 g, yield: 94%).

[0138] 1H-NMR (400 MHz, THF-d8): δ (ppm) = 3.68 (24H), 6.72 (16H), 6.91 (16H), 7.07 (4H), 7.34 (4H), 7.66 (4H), 7.74 (4H), 7.89 (2H), 7.99 (6H), 8.81 (2H).

[0139]

Chem.

[0140] [Synthesis Example 10] Synthesis of Compound (A-97) 2,7-Dibromofluorenone (0.47 g), the compound of the following formula (10) (2.62 g), tetrakis(triphenylphosphine)palladium(0) (0.065 g, manufactured by Kanto Chemical Co., Inc.), potassium carbonate (0.51 g, manufactured by Kanto Chemical Co., Inc.), toluene (7.5 mL), ethanol (2.5 mL), and water (2.5 mL) were charged into a reaction vessel, and degassing was performed under reduced pressure. The mixture was stirred for 8 hours under heating under reflux in an argon atmosphere. After completion of the reaction, toluene (20 mL) and water (10 mL) were added. This was separated by liquid separation, the aqueous layer was extracted twice with toluene (20 mL), and the organic layer was concentrated. The crude product was purified by a silica gel column (toluene:ethyl acetate = 50 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-97) as a red powder (yield: 1.95 g, yield: 86%).

[0141] 1 H-NMR (400 MHz, THF-d8): δ (ppm) = 3.73 (24H), 6.59 - 6.65 (8H), 6.74 (4H), 6.80 (16H), 6.97 (16H), 7.35 (4H), 7.75 (2H), 7.80 (4H), 7.86 (2H), 7.94 (2H).

[0142]

Chem.

[0143] [Synthesis Example 11] Synthesis of Compound (A-113) The compound of the above formula (A-97) (0.60 g), malononitrile (0.10 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (15 mL) were charged into a reaction vessel and stirred under an argon atmosphere. Acetic acid (1.3 mL, manufactured by Kanto Chemical Co., Inc.) and pyridine (1.3 mL, manufactured by Nacalai Tesque, Inc.) were added thereto. The mixture was stirred under heating under reflux for 20 hours. After completion of the reaction, the reaction solution was poured into water (200 mL). This was filtered and washed with water (30 mL) and methanol (20 mL). After washing the crude product with toluene, recrystallization (chloroform / acetone) was performed to obtain the compound represented by the following formula (A-113) as a green powder (yield: 0.56 g, yield: 90%).

[0144] 1 1H-NMR (400 MHz, THF-d8): δ (ppm) = 3.73 (24H), 6.59 - 6.65 (8H), 6.74 (4H), 6.80 (16H), 6.97 (16H), 7.35 (4H), 7.75 (2H), 7.80 (4H), 7.86 (2H), 8.94 (2H).

[0145] [Chemical Formula]

[0146] [Synthesis Example 12] Synthesis of Compound (A-132) 2,7-Dibromofluorenone (0.47 g), the compound of the following formula (11) (2.57 g), tetrakis(triphenylphosphine)palladium(0) (0.065 g, manufactured by Kanto Chemical Co., Inc.), potassium carbonate (0.51 g, manufactured by Kanto Chemical Co., Inc.), toluene (7.5 mL), ethanol (2.5 mL), and water (2.5 mL) were charged into a reaction vessel, and degassing was performed under reduced pressure. The mixture was heated under reflux for 7 hours under an argon atmosphere. After completion of the reaction, toluene (20 mL) and water (10 mL) were added. This was separated by liquid-liquid extraction, the aqueous layer was extracted twice with toluene (20 mL), and the organic layer was concentrated. The crude product was purified by a silica gel column (toluene / ethyl acetate = 50 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-132) as a red powder (yield: 1.67 g, yield: 75%).

[0147] 1H-NMR (400 MHz, THF-d8): δ (ppm) = 3.75 (24H), 6.60 - 6.66 (8H), 6.76 (4H), 6.82 (16H), 6.97 (16H), 7.36 (4H), 7.78 (2H), 7.83 (4H), 7.87 (2H), 7.95 (2H).

[0148]

Chem.

[0149] [Synthesis Example 13] Synthesis of Compound (A-144) Into a reaction vessel were charged the compound of the above formula (A-132) (0.60 g), malononitrile (0.10 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (15 mL), and the mixture was stirred under an argon atmosphere. Acetic acid (1.3 mL, manufactured by Kanto Chemical Co., Inc.) and pyridine (1.3 mL, manufactured by Nacalai Tesque, Inc.) were added thereto. The mixture was stirred under heating under reflux for 15 hours. After completion of the reaction, the reaction solution was poured into water (200 mL). This was filtered and washed with water (30 mL) and methanol (20 mL). The crude product was recrystallized (chloroform / acetone) to obtain the compound represented by the following formula (A-144) as a green powder (yield: 0.54 g, yield rate: 88%).

[0150] 1 H-NMR (400 MHz, THF-d8): δ (ppm) = 3.75 (24H), 6.60 - 6.66 (8H), 6.76 (4H), 6.82 (16H), 6.97 (16H), 7.36 (4H), 7.78 (2H), 7.83 (4H), 7.87 (2H), 8.95 (2H).

[0151]

Chem.

[0152] [Synthesis Example 14] Synthesis of Compound (A-54) The compound of the above formula (A-2) (0.6 g), 1,3-diethylthiobarbituric acid (0.38 g, manufactured by Wako Pure Chemical Industries, Ltd.), and THF (24 mL) were charged into a reaction vessel and stirred under an argon atmosphere. Piperidine (0.07 mL) was added thereto. The temperature was raised, and the mixture was heated under reflux for 4 hours. After completion of the reaction, the reaction solution was poured into a beaker containing 300 mL of water, filtered, and washed with 30 mL of water and 30 mL of methanol. The crude product was purified by a silica gel column (toluene) to obtain the compound represented by the following formula (A-54) as a blackish green powder (yield: 0.44 g, yield: 60%).

[0153] 1 H-NMR (400 MHz, CDCl3): δ (ppm) = 3.81 (12H), 6.85 (8H), 6.98 (4H), 7.10 (8H), 7.43 (4H), 7.53 (2H), 7.67 (2H), 8.41 (2H).

[0154] [Chemical Formula]

[0155] Synthesis of Compound (A-8) [Synthesis Example 15] 2,7-Dibromofluorenone (0.68 g, manufactured by Tokyo Chemical Industry Co., Ltd.), the compound of the following formula (12) (2.52 g), potassium carbonate (0.72 g, manufactured by Kanto Chemical Co., Inc.), tetrakistriphenylphosphine palladium (0.09 g, manufactured by Kanto Chemical Co., Inc.), toluene (11 mL), ethanol (3 mL), and water (3 mL) were charged into a reaction vessel, and degassing was performed under reduced pressure. The mixture was stirred under heating under reflux for 10 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (100 mL). After adding toluene (20 mL) thereto, liquid separation was performed. The organic layer was dried over magnesium sulfate and concentrated. The crude product was purified by a silica gel column (toluene:hexane = 2 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-8) as a red powder (yield: 1.79 g, yield: 84%).

[0156] 1H-NMR (400 MHz, CDCl3): δ (ppm) = 0.92 (12H), 1.31 - 1.36 (16H), 1.40 - 1.47 (8H), 1.74 - 1.81 (8H), 3.94 (8H), 6.84 (8H), 6.98 (4H), 7.08 (8H), 7.43 (4H), 7.52 (2H), 7.60 (2H), 7.86 (2H).

[0157] [Chemical formula]

[0158] [Synthesis Example 16] Synthesis of Compound (A-20) The compound of the above formula (A-8) (0.68 g), malononitrile (0.22 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (26 mL) were charged into a reaction vessel and stirred under an argon atmosphere. A mixed solution of acetic acid and pyridine (volume ratio = 1:1) (4.6 mL) was added thereto, and the mixture was stirred under heating under reflux for 19 hours. After completion of the reaction, the reaction solution was poured into water (150 mL). Toluene (20 mL) was added thereto, and liquid separation was performed. The organic layer was dried over magnesium sulfate and then concentrated. The crude product was purified by a silica gel column (toluene) to obtain a compound represented by the following formula (A-20) as a blackish green solid (yield: 0.59 g, yield rate: 83%).

[0159] 1 H-NMR (400 MHz, CDCl3): δ (ppm) = 0.92 (12H), 1.31 - 1.36 (16H), 1.40 - 1.47 (8H), 1.74 - 1.81 (8H), 3.94 (8H), 6.84 (8H), 6.98 (4H), 7.08 (8H), 7.43 (4H), 7.52 (2H), 7.65 (2H), 8.57 (2H).

[0160] [Chemical formula]

[0161] [Synthesis Example 17] Synthesis of Compound (A-11) Into a reaction vessel were charged a compound represented by the following formula (13) (1.10 g), [4-[bis(4-methoxyphenyl)amino]phenyl]boronic acid (1.75 g, manufactured by Tokyo Chemical Industry Co., Ltd.), potassium carbonate (0.82 g, manufactured by Kanto Chemical Co., Inc.), tetrakistriphenylphosphine palladium (0.10 g, manufactured by Kanto Chemical Co., Inc.), toluene (18 mL), ethanol (5.1 mL), and water (5.1 mL), and degassing was carried out under reduced pressure. The mixture was heated under reflux for 6 hours. After completion of the reaction, it was cooled to 40 °C or lower, and water (10 mL) and methanol (10 mL) were added. This was filtered, washed with methanol (10 mL), and dried. The crude product was purified by a silica gel column (chloroform:toluene = 50 / 1 (volume ratio)) to obtain a compound represented by the following formula (A-11) as a red powder (yield: 1.79 g, yield: 86%).

[0162] 1 1H-NMR (400 MHz, CDCl3): δ (ppm) = 3.81 (12H), 6.86 (8H), 6.93 (4H), 7.09 (8H), 7.18 (2H), 7.34 (2H), 7.42 (4H), 7.50 (2H), 7.71 (2H), 7.92 (2H).

[0163] [Chemical formula]

[0164] [Synthesis Example 18] Synthesis of Compound (A-23) Into a reaction vessel were charged the compound represented by the above formula (A-11) (0.73 g), malononitrile (0.22 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (26 mL), and the mixture was stirred under an argon atmosphere. To this was added a mixture of acetic acid and pyridine (volume ratio = 1:1) (4.6 mL), and the mixture was heated under reflux for 15 hours. After completion of the reaction, the reaction solution was poured into water (150 mL). This was filtered, washed with methanol (20 mL), and dried. The crude product was purified by a silica gel column (chloroform) to obtain a compound represented by the following formula (A-23) as a blackish green solid (yield: 0.63 g, yield: 83%).

[0165] 1H-NMR (400 MHz, CDCl3): δ (ppm) = 3.81 (12H), 6.87 (8H), 6.93 (4H), 7.09 (8H), 7.18 (2H), 7.34 (2H), 7.42 (4H), 7.60 (2H), 7.90 (2H), 8.65 (2H).

[0166]

Chem.

[0167] [Synthesis Example 19] Synthesis of Compound (A-36) The compound of the above formula (A-11) (0.45 g), diethyl malonate (0.42 mL, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (15 mL) were charged into a reaction vessel and stirred under an argon atmosphere. It was cooled to 5°C or lower in an ice bath, and pyridine (0.63 mL) was added. It was cooled again to 5°C or lower, and titanium tetrachloride (0.32 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Then, the temperature was raised, and it was heated under reflux for 9 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (150 mL). This was filtered, washed with water (10 mL) and methanol (30 mL), and dried. The crude product was purified by a silica gel column (chloroform) to obtain a compound represented by the following formula (A-36) as a brown powder (yield: 0.36 g, yield: 71%).

[0168] 1 H-NMR (400 MHz, THF-d8): δ (ppm) = 1.39 (6H), 3.78 (12H), 4.50 (4H), 6.83 - 6.90 (12H), 7.05 (8H), 7.24 (2H), 7.35 (2H), 7.45 (4H), 7.71 (4H), 8.20 (2H).

[0169]

Chem.

[0170] [Synthesis Example 20] Synthesis of Compound (A-49) The compound of the above formula (A-11) (0.45 g), methyl cyanoacetate (0.25 mL, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (15 mL) were charged into a reaction vessel and stirred under an argon atmosphere. It was cooled to 5 °C or lower in an ice bath, and pyridine (0.63 mL) was added. It was cooled again to 5 °C or lower, and titanium tetrachloride (0.32 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Then, the temperature was raised, and it was heated under reflux for 9 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (150 mL). This was filtered, washed with water (10 mL) and methanol (30 mL), and dried. The crude product was purified by a silica gel column (chloroform) to obtain the compound represented by the following formula (A-49) as a brown powder (yield: 0.46 g, yield: 94%).

[0171] 1 1H-NMR (400 MHz, THF-d8): δ (ppm) = 3.78 (12H), 4.07 (3H), 6.84 - 6.89 (12H), 7.05 (8H), 7.24 (2H), 7.37 (1H), 7.40 (1H), 7.45 (4H), 7.71 (4H), 8.43 (1H), 8.92 (1H).

[0172]

Chemical Formula

[0173] [Synthesis Example 21] Synthesis of Compound (A-79) The compound of the above formula (13) (0.50 g), the compound of the above formula (9) (1.89 g), potassium carbonate (0.37 g, manufactured by Kanto Chemical Co., Inc.), tetrakis(triphenylphosphine)palladium (0.05 g, manufactured by Kanto Chemical Co., Inc.), toluene (10 mL), ethanol (2.3 mL), and water (2.3 mL) were charged into a reaction vessel, and degassing was performed under reduced pressure. It was heated under reflux for 13 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (100 mL). This was filtered, washed with water (10 mL) and methanol (30 mL), and dried. The crude product was purified by a silica gel column (toluene:ethyl acetate = 30 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-79) as a reddish-brown powder (yield: 1.23 g, yield: 71%).

[0174] 1 H-NMR (400 MHz, DMSO-d6): δ (ppm) = 3.70 (24H), 6.82 (16H), 6.88 (16H), 7.09 (4H), 7.32 (4H), 7.64 (6H), 7.67 (4H), 7.70 (2H), 7.84 (2H), 7.89 (2H), 7.94 (6H).

[0175]

Chem.

[0176] [Synthesis Example 22] Synthesis of Compound (A-95) The above compound (A-79) (0.66 g), malononitrile (0.11 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (15 mL) were charged into a reaction vessel and stirred under an argon atmosphere. A mixed solution of acetic acid and pyridine (volume ratio = 1:1) (2.3 mL) was added thereto, and the mixture was heated under reflux for 19 hours. After completion of the reaction, the reaction solution was poured into water (100 mL). This was filtered, washed with methanol (20 mL), and dried. The crude product was purified by recrystallization (chloroform) to obtain a compound represented by the following formula (A-95) as a blackish green solid (yield: 0.54 g, yield: 80%).

[0177] 1 H-NMR (400 MHz, DMSO-d6): δ (ppm) = 3.70 (24H), 6.82 (16H), 6.88 (16H), 7.09 (4H), 7.32 (4H), 7.65 (6H), 7.67 (4H), 7.80 (2H), 7.98 (2H), 8.01 (2H), 8.12 (6H).

[0178]

Chem.

[0179] [Synthesis Example 23] Synthesis of Compound (A-96) The compound of the above formula (A-79) (0.40 g), diethyl malonate (0.20 mL, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (9 mL) were charged into a reaction vessel and stirred under an argon atmosphere. It was cooled to 5°C or lower in an ice bath, and pyridine (0.31 mL) was added. It was cooled again to 5°C or lower, and titanium tetrachloride (0.16 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Then, the temperature was raised and heated under reflux for 6 hours. After completion of the reaction, the reaction solution was poured into a beaker containing water (150 mL). This was filtered, washed with water (10 mL) and methanol (30 mL), and dried. The crude product was purified by a silica gel column (toluene:ethyl acetate = 20 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-96) as a blackish green powder (yield: 0.07 g, yield: 16%).

[0180] 1 1H-NMR (400 MHz, DMSO-d6): δ (ppm) = 1.42 (6H), 3.78 (12H), 4.52 (4H), 6.83 - 6.91 (20H), 6.88 (16H), 7.40 (4H), 7.62 (6H), 7.65 (4H), 7.68 (2H), 7.80 (2H), 7.85 (2H), 7.89 (6H).

[0181]

Chemical formula

[0182] [Synthesis Example 24] Synthesis of Compound (A-83) The compound of the above formula (A-67) (0.30 g), methyl cyanoacetate (0.10 mL, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (7 mL) were charged into a reaction vessel and stirred under an argon atmosphere. It was cooled to 5°C or lower in an ice bath, and pyridine (0.25 mL) was added. It was cooled again to 5°C or lower, and titanium tetrachloride (0.13 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was added. Then, the temperature was raised and heated under reflux for 9 hours. After completion of the reaction, water (20 mL) and toluene (10 mL) were added, and liquid separation was performed. The organic layer was dried over magnesium sulfate and then concentrated. The crude product was purified by a silica gel column (toluene:ethyl acetate = 40 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-83) as a blackish green powder (yield: 0.22 g, yield: 70%).

[0183] 1 H-NMR (400 MHz, THF-d8): δ (ppm) = 3.71 (24H), 4.06 (3H), 6.74 (16H), 6.93 (16H), 7.11 (4H), 7.33 (4H), 7.69 - 7.76 (8H), 7.88 - 7.99 (8H), 8.63 (1H), 9.07 (1H).

[0184] [Chemical formula]

[0185] [Synthesis Example 25] Synthesis of Compound (A-155) The compound of the above formula (A-67) (0.30 g), diethyl malonate (0.18 mL, manufactured by Tokyo Chemical Industry Co., Ltd.), and THF (7 mL) were charged into a reaction vessel and stirred under an argon atmosphere. It was cooled to 5°C or lower in an ice bath, and pyridine (0.25 mL) was charged. It was cooled again to 5°C or lower, and titanium tetrachloride (0.13 mL, manufactured by Wako Pure Chemical Industries, Ltd.) was charged. Then, the temperature was raised, and it was heated under reflux for 9 hours. After completion of the reaction, water (20 mL) and toluene (10 mL) were charged and separated by liquid separation. The organic layer was dried over magnesium sulfate and then concentrated. The crude product was purified by a silica gel column (toluene:ethyl acetate = 50 / 1 (volume ratio)) to obtain the compound represented by the following formula (A-155) as a blackish green powder (yield: 0.26 g, yield: 78%).

[0186] 1 H-NMR (400 MHz, THF-d8): δ (ppm) = 1.35 (6H), 3.71 (24H), 4.45 (4H), 6.73 (16H), 6.91 (16H), 7.10 (4H), 7.35 (4H), 7.70 - 7.72 (8H), 7.84 - 7.91 (8H), 8.34 (2H).

[0187] [Chemical formula]

[0188] [Example 1] Fabrication of a Photoelectric Conversion Element and Evaluation of Current-Voltage Characteristics A glass substrate (conductive support 1, manufactured by Solaronix) coated with a fluorine-doped tin oxide (FTO) thin film that had been subjected to an etching process was ultrasonically cleaned with isopropyl alcohol and then subjected to UV ozone treatment. On this FTO thin film, a tin oxide dispersion (coating solution for the electron transport layer) with a volume ratio of Tin(IV) oxide, 15% in H2O colloidal dispersion (manufactured by Alfa Aesar) and purified water of 1:3 was applied by spin coating. Then, by heating at 150 °C for 30 minutes using a hot plate, a tin oxide thin film (electron transport layer 2) with a film thickness of approximately 40 nm was formed.

[0189] In a glove box under a nitrogen stream, formamidinium hydroiodide (1 M, manufactured by Tokyo Chemical Industry Co., Ltd.), lead(II) iodide (1.1 M, manufactured by Tokyo Chemical Industry Co., Ltd.), methylammonium 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 with a volume ratio of dimethylformamide and dimethyl sulfoxide of 4:1. Then, a dimethyl sulfoxide solution of cesium iodide (1.5 M, manufactured by Tokyo Chemical Industry Co., Ltd.) was added so that the charged amount of cesium was 5% in the composition ratio, and a perovskite precursor solution was prepared. In a glove box under a nitrogen atmosphere, the prepared perovskite precursor solution was dropped onto the tin oxide thin film and spin-coated, and 0.3 mL of chlorobenzene was dropped during the spin coating to form a perovskite precursor film. Then, by heating at 100 °C for 1 hour using a hot plate, a Cs(MAFA)Pb(IBr)3 layer (photoelectric conversion layer 3) with a film thickness of approximately 500 nm was formed.

[0190] In a glove box under a nitrogen stream, 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide were dissolved in chlorobenzene as dopants. The hole transport material (Compound (A-2)) obtained in Synthesis Example 1 was dissolved in the chlorobenzene solution so that the concentration became 50 mM, and 4-tert-butylpyridine was adjusted to 3 equivalents and lithium bis(trifluoromethanesulfonyl)imide was adjusted to 0.5 equivalents with respect to Compound (A-2), to obtain a coating solution for the hole transport layer. In a glove box under a nitrogen atmosphere, the coating solution for the hole transport layer was spin-coated on the 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.

[0191] On the hole transport layer, gold was deposited by vacuum evaporation at a degree of vacuum of about 1×10 -4 Pa to form a gold electrode (counter electrode 5) by forming a film with a thickness of 80 to 100 nm, thereby fabricating a photoelectric conversion element.

[0192] Pseudo sunlight (AM1.5, 100 mW / cm 2 ) generated by a white light irradiation device (manufactured by Spectral Instruments Co., Ltd., OTENTO-SUN SH type) was irradiated from the conductive support side of the photoelectric conversion element, and the current-voltage characteristics were measured using a source meter (manufactured by KEITHLEY, Model 2400 Series SourceMeter) to obtain the photoelectric conversion efficiency. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0193] [Example 2] A photoelectric conversion element was fabricated in the same manner as in Example 1 except that Compound (A-15) was dissolved in the chlorobenzene solution of the above dopants so that the concentration became 30 mM and 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.

[0194] [Example 3] A photoelectric conversion element was fabricated in the same manner as in Example 1 except that compound (A-28) was used instead of compound (A-2), and the photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0195] [Example 4] A photoelectric conversion element was fabricated in the same manner as in Example 1 except that compound (A-41) was used instead of compound (A-2), and the photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0196] [Example 5] A photoelectric conversion element was fabricated in the same manner as in Example 1 except that compound (A-67) was used instead of compound (A-2), and the photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0197] [Comparative Example 1] A photoelectric conversion element was fabricated in the same manner as in Example 1 except that Spiro-OMeTAD (manufactured by Sigma-Aldrich), a standard hole transport material represented by the following formula (B-1), was used instead of compound (A-2), and the photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics. The obtained current-voltage characteristics and photoelectric conversion efficiency are shown in Table 1.

[0198] [Chemical formula]

[0199] [Table 1]

[0200] From the results in Table 1, it can be seen that the photoelectric conversion elements using compounds (A-2), (A-15), (A-28), (A-41) and (A-67) having a fluorenone skeleton of the present invention as hole transport materials show higher photoelectric conversion efficiency compared to the photoelectric conversion element using compound (B-1) which is a standard hole transport material.

[0201] [Example 6] Fabrication of Photovoltaic Device and Evaluation of Current-Voltage Characteristics The glass with a FLAT ITO film (conductive support 1, manufactured by Geomatec Co., Ltd.) was ultrasonically cleaned with isopropyl alcohol and then treated with UV ozone. On this ITO film, a tin oxide dispersion (coating solution for the electron transport layer) with a volume ratio of Tin(IV) oxide, 15% in H2O colloidal dispersion (manufactured by Alfa Aesar) and purified water of 1:9 was applied by spin coating. Then, by heating at 150 °C for 30 minutes on a hot plate, a tin oxide thin film (electron transport layer 2) with a film thickness of about 20 nm was formed.

[0202] In a glove box under a nitrogen stream, formamidinium hydroiodide (1 M, manufactured by Tokyo Chemical Industry Co., Ltd.), lead(II) iodide (1.1 M, manufactured by Tokyo Chemical Industry Co., Ltd.), methylammonium 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 with a volume ratio of dimethylformamide and dimethyl sulfoxide of 4:1. Then, a dimethyl sulfoxide solution of cesium iodide (1.5 M, manufactured by Tokyo Chemical Industry Co., Ltd.) was added so that the charged amount of cesium was 5% in the composition ratio to prepare a perovskite precursor solution. In a glove box under a nitrogen atmosphere, the prepared perovskite precursor solution was dropped onto the tin oxide thin film and spin-coated, and 0.3 mL of chlorobenzene was dropped during the spin coating to form a perovskite precursor film. Then, by heating at 100 °C for 1 hour using a hot plate, a Cs(MAFA)Pb(IBr)3 layer (photovoltaic conversion layer 3) with a film thickness of about 500 nm was formed.

[0203] In a glove box under a nitrogen stream, 4-tert-butylpyridine and lithium bis(trifluoromethanesulfonyl)imide were dissolved in chlorobenzene as dopants. The hole transport material (Compound (A-36)) obtained in Synthesis Example 19 was dissolved in the chlorobenzene solution at 60 °C to a concentration of 30 mM, and 4-tert-butylpyridine was adjusted to 3 equivalents and lithium bis(trifluoromethanesulfonyl)imide was adjusted to 0.5 equivalents with respect to Compound (A-36) to prepare a coating solution for the hole transport layer. In a glove box under a nitrogen atmosphere, the coating solution for the hole transport layer was spin-coated on the 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.

[0204] On the hole transport layer, gold was deposited by vacuum evaporation at a vacuum degree of about 1 × 10 -4 Pa to form a gold electrode (counter electrode 5) with a film thickness of about 80 nm, and a photoelectric conversion element was fabricated.

[0205] The simulated sunlight (AM1.5, 100 mW / cm 2 ) generated by a white light irradiation device (manufactured by Spectral Instruments Co., Ltd., OTENTO-SUN SH type) was irradiated from the conductive support side of the photoelectric conversion element, and the initial photoelectric conversion efficiency was obtained by measuring the current-voltage characteristics using a source meter (manufactured by KEITHLEY, Model 2400 Series SourceMeter). The obtained current-voltage characteristics and initial photoelectric conversion efficiency are shown in Table 2.

[0206] After the measurement of the current-voltage characteristics, the photoelectric conversion element was stored in a desiccator equipped with silica gel for 30 days, and the photoelectric conversion efficiency after 30 days was obtained by measuring the current-voltage characteristics again under simulated sunlight irradiation.

[0207] Using the initial photoelectric conversion efficiency and the photoelectric conversion efficiency over time, which is the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from the following formula (a-1) is shown in Table 2.

[0208]

Equation

[0209] [Example 7] A photoelectric conversion device was fabricated in the same manner as in Example 6, except that Compound (A-49) was dissolved in the chlorobenzene solution of the above dopant so as to be 30 mM at 90 °C and used. The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 6. The initial photoelectric conversion efficiency is shown in Table 2. Using the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from the above formula (a-1) is shown in Table 2.

[0210] [Example 8] A photoelectric conversion device was fabricated in the same manner as in Example 6, except that Compound (A-79) was dissolved in the chlorobenzene solution of the above dopant so as to be 30 mM at 90 °C and used. The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 6. The initial photoelectric conversion efficiency is shown in Table 2. Using the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from the above formula (a-1) is shown in Table 2.

[0211] [Example 9] A photoelectric conversion device was fabricated in the same manner as in Example 6, except that Compound (A-96) was dissolved in the chlorobenzene solution of the above dopant so as to be 40 mM at room temperature and used. The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 6. The initial photoelectric conversion efficiency is shown in Table 2. Using the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from the above formula (a-1) is shown in Table 2.

[0212] [Example 10] A photoelectric conversion device was fabricated in the same manner as in Example 6, except that Compound (A-155) was dissolved in the chlorobenzene solution of the above dopant so as to be 50 mM at room temperature and used. The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 6. The initial photoelectric conversion efficiency is shown in Table 2. Using the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from the above formula (a-1) is shown in Table 2.

[0213] [Example 11] A photoelectric conversion device was fabricated in the same manner as in Example 6, except that Compound (A-83) was dissolved in the chlorobenzene solution of the above dopant to a concentration of 50 mM at room temperature and used. The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 6. The initial photoelectric conversion efficiency is shown in Table 2. Using the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from the above formula (a-1) is shown in Table 2.

[0214] [Example 12] A photoelectric conversion device was fabricated in the same manner as in Example 6, except that Compound (A-11) was dissolved in the chlorobenzene solution of the above dopant to a concentration of 20 mM at 90 °C and used. The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 6. The initial photoelectric conversion efficiency is shown in Table 2. Using the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from formula (a-1) is shown in Table 2.

[0215] [Comparative Example 2] A photoelectric conversion device was fabricated in the same manner as in Example 6, except that Spiro-OMeTAD (manufactured by Sigma-Aldrich), a standard hole transport material represented by the above formula (B-1), was dissolved in the chlorobenzene solution of the above dopant to a concentration of 50 mM at room temperature and used. The initial photoelectric conversion efficiency and the photoelectric conversion efficiency after 30 days were obtained in the same manner as in Example 6. The initial photoelectric conversion efficiency is shown in Table 2. Using the photoelectric conversion efficiency after 30 days, the retention rate (%) calculated from formula (a-1) is shown in Table 2.

[0216]

Table 2

[0217] From the results in Table 2, it can be seen that the photoelectric conversion elements using the compounds (A-36), (A-37), (A-79), (A-96), (A-155) and (A-83) having the fluorenone skeleton of the present invention as hole transport materials exhibit higher photoelectric conversion efficiency as compared with the photoelectric conversion elements using the compound (B-1) which is a standard hole transport material.

[0218] From the results in Table 2, it can be seen that the photoelectric conversion elements using the compounds (A-36), (A-37), (A-79), (A-96), (A-155), (A-83) and (A-11) having the fluorenone skeleton of the present invention as hole transport materials have good storage durability as compared with the photoelectric conversion elements using the compound (B-1) which is a standard hole transport material.

Industrial Applicability

[0219] The photoelectric conversion element using the hole transport material according to the present invention exhibits good photoelectric conversion efficiency and can provide clean energy as a solar cell that can efficiently convert solar energy into electrical energy, and can also be applied to other organic ELs, image sensors, etc.

Explanation of Signs

[0220] 1 Conductive support 2 Electron transport layer 3 Photoelectric conversion layer 4 Hole transport layer 5 Counter electrode

Claims

1. A compound represented by the following general formula (1). 【Chemical 1】 In the formula, R1, R2, R4, R7, R9, R10, R11, R12, R14, R17, R19 and R20 represent a hydrogen atom, R5, R6, R15 and R16 represent a hydrogen atom, or R5 and R6, and R15 and R16 are bonded to each other via a single bond to form a ring, When R5, R6, R15 and R16 are hydrogen atoms, R3, R8, R13 and R18 are a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an isopropoxy group, an isobutoxy group, an s-butoxy group, a t-butoxy group, an isooctyloxy group and a t-octyloxy group A group selected from the group consisting of When R5 and R6, and R15 and R16 are bonded to each other via a single bond to form a ring, R3, R8, R13 and R18 are a methoxy group, an ethoxy group, a propoxy group, an n-butoxy group, an n-pentyloxy group, an n-hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, a decyloxy group, an isopropoxy group, an isobutoxy group, an s-butoxy group, a t-butoxy group, an isooctyloxy group and a t-octyloxy group A diphenylamino group substituted with a group selected from the group consisting of X １ and X ２ represents a divalent group represented by the following general formula (2), Y represents CR ２１ R ２２ and R ２１ and R ２２ each independently represents an acyl group having 1 to 10 carbon atoms which may have a substituent, or an alkoxycarbonyl group having 1 to 10 carbon atoms which may have a substituent. 【Chemical 2】 In the formula, R ２３ to R ２８ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 10 carbon atoms which may have a substituent, a cycloalkyl group having 3 to 10 carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 18 carbon atoms which may have a substituent, or a heterocyclic group having 5 to 18 ring-forming atoms which may have a substituent, R ２３ and R ２４ 、R ２５ and R ２６ and R ２７ and R ２８ may be joined to each other to form a ring, Z represents an oxygen atom, a sulfur atom or a selenium atom, m and n represent an integer of 0 to 2, and both m and n do not become 0.

2. A hole transport material comprising the compound according to Claim 1.

3. A photoelectric conversion element using the hole transport material according to Claim 2.

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