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

Abstract

To provide a sensitizing dye with a novel structure capable of extending a photosensitive wavelength region, and further provide a photoelectric conversion element and a dye-sensitized solar cell with good photoelectric conversion characteristics that employ the sensitizing dye as a sensitizing dye composition for photoelectric conversion capable of efficiently extracting an electric current.SOLUTION: The sensitizing dye is represented by the general formula (1) in the figure.SELECTED DRAWING: Figure 1

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, a greenhouse gas produced by fossil fuels such as coal, oil, and natural gas, has been contributing to global warming and environmental destruction. Concerns have been raised that the increase in global energy consumption due to population growth will further accelerate environmental destruction on a global scale. In this context, the use of renewable energy, which, unlike fossil fuels, is unlikely to run out, is being actively considered. The use of solar energy, primarily photovoltaic power generation, is becoming increasingly important as a next-generation renewable energy power generation method that can contribute to preventing global warming, replacing fossil fuel-consuming thermal and nuclear power plants. Development and applications of solar energy are progressing in a variety of fields, from generating and charging electricity for watches and small portable electronic devices to small-scale power generation facilities for homes, buildings, and fallow land, which can reduce utility costs.

[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 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 the main focus of research, 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 difficulty in securing raw materials.

[0004] On the other hand, organic solar cells, such as organic thin-film solar cells and dye-sensitized solar cells, which use a variety of organic materials, are also being 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 manufacturing costs, large area, light weight, thin film, transparency, 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 on the semiconductor surface to widen the photosensitive wavelength range, and an electrolyte containing iodine, and is expected to achieve 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. However, ruthenium is a precious metal, which makes its production cost disadvantageous. Furthermore, if large quantities of ruthenium complexes are required for practical application, resource limitations will also become an issue. Therefore, active research has been conducted into dye-sensitized solar cells using organic dyes that do not contain precious metals such as ruthenium as sensitizing dyes. Examples of organic dyes that do not contain precious metals include coumarin-based dyes, cyanine-based dyes, merocyanine-based dyes, rhodacyanine-based dyes, phthalocyanine-based dyes, porphyrin-based dyes, and xanthene-based dyes (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 also 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 and 7).

[0008] However, although these organic dyes have advantages such as low cost, large absorption coefficients, and the ability to control absorption characteristics due to structural diversity, at present, none of them have been obtained that fully satisfy the required properties in terms of photoelectric conversion efficiency and stability over time. Furthermore, few organic dyes that absorb light in the long wavelength region and exhibit blue or purple colors have high photoelectric conversion efficiency. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 11-214730 [Patent Document 2] Japanese Patent Application Publication No. 11-238905 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-26376 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-60581 [Patent Document 5] Japanese Patent Application Laid-Open No. 2011-207784 [Patent Document 6] Japanese Patent Application Laid-Open No. 2012-51854 [Patent Document 7] Japanese Patent Application Laid-Open 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 that can broaden the photosensitive wavelength range, and further to provide a photoelectric conversion element and a dye-sensitized solar cell that have good photoelectric conversion properties and that use the sensitizing dye as a sensitizing dye composition for photoelectric conversion that can efficiently extract 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 photoelectric conversion element can be obtained by using a sensitizing dye having a specific structure as a sensitizing dye for photoelectric conversion.

[0013] 1. A sensitizing dye represented by the following general formula (1):

[0014] [ka]

[0015] [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 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 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. R 7 ~R 8 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; a linear or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent; Alternatively, it represents a linear or branched alkenyl group having 2 to 36 carbon atoms which may have a substituent. R 7 and R 8 may be bonded to each other to form a ring. m represents an integer of 0 or 1, and n represents an integer of 1 or 2. Y is CR 9 R 10 , N.R. 11 or SiR 12 R 13 represents R 9 ~R 13 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.

[0016] A sensitizing dye composition for photoelectric conversion, comprising a sensitizing dye represented by the above general formula (1).

[0017] A photoelectric conversion element using the above sensitizing dye composition for photoelectric conversion.

[0018] A dye-sensitized solar cell using the above photoelectric conversion element. [Effects of the Invention]

[0019] The sensitizing dye composition according to the present invention can provide a sensitizing dye composition for photoelectric conversion that can efficiently extract current even when the absorption maximum wavelength is longer. Furthermore, by using the sensitizing dye composition for photoelectric conversion, a highly efficient photoelectric conversion element and a highly efficient dye-sensitized solar cell can be obtained. [Brief explanation of the drawings]

[0020] [Figure 1] 1A and 1B are schematic cross-sectional views illustrating the configurations of photoelectric conversion elements according to examples of the present invention and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments. First, the present embodiment will be described by listing its aspects.

[0022] 1. A sensitizing dye represented by the following general formula (1):

[0023] [ka]

[0024] [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 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 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. R 7 and R 8 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; 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 7 and R 8 may be bonded to each other to form a ring. m represents an integer of 0 or 1, and n represents an integer of 1 or 2. Y is CR 9 R 10 , N.R. 11 or SiR 12 R 13 represents R 9 ~R 13 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.

[0025] 2. A sensitizing dye in which, in the general formula (1), A is a monovalent group represented by any one of the following general formulae (2) to (4):

[0026] [ka]

[0027] [In the formula, R 14 and R 15 represents a hydrogen atom or an acidic group, and R 14 and R 15 At least one of R is an acidic group. 16 and R 18 represents an acidic group, and R 17 and R 19represents a hydrogen atom or an electron-withdrawing group.

[0028] 3. A sensitizing dye in which, in the general formula (1), B is a divalent bonding group represented by the following general formula (5) or a single bond.

[0029] [ka]

[0030] [In the formula, R 20 ~R 25 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 20 and R 21 , R 22 and R 23 , and R 24 and R 25 may be the same or different and may be bonded to each other to form a ring. p and q represent integers of 0 or 1.]

[0031] 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; Alternatively, a sensitizing dye is an aryl group having 6 to 26 carbon atoms which may have a substituent.

[0032] 5. In the general formula (1), 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 A sensitizing dye which is an amino group having 0 to 36 carbon atoms which may have a substituent.

[0033] 6. In the general formula (1), X is CR 5 R 6 A sensitizing dye.

[0034] 7. In the general formula (1), Y is CR 9 R 10 or NR 11 A sensitizing dye.

[0035] 8. A sensitizing dye in which m is 0 in the above general formula (1).

[0036] 9. A sensitizing dye composition for photoelectric conversion, comprising a sensitizing dye represented by the above general formula (1).

[0037] 10. A photoelectric conversion element using the above sensitizing dye composition for photoelectric conversion.

[0038] 11. A dye-sensitized solar cell using the above photoelectric conversion element.

[0039] 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 typically comprises 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.

[0040] The sensitizing dyes represented by the general formula (1) will be specifically explained below, but the present invention is not limited to these.

[0041] In 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 formula (1) 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.

[0042] In 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.

[0043] In general formula (1), R 0 Specific examples of 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 above formula include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a cyano group; a hydroxyl group; a nitro group; a nitroso group; a thiol group; linear 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, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a nonyloxy group, or a decyloxy group; branched alkoxy groups having 3 to 30 carbon atoms, such as an isopropoxy group, an isobutoxy group, an 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, and a cyclohexyloxy group; a vinyl group, an allyl group, an isopropenyl group, a 2-butenyl group, a 1-hexenyl group, a diphenylethylene 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 include a carboxyl group; a carboxylic acid ester group such as a methyl ester group or an ethyl ester group; and the like. These "substituents" may be present in only one or in multiple numbers, and when multiple groups are present, they may be the same or different. Furthermore, these "substituents" may further have the substituents exemplified above.

[0044] In general formula (1), R 0is preferably a linear or branched alkyl group of 1 to 20 carbon atoms which may have a substituent, or an aryl group of 6 to 26 carbon atoms which may have a substituent, more preferably an aryl group of 6 to 26 carbon atoms which may have a substituent, and even more preferably an aryl group of 6 to 20 carbon atoms which may have a substituent.

[0045] Also, R 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 20 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.

[0046] In 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.

[0047] In general formula (1), R 1 ~R 4 In the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent," the "straight-chain or branched alkyl group having 1 to 36 carbon atoms" represented by the formula (1) includes, for example, 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:

[0048] In 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 formula (1) 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.

[0049] In 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 formula (1) 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.

[0050] In 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.

[0051] In 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 formula (1) include alkenyl groups such as a vinyl group, an allyl group, an isopropenyl group, a 2-butenyl group, and a 1-hexenyl group, as well as straight-chain or branched alkenyl groups in which a plurality of these alkenyl groups are bonded.

[0052] In general formula (1), R 1 ~R4 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 general formula (1) is, for example, 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:

[0053] In 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 formula (1) 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.

[0054] In general formula (1), R 1 ~R 4 Examples of the "substituent" in the "straight-chain or branched alkyl group of 1 to 36 carbon atoms which may have a substituent", "cycloalkyl group of 3 to 36 carbon atoms which may have a substituent", "straight-chain or branched alkoxy group of 1 to 36 carbon atoms which may have a substituent", "cycloalkoxy group of 3 to 36 carbon atoms which may have a substituent", "straight-chain or branched alkenyl group of 2 to 36 carbon atoms which may have a substituent", "aryl group of 6 to 36 carbon atoms which may have a substituent", or "amino group of 0 to 36 carbon atoms which may have a substituent" represented by the general formula (1) include R 0 Examples of the "substituent" include the same as those in the "linear 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 may have a substituent" represented by the following formula:

[0055] In general formula (1), R 1 ~R 4represents 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.

[0056] In the general formula (1), R 1 ~R 4 may be the same or different, is preferably a hydrogen atom, a halogen 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, more preferably a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms which may have a substituent, a linear or branched alkoxy 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, More preferred are a hydrogen 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.

[0057] Also, R 1 ~R 4 Among them, 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 Among them, R 1 , R 2 and R 4 is a hydrogen atom, and R 3 However, it may also be an aryl group having 6 to 20 carbon atoms.

[0058] In the general formula (1), X is CR 5 R 6 If R 5 and R 6 The "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) includes a group represented by the formula (1), 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 formula: 5 and R 6 Examples of the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) include 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 R 5 and R 6 The "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the formula (1) includes R 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 may be the same or different. In the present invention, X is CR 5 R 6 or sulfur atom is preferred, CR 5 R 6is more preferred.

[0059] 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 which may have a substituent. When the aryl group is a benzene ring, it is sometimes represented as Ph in the present specification.

[0060] In general formula (1), R 7 and R 8 In the "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent," the "straight-chain or branched alkyl group having 1 to 36 carbon atoms" represented by the formula (1) includes, for example, 0 Examples of the alkyl group include the same as the "straight-chain or branched alkyl group having 1 to 36 carbon atoms" represented by the following formula:

[0061] In general formula (1), R 7 and R 8 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 which may have a substituent" includes, in general formula (1), R 1 ~R 4 Examples of the alkoxy group include the same as the "linear or branched alkoxy group having 1 to 36 carbon atoms" represented by the following formula:

[0062] In general formula (1), R 7 and R 8The "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 formula (1) includes, for example, 1 ~R 4 Examples of the alkyl group include the same as the "straight-chain or branched alkenyl group having 2 to 36 carbon atoms" represented by the following formula:

[0063] In general formula (1), R 7 and R 8 Examples of the "substituent" in the "optionally substituted linear or branched alkyl group having 1 to 36 carbon atoms," "optionally substituted linear or branched alkoxy group having 1 to 36 carbon atoms," or "optionally substituted linear or branched alkenyl group having 2 to 36 carbon atoms" represented by the general formula (1) include R 0 Examples of the "substituent" include the same as those in the "linear 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 may have a substituent" represented by the following formula:

[0064] In general formula (1), R 7 and R 8 represents a group 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.

[0065] In the general formula (1), m represents an integer of 0 or 1, and n represents an integer of 1 or 2. m may be 0 and n may be 1, m may be 0 and n may be 2, m may be 1 and n may be 1, or m may be 1 and n may be 2. When n is 2, multiple Ys may be the same or different.

[0066] In the general formula (1), Y is CR 9 R 10 , N.R. 11or SiR 12 R 13 represents R 9 ~R 13 The "alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) includes, for example, R 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 formula: 9 ~R 13 Examples of the "straight-chain or branched alkoxy group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) include 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 R 9 ~R 13 The "aryl group having 6 to 36 carbon atoms which may have a substituent" represented by the formula (1) includes R 0 Examples of the aryl group having 6 to 36 carbon atoms which may have a substituent include those represented by the formula: 9 ~R 13 In the present invention, Y is a group selected from the group consisting of CR 9 R 10 or NR 11 is preferred.

[0067] In the general formula (1), Y is CR 9 R 10 In the case where R 9 and R 10 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.

[0068] In the general formula (1), Y is NR 11 In the case where R 11is 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 is even more preferably a linear or branched alkyl group having 1 to 16 carbon atoms.

[0069] In the general formula (1), Y is SiR 12 R 13 In the case where R 12 and R 13 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.

[0070] In the general formula (1), A is preferably represented by any one of the monovalent groups of the general formulae (2) to (4).

[0071] In general formula (2), R 14 and R 15 represents hydrogen or an acidic group, and R 14 or R 15 At 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 the 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.

[0072] In general formula (3), R 16 and R in general formula (4). 18Examples of the "acidic group" represented by the formula (1) include the same as the "acidic group" in general formula (2).

[0073] In general formula (4), R 17 and R 19 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, and a carboxyl group are preferred.

[0074] In general formula (1), B is preferably a divalent group represented by general formula (5) above or a single bond.

[0075] In general formula (5), R 20 ~R 25 The "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) includes, 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:

[0076] In general formula (5), R 20 ~R 25 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" includes, for example, 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:

[0077] In general formula (5), R 20 ~R 25The "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 general formula (1) is, for example, 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:

[0078] In general formula (5), R 20 ~R 25 The "straight-chain or branched alkyl group having 1 to 36 carbon atoms which may have a substituent" represented by the formula (1) includes, 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:

[0079] In general formula (5), R 20 ~R 25 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" includes, for example, 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:

[0080] In general formula (5), R 20 ~R 25 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 formula (1) includes, for example, R 1 ~R 4 Examples of the alkyl group include the same as the "straight-chain or branched alkenyl group having 2 to 36 carbon atoms" represented by the following formula:

[0081] In general formula (5), R 20 and R 21 , R 22 and R 23 , and R 24and R 25 may be the same or different and represent the above groups, 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.

[0082] In general formula (5), p and q each represent an integer of 0 or 1, and p may be 0 and q may be 0, p may be 1 and q may be 0, p may be 0 and q may be 1, or p may be 1 and q may be 1.

[0083] In the present invention, the sensitizing dye represented by general formula (1) includes all possible stereoisomers. Any stereoisomer can be suitably used as the sensitizing dye in the present invention. For example, in general formula (1), m is 0, B is a single bond, A is a monovalent group represented by general formula (2), and R 14 is a hydrogen atom, and R 15 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.

[0084] [ka]

[0085] Specific examples of the compound represented by formula (1) which is the sensitizing dye of the present invention are shown below, but the present invention is not limited to these. The following exemplary compounds are examples of possible stereoisomers and include all other stereoisomers. Each may also be a mixture of two or more stereoisomers.

[0086] [ka]

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[0119] [ka]

[0120] The sensitizing dye of the present invention represented by general formula (1) can be synthesized by a known method. In general formula (1), m is 0, n is 1, and Y is NC8H. 17 B is a divalent group represented by general formula (5), A is a monovalent group represented by general formula (2), p is 1, q is 0, R 20 , R 21 , R 22 , and R 23 A synthesis example in which is a hydrogen atom is shown below.

[0121] The brominated compounds represented by general formula (9) can be synthesized by cross-coupling reactions such as Suzuki-Miyaura coupling between the corresponding substituted boronate compounds represented by general formula (8) and 2,6-dibromo-4-n-octyldithieno[3,2-b:2',3'-d]pyrrole.

[0122] [ka]

[0123] Subsequently, a cross-coupling reaction between the bromo compound represented by general formula (9) and 4-formylphenylboronic acid can be carried out to synthesize a formyl compound represented by general formula (10).

[0124] [ka]

[0125] 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.

[0126] In general formula (11), R 14 and R 15 represents a hydrogen atom or an acidic group, and at least R 14 or R 15 is an acidic group.

[0127] R in the general formulas (8) to (11) in the above synthesis examples 0 ~R 4 , R 14 and R 15 represents R in the general formula (1) of the present invention. 0 ~R 4 and R in general formula (2) 14 , R 15 It has the same meaning as:

[0128] The starting materials, such as those represented by the general formula (8), may be commercially available or synthesized by known methods. The indenone compound represented by the general formula (11) can be easily synthesized by the methods described in Patent Documents 6 and 7.

[0129] The sensitizing dye compound of the present invention represented by general formula (1) can be purified by 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.

[0130] 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 also 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, and xanthene dyes, other than the sensitizing dye represented by the general formula (1). When the sensitizing dye of the present invention and these other sensitizing dyes are used in combination 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.

[0131] The sensitizing dye of the present invention preferably has a peak wavelength (absorption maximum) of the absorption spectrum of 400 nm or more in the ultraviolet-visible absorption spectrum. Furthermore, from the viewpoint of light absorption in the long wavelength region and exhibiting a blue or purple color, the peak wavelength is preferably 450 nm or more, more preferably 480 nm or more, and particularly preferably 550 nm or more. Furthermore, in order to obtain a device with high sensitivity, a material with a large molar absorption coefficient is preferred. Generally, in order to shift the absorption wavelength to longer wavelengths, it is necessary to introduce a long-chain double bond moiety or the like, but this raises concerns about durability due to oxidation, etc. In the present invention, by introducing a highly durable moiety or having a skeletal structure, it is expected that durability will be improved and high photoelectric conversion efficiency will be achieved.

[0132] The sensitizing dye of the present invention can be used as a spectral sensitizing dye for photoreceptors, photocatalysts, and photofunctional materials for various imaging materials, such as silver halide, zinc oxide, and titanium oxide. It can also be used as a sensitizing dye composition for photoelectric conversion used in dye-sensitized photoelectric conversion devices. While the method for preparing a dye-sensitized photoelectric conversion device in the present invention is not particularly limited, a preferred method is to form a semiconductor layer on a conductive support (electrode) and adsorb (support) the sensitizing dye composition for photoelectric conversion of the present invention onto the semiconductor layer to prepare a photoelectrode (see Figure 1 . Needless to say, the drawing is not a faithful scale representation of the actual device, as it is intended to facilitate understanding). A common method for adsorbing the dye is to dissolve the dye in a solvent and immerse the semiconductor layer in the resulting solution for an extended period of time. 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 resulting solution. Alternatively, separate solutions may be prepared for each dye, and the semiconductor layer may be immersed in each solution in turn.

[0133] 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 its 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. However, it is preferable to use a glass substrate coated with a thin film of fluorine-doped tin oxide.

[0134] Specific examples of semiconductors that form 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.

[0135] The semiconductor layer of the present invention is not particularly limited in its form, but a thin film having a porous structure composed of fine particles is preferred. The porous structure, etc., increases the effective surface area of ​​the semiconductor layer, thereby increasing the amount of dye adsorbed to the semiconductor layer, resulting in a highly efficient photoelectric conversion element. The semiconductor particle diameter is preferably 5 to 500 nm, more preferably 10 to 100 nm. The semiconductor layer typically has a thickness of 1 to 100 μm, more preferably 1 to 20 μm. Examples of methods for producing the semiconductor layer include a method in which a paste containing semiconductor fine particles is applied to a conductive substrate by a wet coating method such as spin coating, doctor blade, squeegee, or screen printing, followed by baking to remove the solvent and additives, and a method in which the layer is produced by sputtering, vapor deposition, electrodeposition, electrodeposition, microwave irradiation, or the like, but is not limited thereto.

[0136] In the present invention, the paste containing semiconductor particles may be a commercially available product, or may be a paste prepared by dispersing commercially available semiconductor fine powder in a solvent. Specific examples of solvents used in preparing the paste include, but are not limited to, water; alcoholic solvents such as methanol, ethanol, and isopropyl alcohol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and hydrocarbon solvents such as n-hexane, cyclohexane, benzene, and toluene. These solvents may be used alone or in combination.

[0137] In the present invention, the semiconductor fine powder may be dispersed in a solvent after grinding the powder in a mortar or the like, or a dispersing machine such as a ball mill, a paint conditioner, a vertical bead mill, a horizontal bead mill, or an attritor may be used. When preparing a paste, it is preferable to add a surfactant or the like to prevent aggregation of the semiconductor fine particles, and it is also preferable to add a thickener such as polyethylene glycol to increase the viscosity.

[0138] The sensitizing dye composition for photoelectric conversion of the present invention can be adsorbed onto the surface of a semiconductor layer by, for example, immersing the semiconductor layer in the dye solution and leaving it at room temperature for 30 minutes to 100 hours or under heated conditions 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.

[0139] Specific examples of solvents used to adsorb the photoelectric conversion sensitizing dye of the present invention onto the semiconductor layer surface include, but are not limited to, alcoholic solvents such as methanol, ethanol, isopropyl alcohol, and t-butyl alcohol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester solvents such as ethyl formate, ethyl acetate, and n-butyl acetate; ether solvents such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, and 1,3-dioxolane; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; nitrile solvents such as acetonitrile, methoxyacetonitrile, and propionitrile; halogenated hydrocarbon solvents such as dichloromethane, chloroform, bromoform, and o-dichlorobenzene; and hydrocarbon solvents such as n-hexane, cyclohexane, benzene, and toluene. These solvents may be used alone or in combination. Among these solvents, it is preferable to use one or more selected from ethanol, t-butyl alcohol, methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and n-butyl acetate.

[0140] When the sensitizing dye composition for photoelectric conversion of the present invention is adsorbed onto the surface of a 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. The use of cholic acid or a cholic acid derivative suppresses the association of the dyes, enabling efficient electron injection from the dye to the semiconductor layer in a 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.

[0141] The counter electrode (electrode) used in the photoelectric conversion element of the present invention is not particularly limited as long as it is conductive. However, it is preferable to use a conductive material with catalytic activity to promote the oxidation-reduction reaction of redox ions. Specific examples of such conductive materials include, but are not limited to, platinum, rhodium, ruthenium, and carbon. In the present invention, it is particularly preferable to use a platinum thin film formed on a conductive support as the counter electrode. Methods for producing conductive thin films include, but are not limited to, a method in which a paste containing a conductive material is applied to a conductive substrate by a wet coating method such as spin coating, doctor blade method, squeegee method, or screen printing, and then the paste is baked to remove solvents and additives, or a method in which the paste is formed by sputtering, vapor deposition, electrodeposition, electrodeposition, microwave irradiation, or the like.

[0142] 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 5 M, more preferably 0.2 to 1 M.

[0143] Examples of solvents for dissolving electrolytes include, but are not limited to, nitrile-based solvents such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile, and benzonitrile; ethyl-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 can be used alone or in combination. Among these solvents, nitrile-based solvents are preferred.

[0144] In the present invention, an amine compound may be contained in the electrolyte solution to further improve the open circuit voltage and fill factor of the dye-sensitized photoelectric conversion element. Examples of the amine 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 compound in the electrolyte solution is preferably 0.05 to 5 M, more preferably 0.2 to 1 M.

[0145] The electrolyte in the photoelectric conversion element of the present invention may be 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. By using a gel electrolyte or a solid electrolyte, volatilization of the electrolytic solution can be reduced.

[0146] 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-phenylene vinylene, polyvinyl carbazole, polyaniline, oxadiazole derivatives, triphenylamine derivatives, pyrazoline derivatives, fluorenone derivatives, hydrazone compounds, and stilbene compounds, but are not limited to these.

[0147] 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 film-forming binder resins include, but are not limited to, polystyrene resins, polyvinyl acetal resins, polycarbonate resins, polysulfone resins, polyester resins, polyphenylene oxide resins, polyarylate resins, alkyd resins, acrylic resins, and phenoxy resins. These resins can be used alone or as copolymers, 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.

[0148] In the photoelectric conversion element of the present invention, the electrode (photoelectrode) provided with a semiconductor layer onto which a 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 migrate to the counter electrode. Meanwhile, the dye that has released electrons and become oxidized returns to its ground state by receiving electrons supplied from the counter electrode via ions in the electrolyte. This cycle allows current to flow, enabling the element to function as a photoelectric conversion element.

[0149] 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 2 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 the short circuit current and open circuit voltage, and is mainly affected by the internal resistance. The photoelectric conversion efficiency is the ratio of maximum output (W) to 1cm 2 The value is calculated by dividing the light intensity (W) per unit area by 100 and expressing it as a percentage.

[0150] 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 is 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. [Example]

[0151] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. 1 This was performed by H-NMR analysis (JNM-ECZ400S or ECA-600 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd.).

[0152] [Synthesis Example 1] Synthesis of Sensitizing Dye (D-2) A nitrogen-purged reaction vessel was charged with 0.88 g of 4-octyl-2-trimethylstannyl-4H-bisthieno[3,2-b:2',3'-d]pyrrole, 1.0 g of 10-biphenyl-9,9-diphenyl-7-bromo-2-phenylacridan, 0.63 g of potassium carbonate, and 15 mL of toluene. The reaction vessel was then subjected to three cycles of vacuum decompression, degassing, and nitrogen purge. Next, 0.106 g of bis(triphenylphosphine)palladium(II) dichloride was added, and the reaction vessel was subjected to three cycles of vacuum decompression, degassing, and nitrogen purge. The reaction was carried out at 60°C with stirring for 20 hours. The reaction mixture was cooled to 40°C, 50 mL of toluene was added, and the solvent was removed under reduced pressure. The crude product was purified by column chromatography (support: silica gel, eluent: hexane / toluene = 5 / 1 (volume ratio)) to obtain 0.309 g of a yellow solid represented by formula (12).

[0153] A nitrogen-substituted reaction vessel was charged with 0.307 g of the compound represented by the following formula (12) and 10 mL of tetrahydrofuran, and the mixture was cooled to 2°C with stirring. 0.064 g of N-bromosuccinimide was added, and the reaction was carried out for 4 hours with stirring at 2°C. 20 mL of toluene and 20 mL of water were added to the reaction solution, and the mixture was stirred, and the organic layer was extracted. The organic layer was washed with 20 mL of saturated saline and then dried over sodium sulfate. The organic layer was concentrated under reduced pressure, and the resulting greenish-gray solid was dispersed and washed with acetonitrile, yielding 0.326 g of the bromine compound represented by the following formula (13).

[0154] [ka]

[0155] A nitrogen-purged reaction vessel was charged with 0.065 g of 5-formyl-2-thiopheneboronic acid, 0.323 g of the bromine compound represented by formula (13), 0.041 g of potassium acetate, and 11 mL of dimethyl sulfoxide. The reaction vessel was then stirred, followed by three cycles of vacuum decompression, degassing, and nitrogen purge. Next, 0.010 g of palladium acetate and 0.032 g of di(1-adamantyl)-n-butylphosphine were added, and the reaction vessel was then vacuum decompressed, degassed, and nitrogen purge. The mixture was then stirred at 80°C for 2 hours. The reaction mixture was allowed to cool to 25°C, followed by the addition of 30 mL of water and 20 mL of saturated saline, followed by stirring. The organic layer was extracted by adding 60 mL of toluene and 30 mL of water. The organic layer was dried over sodium sulfate and concentrated under reduced pressure to obtain the crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: toluene) and dried to obtain a reddish-orange solid (0.305 g) of the formyl compound represented by the following formula (14).

[0156] [ka]

[0157] A nitrogen-purged reaction vessel was charged with 0.295 g of the formyl compound represented by formula (14), 0.082 g of the indenone compound represented by formula (15), 3.2 mL of acetic acid, and 9.7 mL of toluene, and the mixture was stirred at 80°C for 7 hours. After the reaction mixture was allowed to cool to 25°C, 50 mL of toluene was added and the mixture was stirred to extract the organic layer. The organic layer was washed successively with water and saturated brine, and then dried to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: chloroform / methanol = 5 / 1 (volume ratio)) and dried to obtain the desired sensitizing dye as a brown solid (0.285 g, 86% yield).

[0158] The obtained brown solid was subjected to NMR analysis, and the following 55 hydrogen signals were detected, identifying the solid as having the structure represented by the following formula (D-2) (carboxyl group hydrogen was not observed).

[0159] 1H-NMR (600MHz, THF-d8): δ(ppm)=0.89-0.95(3H), 1.31-1.43(10H), 1.89-1.97(2H), 4.33-4.40(2H), 6.62-6.69(2H), 7.18-7.27(6H) , 7.28-7.33(4H), 7.32-7.38(4H), 7.36-7.42(4H), 7.41-7.48(5H), 7.49-7.57(3H), 7.74-7.83(3H), 7.94-8.12(5H), 8.45-8.53(2H).

[0160] [ka]

[0161] [Synthesis Example 2] Synthesis of Sensitizing Dye (D-8) A nitrogen-purged reaction vessel was charged with 0.821 g of (4,4-bis(2-ethylhexyl)-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)tributylstannane, 0.76 g of 10-biphenyl-9,9-diphenyl-7-bromo-2-phenylacridan, and 12.3 mL of toluene. The reaction vessel was then subjected to five cycles of vacuum decompression, degassing, and nitrogen purge. Next, 0.042 g of bis(triphenylphosphine)palladium(II) dichloride was added, and the reaction vessel was subjected to three cycles of vacuum decompression, degassing, and nitrogen purge. The reaction was carried out at 60 °C for 7 hours with stirring. The reaction mixture was cooled to 25 °C, 70 mL of toluene was added, and the solvent was removed under reduced pressure. The crude product was purified by column chromatography (support: silica gel, eluent: hexane / toluene = 7 / 1 (volume ratio)) to obtain 0.469 g of an orange solid represented by the following formula (16):

[0162] A nitrogen-purged reaction vessel was charged with 0.459 g of the compound represented by the following formula (16) and 15 mL of tetrahydrofuran, and the mixture was cooled to 3°C with stirring. 0.084 g of N-bromosuccinimide was added, and the reaction was carried out for 3 hours with stirring at 3°C. 30 mL of toluene and 30 mL of water were added to the reaction solution, and the mixture was stirred, and the organic layer was extracted. 30 mL of saturated saline was added to the organic layer, which was washed and dried over sodium sulfate. The organic layer was concentrated under reduced pressure, and the resulting brown solid was purified by column chromatography (carrier: silica gel, eluent: toluene / hexane = 1 / 3 (volume ratio)) and dried to obtain 0.453 g of the bromine compound represented by the following formula (17).

[0163] [ka]

[0164] A nitrogen-purged reaction vessel was charged with 0.080 g of 5-formyl-2-thiopheneboronic acid, 0.446 g of the bromine compound represented by formula (17), 0.051 g of potassium acetate, and 15 mL of dimethyl sulfoxide. The reaction vessel was then stirred, followed by three cycles of vacuum decompression, degassing, and nitrogen purge. Next, 0.010 g of palladium acetate and 0.032 g of di(1-adamantyl)-n-butylphosphine were added, and the reaction vessel was then vacuum decompressed, degassed, and nitrogen purge. The mixture was then stirred at 80°C for 2 hours. The reaction mixture was allowed to cool to 25°C, followed by the addition of 30 mL of water and 30 mL of saturated saline, followed by stirring. The organic layer was extracted by adding 60 mL of toluene and 30 mL of water. The organic layer was dried over sodium sulfate and concentrated under reduced pressure to obtain the crude product. The crude product was purified by column chromatography (carrier: silica gel, eluent: hexane / toluene=1 / 2 (volume ratio)) and dried to obtain an orange solid (0.370 g) of a formyl compound represented by the following formula (18).

[0165] [ka]

[0166] A nitrogen-purged reaction vessel was charged with 0.364 g of the formyl compound represented by formula (18), 0.091 g of the indenone compound represented by formula (15), 4 mL of acetic acid, and 12 mL of toluene, and the mixture was stirred at 80°C for 11 hours. The reaction solution was allowed to cool to 25°C, and the crude product was washed with toluene. The resulting black solid was purified by column chromatography (carrier: silica gel, eluent: chloroform / methanol = 5 / 1 (volume ratio)) and dried to obtain the desired sensitizing dye as a black solid (0.347 g, 87% yield).

[0167] The obtained black solid was subjected to NMR analysis, and the following 72 hydrogen signals were detected, identifying the structure as represented by the following formula (D-8) (carboxyl group hydrogen was not observed).

[0168] 1H-NMR (600MHz, DMSO-d6): δ(ppm)=0.54-0.64(14H), 0.80-0.97(16H), 1.89-1.97(4H), 6.48-6.57(2H), 7.02-7.10(6H), 7.21- 7.28(4H), 7.34-7.57(16H), 7.78-7.86(3H), 7.95-8.01(3H), 8.04-8.08(1H), 8.18-8.22(1H), 8.26-8.32(1H), 8.35-8.42(1H).

[0169] [ka]

[0170] [Example 1] Characterization Titanium oxide paste (PST-18NR, manufactured by JGC Catalysts and Chemicals Co., Ltd.) was applied by squeegeeing to a glass substrate coated with a fluorine-doped tin oxide thin film. After drying at 110°C for 1 hour, the resulting film 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-2) obtained in Synthesis Example 1 was dissolved in ethyl acetate to prepare 50 mL of a 100 μM solution. 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, resulting in a photoelectrode. The spectral absorption characteristics of the dye solution were measured using a spectrophotometer (U-3000, manufactured by Hitachi, Ltd.). The maximum absorption wavelength was 623 nm, and the solution color was blue when visually observed.

[0171] A platinum thin film with 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 the hole was then sealed to produce a photoelectric conversion element.

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

[0174] [Example 2] A photoelectric conversion element was prepared in the same manner as in Example 1, except that the sensitizing dye for photoelectric conversion (D-8) obtained in Synthesis Example 2 was used instead of the sensitizing dye (D-2) obtained in Synthesis Example 1. The absorption maximum wavelength of the (D-8) dye solution was 592 nm, and the solution color was bluish-purple. The measurement results obtained, as well as the current-voltage characteristics and initial photoelectric conversion efficiency of the photoelectric conversion element, are summarized in Table 1.

[0175] [Comparative Example 1] Characteristic evaluation A photoelectric conversion element was prepared in the same manner as in Example 1, except that the sensitizing dye (E-1) shown below, which does not belong to the present invention, was used instead of (D-2) as the photoelectric conversion sensitizing dye. The dye solution had an absorption maximum wavelength of 540 nm and a reddish-purple color. The measurement results of the current-voltage characteristics and the initial photoelectric conversion efficiency of the photoelectric conversion element obtained are shown in Table 1. (E-1)

[0176] [ka]

[0177] [Table 1]

[0178] As shown in Table 1, the solutions of the sensitizing dyes (D-2) and (D-8) of the present invention exhibited longer absorption maximum wavelengths. It was found that the use of a sensitizing dye composition for photoelectric conversion containing the sensitizing dye (D-2) or (D-8) tends to result in photoelectric conversion elements that exhibit high photoelectric conversion efficiency even when the dye solution is bluish, and that maintain high photoelectric conversion efficiency even after prolonged light irradiation. Therefore, the sensitizing dyes of the present invention are useful for dye-sensitized solar cells, where color variation and design are also important. On the other hand, the molar extinction coefficients of the comparative photoelectric conversion sensitizing dyes were lower than those of the examples, and the photoelectric conversion efficiency of photoelectric conversion elements using the comparative photoelectric conversion sensitizing dyes 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. [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 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): 【Chemical 1】 [In the formula, R ０ 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 optionally substituted aryl group having 6 to 36 carbon atoms, 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 represents R ５ and R ６ may be the same or different, 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 ７ and R ８ 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; R 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; ７ and R ８ may be bonded to each other to form a ring. m represents an integer of 0 or 1; n represents an integer of 1 or 2; Y is CR ９ R １０ or NR １１ represents R ９ to R11 may be the same or different, It represents a linear or branched alkyl group having 1 to 36 carbon atoms which may have a substituent. A represents a monovalent group represented by any one of the following general formulas (2) to (4), and B represents a divalent group represented by the following general formula (5) or a single bond. 【Chemistry 2】 [In the formula, R １４ and R １５ represents a hydrogen atom or an acidic group, and R １４ and R １５ At least one of R is an acidic group. １６ and R １８ represents an acidic group, and R １７ and R １９ represents a hydrogen atom or an electron-withdrawing group. 【Chemistry 3】 [In the formula, R ２０ ~R ２５ 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; 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 ２０ and R ２１ , R ２２ and R ２３ , and R ２４ and R ２５ may be the same or different and may be bonded to each other to form a ring. p represents an integer of 0 and q represents an integer of 1.

2. In the general formula (1), 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 optionally substituted aryl group having 6 to 36 carbon atoms, or 2. The sensitizing dye according to claim 1, which is an amino group having 0 to 36 carbon atoms which may have a substituent.

3. 2. The sensitizing dye according to claim 1, wherein m is 0 in formula (1).

4. A sensitizing dye composition for photoelectric conversion, comprising the sensitizing dye according to any one of claims 1 to 3.

5. A photoelectric conversion element using the sensitizing dye composition for photoelectric conversion according to claim 4.

6. A dye-sensitized solar cell using the photoelectric conversion element according to claim 5.

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