JP6931654B2 - Dye-sensitized dye, sensitizing dye for photoelectric conversion, photoelectric conversion element using it, and dye-sensitized solar cell - Google Patents

Description

The present invention relates to a sensitizing dye used in a dye-sensitized photoelectric conversion element, a photoelectric conversion element using the sensitizing dye, and a dye-sensitized solar cell.

In recent years, carbon dioxide generated from fossil fuels such as coal, petroleum, and natural gas has caused global warming as a greenhouse gas and environmental destruction due to global warming. There is concern that global environmental destruction will continue due to the increase in global energy consumption accompanying the increase in population. Under these circumstances, the use of renewable energy, which is unlikely to be depleted unlike fossil fuels, is being energetically studied. Instead of thermal power generation and nuclear power generation that consume fossil fuels, the use of solar energy centered on solar power generation is important as a next-generation major renewable energy power generation method that can contribute to the prevention of global warming. Is increasing more and more. Development and application are progressing in various fields, from power generation and charging of wristwatches and small portable electronic devices to small-scale power generation facilities in buildings and fallow lands, where utility costs can be saved.

As a means of photovoltaic power generation, a photoelectric conversion element that converts the energy of sunlight into electric energy is used in a solar cell. As solar cells, inorganic solar cells such as single crystal, polycrystalline, amorphous silicon, gallium arsenide, cadmium sulfide, and compound semiconductors such as indium copper selenium have been mainly studied, and are currently used in residential and small-scale power generation facilities. It has been widely put into practical use. However, these inorganic solar cells have problems such as high manufacturing cost and difficulty in securing raw materials.

On the other hand, although the photoelectric conversion efficiency and durability are still much lower than those of inorganic solar cells, organic solar cells such as organic thin-film solar cells and dye-sensitized solar cells using various organic materials have also been developed. ing. Organic solar cells are said to be more advantageous than inorganic solar cells in terms of manufacturing cost, larger area, lighter weight, thinner film, translucency, wider absorption wavelength, flexibility, and securing of raw materials. ..

Among them, the dye-sensitized solar cell proposed by Gretzel et al. (See Non-Patent Document 1) is a thin film electrode made of porous titanium oxide as a semiconductor, and a ruthenium complex dye adsorbed on the semiconductor surface in order to widen the photosensitive wavelength range. It is a wet solar cell composed of an electrolytic solution containing iodine, and is expected to have a high photoelectric conversion efficiency comparable to that of an amorphous silicon solar cell. Dye-sensitized solar cells are attracting attention as next-generation solar cells because they have a simpler element structure than other solar cells and can be manufactured without large-scale manufacturing equipment.

As a dye-sensitized dye used in a dye-sensitized solar cell, the ruthenium complex is considered to be the most superior in terms of photoelectric conversion efficiency. However, since ruthenium is a noble metal, it is disadvantageous in terms of manufacturing cost, and when it is put into practical use and a large amount of ruthenium complex is required, resource restrictions also become a problem. Therefore, research on dye-sensitized solar cells using organic dyes that do not contain precious metals such as ruthenium as sensitizing dyes is being actively conducted. Examples of organic pigments that do not contain noble metals include coumarin-based pigments, cyanine-based pigments, merocyanine-based pigments, rodacyanine-based pigments, phthalocyanine-based pigments, porphyrin-based pigments, and xanthene-based pigments (for example, Patent Documents 1 and 2). reference). In recent years, compounds having a benzopyran structure, a naphthalate imide structure, a fluorene structure, a fluorenone structure, and a dibenzothiophene structure have been reported as sensitizing dyes (see, for example, Patent Documents 3 to 7).

Further, a compound having an indanone structure has also been proposed as an electron attracting portion for adsorbing on the surface of semiconductor particles such as titanium oxide and efficiently transporting excited electrons generated by the sensitizing dye to the semiconductor (for example,. See Patent Documents 8-10). However, 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 variety of structures, they sufficiently satisfy the required characteristics in terms of photoelectric conversion efficiency and stability over time. The current situation is that we have not been able to obtain anything that is satisfactory.

Japanese Patent Application Laid-Open No. 11-214730 Japanese Patent Application Laid-Open No. 11-238905 Japanese Patent Application Laid-Open No. 2003-17146 Japanese Patent Application Laid-Open No. 2004-227825 Japanese Patent Application Laid-Open No. 2009-266633 Japanese Patent Application Laid-Open No. 2009-277527 Japanese Patent Application Laid-Open No. 2015-191934 Japanese Patent Application Laid-Open No. 2011-207784 Japanese Patent Application Laid-Open No. 2012-51854 Japanese Patent Application Laid-Open No. 2016-6811

"Nature", (UK), 1991, Vol. 353, p. 737-740

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 use the sensitizing dye as a sensitizing dye for photoelectric conversion capable of efficiently extracting an electric current. It is an object of the present invention to provide a photoelectric conversion element having good photoelectric conversion and a dye-sensitized solar cell.

In order to solve the above problems, the inventors have diligently studied the improvement of the photoelectric conversion characteristics of the sensitizing dye, and as a result, by using the sensitizing dye having a specific structure as the sensitizing dye for photoelectric conversion, high efficiency and high durability are achieved. It has been found that a sex photoelectric conversion element can be obtained. That is, the present invention is composed of the following contents.

1. 1. A sensitizing dye represented by the following general formula (1).

[In the formula, R ^{1 to} R ⁶ may be the same or different, and independently have a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or 1 to 1 carbon atoms. Represents 6 linear or branched alkoxy groups,
R ⁷ and R ⁸ may be the same or different, and may have a substituent. A linear or branched alkyl group having 1 to 20 carbon atoms, or a carbon which may have a substituent. A cycloalkyl group having 3 to 20 atoms, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, and a carbon atom number 7 to which may have a substituent. It represents an aryl group having 26 aralkyl groups or an aryl group having 6 to 30 carbon atoms which may have a substituent, and R ⁷ and R ⁸ may be bonded to each other to form a ring.
X represents a monovalent group. ]

2. In the general formula (1), a sensitizing dye in which X is a monovalent group represented by the following general formula (X1), (X2) or (X3).

[In the formula, R ⁹ represents an acidic group. ]

[In the formula, L and M may be the same or different, and are linear or branched alkyl groups having 1 to 6 carbon atoms having one or two acidic groups as substituents, or unsubstituted. Represents a linear or branched alkyl group having 1 to 6 carbon atoms. However, at least one of L and M is assumed to be a linear or branched alkyl group having 1 to 6 carbon atoms having one or two acidic groups as substituents. p represents an integer of 0 to 2, and when p is 2, a plurality of Ls existing may be the same or different from each other. ]

[In the formula, R ¹¹ and R ¹² represent a hydrogen atom or an acidic group, and at least one of R ¹¹ or R ¹² is assumed to be an acidic group.
R ¹³ and R ¹⁴ may be the same or different, the hydrogen atom,
A linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent,
A linear or branched alkoxy group having 1 to 18 carbon atoms which may have a substituent,
Alternatively, it represents a linear or branched alkenyl group having 2 to 18 carbon atoms which may have a substituent.
R ¹³ and R ¹⁴ may be connected to each other to form a ring.
r represents an integer of 0 to 4, when r is an integer of 2 to 4, ^{R 13} and ^{R 14} there are a plurality, the ^{R 13 together, R 14} themselves may be the same or different from each other. ]

3. 3. In the general formula (1), a sensitizing dye in which ^{R 1 to} R ^{6 are all hydrogen atoms.}

4. In the general formula (1), R ⁷ and R ⁸ may have a cycloalkyl group having 3 to 20 carbon atoms which may have a substituent, or 6 to 6 carbon atoms which may have a substituent. The sensitizing dye according to 3 above, which is any of the 30 aryl groups, and R ⁷ and R ⁸ may be bonded to each other to form a ring.

5. A sensitizing dye for photoelectric conversion, which comprises the sensitizing dye.

6. A photoelectric conversion element using the photoelectric conversion sensitizing dye.

7. A dye-sensitized solar cell using the photoelectric conversion element.

According to the sensitizing dye according to the present invention, it is possible to obtain a sensitizing dye for photoelectric conversion capable of efficiently extracting an electric current. Further, by using the photoelectric conversion sensitizing dye, a highly efficient and highly durable photoelectric conversion element and a dye sensitized solar cell can be obtained.

It is schematic cross-sectional view which shows the structure of the photoelectric conversion element of the Example of this invention and the comparative example.

Hereinafter, embodiments of the present invention will be described in detail. The sensitizing dye for photoelectric conversion of the present invention is used as a sensitizer in a dye-sensitized photoelectric conversion element. In the photoelectric conversion element of the present invention, a light electrode formed by adsorbing a dye on a semiconductor layer on a conductive support and a counter electrode are arranged to face each other via an electrolyte layer.

Hereinafter, the sensitizing dye represented by the general formula (1) will be specifically described, but the present invention is not limited thereto.

^{Specific examples of the "halogen atom" represented by R 1 to} R ⁶ in the general formula (1) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Specific examples of the "linear or branched alkyl group having 1 to 6 carbon atoms" represented by ^{R 1 to} R ⁶ in the general formula (1) include a methyl group, an ethyl group, and an n-propyl group. , Isopropyl group, n-butyl group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, isohexyl group and the like.

Specific examples of the "linear or branched alkoxy group having 1 to 6 carbon atoms" represented by ^{R 1 to} R ⁶ in the general formula (1) include a methoxy group, an ethoxy group, a propoxy group, and an iso. Examples thereof include propoxy group, n-butoxy group, s-butoxy group, t-butoxy group, n-pentyloxy group, n-hexyloxy group, isohexyloxy group and the like.

In the general formula (1), R ^{1 to} R ⁶ are preferably hydrogen atoms or linear or branched alkyl groups having 1 to 6 carbon atoms, and are hydrogen atoms for reasons such as easy availability of raw materials. Is more preferable.

"Linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) has "1 to 20 carbon atoms". Specific examples of the "linear or branched alkyl group" include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a t-butyl group, and an n-hexyl group. Groups, isohexyl groups and the like can be mentioned.

The "substituent" in the "linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) is used. Specifically, halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; having 1 to 19 carbon atoms such as methoxy group, ethoxy group, propoxy group, t-butoxy group, pentyloxy group and hexyloxy group. Linear or branched alkoxy group; aryl group having 6 to 19 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group, pyrenyl group; dimethylamino group, diethylamino group, ethylmethylamino group, methylpropyl Substitution selected from a linear or branched alkyl group having 1 to 18 carbon atoms, such as an amino group, di-t-butylamino group, diphenylamino group, or an aryl group having 6 to 18 carbon atoms. Examples thereof include a disubstituted amino group having a group; a hydroxyl group; a carboxyl group; a carboxylic acid ester group such as a methyl ester group and an ethyl ester group; and a cyano group. Only one of these "substituents" may be contained, a plurality of these "substituents" may be contained, and when a plurality of these "substituents" are contained, they may be the same or different from each other. In addition, these "substituents" may further have the above-exemplified substituents.

As a "cycloalkyl group having 3 to 20 carbon atoms" in the "cycloalkyl group having 3 to 20 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1). Specific examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, a cyclododecyl group and the like.

Specifically, the "substituent" in the "cycloalkyl group having 3 to 20 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) is a fluorine atom. , Halogen atoms such as chlorine atom, bromine atom, iodine atom; direct group having 1 to 17 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group and hexyl group. Chained or branched alkyl group; linear or branched alkoxy group having 1 to 17 carbon atoms such as methoxy group, ethoxy group, propoxy group, t-butoxy group, pentyloxy group, hexyloxy group; phenyl An aryl group having 6 to 17 carbon atoms such as a group, a naphthyl group, an anthryl group, a phenanthryl group, and a pyrenyl group; a dimethylamino group, a diethylamino group, an ethylmethylamino group, a methylpropylamino group, a di-t-butylamino group, A disubstituted amino group having a substituent selected from a linear or branched alkyl group having 1 to 16 carbon atoms or an aryl group having 6 to 16 carbon atoms, such as a diphenylamino group; hydroxyl group; carboxyl group. A carboxylic acid ester group such as a methyl ester group and an ethyl ester group; an ethenyl group such as a vinyl group, a vinylene group, a phenylethenyl group and a diphenylethenyl group; a cyano group and the like can be mentioned. Only one of these "substituents" may be contained, a plurality of these "substituents" may be contained, and when a plurality of these "substituents" are contained, they may be the same or different from each other. In addition, these "substituents" may further have the above-exemplified substituents.

"Linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) has "2 to 20 carbon atoms". Specific examples of the "linear or branched alkenyl group" include a vinyl group, an allyl group, an isopropenyl group, a 2-butenyl group, a 1-hexenyl group, or a linear chain in which a plurality of these alkenyl groups are bonded. Alternatively, a branched group or the like can be given.

The "substituent" in the "linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) is used. Specifically, halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; number of carbon atoms such as methoxy group, ethoxy group, propoxy group, t-butoxy group, n-pentyloxy group and n-hexyloxy group. 1-18 linear or branched alkoxy groups; aryl groups with 6-18 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group, pyrenyl group; dimethylamino group, diethylamino group, ethylmethylamino From a linear or branched alkyl group having 1 to 17 carbon atoms, such as a group, methylpropylamino group, di-t-butylamino group, diphenylamino group, or an aryl group having 6 to 17 carbon atoms. Disubstituted amino groups having a substituent of choice; hydroxyl groups; carboxyl groups; carboxylic acid ester groups such as methyl ester groups and ethyl ester groups; cyano groups and the like can be mentioned. Only one of these "substituents" may be contained, a plurality of these "substituents" may be contained, and when a plurality of these "substituents" are contained, they may be the same or different from each other. In addition, these "substituents" may further have the above-exemplified substituents.

Specific as the "aralkyl group having 7 to 26 carbon atoms" in the "aralkyl group having 7 to 26 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1). Specific examples thereof include a benzyl group, a phenethyl group, a 3-phenylpropyl group, a benzhydryl group, a trityl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 2-naphthylethyl group and a 2-pyrenylethyl group.

Specific examples of the "substituent" in the "aralkyl group having 7 to 26 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) include a fluorine atom. Halogen atoms such as chlorine atom, bromine atom and iodine atom; linear chain having 1 to 19 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group and hexyl group. Linear or branched alkyl group; linear or branched alkoxy having 1 to 19 carbon atoms such as methoxy group, ethoxy group, propoxy group, t-butoxy group, n-pentyloxy group and n-hexyloxy group. Group: A linear or branched alkyl group having 1 to 18 carbon atoms, such as a dimethylamino group, a diethylamino group, an ethylmethylamino group, a methylpropylamino group, a di-t-butylamino group, or a diphenylamino group. Alternatively, a disubstituted amino group having a substituent selected from an aryl group having 6 to 19 carbon atoms; a hydroxyl group; a carboxyl group; a carboxylic acid ester group such as a methyl ester group or an ethyl ester group; a vinyl group, a vinylene group, or a phenyl Ethenyl groups such as ethenyl group and diphenylethenyl group; cyano group and the like can be mentioned. Only one of these "substituents" may be contained, a plurality of these "substituents" may be contained, and when a plurality of these "substituents" are contained, they may be the same or different from each other. In addition, these "substituents" may further have the above-exemplified substituents.

The "aryl group having 6 to 30 carbon atoms" in the "aryl group having 6 to 30 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) Specific examples thereof include 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 shall represent an aromatic hydrocarbon group and a condensed polycyclic aromatic group. Among these, a phenyl group or a naphthyl group is preferable, and a phenyl group is more preferable.

The "substituent" in the "aryl group having 6 to 30 carbon atoms which may have a substituent" represented by ^{R 7} or R ⁸ in the general formula (1) is specifically a fluorine atom. , Halogen atoms such as chlorine atom, bromine atom, iodine atom; carbon such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, n-hexyl group, t-octyl group. A linear or branched alkyl group having 1 to 24 atoms; a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, an n-pentyloxy group, an n-hexyloxy group, etc. having 1 to 24 carbon atoms. Linear or branched alkoxy group; aryl group having 6 to 24 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group, pyrenyl group; dimethylamino group, diethylamino group, ethylmethylamino group, methylpropyl A substituent selected from a linear or branched alkyl group having 1 to 23 carbon atoms or an aryl group having 6 to 23 carbon atoms, such as an amino group, a di-t-butylamino group, and a diphenylamino group. Disubstituted amino group having: hydroxyl group; carboxyl group; carboxylic acid ester group such as methyl ester group and ethyl ester group; ethenyl group such as vinyl group, vinylene group, phenylethenyl group and diphenylethenyl group; cyano group and the like I can give it. Only one of these "substituents" may be contained, a plurality of these "substituents" may be contained, and when a plurality of these "substituents" are contained, they may be the same or different from each other. In addition, these "substituents" may further have the above-exemplified substituents.

In the general formula (1), R ⁷ and R ⁸ may have a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, and carbon which may have a substituent. A cycloalkyl group having 3 to 20 atoms or an aryl group having 6 to 30 carbon atoms which may have a substituent is preferable, and a cycloalkyl group having 3 to 20 carbon atoms which may have a substituent is preferable. A aryl group having 6 to 30 carbon atoms, which may have a group or a substituent, is more preferable.

In the general formula (1), R ⁷ and R ⁸ represent the substituents as described above, whereas R ⁷ and R ⁸ are single bonds (R ^7- R ⁸ ) or bonds via oxygen atoms (R 7-R 8). it may be bonded to each other to form a ring by coupling through ^{R 7} -O-R ⁸⁾ or sulfur atom ^{(R 7 -S-R 8)} .

In the general formula (1), X represents a monovalent group, and is preferably a monovalent group represented by the general formula (X1), (X2) or (X3). X is more preferably a monovalent group represented by the general formula (X1) or (X3), and particularly preferably a monovalent group represented by the general formula (X3).

^{Specific examples of the "acidic group" represented by R 9} in the general formula (X1) 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. You can give a group. Among these, a carboxyl group or a phosphonic acid group is preferable, and a carboxyl group is more preferable.

"A linear or branched alkyl group having 1 to 6 carbon atoms having one or two acidic groups as substituents" or "unsubstituted alkyl group" represented by L or M in the general formula (X2). Specific examples of the "linear or branched alkyl group having 1 to 6 carbon atoms" in the "linear or branched alkyl group having 1 to 6 carbon atoms" include a methyl group, an ethyl group, and n. -Propyl group, isopropyl group, n-butyl group, t-butyl group, n-hexyl group, isohexyl group and the like can be mentioned. Among these, a linear or branched alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.

As an "acidic group" in "a linear or branched alkyl group having 1 to 6 carbon atoms having one or two acidic groups as substituents" represented by L or M in the general formula (X2). Specific examples thereof 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 preferable, and a carboxyl group is more preferable. When the number of "acidic groups" is one, the substitution position of the "acidic group" is preferably the terminal of the alkyl group, and when the number of "acidic groups" is two, the two "acidic groups" Of the "acidic groups", it is preferable that the substitution position of at least one of the "acidic groups" is the terminal of the alkyl group.

The "linear or branched alkyl group having 1 to 6 carbon atoms having one or two acidic groups as a substituent" represented by L or M in the general formula (X2) includes a carboxyl group or a branched alkyl group. A linear or branched alkyl group having 1 to 3 carbon atoms having one or two acidic groups selected from phosphonic acid groups as substituents is preferable, and one or two carboxyl groups are used as substituents. Methyl or ethyl groups are more preferred.

In the general formula (X2), at least one of L and M is "a linear or branched alkyl group having 1 to 6 carbon atoms having one or two acidic groups as substituents". .. Here, p represents an integer of 0 to 2, and when p is 0, L does not exist, so M is "a direct number of carbon atoms 1 to 6 having one or two acidic groups as substituents. It becomes a chain or branched alkyl group. When p is 2, at least one of the two existing L or M is "a linear chain having 1 to 6 carbon atoms having one or two acidic groups as substituents". Alternatively, it may be a branched alkyl group.

In the general formula (X3), the ^{"acidic group" in the "hydrogen atom or acidic group" represented by R 11} and R ¹² specifically includes a carboxyl group, a sulfonic acid group, a phosphoric acid group, and a hydroxamic acid group. Examples thereof include 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 preferable, and a carboxyl group is more preferable.

In the general formula (X3), the "linear or branched alkyl group having 1 to 18 carbon atoms which may have a substituent" represented by ^{R 13} and R ^{14 has "1 carbon atom number".} Specific examples of the "to 18 linear or branched alkyl group" include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group and a decyl group. Linear alkyl groups; branched alkyl groups such as isopropyl group, isobutyl group, s-butyl group, t-butyl group and isooctyl group can be mentioned.

In the general formula (X3), the "linear or branched alkoxy group having 1 to 18 carbon atoms which may have a substituent" represented by ^{R 13} and R ^{14 has "1 carbon atom number".} Specific examples of the "to 18 linear or branched alkoxy groups" include methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group and nonyloxy group. Linear alkoxy groups such as decyloxy group; branched alkoxy groups such as isopropoxy group, isobutoxy group, s-butoxy group, t-butoxy group and isooctyloxy group can be mentioned.

In the general formula (X3), the "linear or branched alkenyl group having 2 to 18 carbon atoms which may have a substituent" represented by ^{R 13} and R ^{14 has a "carbon atom number 2".} Specific examples of the "to 18 linear or branched alkenyl groups" include alkenyl groups such as vinyl group, allyl group, isopropenyl group, 2-butenyl group and 1-hexenyl group, or alkenyl groups thereof. Examples thereof include a plurality of bonded linear or branched alkenyl groups.

In the general formula (X3), "a linear or branched alkyl group having 1 to 18 carbon atoms having a substituent" represented by ^{R 13} and R ^14.
"Substituent" in "linear or branched alkoxy group having 1 to 18 carbon atoms having a substituent" or "linear or branched alkoxy group having 2 to 18 carbon atoms having a substituent" as,
Specifically, halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom;
Cyan group; hydroxyl group; nitro group; nitroso group; thiol group;
A cycloalkyl group having 3 to 16 carbon atoms such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group;
A linear alkoxy group having 1 to 16 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, and a decyloxy group;
A branched alkoxy group having 3 to 16 carbon atoms such as an isopropoxy group, an isobutoxy group, an s-butoxy group, a t-butoxy group, and an isooctyloxy group;
Cycloalkoxy groups having 3 to 16 carbon atoms such as cyclopropoxy group, cyclobutoxy group, cyclopentyloxy group, cyclohexyloxy group;
Aryl groups having 6 to 16 carbon atoms such as phenyl group, naphthyl group, biphenyl group, anthryl group, phenanthryl group, pyrenyl group, indenyl group and fluorenyl group;
Unsubstituted Amino Group; Substituents having 1 to 16 carbon atoms such as methylamino group, dimethylamino group, diethylamino group, ethylmethylamino group, methylpropylamino group, di-t-butylamino group and diphenylamino group. Amino group having;
Carboxyl groups; carboxylic acid ester groups such as methyl ester groups and ethyl ester groups; and the like can be mentioned. Only one of these "substituents" may be contained, a plurality of these "substituents" may be contained, and when a plurality of these "substituents" are contained, they may be the same or different from each other. In addition, these "substituents" may further have the above-exemplified substituents.

In the general formula (X3), R ¹³ and R ¹⁴ are preferably a linear or branched alkyl group having 1 to 18 carbon atoms which may have a hydrogen atom or a substituent, and more preferably a hydrogen atom. ..

In the general formula (X3), R ¹³ and R ¹⁴ may be bonded to each other to form a ring, which may be a single bond or an atom of either a nitrogen atom, an oxygen atom or a sulfur atom. They may be bonded to each other to form a ring by bonding through the cells.

In the general formula (X3), r represents the number of thiophene groups. Here, the thiophene group has a role of a linking group that transports (transfers) the electrons excited in the dye portion to the indanone group which is an electron attracting portion. r represents an integer of 0 to 4, preferably 0 to 2.

Among the sensitizing dyes of the present invention represented by the general formula (1), the sensitizing dye containing a carboxyl group or a phosphonic acid group as an acidic group can be easily adsorbed on the surface of the semiconductor layer. This leads to further improvement of the photoelectric conversion characteristics of the photoelectric conversion element using the sensitizing dye.

The sensitizing dye of the present invention represented by the general formula (1) shall include all possible stereoisomers. Any isomer can be suitably used as the sensitizing dye in the present invention. For example, in the general formula (1), the ^{sensitizing dye of the present invention in which R 1 to} R ⁶ are hydrogen atoms and X is a monovalent group represented by the general formula (X1) is described in the following general formula (2). And the compound represented by (3) shall be included.

Specific examples of the sensitizing dye of the present invention represented by the general formula (1) are shown in the following formulas (A-1) to (A-51), but the present invention is not limited thereto. The following exemplary compounds show an example of possible stereoisomers and are intended to include all other stereoisomers. Further, it may be a mixture of two or more kinds of stereoisomers.

The sensitizing dye of the present invention represented by the general formula (1) can be synthesized by using a known method. In the general formula (1), when R ^{1 to} R ⁶ are all hydrogen atoms, they can be synthesized as follows, for example. An intermediate represented by the following formula (6) by performing a Buchwald-Hartwig reaction between 3,7-dibromodibenzothiophene represented by the following formula (4) and an amine compound represented by the following formula (5). A monobromo compound can be obtained. Further, the formyl group (—Br) of the general formula (6) is subjected to a cross-coupling reaction such as Suzuki coupling with a boronic acid having a corresponding substituent or according to a conventional method. -By converting to CHO), a formyl form, which is an intermediate represented by the following general formula (7), can be obtained. However, in the following general formulas (5) to (7), R ⁷ , R ⁸ , R ¹³ and R ¹⁴ have the same meanings as the symbols in the general formula (1), and similarly, r is 0 to 4. Represents an integer of.

The formyl form (r = 0) represented by the following general formula (7) is, for example, an aryllithium obtained by exchanging a metal halogen between a bromo form represented by the general formula (6) and butyllithium or the like. It can be synthesized by capturing with N, N-dimethylformamide (DMF).

The synthesis of the formyl form (r = 1 to 4) represented by the following general formula (7) is, for example, 5-formyl-2-thiopheneboronic acid or 5'-formyl-2,2'-bithiophene-5-boron. A formyl compound represented by the general formula (7) can be synthesized by carrying out a cross-coupling reaction using a boronic acid having a thiophene ring having a formyl group and a corresponding substituent such as an acid.

The sensitizing dye in which X in the general formula (1) of the present invention is a monovalent group represented by the general formula (X1), (X2) or (X3) is described above according to the target X1 to X3. It can be synthesized by carrying out a condensation reaction between an intermediate (formyl form) of the general formula (7) and a compound suitable for each. Specifically, cyanoacetic acid or the like (when X is the general formula (X1)), a rhodanine compound such as rhodanine-3-acetic acid (when X is the general formula (X2)), or the following formula (8). It can be synthesized by performing a condensation reaction with an indenone compound as represented (when X is the general formula (X3)).

As the starting material such as the above formula (4) or (5), a commercially available product may be used, or a product synthesized by a known method may be used. The indenone compound represented by the general formula (8) can be easily synthesized by the method described in Patent Documents 8 to 10 described above.

When R ^{1 to} R ⁶ are substituents other than hydrogen atoms, they are represented by the general formula (1) by carrying out the same reaction as above using the corresponding dibromodibenzothiophene derivatives and the like. The sensitizing dye of the present invention can be synthesized.

Examples of the method for purifying the sensitizing dye compound of the present invention represented by the general formula (1) include purification by column chromatography; adsorption purification with silica gel, activated charcoal, activated white clay, etc.; recrystallization with a solvent, crystallization method, etc. Known methods can be mentioned. In addition, these compounds can be identified by nuclear magnetic resonance spectroscopy (NMR) or the like.

The sensitizing dye of the present invention may be used alone or in combination of two or more. In addition, the sensitizing dye of the present invention can be used in combination with other sensitizing dyes that do not belong to the present invention. Specific examples of other sensitizing dyes include the above general formula (1) such as a ruthenium complex, a coumarin dye, a cyanine dye, a merocyanine dye, a rodacyanine dye, a phthalocyanine dye, a porphyrin dye, and a xanthene dye. Examples include sensitizing pigments other than the represented sensitizing pigments. When the sensitizing dye of the present invention is used in combination with these other sensitizing dyes, the amount of the other sensitizing dye used with respect to the sensitizing dye of the present invention is preferably 10 to 200% by weight, 20 More preferably, it is ~ 100% by weight.

The sensitizing dye of the present invention can be applied as a spectral sensitizing dye for various imaging materials such as silver halide, zinc oxide, and titanium oxide, a photocatalyst, and a photofunctional material, and is a dye-sensitized photoelectric conversion. It can also be applied as a sensitizing dye for photoelectric conversion used for elements and the like. In addition, light from next-generation solar cells such as organic thin-film solar cells and perovskite solar cells, and next-generation storage cells manufactured in combination with other photoelectric conversion elements using the energy excited by the sensitizing dye of the present invention. It can be applied to energy (electricity, heat, information, etc.) conversion elements. For example, the method for producing a dye-sensitized photoelectric conversion element in the present invention is not particularly limited, but a semiconductor layer is formed on a conductive support (electrode), and the semiconductor layer is used for the photoelectric conversion of the present invention. A method of producing a photoelectrode by adsorbing (supporting) a sensitive dye is preferable (see FIG. 1). 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 time is common. When two or more kinds of photoelectric conversion sensitizing dyes of the present invention are used in combination, or when the photoelectric conversion sensitizing dye of the present invention is used in combination with other sensitizing dyes, a mixed solution of all the dyes to be used is prepared. The semiconductor layer may be immersed in the semiconductor layer, or a separate solution may be prepared for each dye and the semiconductor layer may be immersed in each solution in order.

In the present invention, in addition to the 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. However, it is preferable to use a glass substrate coated with a fluorine-doped tin oxide thin film.

Specific examples of the semiconductor forming the semiconductor layer in the present invention include metals 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. Oxides: Metal sulfides such as titanium sulfide, zinc sulfide, zirconium sulfide, copper sulfide, tin sulfide, indium sulfide, tungsten sulfide, cadmium sulfide, silver sulfide; titanium selenium, zirconium selenium, indium selenium, tungsten selenium Metallic sulphides such as; single semiconductors such as silicon and germanium can be mentioned. These semiconductors can be used not only alone but also in combination of two or more. In the present invention, it is preferable to use one or more selected from titanium oxide, zinc oxide, and tin oxide as the semiconductor.

The aspect of the semiconductor layer in the present invention is not particularly limited, but a thin film having a porous structure composed of fine particles is preferable. When the substantial surface area of the semiconductor layer is increased due to the porous structure or the like and the amount of dye adsorbed on the semiconductor layer is increased, a highly efficient photoelectric conversion element can be obtained. The semiconductor particle size is preferably 5 to 500 nm, more preferably 10 to 100 nm. The film thickness of the semiconductor layer is usually 2 to 100 μm, but more preferably 5 to 20 μm. As a method for forming the semiconductor layer, 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 a solvent or an additive is formed by firing. A method of forming a film by removing the above-mentioned material, a method of forming a film by a sputtering method, a vapor deposition method, an electrodeposition method, an electrodeposition method, a microwave irradiation method, or the like can be mentioned, but the method is not limited thereto.

In the present invention, as the paste containing the semiconductor fine particles, a commercially available product may be used, or a paste prepared by dispersing the commercially available semiconductor fine powder in a solvent may be used. Specific examples of the solvent used when preparing the paste include water; alcohol solvents such as methanol, ethanol and isopropyl alcohol; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; n-hexane, cyclohexane and benzene. A hydrocarbon solvent such as toluene can be mentioned, but the present invention is not limited to these. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.

In the present invention, as a method for dispersing the semiconductor fine powder in a solvent, a mortar or the like may be used for grinding, or a ball mill, a paint conditioner, a vertical bead mill, a horizontal bead mill, an attritor or the like may be used. When preparing the paste, it is preferable to add a surfactant or the like in order to prevent agglomeration of the semiconductor fine particles, and it is preferable to add a thickener such as polyethylene glycol in order to thicken the paste.

The adsorption of the sensitizing dye for photoelectric conversion of the present invention on the surface of the semiconductor layer is carried out by immersing the semiconductor layer in the dye solution and leaving it at room temperature for 30 minutes to 100 hours or under heating conditions for 10 minutes to 24 hours. However, it is preferable to leave it at room temperature for 10 to 20 hours. The dye concentration in the dye solution is preferably 10 to 2000 μM, more preferably 50 to 500 μM.

Specific examples of the solvent used when adsorbing the sensitizing dye for photoelectric conversion of the present invention on the surface of the semiconductor layer include alcohol solvents such as methanol, ethanol, isopropyl alcohol and t-butyl alcohol; acetone, methyl ethyl ketone and methyl. Ketone solvents such as isobutyl ketone; ester solvents such as ethyl formate, ethyl acetate, n-butyl acetate; ether solvents such as diethyl ether, 1,2-dimethoxyethane, tetrahydrofuran, 1,3-dioxolane; N, N Amido solvents such as -dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone; nitrile solvents such as acetonitrile, methoxynitrile, propionitrile; dichloromethane, chloroform, bromoform, o-dichlorobenzene and the like. Halogenated hydrocarbon solvents; hydrocarbon solvents such as n-hexane, cyclohexane, benzene and toluene can be mentioned, but are not limited thereto. These solvents are used alone or as a mixed solvent of two or more kinds. 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.

When adsorbing the sensitizing dye for photoelectric conversion of the present invention 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 is dissolved in the dye solution. It may be co-adsorbed with the dye. By using cholic acid or a cholic acid derivative, association between 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 cholic acid derivative is used, their concentration in the dye solution is preferably 0.1 to 100 mM, more preferably 0.5 to 10 mM.

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 a conductive material having catalytic ability is used in order to promote the redox reaction of redox ions. It is preferable to do so. Specific examples of the conductive material include, but are not limited to, platinum, rhodium, ruthenium, carbon and the like. In the present invention, it is particularly preferable to use a platinum thin film formed on a conductive support as a counter electrode. As a method for forming a conductive thin film, a paste containing a conductive material 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 fired. Examples thereof include a method of forming a film by removing a solvent and additives, and a method of 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 the method is not limited thereto.

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

Examples of the solvent for dissolving the electrolyte include nitrile solvents such as acetonitrile, methoxyacetonitrile, propionitrile, 3-methoxypropionitrile and benzonitrile; ether solvents such as diethyl ether, 1,2-dimethoxyethane and tetrahydrofuran; N. , N-dimethylformamide, N, N-dimethylacetoamide and other amide solvents; ethylene carbonate, propylene carbonate and other carbonate solvents; γ-butyrolactone, γ-valerolactone and other lactone solvents can be mentioned. Not limited to. These solvents are used alone or as a mixed solvent of two or more kinds. Among these solvents, a nitrile solvent is preferable.

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 compound may be contained in the electrolytic solution. Examples of amine compounds include 4-t-butylpyridine, 4-methylpyridine, 2-vinylpyridine, N, N-dimethyl-4-aminopyridine, N, N-dimethylaniline, N-methylbenzimidazole and the like. Can be done. The concentration of the amine compound in the electrolytic solution is preferably 0.05 to 5 M, more preferably 0.2 to 1 M.

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

In the photoelectric conversion element of the present invention, a solid charge transport layer may be formed between the pair of opposing electrodes instead of the electrolyte. The charge transport material contained in the solid charge transport layer is preferably a hole transport material. Specific examples of charge transporting substances include inorganic hole transporting substances such as copper iodide, copper bromide, and copper thiocyanate, polypyrrole, polythiophene, poly-p-phenylene vinylene, polyvinylcarbazole, polyaniline, oxadiazole derivatives, and birds. Examples thereof include, but are not limited to, organic hole transporting substances such as phenylamine derivatives, pyrazoline derivatives, fluorenone derivatives, hydrazone compounds, and stylben compounds. The solid charge transport layer may contain a lithium compound such as lithium bis (trifluoromethanesulfonyl) imide or lithium diisopropylimide, a basic amine compound such as 4-t-butylpyridine or 2-amylpyridine, and the like as additives. preferable. Further, for the purpose of improving the conductivity, an oxidizing agent for converting a part of the organic hole transporting substance into a radical cation may be added. Examples of the oxidizing agent include cobalt complexes such as tris (2- (1H-pyrazole-1-yl) -4-t-butylpyridine) cobalt (III) tris (bis (trifluoromethylsulfonyl) imide).

When the solid charge transport layer is formed by using the organic hole transport material in the present invention, a film-forming binder resin may be used in combination. Specific examples of the film-forming binder resin include polystyrene resin, polyvinyl acetal resin, polycarbonate resin, polysulfone resin, polyester resin, polyphenylene oxide resin, polyallylate resin, alkyd resin, acrylic resin, and phenoxy resin. , Not limited to these. These resins can be used alone or as a copolymer of one or a mixture of two or more. The amount of these binder resins used for the organic hole transporting substance is preferably 20 to 1000% by weight, more preferably 50 to 500% by weight.

In the photoelectric conversion element of the present invention, the electrode (optical electrode) provided with the semiconductor layer on which the sensitizing dye for photoelectric conversion is adsorbed serves as a cathode, and the counter electrode serves as an anode. Light such as sunlight may be emitted from either the light electrode side or the counter electrode side, but it is preferable to irradiate from the light electrode side. When irradiated with sunlight or the like, the dye absorbs light and becomes excited to emit electrons. These electrons flow to the outside via the semiconductor layer and move to the opposite electrode. On the other hand, the dye that has been in an oxidized state by emitting electrons returns to the ground state by receiving the electrons supplied from the counter electrode via the ions in the electrolyte. This cycle causes a current to flow and functions as a photoelectric conversion element.

When evaluating the 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 represents the current per 1 cm 2} flowing between the two terminals when the output terminal is short-circuited, and the open circuit voltage represents the voltage between the two terminals when the output terminal is opened. The fill factor is a value obtained by dividing the maximum output (product of current and voltage) by the product of short-circuit current and open circuit voltage, and is mainly affected by internal resistance. The photoelectric conversion efficiency is obtained as a value obtained by dividing the maximum output (W) by ^{the light intensity (W) per 1 cm 2} and multiplying it by 100 to display it as a percentage.

The photoelectric conversion element of the present invention can be applied to a dye-sensitized solar cell, various optical sensors, and the like. In the dye-sensitized solar cell of the present invention, a photoelectric conversion element containing a photoelectric conversion sensitizing dye composed of the sensitizing dye represented by the general formula (1) becomes a cell, and the required number of cells are arranged in a module. It is obtained by providing a predetermined electrical wiring.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples. In the synthetic example, the compound was identified by ¹ H-NMR analysis (nuclear magnetic resonance apparatus manufactured by JEOL Ltd., JNM-ECA-600 or JNM-EX270).

[Synthesis Example 1] Synthesis of sensitizing dye (A-5) In a nitrogen-substituted reaction vessel, 165 mL of toluene, 8.00 g of 3,7-dibromodibenzothiophene, and 10.12 g of bis (4-t-octylphenyl) amine. , 3.37 g of sodium-t-butoxide, 1.07 g of tris (dibenzylideneacetone) dipalladium (0), and 2.36 mL of tri-t-butylphosphine / toluene solution at a concentration of 0.2 mg / mL, and added at 80 ° C. Was stirred for 2 hours. After allowing the reaction solution to cool to 25 ° C., 380 mL of water and 380 mL of ethyl acetate were added and stirred to extract the organic layer. The organic layer was washed with saturated brine, dried over sodium sulfate, and dried under reduced pressure to give a crude product. The crude product is purified by column chromatography (carrier: silica gel, solvent (n-hexane)) and dried under reduced pressure to obtain a white solid (5.96 g) of a monobromo compound represented by the following formula (9). rice field.

1.20 g of the monobromo compound represented by the above formula (9) and 16 mL of dehydrated tetrahydrofuran were placed in a nitrogen-substituted reaction vessel, and 1.5 mL of a 1.6 M n-butyllithium hexane solution was added while stirring at −72 ° C. After the reaction for 1 hour, 0.3 mL of dehydrated dimethylformaldehyde was added dropwise, and the reaction was carried out for 2 hours. Then, the reaction solution was put into ice water, and the organic layer was extracted with methylene chloride. The organic layer was washed with water, separated, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by chromatography (carrier: silica gel, solvent: hexane / toluene = 9/1 (volume ratio)) to obtain a white solid (0.78 g) of a formyl compound represented by the following formula (10). ..

To a nitrogen-substituted reaction vessel, 25 mL of acetic acid, 0.362 g of a formyl compound represented by the above formula (10), 0.297 g of cyanoacetic acid, and 0.027 g of ammonium acetate were added, and the mixture was heated and stirred at 110 ° C. for 21 hours. After allowing the reaction solution to cool to 25 ° C., 125 mL of water was added and the mixture was stirred to extract the organic layer. The organic layer was washed successively with water and saturated brine, and the obtained organic layer was dried to obtain the desired sensitizing dye as a red solid (0.333 g, yield 86%).

The obtained red solid was subjected to NMR analysis, and the following 49 hydrogen signals were detected and identified as a structure represented by the following formula (A-5) (hydrogen of a carboxyl group was not observed).

^{1 1} H-NMR (600 MHz, CDCl ₃ ): δ (ppm) = 0.66-0.88 (18H), 1.24-1.40 (12H), 1.60-1.80 (4H), 6 .95-7.10 (4H), 7.14-7.18 (1H), 7.22-7.34 (4H), 7.35-7.40 (1H), 7.94-8.00 (1H), 8.02-8.12 (2H), 8.36-8.41 (1H), 8.42-8.48 (1H).

[Synthesis Example 2] Synthesis of sensitizing dye (A-22) In a nitrogen-substituted reaction vessel, 10.7 mL of a mixed solution of acetic acid / toluene = 5/2 (volume ratio) was added to the formula obtained in Synthesis Example 1 (Synthesis Example 2). 0.247 g of the formyl compound represented by 10) and 0.117 g of the indanone compound represented by the following formula (11) were added, and the mixture was stirred at 90 ° C. for 3 hours. After allowing the reaction solution to cool to 25 ° C., 50 mL of water was added and the mixture was stirred to extract the organic layer. The organic layer was washed successively with water and saturated brine, and dried to obtain the desired sensitizing dye as a reddish brown solid (0.283 g, yield 93%).

The obtained reddish brown solid was subjected to NMR analysis, and the following 52 hydrogen signals were detected and identified as a structure represented by the following formula (A-22) (hydrogen of a carboxyl group was not observed).

^{1 1} H-NMR (600 MHz, CDCl ₃ ): δ (ppm) = 0.64-0.85 (18H), 1.22-1.45 (12H), 1.70-1.91 (4H), 6 .95-7.00 (1H), 7.01-7.05 (4H), 7.22-7.30 (1H), 7.35-7.40 (4H), 7.90-8.00 (1H), 8.04-8.07 (1H), 8.20-8.24 (1H), 8.27-8.33 (1H), 8.34-8.38 (1H), 8. 39-8.41 (1H), 8.54-8.59 (1H), 9.10-9.15 (1H).

[Synthesis Example 3] Synthesis of sensitizing dye (A-28) In a reaction vessel substituted with nitrogen, 200 mL of toluene, 10.78 g of 3,7-dibromodibenzothiophene, and an amine compound represented by the following formula (12). 27 g, sodium-t-butoxide 4.54 g, tris (dibenzylideneacetone) dipalladium (0) 1.44 g, concentration 0.2 mg / mL tri-t-butylphosphine / toluene solution 2.6 mL was added, and 85 ° C. Was stirred for 2 hours. After allowing the reaction solution to cool to 25 ° C., 150 mL of water and 500 mL of ethyl acetate were added and stirred to extract the organic layer. The organic layer was washed with saturated brine, and the obtained 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, solvent: n-hexane) and dried to obtain a white solid (5.32 g) of a monobromo compound represented by the following formula (13).

34.5 mL of N, N-dimethylformamide, 2.30 g of the monobromo compound of the above formula (13), and 1.01 g of phosphorus oxychloride were placed in a nitrogen-substituted reaction vessel, stirred at 25 ° C. for 90 minutes, and 2 at 60 ° C. Stirred for hours. The reaction mixture was placed in 175 mL of ice water, and 175 mL of ethyl acetate was added to extract the organic layer. Extraction with ethyl acetate was performed 3 times. The organic layer was dried over magnesium sulfate and the solvent was distilled off to obtain a crude product. The obtained crude product was purified by column chromatography (carrier: silica gel, solvent: toluene) to obtain 2.25 g (yield 91%) of a compound represented by the following formula (14) as a brown solid.

In a nitrogen-substituted reaction vessel, 35 mL of N, N-dimethylformamide, 2.23 g of the compound represented by the above formula (14), 1.97 g of diethyl diphenylmethylphosphonate, and 1.00 g of potassium t-butoxide were placed, and 3 at 25 ° C. Stirred for hours. After stopping the reaction by adding 90 mL of water, the reaction was washed with water / methanol = 1/1 (volume ratio). The obtained crude product was purified by column chromatography (carrier: silica gel, solvent: hexane / toluene = 5/1 (volume ratio)), and 2.89 g of a monobromo compound represented by the following formula (15) (2.89 g (volume ratio)). A yellow solid with a yield of 97%) was obtained.

0.500 g of the monobromo compound represented by the above formula (15) and 10 mL of dehydrated tetrahydrofuran were placed in a nitrogen-substituted reaction vessel, and 0.71 mL of a 1.6 M n-butyllithium / hexane solution was added while stirring at −72 ° C. Was added dropwise, and the reaction was carried out for 2 hours. After the reaction, 0.3 mL of dehydrated dimethylformaldehyde was added dropwise to the reaction solution, and the reaction was carried out for 2 hours. Then, the reaction solution was put into ice water, methylene chloride was added, and the organic layer was extracted. The organic layer was washed with water, separated, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by chromatography (carrier: silica gel, solvent: hexane / toluene = 9/1 (volume ratio)) to obtain a yellow solid (0.196 g) of a formyl compound represented by the following formula (16). ..

In a nitrogen-substituted reaction vessel, 8.5 mL of a mixed solution of acetic acid / toluene = 5/2 (volume ratio), 0.188 g of a formyl compound represented by the above formula (16), and indanone represented by the above formula (11). 0.102 g of the compound was added, and the mixture was stirred at 90 ° C. for 5 hours. After allowing the reaction solution to cool to 25 ° C., 17 mL of methanol was added and stirred, and the reaction product was filtered. The reaction product was washed with methanol and the obtained organic layer was dried to obtain the desired sensitizing dye as a black solid (0.242 g, yield 98%).

The obtained black solid was subjected to NMR analysis, and the following 32 hydrogen signals were detected and identified as a structure represented by the following formula (A-28) (hydrogen of a carboxyl group was not observed).

^{1 1} H-NMR (600 MHz, CDCl ₃ ): δ (ppm) = 1.25-1.28 (1H), 1.47-1.49 (1H), 1.55-1.60 (1H), 1 .72-1.76 (1H), 1.80-1.89 (1H), 1.90-1.96 (3H), 6.60-6.70 (1H), 6.80-6.95 (1H), 7.00-7.10 (2H), 7.15-7.21 (2H), 7.24-7.35 (5H), 7.40-7.50 (4H), 7. 80-7.90 (1H), 7.95-7.97 (1H), 8.00-8.09 (1H), 8.30-8.43 (4H), 8.58-8.62 ( 1H), 9.10-9.21 (1H).

[Synthesis Example 4] Synthesis of sensitizing dye (A-32) In a reaction vessel substituted with nitrogen, 41 mL of toluene, 2.2 g of 3,7-dibromodibenzothiophene, and an amine compound represented by the following formula (17) 1. 68 g, sodium-t-butoxide 0.93 g, tris (dibenzylideneacetone) dipalladium (0) 0.29 g, concentration 0.2 mg / mL tri-t-butylphosphine / toluene solution 0.37 mL was added, and 80 ° C. Was stirred for 5 hours. After allowing the reaction solution to cool to 25 ° C., 30 mL of water and 80 mL of ethyl acetate were added and stirred to extract the organic layer. The organic layer was washed with saturated brine, dried over sodium sulfate, and concentrated under reduced pressure to give a crude product. The crude product is purified by column chromatography (carrier: silica gel, mixed solvent: n-hexane / toluene), dried, and a white-yellow solid (1.08 g) of a monobromo compound represented by the following formula (18). Got

1. 1.00 g of the monobromo compound represented by the above formula (18) and 20 mL of dehydrated tetrahydrofuran were placed in a nitrogen-substituted reaction vessel, and the n-butyllithium / hexane solution having a concentration of 1.6 M was added while stirring at −72 ° C. 4 mL was added dropwise and the reaction was carried out for 3 hours. After the reaction, 0.4 mL of dehydrated dimethylformaldehyde was added dropwise to the reaction solution, and the reaction was carried out for 2 hours. Then, the reaction solution was put into ice water, methylene chloride was added, and the organic layer was extracted. The organic layer was washed with water, separated, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by chromatography (carrier: silica gel, solvent: hexane / toluene = 9/1 (volume ratio)) to obtain a yellow solid (0.56 g) of a formyl compound represented by the following formula (19). ..

11 mL of acetic acid, 0.160 g of the formyl compound represented by the above formula (19), 0.168 g of cyanoacetic acid and 0.015 g of ammonium acetate were placed in a nitrogen-substituted reaction vessel, and the mixture was stirred at 105 ° C. for 7 hours. After allowing the reaction solution to cool to 25 ° C., 65 mL of water was added and the mixture was stirred to extract the organic layer. The organic layer was washed successively with water and saturated brine, and dried to obtain the desired sensitizing dye as a red solid (0.155 g, yield 89%).

The obtained red solid was subjected to NMR analysis, and the following 25 hydrogen signals were detected and identified as a structure represented by the following formula (A-32) (hydrogen of a carboxyl group was not observed).

^{1 1} H-NMR (270 MHz, dimethyl sulfoxide (DMSO) -d ₆ ): δ (ppm) = 1.90-2.06 (4H), 2.30-2.40 (4H), 3.90-4. 00 (1H), 4.90-5.10 (1H), 7.29-7.60 (8H), 7.89-8.00 (1H), 8.10-8.22 (1H), 8 .30-8.50 (4H), 8.51-8.65 (1H).

[Synthesis Example 5] Synthesis of sensitizing dye (A-33) In a nitrogen-substituted reaction vessel, 7.2 mL of a mixed solution of acetic acid / toluene = 5/2 (volume ratio), formyl represented by the above formula (19). 0.160 g of the body compound and 0.078 g of the indanone compound represented by the above formula (11) were added, and the mixture was stirred at 90 ° C. for 6 hours. After allowing the reaction solution to cool to 25 ° C., 15 mL of toluene was added, the mixture was stirred, and the reaction product was filtered. The reaction was washed with methanol and dried to give the desired sensitizing dye as a black solid (0.133 g, 68% yield).

The obtained black solid was subjected to NMR analysis, and the following 28 hydrogen signals were detected and identified as a structure represented by the following formula (A-33) (hydrogen of a carboxyl group was not observed).

^{1 1} H-NMR (270 MHz, DMSO-d ₆ ): δ (ppm) = 1.39-1.41 (1H), 1.64-1.67 (1H), 1.83-1.92 (2H) , 2.00-2.11 (2H), 2.23-2.35 (3H), 3.89-4.00 (1H), 4.93-4.96 (1H), 7.20-7 .61 (8H), 7.80-7.99 (2H), 8.00-8.11 (1H), 8.31-8.43 (4H), 8.50-8.63 (1H), 9.18-9.21 (1H).

[Synthesis Example 6] Synthesis of sensitizing dye (A-34) In a nitrogen-substituted reaction vessel, 100 mL of dimethyl sulfoxide, 2.86 g of a monobromo compound represented by the above formula (9), 5'-formyl-2,2 Add 1.25 g of ′ -bitiophen-5-boronic acid, 0.515 g of potassium carbonate, 0.049 g of palladium (II) acetate, and 0.157 g of di (1-adamantyl) -n-butylphosphine, and stir at 80 ° C. for 3 hours. bottom. After allowing the reaction solution to cool to 25 ° C., 460 mL of water and 460 mL of ethyl acetate were added and stirred to extract the organic layer. The organic layer was washed with saturated brine, dried over sodium sulfate, and concentrated under reduced pressure to give a crude product. The crude product is purified by column chromatography (carrier: silica gel, solvent: hexane / toluene = 1/2 (volume ratio)), dried, and a yellowish brown solid of a formyl compound represented by the following formula (20). (2.86 g) was obtained.

Acetic acid / toluene = 5/2 (volume ratio) mixed solution 35 mL, 0.770 g of formyl compound represented by the above formula (20), and indanone compound 0 represented by the above formula (11) in a nitrogen-substituted reaction vessel. .300 g was added and stirred at 90 ° C. for 7 hours. After allowing the reaction solution to cool to 25 ° C., the reaction solution was concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, solvent: chloroform / methanol = 5/2 (volume ratio)) to obtain the desired sensitizing dye as a black solid (0.730 g, yield 78%). ).

The obtained black solid was subjected to NMR analysis, and the following 56 hydrogen signals were detected and identified as a structure represented by the following formula (A-34) (hydrogen of a carboxyl group was not observed).

^{1 1} H-NMR (600 MHz, DMSO-d ₆ ): δ (ppm) = 1.00-1.04 (18H), 1.59-1.63 (12H), 1.93-2.02 (4H) , 7.25-7.37 (5H), 7.53-7.59 (4H), 7.61-7.67 (2H), 7.74-7.81 (2H), 7.92-7 .97 (1H), 8.11-8.41 (6H), 8.57-8.70 (2H).

[Synthesis Example 7] Synthesis of sensitizing dye (A-35) In a nitrogen-substituted reaction vessel, 46 mL of dimethyl sulfoxide, 1.30 g of monobromo compound represented by the above formula (13), 5-formyl-2-thiopheneborone. 0.579 g of acid, 0.364 g of potassium carbonate, 0.035 g of palladium (II) acetate and 0.111 g of di (1-adamantyl) -n-butylphosphene were added, and the mixture was stirred at 85 ° C. for 2 hours. After allowing the reaction solution to cool to 25 ° C., 200 mL of water and 200 mL of chloroform were added and stirred to extract the organic layer. The organic layer was washed with saturated brine, dried over sodium sulfate, and dried under reduced pressure to give a crude product. The crude product is purified by column chromatography (carrier: silica gel, solvent: hexane / toluene = 1/2 (volume ratio)), dried, and a yellowish brown solid of a formyl compound represented by the following formula (21). (1.33 g) was obtained.

20 mL of acetic acid / toluene = 1/3 (volume ratio) mixed solution, 0.270 g of formyl compound represented by the above formula (21), and indanone compound 0 represented by the above formula (11) in a nitrogen-substituted reaction vessel. .193 g was added and stirred at 90 ° C. for 8 hours. After allowing the reaction solution to cool to 25 ° C., the reaction solution was dried under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (carrier: silica gel, solvent: chloroform / methanol = 5/1 (volume ratio)) to obtain the desired sensitizing dye as a reddish brown solid (0.280 g, yield 75%). ).

The obtained reddish brown solid was subjected to NMR analysis, and the following 24 hydrogen signals were detected and identified as a structure represented by the following formula (A-35) (hydrogen of a carboxyl group was not observed).

^{1 1} H-NMR (600 MHz, DMSO-d ₆ ): δ (ppm) = 1.06-1.19 (1H), 1.31-1.35 (1H), 1.55-1.59 (1H) 1.72-1.76 (1H), 1.91-2.02 (2H), 3.78-3.82 (1H), 4.78-4.82 (1H), 6.69-6 .73 (1H), 7.00-7.12 (3H), 7.37-7.41 (1H), 7.75-8.39 (11H).

[Example 1]
Titanium oxide paste (PST-18NR manufactured by JGC Catalysts and Chemicals Co., Ltd.) was applied by the squeegee method on a glass substrate coated with a fluorine-doped tin oxide thin film. After drying at 110 ° C. for 1 hour, it was calcined at 450 ° C. for 30 minutes to obtain a titanium oxide thin film having a film thickness of 7 μm. Next, the sensitizing dye (A-5) and deoxycholic acid obtained in Synthesis Example 1 were mixed with acetonitrile / t-butyl alcohol = 1/1 (volume ratio) so that the concentrations were 100 μM and 1 mM, respectively. A solution of 50 mL was prepared by dissolving in a mixed solvent, and a glass substrate coated with titanium oxide and sintered was immersed in this solution for 15 hours at room temperature to adsorb the sensitizing dye as a sensitizing dye for photoelectric conversion. It was used as an optical electrode.

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

Next, a spacer (heat fusion film) having a thickness of 60 μm is sandwiched between the photoelectrode and the counter electrode and bonded by heat fusion, and the hole is sealed after the electrolytic solution is injected from the hole formed in advance in the counter electrode. Then, a photoelectric conversion element was manufactured. As the electrolytic solution, a 3-methoxypropionitrile solution of lithium iodide 0.1M, dimethylpropyl imidazolium iodide 0.6M, iodine 0.05M, and 4-t-butyl pyridine 0.5M was used.

Light generated by a pseudo-sunlight irradiation device (OTENTO-SUN III type manufactured by Spectrometer Co., Ltd.) is irradiated from the light electrode side of the photoelectric conversion element, and a source meter (Model 2400 General-Purpose Source Meter manufactured by KEITHLEY) is used. The current-voltage characteristics were measured using. The light intensity was adjusted to ^{100 mW / cm 2.} In addition, the photoelectric conversion efficiency was measured even after irradiation with light for 20 hours, and the characteristic change was evaluated. The measurement results are summarized in Table 1.

[Examples 2 to 9]
A photoelectric conversion element was produced in the same manner as in Example 1 except that the sensitizing dyes shown in Table 1 were used instead of (A-5) as the sensitizing dye for photoelectric conversion, and the current-voltage characteristics were measured. .. In addition, the photoelectric conversion efficiency was measured even after irradiation with light for 20 hours, and the characteristic change was evaluated. The measurement results are summarized in Table 1.

[Comparative Examples 1 to 4]
As the sensitizing dye for photoelectric conversion, instead of (A-5), the following formulas (B-1) to (B) which do not belong to the present invention and are disclosed in the prior art (Patent Documents 4 to 6) A photoelectric conversion element was produced in the same manner as in Example 1 except that the sensitizing dye shown in -4) was used, and the current-voltage characteristics were measured. In addition, the photoelectric conversion efficiency was measured even after irradiation with light for 20 hours, and the characteristic change was evaluated. The measurement results are summarized in Table 1.

From the results in Table 1, by using the sensitizing dye for photoelectric conversion made of the sensitizing dye of the present invention, the photoelectric conversion efficiency is high and the high photoelectric conversion efficiency is maintained even if the light irradiation is continued for a long time. It turned out that the element can be obtained. On the other hand, the photoelectric conversion efficiency of the photoelectric conversion element using the photoelectric conversion sensitizing dye of the comparative example was insufficient.

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 modifications and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application (Japanese Patent Application No. 2016-188633) filed on September 27, 2016, and the entire application is incorporated by reference. Also, all references cited here are taken in as a whole.

The sensitizing dye for photoelectric conversion composed of the sensitizing dye of the present invention is useful as a highly efficient and highly durable photoelectric conversion element and a dye-sensitized solar cell, and is a solar cell capable of efficiently converting solar energy into electric energy. As clean energy can be provided.

1 Conductive support 2 Dye-supporting semiconductor layer 3 Electrolyte layer 4 Counter electrode 5 Conductive support

Claims (6)

A sensitizing dye represented by the following general formula (1).

[In the formula, R ^{1 to} R ⁶ may be the same or different, and independently have a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or 1 to 1 carbon atoms. Represents 6 linear or branched alkoxy groups,
R ⁷ and R ⁸ may be the same or different, and may have a substituent. A linear or branched alkyl group having 1 to 20 carbon atoms, or a carbon which may have a substituent. A cycloalkyl group having 3 to 20 atoms, a linear or branched alkenyl group having 2 to 20 carbon atoms which may have a substituent, and a carbon atom number 7 to which may have a substituent. It represents an aryl group having 26 aralkyl groups or an aryl group having 6 to 30 carbon atoms which may have a substituent, and R ⁷ and R ⁸ may be bonded to each other to form a ring.
X is a monovalent group represented by the following general formula (X1), (X2) or (X3).

[In the formula, R ⁹ represents an acidic group. ]

[In the formula, L and M may be the same or different, and are linear or branched alkyl groups having 1 to 6 carbon atoms having one or two acidic groups as substituents, or unsubstituted. Represents a linear or branched alkyl group having 1 to 6 carbon atoms. However, at least one of L and M is assumed to be a linear or branched alkyl group having 1 to 6 carbon atoms having one or two acidic groups as substituents. p represents an integer of 0 to 2, and when p is 2, a plurality of Ls existing may be the same or different from each other. ]

[In the formula, R ¹¹ and R ¹² represent a hydrogen atom or an acidic group, and at least one of R ¹¹ or R ¹² is assumed to be an acidic group. R ¹³ and R ¹⁴ may be the same or different, and may have a hydrogen atom and a substituent, and have a linear or branched alkyl group and a substituent having 1 to 18 carbon atoms. also represents an straight-chain or branched alkoxy group having 1 to 18 carbon atoms or optionally substituted linear or branched alkenyl group having 2 to 18 carbon atoms,, R ¹³ And R ¹⁴ may be coupled to each other to form a ring. r represents an integer of 0 to 4, when r is an integer of 2 to 4, ^{R 13} and ^{R 14} there are a plurality, the ^{R 13 together, R 14} themselves may be the same or different from each other. ] ]] The sensitizing dye according to claim 1, wherein in the general formula (1), R ^{1 to} R ⁶ are all hydrogen atoms. In the general formula (1), R ⁷ and R ⁸ may have a cycloalkyl group having 3 to 20 carbon atoms which may have a substituent, or 6 to 6 carbon atoms which may have a substituent. The sensitizing dye according to claim 2 , which is any of the 30 aryl groups, and R ⁷ and R ⁸ may be bonded to each other to form a ring. A sensitizing dye for photoelectric conversion, which comprises the sensitizing dye according to any one of claims 1 to 3. A photoelectric conversion element using the photoelectric conversion sensitizing dye according to claim 4. A dye-sensitized solar cell using the photoelectric conversion element according to claim 5.

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