Sensitizing dye, sensitizing dye composition for photoelectric conversion, photoelectric conversion element, and dye-sensitized solar cell

Abstract

To provide a sensitizing dye of a novel structure that can widen a photosensitive wavelength region, and provide a photoelectric conversion element and a dye-sensitized solar cell which use the sensitizing dye as a sensitizing dye composition for photoelectric conversion allowing efficient extraction of current and has excellent photoelectric conversion properties.SOLUTION: A sensitizing dye is represented by formula (1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sensitizing dye, a sensitizing dye composition for photoelectric conversion, a photoelectric conversion element, and a dye-sensitized solar cell. [Background technology]

[0002] In recent years, carbon dioxide generated from fossil fuels such as coal, oil, and natural gas has been causing global warming as a greenhouse gas and environmental destruction due to global warming. It is feared that the increase in global energy consumption due to population growth will lead to further environmental destruction on a global scale. In this situation, the use of renewable energy, which is unlikely to run out unlike fossil fuels, is being actively considered. The use of solar energy, mainly photovoltaic power generation, is becoming increasingly important as a next-generation major renewable energy power generation method that can contribute to preventing global warming, replacing thermal power generation and nuclear power generation that consume fossil fuels. Development and application of solar energy in various fields is progressing, from power generation and charging for watches and small portable electronic devices to small-scale power generation facilities in homes, buildings, and fallow land that can save on utility bills.

[0003] As a means of photovoltaic power generation, photoelectric conversion elements that convert the energy of sunlight into electrical energy are used in solar cells, and as solar cells, inorganic solar cells such as single crystal, polycrystalline, and amorphous silicon, as well as compound semiconductors such as gallium arsenide, cadmium sulfide, and copper indium selenide, have been mainly researched and are currently widely used in homes and small-scale power generation facilities. However, these inorganic solar cells have problems such as high manufacturing costs and difficulties in securing raw materials.

[0004] On the other hand, organic solar cells, such as organic thin-film solar cells and dye-sensitized solar cells, using various organic materials, have also been developed, although their photoelectric conversion efficiency and durability are still significantly lower than those of inorganic solar cells. Organic solar cells are said to have advantages over inorganic solar cells in terms of production costs, large area, light weight, thin film, light transmittance, wide range of absorption wavelengths, flexibility, and availability of raw materials.

[0005] Among these, the dye-sensitized solar cell proposed by Graetzel et al. (see Non-Patent Document 1) is a wet solar cell consisting of a thin-film electrode made of porous titanium oxide as a semiconductor, a ruthenium complex dye adsorbed onto the semiconductor surface to widen the photosensitive wavelength range, and an electrolyte solution containing iodine, and is expected to have a high photoelectric conversion efficiency comparable to that of amorphous silicon solar cells. Dye-sensitized solar cells have a simpler element structure than other solar cells and can be manufactured without large-scale manufacturing facilities, so they are attracting attention as next-generation solar cells.

[0006] Ruthenium complexes are considered to be the most advantageous sensitizing dyes used in dye-sensitized solar cells in terms of photoelectric conversion efficiency, but ruthenium is a precious metal, which is disadvantageous in terms of manufacturing costs, and when a large amount of ruthenium complexes is required for practical use, resource limitations will also be a problem. Therefore, research into dye-sensitized solar cells using organic dyes that do not contain precious metals such as ruthenium as sensitizing dyes has been actively conducted. As organic dyes that do not contain precious metals, coumarin dyes, cyanine dyes, merocyanine dyes, rhodacyanine dyes, phthalocyanine dyes, porphyrin dyes, xanthene dyes, etc. have been reported (see, for example, Patent Documents 1 to 3). The present inventors have also proposed compounds having an acridan skeleton or a phenothiazine skeleton as organic dyes with excellent sensitizing effects (see Patent Document 4).

[0007] In addition, compounds having an indanone structure have been proposed as electron-withdrawing moieties that adsorb onto the surface of semiconductor particles such as titanium oxide and efficiently transport excited electrons generated by a sensitizing dye to the semiconductor (see, for example, Patent Documents 6 to 7).

[0008] Although these organic dyes have the advantages of being inexpensive, having a large absorption coefficient, and being able to control the absorption characteristics due to the diversity of their structures, the current situation is that no dyes that fully satisfy the required characteristics in terms of photoelectric conversion efficiency and stability over time have been obtained. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 11-214730 [Patent Document 2] Japanese Patent Publication No. 11-238905 [Patent Document 3] Japanese Patent Publication No. 2011-26376 [Patent Document 4] Japanese Patent Application Publication No. 2013-60581 [Patent Document 5] Japanese Patent Application Publication No. 2011-207784 [Patent Document 6] Japanese Patent Application Publication No. 2012-51854 [Patent Document 7] Japanese Patent Publication No. 2016-6811 [Non-patent literature]

[0010] [Non-Patent Document 1] Nature, (UK), 1991, Vol. 353, pp. 737-740 Summary of the Invention [Problem to be solved by the invention]

[0011] The problem to be solved by the present invention is to provide a sensitizing dye having a novel structure capable of widening the photosensitive wavelength range, and further to provide a photoelectric conversion element and a dye-sensitized solar cell having good photoelectric conversion characteristics, which use the sensitizing dye as a sensitizing dye composition for photoelectric conversion capable of efficiently extracting electric current. [Means for solving the problem]

[0012] In order to solve the above problems, the inventors have conducted extensive research into improving the photoelectric conversion properties of sensitizing dyes and have found that a highly efficient and durable photoelectric conversion element can be obtained by using a sensitizing dye having a specific structure as a sensitizing dye for photoelectric conversion.

[0013] A sensitizing dye represented by the following general formula (1): [ka] [In the formula, R 0 teeth, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. R 1 ~R 4 may be the same or different, Hydrogen atom, halogen atom, cyano group, hydroxyl group, nitro group, nitroso group, thiol group, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent; an aryl group having 6 to 36 carbon atoms which may have a substituent, or represents an amino group having 0 to 36 carbon atoms which may have a substituent, R 1 ~R 4 Adjacent groups may be bonded to each other to form a ring. X is CR 5 R6 , a sulfur atom, or an oxygen atom; R 5 and R 6 may be the same or different, and each represents a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. Y is a sulfur atom, an oxygen atom, or a CR 7 R 8 or NR 9 represents R 7 ~R 9 may be the same or different, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. A represents a monovalent group, and B represents a divalent group or a single bond.

[0014] A sensitizing dye composition for photoelectric conversion, comprising a sensitizing dye represented by the above general formula (1).

[0015] A photoelectric conversion element using the above sensitizing dye composition for photoelectric conversion.

[0016] A dye-sensitized solar cell using the above photoelectric conversion element. Effect of the Invention

[0017] The sensitizing dye according to the present invention can provide a sensitizing dye composition for photoelectric conversion that can efficiently extract electric current. Furthermore, by using the sensitizing dye composition for photoelectric conversion, a highly efficient and durable photoelectric conversion element and a dye-sensitized solar cell can be obtained. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic cross-sectional view illustrating the configuration of a photoelectric conversion element according to an example of the present invention and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiment. First, the present embodiment will be described by listing its aspects.

[0020] 1. A sensitizing dye represented by the following general formula (1):

[0021] [ka]

[0022] [In the formula, R 0 teeth, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. R 1 ~R 4 may be the same or different, Hydrogen atom, halogen atom, cyano group, hydroxyl group, nitro group, nitroso group, thiol group, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent; an aryl group having 6 to 36 carbon atoms which may have a substituent, or represents an amino group having 0 to 36 carbon atoms which may have a substituent, R 1 ~R 4Adjacent groups may be bonded to each other to form a ring. X is CR 5 R 6 , sulfur atom, or oxygen atom; R 5 and R 6 may be the same or different, and each represents a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. Y is a sulfur atom, an oxygen atom, or a CR 7 R 8 or NR 9 represents R 7 ~R 9 may be the same or different, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. A represents a monovalent group, and B represents a divalent group or a single bond.

[0023] 2. A sensitizing dye in which, in the above general formula (1), A is a monovalent group represented by any one of the following general formulae (2) to (4):

[0024] [ka]

[0025] [In the formula, R 20 and R 21 represents a hydrogen atom or an acidic group, R 20 and R 21 At least one of R is an acidic group. 22 and R 24 represents an acidic group, R 23 and R 25represents a hydrogen atom or an electron-withdrawing group.

[0026] 3. A sensitizing dye represented by the above general formula (1), in which B is a divalent bonding group represented by the following general formula (5) or a single bond:

[0027] [ka]

[0028] [In the formula, Z represents a carbon atom or a silicon atom, R 30 and R 31 may be the same or different, Hydrogen atom, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; It represents a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or an aryl group having 6 to 36 carbon atoms which may have a substituent. R 32 ~R 37 may be the same or different, Hydrogen atom, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; It represents a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent. R 32 and R 33 , R 34 and R 35 , and R 36 and R 37 may be the same or different and may be bonded to each other to form a ring. p, q, and r represent 0 or 1.]

[0029] 4. In the general formula (1), R 0 but, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 26 carbon atoms which may have a substituent, R 1 ~R 4 but, Hydrogen atom, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent; an aryl group having 6 to 36 carbon atoms which may have a substituent, or an amino group having 0 to 36 carbon atoms which may have a substituent, X is CR 5 R 6 , a sulfur atom, Y is a sulfur atom, CR 7 R 8 or NR 9 A sensitizing dye.

[0030] 5. A sensitizing dye composition for photoelectric conversion, comprising the above sensitizing dye.

[0031] 6. A photoelectric conversion element using the above sensitizing dye composition for photoelectric conversion.

[0032] 7. A dye-sensitized solar cell using the above photoelectric conversion element.

[0033] The sensitizing dye composition for photoelectric conversion comprising the sensitizing dye of the present invention is used as a sensitizer in a dye-sensitized photoelectric conversion element. In this specification, the term "sensitizing dye" refers to a compound represented by general formula (1), and the term "sensitizing dye composition for photoelectric conversion" refers to a composition containing one or more compounds represented by general formula (1) and optionally containing other sensitizing dyes not belonging to the present invention. The "photoelectric conversion element" of the present invention is typically a photoelectrode formed by adsorbing a dye to a semiconductor layer on a conductive support, and a counter electrode arranged opposite each other via an electrolyte layer.

[0034] The sensitizing dyes represented by the above formula (1) will be specifically explained below, but the present invention is not limited thereto.

[0035] In the general formula (1), R 0 Specific examples of the "straight-chain or branched alkyl group having 1 to 36 carbon atoms" in the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the above formula include straight-chain alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, and decyl group; and branched alkyl groups such as isopropyl group, isobutyl group, s-butyl group, t-butyl group, and isooctyl group.

[0036] In the general formula (1), R 0 Specific examples of the "aryl group having 6 to 36 carbon atoms" in the "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the formula (1) include aryl groups such as a phenyl group, a naphthyl group, a biphenyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a triphenylenyl group, an indenyl group, and a fluorenyl group. Here, the "aryl group" in the present invention represents an aromatic hydrocarbon group and a condensed polycyclic aromatic group, and among these, a phenyl group, a naphthyl group, and a biphenyl group are preferred.

[0037] In the general formula (1), R 0 The "substituent" in the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" and the "aryl group having 6 to 36 carbon atoms which has a substituent" represented by the following formula is Specifically, halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; Cyano group; Hydroxyl group; Nitro group; Nitroso group; Thiol group; Straight-chain alkyl groups having 1 to 30 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups; Branched alkyl groups having 3 to 30 carbon atoms, such as an isopropyl group, an isobutyl group, a s-butyl group, a t-butyl group, or an isooctyl group; cycloalkyl groups having 3 to 30 carbon atoms, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group; linear alkoxy groups having 1 to 30 carbon atoms, such as a methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, or decyloxy group; Branched alkoxy groups having 3 to 30 carbon atoms, such as an isopropoxy group, an isobutoxy group, a s-butoxy group, a t-butoxy group, or an isooctyloxy group; cycloalkoxy groups having 3 to 30 carbon atoms, such as a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, or a cyclohexyloxy group; a vinyl group, an allyl group, an isopropenyl group, a 2-butenyl group, a 1-hexenyl group, or a linear or branched alkenyl group having 2 to 30 carbon atoms in which a plurality of these alkenyl groups are bonded; Aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a naphthyl group, a biphenyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a triphenylenyl group, an indenyl group, or a fluorenyl group; Unsubstituted amino groups; amino groups having a substituent having 1 to 30 carbon atoms, such as a methylamino group, a dimethylamino group, a diethylamino group, an ethylmethylamino group, a methylpropylamino group, a di-t-butylamino group, or a diphenylamino group; Examples of the substituents include a carboxyl group, a carboxylate group such as a methyl ester group or an ethyl ester group, and the like. Only one or more of these "substituents" may be included, and when more than one is included, they may be the same or different. Furthermore, these "substituents" may further have the substituents exemplified above.

[0038] In the general formula (1), R 0is preferably a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 26 carbon atoms which may have a substituent, more preferably an aryl group having 6 to 16 carbon atoms which may have a substituent, and even more preferably an aryl group having 6 to 12 carbon atoms. 0 The "substituent" in the formula (I) is preferably a linear alkoxy group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent, more preferably a linear alkoxy group having 1 to 10 carbon atoms, a linear or branched alkenyl group having 2 to 6 carbon atoms which may have a substituent, or an aryl group having 6 to 16 carbon atoms which may have a substituent, and even more preferably a linear alkoxy group having 1 to 10 carbon atoms, a linear or branched alkenyl group having 2 to 6 carbon atoms substituted with an aryl group having 6 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0039] In the general formula (1), R 1 ~R 4 Specific examples of the "halogen atom" represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0040] In the general formula (1), R 1 ~R 4 In the "linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1), the "alkyl group having 1 to 36 carbon atoms" is, for example, 0 Examples of the alkyl group include the same as the "alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0041] In the general formula (1), R 1 ~R 4Specific examples of the "cycloalkyl group having 3 to 36 carbon atoms" in the "cycloalkyl group having 3 to 36 carbon atoms which may have a substituent" represented by the following formula include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group.

[0042] In the general formula (1), R 1 ~R 4 Specific examples of the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms" in the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the above formula include straight-chain alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, and decyloxy group; and branched alkoxy groups such as isopropoxy group, isobutoxy group, s-butoxy group, t-butoxy group, and isooctyloxy group.

[0043] In the general formula (1), R 1 ~R 4 Specific examples of the "cycloalkoxy group having 3 to 36 carbon atoms" in the "cycloalkoxy group having 3 to 36 carbon atoms which may have a substituent" represented by the following formula include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

[0044] In the general formula (1), R 1 ~R 4 Specific examples of the "straight-chain or branched alkenyl group having 2 to 36 carbon atoms" in the "straight-chain or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent" represented by the above formula include alkenyl groups such as a vinyl group, an allyl group, an isopropenyl group, a 2-butenyl group, and a 1-hexenyl group, or straight-chain or branched alkenyl groups in which a plurality of these alkenyl groups are bonded.

[0045] In the general formula (1), R 1 ~R4 In the "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the general formula (1), R 0 Examples of the aryl group include the same as the "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0046] In the general formula (1), R 1 ~R 4 Specific examples of the "amino group having 0 to 36 carbon atoms" in the "amino group having 0 to 36 carbon atoms which may have a substituent" represented by the above formula include an unsubstituted amino group (—NH2: amino group); a methylamino group, a dimethylamino group, a diethylamino group, an ethylmethylamino group, a methylpropylamino group, a di-t-butylamino group, and a diphenylamino group.

[0047] In the general formula (1), R 1 ~R 4 Examples of the "substituent" in the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which has a substituent", "a cycloalkyl group having 3 to 36 carbon atoms which may have a substituent", "a straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent", "a cycloalkoxy group having 3 to 36 carbon atoms which may have a substituent", "a straight-chain or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent", "an aryl group having 6 to 36 carbon atoms which may have a substituent", or "an amino group having 0 to 36 carbon atoms which may have a substituent" represented by the formula (1) include R 0 Examples of the "substituent" include the same as those in the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" and the "aryl group having 6 to 36 carbon atoms which has a substituent" represented by the following formula:

[0048] In the general formula (1), R 1 ~R 4may be the same or different and are preferably a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms which may have a substituent, an aryl group having 6 to 24 carbon atoms which may have a substituent, or an amino group having 0 to 24 carbon atoms which may have a substituent, and more preferably a hydrogen atom or an aryl group having 6 to 24 carbon atoms which may have a substituent.

[0049] In the general formula (1), R 1 ~R 4 represents a substituent as described above, but adjacent groups may be bonded to each other to form a ring, and these rings may be bonded to each other via a single bond, a nitrogen atom, an oxygen atom, or a sulfur atom to form a ring.

[0050] In the general formula (1), R 1 ~R 4 is preferably a hydrogen atom, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent, a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent, an aryl group having 6 to 36 carbon atoms which may have a substituent, or an amino group having 0 to 36 carbon atoms which may have a substituent, and is preferably a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent. 1 ~R 4 Of these, R 1 , R 2 and R 4 is a hydrogen atom, and R 3may be a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a linear or branched alkoxy group having 1 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, or an amino group having 0 to 20 carbon atoms which may have a substituent. 1 ~R 4 Of these, R 1 , R 2 and R 4 is a hydrogen atom, and R 3 However, it may be an aryl group having 6 to 20 carbon atoms.

[0051] In the general formula (1), X is CR 5 R 6 , sulfur or oxygen atom, CR 5 R 6 In R 5 and R 6 The "alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, 0 The alkyl group may be the same as the "alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula: 5 and R 6 The "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, R 1 ~R 4 Examples of the alkoxy group include the same as the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula: 5 and R 6 The "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, 0 Examples of the aryl group having 6 to 36 carbon atoms which may have a substituent include those represented by the formula: 5 and R 6 In the present invention, X is CR 5 R 6 or a sulfur atom is preferred, CR 5 R6 is more preferred.

[0052] In the general formula (1), X is CR 5 R 6 In the case where R 5 and R 6 is preferably a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent, or an aryl group having 6 to 36 carbon atoms which may have a substituent, more preferably an aryl group having 6 to 36 carbon atoms which may have a substituent, and even more preferably an aryl group having 6 to 20 carbon atoms. When the aryl group is a benzene ring, it is sometimes represented as Ph in the present specification.

[0053] In the general formula (1), Y is a sulfur atom, an oxygen atom, CR 7 R 8 or NR 9 CR 7 R 8 or NR 9 In R 7 ~R 9 The "alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, 0 The alkyl group may be the same as the "alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula: 7 ~R 9 The "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, R 1 ~R 4 Examples of the alkoxy group include the same as the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula: 7 ~R 9 The "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, 0 Examples of the aryl group having 6 to 36 carbon atoms which may have a substituent include those represented by the formula: 7 ~R 9may be the same or different. In the present invention, Y is a sulfur atom, CR 7 R 8 or NR 9 is preferred, and a sulfur atom or CR 7 R 8 is more preferred.

[0054] In the general formula (1), Y is CR 7 R 8 In the case where R 7 and R 8 is preferably a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent, or an aryl group having 6 to 36 carbon atoms which may have a substituent, more preferably a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent, and even more preferably a linear or branched alkyl group having 1 to 16 carbon atoms.

[0055] In the general formula (1), Y is NR 9 In the case where R 9 is more preferably a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent, or an aryl group having 6 to 36 carbon atoms which may have a substituent, and further preferably a linear or branched alkyl group having 1 to 16 carbon atoms.

[0056] In the general formula (1), A is preferably represented by any one of the monovalent groups of the general formulae (2) to (4) above.

[0057] In general formula (2), R 20 and R 21 represents hydrogen or an acidic group, R 20 or R 21At least one of the groups is an acidic group. Specific examples of the "acidic group" include a carboxyl group, a sulfonic acid group, a phosphoric acid group, a hydroxamic acid group, a phosphonic acid group, a boric acid group, a phosphinic acid group, and a silanol group. Among these, a carboxyl group or a phosphonic acid group is preferred, and a carboxyl group is more preferred. A sensitizing dye containing a carboxyl group or a phosphonic acid group as an acidic group can be easily adsorbed onto the surface of a semiconductor layer, which leads to further improvement in the photoelectric conversion characteristics of a photoelectric conversion element using the sensitizing dye.

[0058] In general formula (3), R 22 and R in general formula (4). 24 Examples of the "acidic group" represented by the formula (1) include the same as the "acidic group" in general formula (2).

[0059] In general formula (4), R 23 and R 25 represents a hydrogen atom or an electron-withdrawing group, and specific examples of the "electron-withdrawing group" include: Halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; Examples include a cyano group, a hydroxyl group, a nitro group, a nitroso group, a carboxyl group, a formyl group, an ester group, a trifluoromethyl group, etc. Among these, a cyano group, a nitro group, a trifluoromethyl group, a carboxyl group, etc. are preferred.

[0060] In general formula (1), B is preferably a divalent group represented by general formula (5) above or a single bond.

[0061] In general formula (5), R 30 and R 31 The "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, R 0 Examples of the alkyl group include the same as the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0062] In the general formula (5), R 30 and R 31 In the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1), the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms" is represented by the formula (1), 1 ~R 4 Examples of the alkoxy group include the same as the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0063] In the general formula (5), R 30 and R 31 In the "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the general formula (1), R 0 Examples of the aryl group include the same as the "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0064] In the general formula (5), R 32 ~R 37 The "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) is, for example, R 0 Examples of the alkyl group include the same as the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0065] In the general formula (5), R 32 ~R 37 In the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1), the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms" is represented by the formula (1), 1 ~R 4 Examples of the alkoxy group include the same as the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the following formula:

[0066] In the general formula (5), R32 ~R 37 In the "straight-chain or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent" represented by the formula (1), R 1 ~R 4 Examples of the alkyl group include the "straight-chain or branched alkenyl group having 2 to 36 carbon atoms" represented by the following formula:

[0067] In the general formula (5), R 32 and R 33 , R 34 and R 35 , and R 36 and R 37 may be the same or different and represent the substituents as described above, but adjacent groups may be bonded to each other to form a ring, and these rings may be bonded to each other to form a ring via a single bond, a nitrogen atom, an oxygen atom, or a sulfur atom.

[0068] In general formula (5), p may be 0, q may be 0, and r may be 0; p may be 1, q may be 0, and r may be 0; p may be 0, q may be 1, and r may be 0; p may be 0, q may be 0, and r may be 1; p may be 1, q may be 1, and r may be 0; p may be 1, q may be 0, and r may be 1; p may be 0, q may be 1, and r may be 1; p may be 1, q may be 1, and r may be 1.

[0069] In the present invention, the sensitizing dye represented by formula (1) includes all possible stereoisomers. Any stereoisomer can be suitably used as the sensitizing dye in the present invention. For example, in formula (1), B is a divalent group or single bond represented by formula (5), A is a monovalent group represented by formula (2), p is 0, q is 0, r is 0, R 20 is a hydrogen atom, and R 21 When is a carboxyl group, the sensitizing dye of the present invention includes compounds represented by the following general formulas (6) and (7). The sensitizing dye may also be a mixture of two or more kinds selected from these stereoisomers.

[0070] [ka]

[0071] Specific examples of the sensitizing dye compound of the present invention represented by formula (1) are shown below, but the present invention is not limited to these. The following exemplary compounds are merely examples of possible stereoisomers and include all other stereoisomers. Each may also be a mixture of two or more stereoisomers.

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079]

change

[0080]

change

[0081]

change

[0082]

change

[0083]

change

[0084]

change

[0085]

change

[0086]

change

[0087]

change

[0088]

change

[0089]

change

[0090]

change

[0091]

change

[0092]

change

[0093]

change

[0094]

change

[0095]

change

[0096]

change

[0097]

change

[0098]

change

[0099]

change

[0100]

change

[0101]

change

[0102]

change

[0103]

change

[0104]

change

[0105]

change

[0106]

change

[0107]

change

[0108]

change

[0109]

change

[0110]

change

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] The sensitizing dye of the present invention represented by general formula (1) can be synthesized by a known method. In the following, in general formula (1), Y is a sulfur atom, B is a divalent group or a single bond represented by general formula (5), A is a monovalent group represented by general formula (2), p is 0, q is 1, r is 0, R 32 , R 33 , R 34 , and R 35 A synthesis example in which is a hydrogen atom is shown below.

[0117] The bromo compound represented by general formula (9) can be synthesized by carrying out a cross-coupling reaction such as Suzuki-Miyaura coupling between the corresponding substituted boronate compound represented by general formula (8) and 4-bromo-2,1,3-benzothiadiazole, followed by a bromination reaction.

[0118] [ka]

[0119] Subsequently, a cross-coupling reaction between the bromo compound represented by the general formula (9) and 4-formylphenylboronic acid is carried out to synthesize a formyl compound represented by the general formula (10).

[0120] [ka]

[0121] Subsequently, the formyl compound represented by general formula (10) obtained as above is subjected to a condensation reaction with an indenone compound represented by general formula (11), whereby the sensitizing dye represented by general formula (1) of the present invention can be synthesized.

[0122] In the general formula (11), R 20 and R 21 represents a hydrogen atom or an acidic group, and at least R 20 or R 21 is an acidic group.

[0123] R in the general formulas (8) to (11) in the above synthesis examples 0 ~R 4 , R 20 and R 21 represents R in the general formula (1) of the present invention. 0 ~R 4 and R in general formula (2) 20 , R 21 It has the same meaning as:

[0124] The starting material represented by the general formula (8) may be a commercially available product or may be synthesized by a known method. The indenone compound represented by the general formula (11) may be easily synthesized by the method described in the above Patent Documents 6 to 7.

[0125] Methods for purifying the sensitizing dye compound of the present invention represented by general formula (1) include known methods such as purification by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, etc., recrystallization or crystallization using a solvent, etc. Furthermore, these compounds can be identified by nuclear magnetic resonance analysis (NMR), etc.

[0126] The sensitizing dye of the present invention may be used alone or in combination of two or more kinds. The sensitizing dye of the present invention may be used in combination with other sensitizing dyes not belonging to the present invention. Specific examples of other sensitizing dyes include ruthenium complexes, coumarin dyes, cyanine dyes, merocyanine dyes, rhodacyanine dyes, phthalocyanine dyes, porphyrin dyes, xanthene dyes, and other sensitizing dyes other than the sensitizing dye represented by the general formula (1). When the sensitizing dye of the present invention is used in combination with these other sensitizing dyes as a photoelectric conversion composition, the amount of the other sensitizing dye relative to the sensitizing dye of the present invention is preferably 10 to 200% by weight, more preferably 20 to 100% by weight.

[0127] The sensitizing dye of the present invention can be applied as a spectral sensitizing dye for photoconductors, photocatalysts, photofunctional materials, etc. for various imaging materials such as silver halide, zinc oxide, and titanium oxide, and can also be applied as a photoelectric conversion sensitizing dye composition used in dye-sensitized photoelectric conversion elements. In the present invention, the method for producing a dye-sensitized photoelectric conversion element is not particularly limited, but a method of forming a semiconductor layer on a conductive support (electrode) and adsorbing (supporting) the photoelectric conversion sensitizing dye composition of the present invention to the semiconductor layer to produce a photoelectrode is preferred (see FIG. 1. Needless to say, the figure is not a faithful scale representation of the actual element, in order to prioritize understanding). As a method for adsorbing the dye, a method of immersing the semiconductor layer in a solution obtained by dissolving the dye in a solvent for a long period of time is common. When two or more sensitizing dyes of the present invention are used in combination, or when the sensitizing dye of the present invention is used in combination with another sensitizing dye, a mixed solution of all the dyes to be used may be prepared and the semiconductor layer may be immersed in the mixed solution, or a separate solution may be prepared for each dye and the semiconductor layer may be immersed in each solution in turn.

[0128] In the present invention, in addition to a metal plate, a glass substrate or a plastic substrate having a conductive layer having a conductive material on the surface can be used as the conductive support. Specific examples of the conductive material include metals such as gold, silver, copper, aluminum, and platinum, conductive transparent oxide semiconductors such as fluorine-doped tin oxide and indium-tin composite oxide, and carbon, but it is preferable to use a glass substrate coated with a fluorine-doped tin oxide thin film.

[0129] Specific examples of the semiconductor forming the semiconductor layer in the present invention include metal oxides such as titanium oxide, zinc oxide, tin oxide, indium oxide, zirconium oxide, tungsten oxide, tantalum oxide, iron oxide, gallium oxide, nickel oxide, and yttrium oxide; metal sulfides such as titanium sulfide, zinc sulfide, zirconium sulfide, copper sulfide, tin sulfide, indium sulfide, tungsten sulfide, cadmium sulfide, and silver sulfide; metal selenides such as titanium selenide, zirconium selenide, indium selenide, and tungsten selenide; and elemental semiconductors such as silicon and germanium. These semiconductors can be used alone or in combination of two or more. In the present invention, it is preferable to use one or more semiconductors selected from titanium oxide, zinc oxide, and tin oxide as the semiconductor.

[0130] The embodiment of the semiconductor layer in the present invention is not particularly limited, but a thin film having a porous structure made of fine particles is preferred. When the substantial surface area of ​​the semiconductor layer is increased by the porous structure or the like, and the amount of dye adsorbed to the semiconductor layer is increased, a highly efficient photoelectric conversion element can be obtained. The diameter of the semiconductor particles is preferably 5 to 500 nm, more preferably 10 to 100 nm. The film thickness of the semiconductor layer is usually 1 to 100 μm, more preferably 1 to 20 μm. Examples of the method for producing the semiconductor layer include a method in which a paste containing semiconductor fine particles is applied onto a conductive substrate by a wet coating method such as a spin coating method, a doctor blade method, a squeegee method, or a screen printing method, and then the paste is baked to remove the solvent or additives to form a film, and a method for forming a film by a sputtering method, a vapor deposition method, an electrodeposition method, an electrodeposition method, a microwave irradiation method, or the like, but is not limited thereto.

[0131] In the present invention, the paste containing semiconductor fine particles may be a commercially available product, or a paste prepared by dispersing commercially available semiconductor fine powder in a solvent may be used. Specific examples of the solvent used in preparing the paste include, but are not limited to, water; alcohol-based solvents such as methanol, ethanol, and isopropyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and hydrocarbon-based solvents such as n-hexane, cyclohexane, benzene, and toluene. These solvents may be used alone or as a mixture of two or more of them.

[0132] In the present invention, the semiconductor fine powder may be dispersed in a solvent after grinding the powder in a mortar or the like, or a dispersing machine such as a ball mill, a paint conditioner, a vertical bead mill, a horizontal bead mill, an attritor, etc. When preparing a paste, it is preferable to add a surfactant or the like to prevent aggregation of the semiconductor fine particles, and it is preferable to add a thickener such as polyethylene glycol to thicken the paste.

[0133] The adsorption of the sensitizing dye composition for photoelectric conversion of the present invention onto the surface of a semiconductor layer can be carried out, for example, by immersing the semiconductor layer in the dye solution and leaving it at room temperature for 30 minutes to 100 hours or under heating for 10 minutes to 24 hours. In this case, it is preferable to leave it at room temperature for 10 to 20 hours, and the dye concentration in the dye solution is preferably 10 to 2000 μM, more preferably 50 to 500 μM.

[0134] Specific examples of the solvent used when adsorbing the photoelectric conversion sensitizing dye of the present invention on the semiconductor layer surface include, but are not limited to, alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, and t-butyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based solvents such as ethyl formate, ethyl acetate, and n-butyl acetate; ether-based solvents such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, and 1,3-dioxolane; amide-based solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; nitrile-based solvents such as acetonitrile, methoxyacetonitrile, and propionitrile; halogenated hydrocarbon-based solvents such as dichloromethane, chloroform, bromoform, and o-dichlorobenzene; and hydrocarbon-based solvents such as n-hexane, cyclohexane, benzene, and toluene. These solvents are used alone or as a mixture of two or more of them. Among these solvents, it is preferable to use one or more selected from methanol, ethanol, t-butyl alcohol, acetone, methyl ethyl ketone, tetrahydrofuran, and acetonitrile.

[0135] When the photoelectric conversion sensitizing dye composition of the present invention is adsorbed on the surface of the semiconductor layer, cholic acid or a cholic acid derivative such as deoxycholic acid, chenodeoxycholic acid, lithocholic acid, or dehydrocholic acid may be dissolved in the dye solution and co-adsorbed with the dye. By using cholic acid or a cholic acid derivative, the association of the dyes is suppressed, and electrons can be efficiently injected from the dye to the semiconductor layer in the photoelectric conversion element. When cholic acid or a cholic acid derivative is used, the concentration of the cholic acid or a cholic acid derivative in the dye solution is preferably 0.1 to 100 mM, more preferably 0.5 to 10 mM.

[0136] The counter electrode (electrode) used in the photoelectric conversion element of the present invention is not particularly limited as long as it has conductivity, but it is preferable to use a conductive material with catalytic ability in order to promote the oxidation-reduction reaction of redox ions. Specific examples of the conductive material include, but are not limited to, platinum, rhodium, ruthenium, carbon, etc. In the present invention, it is particularly preferable to use a platinum thin film formed on a conductive support as the counter electrode. In addition, as a method for producing a conductive thin film, a method in which a paste containing a conductive material is applied to a conductive substrate by a wet coating method such as a spin coating method, a doctor blade method, a squeegee method, or a screen printing method, and then the paste is baked to remove the solvent or additives to form a film, or a method for forming a film by a sputtering method, a vapor deposition method, an electrodeposition method, an electrodeposition method, a microwave irradiation method, or the like, but is not limited to these.

[0137] In the photoelectric conversion element of the present invention, an electrolyte is filled between a pair of opposing electrodes to form an electrolyte layer. The electrolyte used is preferably a redox electrolyte. Examples of redox electrolytes include, but are not limited to, redox ion pairs such as iodine, bromine, tin, iron, chromium, and anthraquinone. Among these, iodine-based electrolytes and bromine-based electrolytes are preferred. In the case of iodine-based electrolytes, for example, mixtures of iodine such as potassium iodide, lithium iodide, and dimethylpropylimidazolium iodide are used. In the present invention, it is preferable to use an electrolyte solution obtained by dissolving these electrolytes in a solvent. The concentration of the electrolyte in the electrolyte solution is preferably 0.05 to 5M, more preferably 0.2 to 1M.

[0138] Examples of the solvent for dissolving the electrolyte include, but are not limited to, nitrile-based solvents such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and benzonitrile; ether-based solvents such as diethyl ether, 1,2-dimethoxyethane, and tetrahydrofuran; amide-based solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and lactone-based solvents such as γ-butyrolactone and γ-valerolactone. These solvents are used alone or as a mixed solvent of two or more kinds. Among these solvents, nitrile-based solvents are preferred.

[0139] In the present invention, in order to further improve the open circuit voltage and fill factor of the dye-sensitized photoelectric conversion element, an amine-based compound may be contained in the electrolyte. Examples of the amine-based compound include 4-t-butylpyridine, 4-methylpyridine, 2-vinylpyridine, N,N-dimethyl-4-aminopyridine, N,N-dimethylaniline, and N-methylbenzimidazole. The concentration of the amine-based compound in the electrolyte is preferably 0.05 to 5M, more preferably 0.2 to 1M.

[0140] As the electrolyte in the photoelectric conversion element of the present invention, a gel electrolyte obtained by adding a gelling agent or a polymer, or a solid electrolyte using a polymer such as a polyethylene oxide derivative may be used. By using a gel electrolyte or a solid electrolyte, volatilization of the electrolytic solution can be reduced.

[0141] In the photoelectric conversion element of the present invention, a solid charge transport layer may be formed between a pair of opposing electrodes instead of an electrolyte. The charge transport material contained in the solid charge transport layer is preferably a hole transport material. Specific examples of the charge transport material include inorganic hole transport materials such as copper iodide, copper bromide, and copper thiocyanide, and organic hole transport materials such as polypyrrole, polythiophene, poly-p-phenylenevinylene, polyvinylcarbazole, polyaniline, oxadiazole derivatives, triphenylamine derivatives, pyrazoline derivatives, fluorenone derivatives, hydrazone compounds, and stilbene compounds, but are not limited thereto.

[0142] In the present invention, when a solid charge transport layer is formed using an organic hole transport material, a film-forming binder resin may be used in combination. Specific examples of the film-forming binder resin include, but are not limited to, polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polysulfone resin, polyester resin, polyphenylene oxide resin, polyarylate resin, alkyd resin, acrylic resin, and phenoxy resin. These resins can be used alone or as a copolymer, or two or more types can be mixed together. The amount of these binder resins used relative to the organic hole transport material is preferably 20 to 1000% by weight, more preferably 50 to 500% by weight.

[0143] In the photoelectric conversion element of the present invention, the electrode (photoelectrode) provided with the semiconductor layer to which the photoelectric conversion sensitizing dye composition is adsorbed serves as the cathode, and the counter electrode serves as the anode. Light such as sunlight may be irradiated from either the photoelectrode side or the counter electrode side, but it is preferable to irradiate from the photoelectrode side. When irradiated with sunlight or the like, the dye absorbs the light, becomes excited, and releases electrons. These electrons flow to the outside via the semiconductor layer and move to the counter electrode. Meanwhile, the dye that has released electrons and is in an oxidized state receives electrons supplied from the counter electrode via ions in the electrolyte, and returns to the ground state. This cycle allows current to flow, and the element functions as a photoelectric conversion element.

[0144] When evaluating the performance (characteristics) of the photoelectric conversion element of the present invention, the short-circuit current, open-circuit voltage, fill factor, and photoelectric conversion efficiency are measured. The short-circuit current is the current of 1 cm that flows between both terminals when the output terminals are short-circuited. 2 The open circuit voltage is the voltage between the output terminals when they are open. The fill factor is the maximum output (product of current and voltage) divided by the product of short circuit current and open circuit voltage, and is mainly dependent on the internal resistance. The photoelectric conversion efficiency is the ratio of maximum output (W) to 1 cm 2 It is calculated as a percentage by dividing the value by the light intensity (W) per unit and multiplying it by 100.

[0145] The photoelectric conversion element of the present invention can be applied to dye-sensitized solar cells, various photosensors, etc. The dye-sensitized solar cell of the present invention can be obtained by arranging a required number of photoelectric conversion elements, each of which contains a sensitizing dye composition for photoelectric conversion containing a sensitizing dye represented by the general formula (1), into modules and providing predetermined electrical wiring. EXAMPLES

[0146] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples. In the synthesis examples, the compounds are identified by 1 This was performed by H-NMR analysis (JNM-ECZ400S nuclear magnetic resonance spectrometer, manufactured by JEOL Ltd.).

[0147] [Synthesis Example 1] Synthesis of Sensitizing Dye (D-20) In a nitrogen-substituted reaction vessel, 7.03 g of (4,4-dihexyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)trimethylstannane, 4.47 g of 4,7-dibromobenzo[c][1,2,5]thiadiazole, and 130 mL of toluene were placed, and 0.239 g of bis(triphenylphosphine)palladium(II) dichloride was added and degassed under reduced pressure. The reaction was carried out for 6 hours while stirring at 60°C. After cooling to 40°C and removing the solvent under reduced pressure, the crude product was purified by column chromatography (carrier: silica gel, eluent: hexane / chloroform = 1 / 1 (volume ratio)) to obtain 3.94 g of a red oily product represented by the following formula (12).

[0148] [ka]

[0149] In a nitrogen-substituted reaction vessel, 0.406 g of the compound represented by the above formula (12), 0.54 g of 10-biphenyl-9,9-diphenyl-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-phenyl-acridan, 0.924 g of sodium carbonate, 12 mL of ethanol, 24 mL of water, and 0.11 g of tetrakis(triphenylphosphine)palladium(0) were added and degassed under reduced pressure. The reaction was carried out for 3 hours while stirring at 75°C. After the reaction solution was cooled to 25°C, 180 mL of chloroform and 60 mL of water were added and stirred to extract the organic layer. The organic layer was dried over sodium sulfate and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: hexane / toluene = 5 / 1 (volume ratio)). The resulting reddish-black oil (0.972 g) was brominated in a conventional manner to obtain 0.988 g of the brominated compound represented by the above formula (13).

[0150] In a nitrogen-substituted reaction vessel, 0.066 g of 4-formylphenylboronic acid, 0.494 g of the bromine compound represented by the above formula (13), 20 mL of dioxane, 4 mL of water, 0.469 g of tripotassium phosphate, and 0.009 g of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl were added and stirred, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. Next, 0.005 g of palladium acetate was added, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. Then, the reaction liquid was stirred at 60°C for 2 hours. After the reaction liquid was allowed to cool to 25°C, 90 mL of chloroform and 30 mL of water were added and stirred, and the organic layer was extracted. The organic layer was dried over sodium sulfate and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene / hexane=1 / 1 (volume ratio)) and dried to obtain a reddish black solid (0.299 g) of the formyl compound represented by the above formula (14).

[0151] In a nitrogen-purged reaction vessel, 0.149 g of the formyl compound represented by the above formula (14), 0.198 g of cyanoacetic acid, 13 mL of acetic acid, and 0.024 g of ammonium acetate were placed and stirred at 100°C for 7 hours. After the reaction solution was allowed to cool to 25°C, 70 mL of water was added and stirred to extract the organic layer. The organic layer was washed successively with water and saturated saline, and then dried to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: chloroform / methanol = 10 / 1 (volume ratio)), dried, and the desired sensitizing dye was obtained as a black solid (0.127 g, 81% yield).

[0152] The obtained black solid was subjected to NMR analysis, and the following 65 hydrogen signals were detected, identifying the structure as represented by the following formula (D-20) (carboxyl group hydrogen was not observed).

[0153] 1H-NMR (400MHz, DMSO-d6): δ(ppm)=0.75-0.79(6H), 0.97-1.01(4H), 1.10-1.18(12H), 1.91-1.98(4H), 6.54-6 .65(2H), 7.08-7.17(5H), 7.27-7.57(17H), 7.66-7.70(2H), 7.78-7.87(6H), 7.97-8.03(4H), 8.09-8.19(3H).

[0154] [ka]

[0155] [Synthesis Example 2] Synthesis of sensitizing dye (D-19) In a nitrogen-substituted reaction vessel, 0.401 g of the formyl compound represented by the above formula (14), 0.094 g of the indenone compound represented by the following formula (15), 5.7 mL of acetic acid, and 14.5 mL of toluene were placed and stirred at 90°C for 8 hours. After the reaction solution was allowed to cool to 25°C, 50 mL of toluene was added and stirred to extract the organic layer. The organic layer was washed successively with water and saturated saline, and dried to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: chloroform / methanol = 10 / 1 (volume ratio)), dried, and the desired sensitizing dye was obtained as a black-purple solid (0.328 g, yield 71%).

[0156] [ka]

[0157] The obtained black-purple solid was subjected to NMR analysis, and the following 68 hydrogen signals were detected, identifying the structure as represented by the following formula (D-19) (carboxyl group hydrogen was not observed).

[0158] 1H-NMR (400MHz, THF-d8): δ(ppm)=0.82-0.90(6H), 1.15-1.27(16H), 2.07-2.15( 4H), 6.68-6.77(2H), 7.20-7.30(5H), 7.30-7.42(11H), 7.40-7.48(4H), 7.51-7 .59(2H), 7.62-7.68(1H), 7.77-7.83(4H), 7.91-8.01(6H), 8.02-8.08(1H), 8.0 6-8.17(1H), 8.24-8.28(1H), 8.50-8.56(1H), 8.57-8.65(1H), 8.70-8.76(2H).

[0159] [ka]

[0160] [Synthesis Example 3] Synthesis of sensitizing dye (D-18) In a nitrogen-purged reaction vessel, 0.319 g of the bromine compound represented by the above formula (13), 0.138 g of 4-ethynylbenzoic acid, 10 mL of ultra-dehydrated tetrahydrofuran, and 1.5 mL of dried triethylamine were added, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. Next, 0.053 g of tetrakis(triphenylphosphine)palladium(0) and 0.009 g of copper iodide were added, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. Then, the mixture was stirred at 70°C for 3 hours. The reaction solution was allowed to cool to 25°C, and then concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: chloroform) and dried to obtain the desired sensitizing dye as a black-red solid (0.317 g, yield 69%).

[0161] The obtained black-red solid was subjected to NMR analysis, and the following 64 hydrogen signals were detected, identifying the structure as represented by the following formula (D-18) (carboxyl group hydrogen was not observed).

[0162] 1H-NMR (400MHz, THF-d8): δ(ppm)=0.83-0.91(6H), 1.10-1.15(4H), 1.19-1. 31(12H), 2.01-2.09(4H), 6.67-6.77(2H), 7.20-7.29(5H), 7.29-7.41(11H) , 7.41-7.46(4H), 7.51-7.58(3H), 7.62-7.68(3H), 7.69-7.78(1H), 7.78-7 .84(3H), 7.90-8.02(3H), 8.01-8.07(1H), 8.05-8.13(1H), 8.21-8.26(1H).

[0163] [ka]

[0164] [Synthesis Example 4] Synthesis of sensitizing dye (D-26) In a nitrogen-purged reaction vessel, 0.720 g of 10-biphenyl-9,9-diphenyl-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-phenyl-acridan, 0.335 g of 4,7-dibromobenzo[c][1,2,5]thiadiazole, 1.32 g of sodium carbonate, 21 mL of ethanol, and 41 mL of water were added, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. 0.141 g of tetrakis(triphenylphosphine)palladium(0) was added, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. The reaction was carried out for 3 hours while stirring at 75°C. After the reaction solution was allowed to cool to 25°C, 30 mL of toluene was added and stirred, and the organic layer was extracted. The organic layer was dried over sodium sulfate and concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: hexane / toluene=5 / 1 (volume ratio)) to obtain 0.520 g of a bromine compound represented by the following formula (16).

[0165] [ka]

[0166] In a nitrogen-purged reaction vessel, 0.482 g of the bromine compound represented by the above formula (16), 0.085 g of 4-ethynylbenzoic acid, 15 mL of ultra-dehydrated tetrahydrofuran, and 2.2 mL of dried triethylamine were added, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. Next, 0.128 g of tetrakis(triphenylphosphine)palladium(0) and 0.021 g of copper iodide were added, and the reaction vessel was repeatedly subjected to pressure reduction, degassing, and nitrogen replacement five times. Then, the mixture was stirred at 65°C for 4 hours. The reaction solution was allowed to cool to 25°C, and then concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: chloroform / methanol = 10 / 1 (volume ratio)) and dried to obtain the desired sensitizing dye as a red solid (0.243 g, yield 49%).

[0167] The resulting red solid was subjected to NMR analysis, and the following 36 hydrogen signals were detected, identifying the structure as represented by the following formula (D-26) (carboxyl group hydrogen was not observed).

[0168] 1 H-NMR (400MHz, THF-d8): δ(ppm)=6.54-6.65(2H), 7.05-7.10(1H), 7.09-7. 15(4H), 7.24-7.58(17H), 7.67-7.77(4H), 7.78-7.86(3H), 7.97-8.04(5H).

[0169] [ka]

[0170] [Example 1] Characterization Titanium oxide paste (PST-18NR, manufactured by JGC Catalysts and Chemicals Co., Ltd.) was applied by the squeegee method onto a glass substrate coated with a fluorine-doped tin oxide thin film. After drying at 110°C for 1 hour, the substrate was baked at 450°C for 30 minutes to obtain a titanium oxide thin film with a thickness of 6 μm. Next, the sensitizing dye (D-20) obtained in Synthesis Example 1 was dissolved in a mixture of acetonitrile / t-butyl alcohol = 1 / 1 (volume ratio) to prepare 50 mL of a solution with a concentration of 100 μM. The glass substrate coated and sintered with titanium oxide was immersed in this solution for 15 hours at 25 ± 2°C to adsorb the dye and form a photoelectrode.

[0171] A platinum thin film having a thickness of 15 nm was formed as a counter electrode on a glass substrate coated with a fluorine-doped tin oxide thin film by sputtering using an autofine coater (JFC-1600 manufactured by JEOL Ltd.).

[0172] Next, a 60 μm-thick spacer (heat-sealing film) was sandwiched between the photoelectrode and counter electrode and they were bonded together by heat fusion. An electrolyte (0.1 M lithium iodide, 0.6 M dimethylpropylimidazolium iodide, 0.05 M iodine, 0.5 M 4-t-butylpyridine) / 3-methoxypropionitrile solution) was injected through the hole in the counter electrode and then the hole was sealed to produce a photoelectric conversion element.

[0173] The photoelectrode side of the photoelectric conversion element was irradiated with light generated by a simulated solar light irradiation device (OTENTO-SUN III model manufactured by Bunkoukeiki Co., Ltd.), and the current-voltage characteristics were measured using a source meter (Model 2400 General-Purpose Source Meter manufactured by KEITHLEY). The light intensity was 100 mW / cm. 2 The measurement results and initial photoelectric conversion efficiency are shown in Table 1.

[0174] [Examples 2 and 3] Photoelectric conversion elements were prepared in the same manner as in Example 1, except that the sensitizing dyes shown in Table 1 were used as the photoelectric conversion sensitizing dyes instead of the sensitizing dye (D-20) obtained in Synthesis Example 1. The current-voltage characteristics and initial photoelectric conversion efficiency of the photoelectric conversion elements are summarized in Table 1.

[0175] [Comparative Example 1 and Comparative Example 2] Characteristic evaluation A photoelectric conversion element was prepared in the same manner as in Example 1, except that the following sensitizing dyes (E-1) and (E-2), which are not included in the present invention, were used instead of (D-20) as the photoelectric conversion sensitizing dye. The measurement results of the current-voltage characteristics and the initial photoelectric conversion efficiency of the photoelectric conversion element are shown in Table 1.

[0176] [ka]

[0177] [Table 1]

[0178] It was found that by using the sensitizing dye composition for photoelectric conversion containing the sensitizing dye of the present invention, a photoelectric conversion element having high photoelectric conversion efficiency and maintaining high photoelectric conversion efficiency even after long-term light irradiation can be obtained. On the other hand, the photoelectric conversion efficiency of the photoelectric conversion element using the sensitizing dye for photoelectric conversion of the comparative example was insufficient.

[0179] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application (Patent Application No. 2020-33131) filed on February 28, 2020, the entirety of which is incorporated by reference. In addition, all references cited herein are incorporated in their entirety. [Industrial Applicability]

[0180] The sensitizing dye of the present invention and the sensitizing dye composition for photoelectric conversion containing the sensitizing dye are useful for highly efficient and highly durable photoelectric conversion elements and dye-sensitized solar cells, and can provide clean energy as solar cells that can efficiently convert solar light energy into electrical energy. [Explanation of symbols]

[0181] 1. Conductive support 2. Dye-supported semiconductor layer 3 Electrolyte layer 4. Opposite 5. Conductive support

Claims

1. A sensitizing dye represented by the following general formula (1): 【Chemistry 1】 [In the formula, R ０ teeth, It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. R １ ~R ４ may be the same or different, Hydrogen atom, halogen atom, cyano group, hydroxyl group, nitro group, nitroso group, thiol group, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent, an aryl group having 6 to 36 carbon atoms which may have a substituent, or represents an amino group having 0 to 36 carbon atoms which may have a substituent, R １ ~R ４ Adjacent groups may be bonded to each other to form a ring. X is CR ５ R ６ , a sulfur atom, or an oxygen atom; R ５ and R ６ are the same or different, and each is a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. Y is a sulfur atom, an oxygen atom, or CR ７ R ８ Or N.R. ９ represents R 7 ~R ９ may be the same or different, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. A is a monovalent group represented by the following general formula (2) or (4). 【Chemistry 2】 [In the formula, R ２０ and R ２１ represents a hydrogen atom or a carboxyl group, R ２０ and R ２１ At least one of R is a carboxyl group. ２４ represents a carboxyl group, R ２３ and R ２５ represents a hydrogen atom or an electron-withdrawing group. B represents a divalent group represented by the following general formula (5) or a single bond. 【Chemistry 3】 [wherein Z represents a carbon atom or a silicon atom; R ３０ and R ３１ may be the same or different, Hydrogen atoms, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; It represents a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or an aryl group having 6 to 36 carbon atoms which may have a substituent. R ３２ ~R ３７ may be the same or different, Hydrogen atoms, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; It represents a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent. R ３２ and R ３３ , R ３４ and R ３５ , and R ３６ and R ３７ may be the same or different and may be bonded to each other to form a ring. p, q, and r each represent 0 or 1.

2. A sensitizing dye represented by the following general formula (1): 【Chemistry 4】 [In the formula, R ０ teeth, It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. R １ ~R ４ may be the same or different, Hydrogen atom, halogen atom, cyano group, hydroxyl group, nitro group, nitroso group, thiol group, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a cycloalkyl group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent; a cycloalkoxy group having 3 to 36 carbon atoms which may have a substituent; a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent, an aryl group having 6 to 36 carbon atoms which may have a substituent, or represents an amino group having 0 to 36 carbon atoms which may have a substituent, R １ ~R ４ Adjacent groups may be bonded to each other to form a ring. X is CR ５ R ６ or an oxygen atom, R ５ and R ６ are the same or different, and each is a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. Y is a sulfur atom, an oxygen atom, or CR ７ R ８ Or N.R. ９ represents R 7 ~R ９ may be the same or different, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or It represents an aryl group having 6 to 36 carbon atoms which may have a substituent. A is a monovalent group represented by the following general formula (3). 【Chemistry 5】 [In the formula, R ２２ represents a carboxyl group. B is a divalent bonding group represented by the following general formula (5) or a single bond. 【Chemistry 6】 [wherein Z represents a carbon atom or a silicon atom; R ３０ and R ３１ may be the same or different, Hydrogen atoms, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; It represents a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or an aryl group having 6 to 36 carbon atoms which may have a substituent. R ３２ ~R ３７ may be the same or different, Hydrogen atoms, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; It represents a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, or a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent. R ３２ and R ３３ , R ３４ and R ３５ , and R ３６ and R ３７ may be the same or different and may be bonded to each other to form a ring. p, q, and r each represent 0 or 1.

3. In the general formula (1), R ０ is an optionally substituted aryl group having 6 to 26 carbon atoms, R １ ~R ４ but, Hydrogen atoms, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent, an aryl group having 6 to 36 carbon atoms which may have a substituent, or an amino group having 0 to 36 carbon atoms which may have a substituent, X is CR ５ R ６ , a sulfur atom, Y is a sulfur atom, CR ７ R ８ Or N.R. ９ That is, The sensitizing dye according to claim 1 .

4. In the general formula (1), R ０ is an optionally substituted aryl group having 6 to 26 carbon atoms, R １ ~R ４ but, Hydrogen atoms, a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent, a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent, an aryl group having 6 to 36 carbon atoms which may have a substituent, or an amino group having 0 to 36 carbon atoms which may have a substituent, X is CR ５ R ６ and Y is a sulfur atom, CR ７ R ８ Or N.R. ９ That is, The sensitizing dye according to claim 2 .

5. A sensitizing dye composition for photoelectric conversion, comprising the sensitizing dye according to any one of claims 1 to 4.

6. A photoelectric conversion element using the sensitizing dye composition for photoelectric conversion according to claim 5.

7. A dye-sensitized solar cell using the photoelectric conversion element according to claim 6.

Images