JP2006063221A - Squarylium compound, its metal complex, photoelectric conversion material using the same, photoelectric transducer and photoelectrochemical cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a squarylium compound useful for a photoelectric transducer, its metal complex and a photoelectrochemical cell, etc., using the same. <P>SOLUTION: The squarylium compound is represented by general formula (I) or its metal complex. The squarylium compound is used in an inexpensive photoelectric transducer having high energy conversion efficiency. The metal complex of the squarylium compound is obtained. The photoelectrochemical cell, etc., are obtained by using the photoelectric transducer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a squarylium compound that can be used in a photoelectric conversion element, a metal complex thereof, a photoelectrochemical cell using the same, and the like.

  In solar power generation, solar cells such as single crystal silicon solar cells, polycrystalline silicon solar cells, and amorphous silicon solar cells have been put into practical use or main research and development. It is necessary to overcome such problems. On the other hand, many solar cells using organic materials aimed at film formation and cost reduction have been proposed so far, but there are problems of low energy conversion efficiency and poor durability.

Under such circumstances, a photoelectric conversion element and a photoelectrochemical cell using a semiconductor thin film electrode sensitized with a dye, and a material and a manufacturing technique for producing them are known. This battery is a wet solar battery using a ruthenium complex as a photosensitizer and a porous titanium dioxide thin film as a working electrode (see, for example, Patent Document 1 and Non-Patent Document 1).
However, since a ruthenium complex of a sensitizing dye is expensive, development of a photoelectric conversion element that is sensitized by an inexpensive organic dye is desired.
Furthermore, attempts have been made to use organic dyes as sensitizing dyes, but there are problems such as low energy conversion efficiency, which are not satisfactory in practice (see, for example, Patent Document 2 and Patent Document 3).

  Moreover, it is known to use a squaric acid derivative for a photoelectric conversion element (for example, refer patent document 4).

US Pat. No. 4,927,721 Japanese Patent Application Laid-Open No. 11-86916 European Patent No. 911841 JP 2001-76773 A “Nature”, 1991, Vol. 353, p. 737-740

  The objective of this invention is providing the squarylium compound which can be used for the photoelectric conversion element which has low cost and high energy conversion efficiency, the metal complex of this squarylium compound, a photoelectrochemical cell using them, etc.

［式中、
Ｒ^１およびＲ^２は同一または異なって、水素原子、置換基を有していてもよいアルキル基、置換基を有していてもよいアラルキル基または置換基を有していてもよいアリール基を表すか、あるいは後述するＸが炭素原子のとき、Ｒ^１とＲ^２は隣接する炭素原子と一緒になって、脂環式炭化水素環または複素環を形成してもよく、
Ｒ^３は水素原子、置換基を有していてもよいアルキル基、置換基を有していてもよいアラルキル基または置換基を有していてもよいアリール基を表し、
Ｒ^４はハロゲン原子、置換基を有していてもよいアルキル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアリール基、ニトロ基、シアノ基または置換基を有していてもよいアルコキシル基を表し、
ｎは０〜３の整数を表し、
ここに、ｎが２〜３の場合、それぞれのＲ^４は同一または異なってもよく、さらに互いに隣り合う２つのＲ^４がそれぞれが隣接する２つの炭素原子と一緒になって、置換基を有していてもよい芳香族環を形成してもよく、
Ｘは炭素原子、硫黄原子、窒素原子または酸素原子を表し（ただし、Ｘが硫黄原子または酸素原子である場合、Ｒ^１とＲ^２は存在せず、Ｘが窒素原子である場合、Ｒ^２は存在しない。）、
Ｒ^５およびＲ^６は同一または異なって、水素原子、ヒドロキシル基、ハロゲン原子、置換基を有していてもよいアミノ基、置換基を有していてもよいアルキル基、置換基を有していてもよいアルコキシル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアリール基、ニトロ基、シアノ基または置換基を有していてもよい複素環基を表し、
Ｙは窒素原子または酸素原子を表し（ただし、Ｙが酸素原子である場合、Ｒ^５は存在しない。）、
Ａは酸性基を表し、
ｍは１〜４の整数を表し、
ここに、ｍが２〜４の場合、それぞれのＡは同一または異なってもよい。］
で表されるスクアリリウム化合物。
［２］ Ｘが炭素原子であって、Ｙが窒素原子である［１］記載のスクアリリウム化合物。
［３］ ［１］記載のスクアリリウム化合物の金属錯体。
［４］ Ｘが炭素原子であって、Ｙが窒素原子である［３］記載のスクアリリウム化合物の金属錯体。
［５］ ［１］または［２］記載のスクアリリウム化合物と半導体とを含む光電変換材料。
［６］ ［３］または［４］記載のスクアリリウム化合物の金属錯体と半導体とを含む光電変換材料。
［７］ ［５］記載の光電変換材料を用いた光電変換素子。
［８］ ［６］記載の光電変換材料を用いた光電変換素子。
［９］ ［７］記載の光電変換素子を含有する光電気化学電池。
［１０］ ［８］記載の光電変換素子を含有する光電気化学電池。 The present invention provides the following [1] to [10].
[1] General formula (I)

[Where:
R ¹ and R ² are the same or different and each represents a hydrogen atom, an alkyl group that may have a substituent, an aralkyl group that may have a substituent, or an aryl group that may have a substituent. Or when X described below is a carbon atom, R ¹ and R ² may be combined with adjacent carbon atoms to form an alicyclic hydrocarbon ring or a heterocyclic ring;
R ³ represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent,
R ⁴ represents a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a nitro group, a cyano group or a substituent. Represents an alkoxyl group which may have
n represents an integer of 0 to 3,
Here, when n is 2 to 3, each R ⁴ may be the same or different, and two adjacent R ⁴ groups together with two adjacent carbon atoms each have a substituent. May form an aromatic ring that may have
X represents a carbon atom, a sulfur atom, a nitrogen atom or an oxygen atom (provided that when X is a sulfur atom or an oxygen atom, R ¹ and R ² are not present, and when X is a nitrogen atom, R ² is not exist.),
R ⁵ and R ⁶ are the same or different and have a hydrogen atom, a hydroxyl group, a halogen atom, an amino group which may have a substituent, an alkyl group which may have a substituent, or a substituent. Represents an optionally substituted alkoxyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, a nitro group, a cyano group, or an optionally substituted heterocyclic group. ,
Y represents a nitrogen atom or an oxygen atom (provided that when Y is an oxygen atom, R ⁵ does not exist);
A represents an acidic group,
m represents an integer of 1 to 4,
Here, when m is 2 to 4, each A may be the same or different. ]
A squarylium compound represented by:
[2] The squarylium compound according to [1], wherein X is a carbon atom and Y is a nitrogen atom.
[3] A metal complex of the squarylium compound according to [1].
[4] The metal complex of the squarylium compound according to [3], wherein X is a carbon atom and Y is a nitrogen atom.
[5] A photoelectric conversion material comprising the squarylium compound according to [1] or [2] and a semiconductor.
[6] A photoelectric conversion material comprising a metal complex of a squarylium compound according to [3] or [4] and a semiconductor.
[7] A photoelectric conversion element using the photoelectric conversion material according to [5].
[8] A photoelectric conversion element using the photoelectric conversion material according to [6].
[9] A photoelectrochemical cell containing the photoelectric conversion element according to [7].
[10] A photoelectrochemical cell comprising the photoelectric conversion element according to [8].

  Hereinafter, the squarylium compound represented by the general formula (I) may be expressed as the squarylium compound (I). In addition, each compound represented by the formula (i) in the reaction formula described below may be expressed as a compound (i).

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a squarylium compound, a metal complex of the squarylium compound, a photoelectrochemical cell using the squarylium compound that can be used for a photoelectric conversion element having a low cost and high energy conversion efficiency.

  In the definition of each group in the general formula, examples of the alkyl moiety in the alkyl group and the alkoxyl group include a linear or branched alkyl group having 1 to 20 carbon atoms (preferably an alkyl group having 1 to 6 carbon atoms). Or a cyclic alkyl group having 3 to 8 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and pentyl. Group, isopentyl group, 1-methylbutyl group, 2-methylbutyl group, tert-pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, eicosyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group , Cycloheptyl group, cyclooctyl group and the like.

  Examples of the aralkyl group include an aralkyl group having 7 to 15 carbon atoms, and specific examples thereof include a benzyl group, a phenethyl group, a phenylpropyl group, and a naphthylmethyl group.

  Examples of the aryl group include an aryl group having 6 to 14 carbon atoms, and specific examples thereof include a phenyl group, a naphthyl group, an anthryl group, and an azulenyl group.

  Examples of the halogen atom include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom.

The aromatic rings in which two R ⁴ adjacent to form together with the two carbon atoms to which each adjacent benzene ring and the like.

Examples of the heterocyclic ring in the heterocyclic group and the heterocyclic ring formed by combining R ¹ and R ² with adjacent carbon atoms include at least one atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom. A 5- or 6-membered monocyclic aromatic or aliphatic heterocyclic ring, a bicyclic or tricyclic condensed 3- to 8-membered ring, and at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom; Specific examples thereof include pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, quinoline ring, isoquinoline ring, phthalazine ring, quinazoline ring, quinoxaline ring, and naphthyridine. Ring, cinnoline ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiophene ring, furan ring, thiazole ring, o Sazole ring, indole ring, isoindole ring, indazole ring, benzimidazole ring, benzotriazole ring, benzothiazole ring, benzoxazole ring, purine ring, carbazole ring, pyrrolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring , Homopiperidine ring, homopiperazine ring, tetrahydropyridine ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydrofuran ring, tetrahydropyran ring, dihydrobenzofuran ring, tetrahydrocarbazole ring and the like.

Examples of the alicyclic hydrocarbon ring formed by combining R ¹ and R ² with adjacent carbon atoms include those having 3 to 8 carbon atoms, and may be saturated or unsaturated. Specific examples thereof include cyclopropane ring, cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclopentene ring, 1,3-cyclopentadiene ring, cyclohexene ring, cyclohexadiene ring and the like. It is done.

Examples of the aralkyl group, the aryl group, the aromatic ring formed by combining two adjacent R ⁴ atoms with two adjacent carbon atoms, and the substituent of the heterocyclic group are the same or different. ˜5 substituents, specifically, hydroxyl group, carboxyl group, halogen atom, alkyl group, alkoxyl group, nitro group, alkyl-substituted or unsubstituted amino group, and the like. A halogen atom, an alkyl group, and an alkoxyl group are respectively synonymous with the above, and the alkyl part of the alkyl-substituted amino group is synonymous with the alkyl group.

  Examples of the substituent of the alkyl group and the alkoxyl group include the same or different 1 to 3 substituents, specifically, a hydroxyl group, a carboxyl group, a halogen atom, an alkoxyl group and the like. A halogen atom and an alkoxyl group are respectively synonymous with the above.

  Examples of the substituent of the amino group include one or two alkyl groups that are the same or different, and the alkyl group in this case is as defined above.

  “Acid group” refers to a group having a hydrogen atom that can be dissociated, and examples thereof include a carboxyl group, a hydroxyl group, a phosphono group, and a sulfo group. These groups may form salts with alkali metal ions, ammonium ions, organic ammonium ions and the like. In addition, an intramolecular complex salt may be formed. Examples of the alkali metal include lithium, sodium and potassium. Examples of the organic ammonium in the organic ammonium ion include tetrabutylammonium.

  The metal in the metal complex of the squarylium compound (I) is not particularly limited as long as it forms a complex with the squarylium compound (I). For example, aluminum, ruthenium, osmium, iron, platinum, zinc, beryllium, copper , Nickel, chromium, cobalt, manganese, iridium, vanadium, titanium, europium, and the like, and aluminum is preferred.

  The squarylium compound (I) is produced by a known method (WO01 / 44233 or the like) or according thereto. Hereinafter, the example of the manufacturing method of squarylium compound (I) is demonstrated.

［式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５、Ｒ^６、Ａ、Ｘ、Ｙ、ｍおよびｎは、それぞれ前記と同義であり、Ｖは塩素、臭素、ヨウ素等のハロゲン原子、またはトシル基、メシル基等を表し、Ｗは塩素、臭素等のハロゲン原子、またはＯＲ^７（式中、Ｒ^７は前記と同義のアルキル基を表す。）を表す。］

[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , A, X, Y, m and n are as defined above, and V is a halogen such as chlorine, bromine, iodine, etc. atom or tosyl group, a mesyl group or the like,, W is a chlorine, a halogen atom such as bromine or oR 7 ^(wherein, R ⁷ is. represents an alkyl group as defined above) represents. ]

Reaction formula (1-a)
Compound (V) is a compound (III) and 1 to 2 moles of Compound (IVa) or Compound (IVb), if necessary, in the presence of 1 to 2 moles of a base in a solvent at 0 ° C. It is obtained by reacting at room temperature for 30 minutes to 70 hours.
Examples of the solvent include halogenated hydrocarbons such as chloroform, dichloromethane and 1,2-dichloroethane, ethers such as diethyl ether and tert-butyl methyl ether, aromatic hydrocarbons such as toluene and benzene, methanol, ethanol, Examples include alcohols such as propanol, tetrahydrofuran, ethyl acetate, dimethylformamide, dimethyl sulfoxide and the like.
Examples of the base include organic bases such as quinoline, triethylamine, and pyridine, and inorganic bases such as potassium carbonate, potassium bicarbonate, and sodium bicarbonate.
Compound (IVa) and compound (IVb) can be produced by a known method (Tetrahedron, 1989, Vol. 45, No. 15, p. 4845, etc.) or according thereto.

Reaction formula (1-b)
Compound (VI) is compound (V) in 50 to 90% by volume acetic acid aqueous solution at 90 to 110 ° C. for 1 to 7 hours, or in 50 to 99% by weight trifluoroacetic acid aqueous solution and 45 to 50 ° C. It is obtained by processing for 1 to 3 hours.

Reaction formula (1-c)
Compound (I) is compound (VI) and 1 to 2 moles of compound (VII), if necessary, in the presence of 1 to 2 moles of a base in a solvent at 80 to 120 ° C. for 10 minutes. It is obtained by reacting for ˜15 hours.
Examples of the solvent include only alcohol solvents having 2 to 8 carbon atoms such as ethanol, propanol, isopropyl alcohol, butanol, and octanol, or a mixed solvent of the alcohol solvent and benzene or toluene (alcohol 50% by volume or more). Is used.
Examples of the base include organic bases such as quinoline, triethylamine, and pyridine, and inorganic bases such as potassium carbonate, potassium bicarbonate, and sodium bicarbonate.
Compound (VII) can be produced by a known method (WO01 / 4437 or the like) or according thereto.

Reaction formula (2-a)
Compound (VIII) is obtained by reacting Compound (III) with 1 to 2 moles of Compound (VII) in the presence of 1 to 2 moles of a base in a solvent at 0 to 40 ° C. for 10 minutes to 20 hours. The precipitate is obtained by treatment with an acidic aqueous solution.
Examples of the solvent are the same as those described in the description of the reaction formula (1-a).
As the base, for example, an organic base such as quinoline, triethylamine, pyridine, or an inorganic base such as potassium carbonate, potassium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, or sodium hydroxide is used.
Examples of the acidic aqueous solution include aqueous solutions such as hydrochloric acid.

Reaction formula (2-b)
Compound (IX) can be obtained by treating compound (VIII) in an alkaline solvent or an acidic solvent at 0 to 80 ° C. for 30 minutes to 15 hours.
Examples of the alkaline solvent include an aqueous potassium carbonate solution, an aqueous sodium carbonate solution, and an aqueous potassium hydroxide solution.
Examples of the acidic solvent include 50% by volume dimethyl sulfoxide aqueous solution of hydrochloric acid, 50% by volume dimethylformamide aqueous solution of hydrochloric acid, and the like.

Reaction formula (2-c)
Compound (I) is the same as that in the above reaction formula (1-c) except that compound (IX) is used instead of compound (VI), and compound (IVa) or compound (IVb) is used instead of compound (VII). It can be obtained by performing an operation similar to that shown in the description.
After the reaction, the compound (I) can be further purified by, for example, evaporation of the solvent or filtration, and if necessary, by a method usually used in organic synthetic chemistry (column chromatography, recrystallization or washing with a solvent, etc.). It can be isolated and purified by purification treatment.
Next, the manufacturing method of the metal complex of squarylium compound (I) is demonstrated.

（式中、Ｑ^ｑ＋は、配位能を有する金属イオンを表し、Ｑは金属を、ｑは該金属から生成するイオンの価数を表す。）

(In the formula, Q ^{q +} represents a metal ion having coordination ability, Q represents a metal, and q represents a valence of an ion generated from the metal.)

A metal complex of the squarylium compound (I) is prepared by combining a squarylium compound (I) and a raw material providing a metal ion having coordination ability (raw material providing Q ^{q +} ) in the presence of an acid in a solvent at room temperature. It is obtained by reacting at ˜120 ° C. for 5 minutes to 15 hours. The raw material giving Q ^{q +} is preferably used so that the ratio of the number of moles of squarylium compound (I): the number of moles of raw material giving Q ^{q +} × q is 1: 0.5-2.

Examples of the raw material that gives Q ^{q +} include aluminum tris (acetylacetonate), aluminum tris (ethyl acetoacetate), aluminum triisopropoxide, aluminum trisec-butoxide, aluminum triethoxide, aluminum chloride, zinc acetate, and chloride. Zinc, beryllium sulfate, copper chloride, copper acetate, nickel acetate, etc. are used.

  Examples of the acid include organic acids such as acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, and p-toluenesulfonic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid. The amount is preferably 0.1 to 2 equivalents (molar ratio) with respect to the squarylium compound (I).

  Examples of the solvent include halogen solvents such as chloroform and dichloromethane, aromatic solvents such as toluene and xylene, ether solvents such as tetrahydrofuran and tert-butyl methyl ether, ester solvents such as ethyl acetate, and the like. The amount used is preferably 1 to 500 times (weight ratio) with respect to the squarylium compound (I).

  Although the specific example of the squarylium compound (I) or its metal complex of this invention is illustrated in list | wrist 1, the squarylium compound (I) or its metal complex of this invention is not limited to these. In List 1, Me represents a methyl group, Pr represents a propyl group, and i-Pr represents an isopropyl group.

Next, the photoelectric conversion material, photoelectric conversion element, and photoelectrochemical cell of the present invention will be described in detail.
The photoelectric conversion material of the present invention contains a squarylium compound (I) or a metal complex of the squarylium compound (I) and a semiconductor.

The photoelectric conversion element of the present invention includes a conductive support, a semiconductor thin film electrode comprising a semiconductor sensitized by a squarylium compound (I) or a metal complex of the squarylium compound (I) placed on the conductive support, a charge Consists of moving layer, counter electrode, etc. A photoelectrochemical cell according to the present invention is one in which this photoelectric conversion element can be used for a battery for causing work in an external circuit.
That is, the photoelectrochemical cell of the present invention is such that an external circuit connected to the conductive support and the counter electrode of the photoelectric conversion element of the present invention via a lead works. The photoelectrochemical cell is preferably sealed on the side with a polymer, an adhesive or the like in order to prevent deterioration of the constituents and volatilization of the electrolyte used for the charge transfer layer.

  A semiconductor used for the photoelectric conversion material is a so-called photoconductor, which absorbs light and separates charges to generate electrons and holes. In the semiconductor sensitized by the squarylium compound (I) or the metal complex of the squarylium compound (I), the light absorption and the generation of electrons and holes are mainly caused by the squarylium compound (I) or the metal of the squarylium compound (I). It occurs in the complex and the semiconductor is responsible for receiving and transmitting these electrons.

  Although it does not specifically limit as a semiconductor, For example, single metal oxides, such as a titanium oxide, an indium oxide, a tin oxide, a bismuth oxide, a zirconium oxide, a tantalum oxide, niobium oxide, a tungsten oxide, an iron oxide, a gallium oxide, nickel oxide , Composite oxides such as strontium titanate, barium titanate, potassium niobate, sodium tantalate, metal halides such as silver iodide, silver bromide, copper iodide, copper bromide, zinc sulfide, titanium sulfide, sulfide Indium, bismuth sulfide, cadmium sulfide, zirconium sulfide, tantalum sulfide, silver sulfide, tin sulfide, tungsten sulfide, molybdenum sulfide, cadmium selenide, zirconium selenide, zinc selenide, titanium selenide, indium selenide, tungsten selenide, Molybdenum selenide, bismuth selenide Cadmium telluride, tellurium, tungsten, tellurium, molybdenum, zinc telluride, chalcogenide compounds such as bismuth telluride and the like.

The above semiconductors are used alone or in combination of two or more.
The semiconductor thin film is preferably a compound semiconductor having a nanoporous structure composed of nanoparticles, and can be manufactured using the semiconductors listed above [“Journal of American Ceramic Society”. ) ", 1997, Vol. 80, No. 12, p. 3157].

The semiconductor thin film electrode used for the photoelectric conversion element of the present invention is prepared, for example, by preparing a transparent electrode as a conductive support, laminating a semiconductor thin film thereon, and forming the squarylium compound (I) or It can be produced by adsorbing the metal complex of the squarylium compound (I).
The transparent electrode only needs to have conductivity, for example, on a transparent or translucent glass substrate or plastic plate, for example, conductive material such as fluorine or antimony-doped tin oxide, tin-doped indium oxide, or zinc oxide. The one coated with a conductive transparent oxide semiconductor thin film, preferably one coated with a fluorine-doped tin oxide thin film is used.

Examples of the method of placing the compound semiconductor on the conductive support include a method of applying a dispersion or colloidal solution of the compound semiconductor on the conductive support.
Examples of the coating method include a roller method, a dip method, an air knife method, a blade method, a spin method, and a spray method.

  The compound semiconductor is preferably subjected to a heat treatment in order to electronically contact the semiconductor fine particles after being applied to the conductive support, and to improve the coating film strength and the adhesion to the support. The range of preferable heat processing temperature is 100-600 degreeC. The heat treatment time is 10 minutes to 10 hours. When using a conductive support having a low melting point and softening point, such as a polymer film, the high temperature treatment causes deterioration of the support. Therefore, heat treatment in the presence of a mineral acid or a combination of small semiconductor particles of 5 nm or less is required. A method in which a dispersion of a compound semiconductor or a mixture of a colloidal solution and a titanium salt (for example, titanium tetrachloride) is applied to a conductive support, followed by hydrothermal treatment, a compound semiconductor in a polar organic solvent (for example, tert- A method of performing electrophoretic electrodeposition by electrophoresis, applying a compound semiconductor dispersion or colloidal solution to a conductive support, and pressing and pressing at a pressure of about 98,070 kPa, a compound semiconductor dispersion Alternatively, a method of irradiating a microwave of about 28 GHz after applying the colloidal solution to the conductive support is used. The film thickness of the semiconductor thin film is preferably from 0.1 to 100 μm, more preferably from 2 to 25 μm.

  The adsorption of the squarylium compound (I) or the metal complex of the squarylium compound (I) onto the semiconductor thin film is carried out by applying the semiconductor thin film coated on the support in the metal complex solution of the squarylium compound (I) or the squarylium compound (I). And is allowed to stand for 1 minute to 2 days at room temperature or for 1 minute to 24 hours under heating conditions. The solvent used when the squarylium compound (I) or the metal complex of the squarylium compound (I) is adsorbed on the semiconductor thin film may be a solvent that dissolves the squarylium compound (I) or the metal complex of the squarylium compound (I). Examples thereof include, but are not limited to, alcohol solvents such as methanol and ethanol, hydrocarbon solvents such as benzene, organic solvents such as tetrahydrofuran and acetonitrile, and a mixed solvent thereof may be used, preferably acetonitrile. Etc. When the squarylium compound (I) or the metal complex of the squarylium compound (I) is adsorbed on the semiconductor thin film, the concentration of the squarylium compound (I) or the metal complex solution of the squarylium compound (I) is 0.01 mmol / l or more. It is preferable that it is 0.1 to 1.0 mmol / l.

In order to make the wavelength range of photoelectric conversion as wide as possible and increase the energy conversion efficiency, the squarylium compound (I) or a metal complex of the squarylium compound (I) and a known dye, such as a ruthenium complex dye, other organic dyes (for example, , Polymethine dyes) and the like.
Further, a steroid compound having a carboxyl group (for example, chenodeoxycholic acid) or the like may be co-adsorbed on the semiconductor thin film for the purpose of reducing interaction between dyes such as association. Furthermore, you may use a ultraviolet absorber together.

The charge transfer layer is a layer having a function of replenishing electrons to an oxidized form of the squarylium compound (I) or the metal complex of the squarylium compound (I) [light-absorbing squarylium compound (I) or the squarylium compound (I The metal complex of) is converted into an oxidant due to the sensitizing action to release electrons.
Examples of the charge transfer layer used in the photoelectric conversion device of the present invention include a liquid (electrolytic solution) in which a redox ion pair is dissolved in an organic solvent, and a gel electrolyte in which a polymer is impregnated in a liquid in which a redox ion pair is dissolved in an organic solvent. And a molten salt containing a redox ion pair, a solid electrolyte, an inorganic compound semiconductor, and an organic hole transport material.

Examples of redox ion pairs include, but are not limited to, iodine redox, bromine redox, iron redox, tin redox, chromium redox, vanadium redox, sulfide ion redox, anthraquinone redox, and the like. More specifically, iodine redox includes imidazolium iodide derivatives, lithium iodide, potassium iodide, tetraalkylammonium iodide and the like and a mixture of iodine, and bromine redox includes imidazolium bromide derivatives. And a mixture of bromine with lithium bromide, potassium bromide, tetraalkylammonium bromide and the like. Of these, a mixture of lithium iodide, an imidazolium iodide derivative and the like and iodine is preferable. The organic solvent that dissolves the redox ion pair is not limited as long as it is a stable solvent that dissolves the redox ion pair. For example, acetonitrile, methoxyacetonitrile, propionitrile, methoxypropionitrile, ethylene carbonate, propylene carbonate, dimethyl Organic solvents such as sulfoxide, dimethylformamide, tetrahydrofuran, nitromethane and the like may be used, and a mixed solvent thereof may be used, preferably acetonitrile, methoxyacetonitrile, propionitrile, methoxypropionitrile and the like. The concentration of the redox ion pair in the electrolytic solution is preferably 0.01 to 5.0 mol / l, more preferably 0.05 to 1.0 mol / l.
The electrolytic solution may contain a basic compound such as tert-butylpyridine, 2-picoline, 2,6-lutidine. The concentration of the basic compound is preferably 0.01 to 5.0 mol / l, more preferably 0.1 to 1.0 mol / l.

Examples of the polymer used for the gel electrolyte include polyacrylonitrile and polyvinylidene fluoride.
Examples of the molten salt include 1-butyl-3-methylpyridinium iodide, 1-butyl-3-methylimidazolium iodide, lithium salts such as lithium iodide, lithium acetate, and lithium perchlorate. The fluidity at room temperature may be increased by mixing a polymer such as polyethylene oxide.
Examples of the solid electrolyte include polymers such as polyethylene oxide derivatives.
Examples of the inorganic compound semiconductor include copper iodide, copper bromide, and copper thiocyanide. The inorganic compound semiconductor may contain a molten salt such as triethylammonium thiocyanate.
Examples of the organic hole transport material include polythiophene derivatives and polypyrrole derivatives.
When using an inorganic compound semiconductor or an organic hole transport material, a titanium dioxide thin film may be applied as an undercoat layer (short-circuit prevention layer) using a technique such as spray pyrolysis to prevent short circuit.

There are two methods for forming the charge transfer layer. One is a method in which a counter electrode is first bonded to a semiconductor thin film electrode on which a dye is adsorbed, and a liquid charge transfer layer is injected into the gap. . The other is a method in which a charge transfer layer is directly applied to a semiconductor thin film electrode, and a counter electrode is subsequently applied.
As the injection method of the charge transfer layer in the former case, a normal pressure process using capillary action and a vacuum process in which the gas phase is replaced with a liquid phase at a pressure lower than normal pressure can be used. In the latter case, in the wet charge transfer layer, a counter electrode is provided without being dried, and measures for preventing liquid leakage at the edge portion are also taken. In the case of a gel electrolyte, there is also a method in which it is applied in a wet manner and fixed by a method such as polymerization. In that case, after drying and fixing, a counter electrode can be applied. As a method for applying an electrolytic solution, a wet organic hole transport material or a gel electrolyte, as in the case of applying a semiconductor thin film electrode or a dye, a dipping method, a roller method, a dipping method, an air knife method, a blade method, a spin method The spray method can also be mentioned. In the case of a solid electrolyte, an inorganic compound semiconductor, or a solid organic hole transport material, a material dissolved in a solvent or the like is dropped onto a heated semiconductor thin film electrode, and the solvent is evaporated on the semiconductor thin film electrode to dry the material. A counter electrode can be applied after the charge transfer layer is formed by forming a solidified charge transfer layer, or by forming a charge transfer layer by a dry film forming process such as a vacuum deposition method or a CVD method (chemical vapor deposition method).

Examples of the counter electrode used in the photoelectric conversion element of the present invention include platinum, rhodium, ruthenium, carbon, and oxide semiconductor electrodes coated in a thin film on a conductive substrate. Platinum coated with carbon, carbon electrode and the like are preferable.
In the photoelectric conversion element of the present invention, a spacer may be used and is not limited as long as it prevents contact between the semiconductor thin film electrode and the counter electrode. For example, a polymer film such as polyethylene is used.
Further, the squarylium compound (I) or the metal complex of the squarylium compound (I) used in the present invention is inexpensive.

  Hereinafter, the present invention will be described more specifically with reference to examples.

1.35 g of 3,4-dimethoxy-3-cyclobutene-1,2-dione and 1.97 g of 1-phenyl-3-propylpyrazolin-5-one were dissolved in 16 ml of methanol. To this solution, 1.32 g of potassium carbonate was added and stirred at 25 ° C. for 1 hour. After the reaction, the precipitate was collected by filtration, and the resulting solid was added to a mixture of 0.56 g of potassium carbonate and 20 ml of water and reacted at 50 ° C. for 5 hours. After completion of the reaction, 20 ml of 1 mol / l hydrochloric acid aqueous solution was added, and insoluble matters were collected by filtration. 42 ml of n-butanol, 21 ml of toluene, 2.70 g of 5-carboxy-1,2,3,3-tetramethyl-3H-indolium iodide and 1.06 g of quinoline were added to the obtained solid, Reacted for hours. Thereafter, 30 ml of methanol was added and stirred at 50 ° C. for 1 hour, and then the precipitate was collected by filtration to obtain 3.41 g of Compound (1).
1H NMR (DMSO-d ₆ ) δ ppm: 0.97 (3H, t, J = 7.3 Hz), 1.65-1.69 (2H, m), 1.71 (6H, s), 2.84 (2H, t, J = 7.6 Hz) , 3.76 (3H, s), 5.91 (1H, s), 7.31 (1H, t, J = 7.6 Hz), 7.49 (2H, t, J = 7.6 Hz), 7.63 (1H, d, J = 8.5 Hz) 7.80 (2H, d, J = 7.6 Hz), 8.04 (1H, d, J = 8.3 Hz), 8.15 (1H, s), 13.03 (1H, s).
Maximum absorption wavelength (CHCl ₃ ): 581 nm

1.35 g of 3,4-dimethoxy-3-cyclobutene-1,2-dione and 1.97 g of 1-phenyl-3-propylpyrazolin-5-one were dissolved in 16 ml of methanol. To this solution, 1.32 g of potassium carbonate was added and stirred at 25 ° C. for 1 hour. After the reaction, the precipitate was collected by filtration, and the resulting solid was added to a mixture of 0.56 g of potassium carbonate and 20 ml of water and reacted at 50 ° C. for 5 hours. After completion of the reaction, 20 ml of 1 mol / l hydrochloric acid aqueous solution was added, and insoluble matters were collected by filtration. To the obtained solid, 42 ml of n-butanol, 21 ml of toluene, 3.00 g of 5′-carboxy-1 ′, 2′-dimethylspiro (cyclohexane-1,3′-3′H-indolium) iodide and quinoline 01g was added and it was made to react at 110 degreeC for 1 hour. Thereafter, 30 ml of methanol was added and stirred at 50 ° C. for 1 hour, and then the precipitate was collected by filtration to obtain 4.00 g of Compound (4).
1H NMR (DMSO-d ₆ ) δ ppm: 0.97 (3H, t, J = 7.3 Hz), 1.42-2.50 (12H, m), 2.84 (2H, t, J = 7.3 Hz), 3.79 (3H, s) , 5.89 (1H, s), 7.30 (1H, t, J = 7.3 Hz), 7.48 (2H, t, J = 7.6 Hz), 7.69 (1H, d, J = 8.5 Hz), 7.81 (2H, d, J = 8.8 Hz), 8.09 (1H, d, J = 8.3 Hz), 8.41 (1H, s), 13.13 (1H, s).
Maximum absorption wavelength (DMSO): 564 nm

1.35 g of 3,4-dimethoxy-3-cyclobutene-1,2-dione and 1.97 g of 1-phenyl-3-propylpyrazolin-5-one were dissolved in 16 ml of methanol. To this solution, 1.32 g of potassium carbonate was added and stirred at 25 ° C. for 1 hour. After the reaction, the precipitate was collected by filtration, and the resulting solid was added to a mixture of 0.56 g of potassium carbonate and 20 ml of water and reacted at 50 ° C. for 5 hours. After completion of the reaction, 20 ml of 1 mol / l hydrochloric acid aqueous solution was added, and insoluble matters were collected by filtration. To the obtained solid, 42 ml of n-butanol, 21 ml of toluene, 3.34 g of 5′-carboxy-2′-methyl-1′-phenethylspiro (cyclohexane-1,3′-3′H-indolium) bromide and quinoline 1.01 g was added and reacted at 110 ° C. for 1 hour. Thereafter, 30 ml of methanol was added and stirred at 50 ° C. for 1 hour, and then the precipitate was collected by filtration to obtain 4.51 g of Compound (5).
1H NMR (DMSO-d ₆ ) δ ppm: 0.98 (3H, t, J = 7.3 Hz), 1.02-2.50 (12H, m), 2.83 (2H, t, J = 7.6 Hz), 3.09 (2H, t, J = 7.1 Hz), 4.58 (2H, t, J = 6.8 Hz), 5.81 (1H, s), 7.12-8.82 (13H, m), 13.35 (1H, s).
Maximum absorption wavelength (DMSO): 566 nm

1.35 g of 3,4-dimethoxy-3-cyclobutene-1,2-dione and 1.97 g of 1-phenyl-3-propylpyrazolin-5-one were dissolved in 16 ml of methanol. To this solution, 1.32 g of potassium carbonate was added and stirred at 25 ° C. for 1 hour. After the reaction, the precipitate was collected by filtration, and the resulting solid was added to a mixture of 0.56 g of potassium carbonate and 20 ml of water and reacted at 50 ° C. for 5 hours. After completion of the reaction, 20 ml of 1 mol / l hydrochloric acid aqueous solution was added, and insoluble matters were collected by filtration. To the obtained solid, 42 ml of n-butanol, 21 ml of toluene, 4.65 g of 5′-carboxy-1′-hexadecyl-2′-methylspiro (cyclohexane-1,3′-3′H-indolium) iodide and quinoline 1 .01 g was added and reacted at 110 ° C. for 1 hour. Thereafter, 30 ml of methanol was added and stirred at 50 ° C. for 1 hour, and then the precipitate was collected by filtration to obtain 4.95 g of Compound (6).
1H NMR (DMSO-d ₆ ) δ ppm: 0.82 (3H, t, J = 6.6 Hz), 0.97 (3H, t, J = 7.3 Hz), 1.22-2.47 (40H, m), 2.82 (2H, t, J = 7.3 Hz), 4.29 (2H, t, J = 6.8 Hz), 5.92 (1H, s), 7.30 (1H, t, J = 7.3 Hz), 7.47 (2H, t, J = 8.5 Hz), 7.69 (1H, d, J = 8.6 Hz), 7.80 (2H, d, J = 7.6 Hz), 8.08 (1H, d, J = 8.5 Hz), 8.42 (1H, s), 13.09 (1H, s).
Maximum absorption wavelength (CHCl ₃ ): 586 nm

A mixture of 0.50 g of compound (1), 0.14 g of aluminum tris (ethyl acetoacetate), 0.06 g of acetic acid and 5 ml of ethyl acetate was reacted at 60 ° C. for 8 hours, and then the precipitate was collected by filtration. 7) 0.40 g was obtained.
1H NMR (DMSO-d ₆ ) δ ppm: 0.84 (9H, t, J = 7.3 Hz), 1.43-1.48 (6H, m), 1.63 (18H, s), 2.72-2.88 (6H, m), 3.61 ( 9H, s), 5.74 (3H, s), 6.99-7.97 (24H, m), 12.94 (3H, s).
Maximum absorption wavelength (CHCl ₃ ): 550 nm

Fluorine-doped tin oxide coated transparent conductive glass (manufactured by Nippon Sheet Glass, surface resistance is about 15 Ω / cm ² ) on the conductive surface side with titanium dioxide paste (Solaronix, SA Ti-Nanoxide T) using a glass rod After coating at room temperature for 30 minutes, it was baked at 450 ° C. for 30 minutes in an electric furnace. The film thickness of titanium dioxide was 10 μm. After the glass was taken out and cooled, it was immersed in an acetonitrile solution (compound (1) 0.1 mmol / l, chenodeoxycholic acid 10 mmol / l) mixed with compound (1) and chenodeoxycholic acid for 1 hour at room temperature. The glass adsorbed with the dye was washed with acetonitrile and air dried.
The titanium dioxide electrode substrate (1 cm × 3 cm) prepared as described above was superposed on the platinum-deposited glass having the same size. Next, an electrolytic solution (iodine 0.05 mol / l, lithium iodide 0.1 mol / l, dimethylpropylimidazolyl iodine 0.62 mol / l and tert-butylpyridine 0.5 mol / l in acetonitrile) was added to both glasses. A photoelectrochemical cell was obtained by impregnating the gap using a capillary phenomenon and introducing it between the titanium dioxide electrode and the counter electrode. The photoelectrochemical cell was irradiated with simulated sunlight by a solar simulator [manufactured by Spectrometer Co., Ltd., solar cell characteristic measurement system], and its characteristics were evaluated. As a result, the characteristics of the obtained photoelectrochemical cell were a short-circuit current density of 8.39 mA / cm ² , an open-circuit voltage of 0.70 V, a form factor (fill factor) of 0.61, and an energy conversion efficiency of 3.6%. .

Fluorine-doped tin oxide coated transparent conductive glass (manufactured by Nippon Sheet Glass, surface resistance is about 15 Ω / cm ² ) on the conductive surface side with titanium dioxide paste (Solaronix, SA Ti-Nanoxide T) using a glass rod After coating at room temperature for 30 minutes, it was baked at 450 ° C. for 30 minutes in an electric furnace. The film thickness of titanium dioxide was 10 μm. After the glass was taken out and cooled, it was immersed in an acetonitrile solution (compound (4) 0.1 mmol / l, chenodeoxycholic acid 10 mmol / l) mixed with compound (4) and chenodeoxycholic acid at room temperature for 1 hour. The glass adsorbed with the dye was washed with acetonitrile and air dried.
The titanium dioxide electrode substrate (1 cm × 3 cm) prepared as described above was superposed on the platinum-deposited glass having the same size. Next, an electrolytic solution (iodine 0.05 mol / l, lithium iodide 0.1 mol / l, dimethylpropylimidazolyl iodine 0.62 mol / l and tert-butylpyridine 0.5 mol / l in acetonitrile) was added to both glasses. A photoelectrochemical cell was obtained by impregnating the gap using a capillary phenomenon and introducing it between the titanium dioxide electrode and the counter electrode. The photoelectrochemical cell was irradiated with simulated sunlight by a solar simulator [manufactured by Spectrometer Co., Ltd., solar cell characteristic measurement system], and its characteristics were evaluated. As a result, the characteristics of the obtained photoelectrochemical cell were a short-circuit current density of 8.02 mA / cm ² , an open-circuit voltage of 0.71 V, a form factor (fill factor) of 0.56, and an energy conversion efficiency of 3.1%. .

Fluorine-doped tin oxide coated transparent conductive glass (manufactured by Nippon Sheet Glass, surface resistance is about 15 Ω / cm ² ) on the conductive surface side with titanium dioxide paste (Solaronix, SA Ti-Nanoxide T) using a glass rod After coating at room temperature for 30 minutes, it was baked at 450 ° C. for 30 minutes in an electric furnace. The film thickness of titanium dioxide was 10 μm. After the glass was taken out and cooled, it was immersed in an acetonitrile solution (compound (5) 0.1 mmol / l, chenodeoxycholic acid 10 mmol / l) mixed with compound (5) and chenodeoxycholic acid for 1 hour at room temperature. The glass adsorbed with the dye was washed with acetonitrile and air dried.
The titanium dioxide electrode substrate (1 cm × 3 cm) prepared as described above was superposed on the platinum-deposited glass having the same size. Next, an electrolytic solution (iodine 0.05 mol / l, lithium iodide 0.1 mol / l, dimethylpropylimidazolyl iodine 0.62 mol / l and tert-butylpyridine 0.5 mol / l in acetonitrile) was added to both glasses. A photoelectrochemical cell was obtained by impregnating the gap using a capillary phenomenon and introducing it between the titanium dioxide electrode and the counter electrode. The photoelectrochemical cell was irradiated with simulated sunlight by a solar simulator [manufactured by Spectrometer Co., Ltd., solar cell characteristic measurement system], and its characteristics were evaluated. As a result, the characteristics of the obtained photoelectrochemical cell were a short-circuit current density of 7.65 mA / cm ² , an open-circuit voltage of 0.73 V, a form factor (fill factor) of 0.57, and an energy conversion efficiency of 2.8%. .

Fluorine-doped tin oxide coated transparent conductive glass (manufactured by Nippon Sheet Glass, surface resistance is about 15 Ω / cm ² ) on the conductive surface side with titanium dioxide paste (Solaronix, SA Ti-Nanoxide T) using a glass rod After coating at room temperature for 30 minutes, it was baked at 450 ° C. for 30 minutes in an electric furnace. The film thickness of titanium dioxide was 10 μm. After the glass was taken out and cooled, it was immersed in an acetonitrile solution (compound (6) 0.1 mmol / l, chenodeoxycholic acid 10 mmol / l) mixed with compound (6) and chenodeoxycholic acid for 1 hour at room temperature. The glass adsorbed with the dye was washed with acetonitrile and air dried.
The titanium dioxide electrode substrate (1 cm × 3 cm) prepared as described above was superposed on the platinum-deposited glass having the same size. Next, an electrolytic solution (iodine 0.05 mol / l, lithium iodide 0.1 mol / l, dimethylpropylimidazolyl iodine 0.62 mol / l and tert-butylpyridine 0.5 mol / l in acetonitrile) was added to both glasses. A photoelectrochemical cell was obtained by impregnating the gap using a capillary phenomenon and introducing it between the titanium dioxide electrode and the counter electrode. The photoelectrochemical cell was irradiated with simulated sunlight by a solar simulator [manufactured by Spectrometer Co., Ltd., solar cell characteristic measurement system], and its characteristics were evaluated. As a result, the characteristics of the obtained photoelectrochemical cell were a short-circuit current density of 8.7 mA / cm ² , an open-circuit voltage of 0.70 V, a form factor (fill factor) of 0.57, and an energy conversion efficiency of 3.4%. .

A transparent thin film of titanium dioxide (about 0.1 μm) was doped with fluorine by spray pyrolysis from an ethanol solution of Ti (OiPr) ₄ (1 mol / l: iPr represents isopropyl) and acetylacetone (2 mol / l). It was prepared on a transparent conductive glass coated with tin oxide [manufactured by Nippon Sheet Glass, surface resistance is about 15 Ω / cm ² ]. A titanium dioxide paste (manufactured by Solaronix, SA Ti-Nanoxide T) was applied to the conductive surface side of the glass using a glass rod, dried at room temperature for 30 minutes, and then baked at 450 ° C. for 30 minutes in an electric furnace. The film thickness of titanium dioxide was 10 μm. The glass was taken out and cooled, and then immersed in an acetonitrile solution (0.1 mmol / l) of compound (7) at room temperature for 1 hour. The glass adsorbed with the dye was washed with acetonitrile and air dried.
0.3 g of CuI was dissolved in 10 ml of acetonitrile to prepare a saturated solution, and 10 mg of triethylammonium thiocyanate was added to 6 g of this saturated solution to prepare a solution. This solution was dropped on a glass adsorbed with a dye placed on a hot plate heated to 80 ° C. to form a CuI layer.
A photoelectrochemical cell was obtained by superimposing platinum-deposited glass of the same size on the glass on which the CuI layer was formed. The photoelectrochemical cell was irradiated with simulated sunlight by a solar simulator [manufactured by Spectrometer Co., Ltd., solar cell characteristic measurement system], and its characteristics were evaluated. As a result, the characteristics of the obtained photoelectrochemical cell were a short-circuit current density of 5.1 mA / cm ² , an open-circuit voltage of 0.54 V, a form factor (fill factor) of 0.51, and an energy conversion efficiency of 1.4%. .

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a squarylium compound that can be used in a photoelectric conversion element that is inexpensive and has high energy conversion efficiency, a metal complex of the squarylium compound, a photoelectrochemical cell using the same, and the like.

Claims (10)

Formula (I)

[Where:
R ¹ and R ² are the same or different and each represents a hydrogen atom, an alkyl group that may have a substituent, an aralkyl group that may have a substituent, or an aryl group that may have a substituent. Or when X described below is a carbon atom, R ¹ and R ² may be combined with adjacent carbon atoms to form an alicyclic hydrocarbon ring or a heterocyclic ring;
R ³ represents a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent,
R ⁴ represents a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a nitro group, a cyano group or a substituent. Represents an alkoxyl group which may have
n represents an integer of 0 to 3,
Here, when n is 2 to 3, each R ⁴ may be the same or different, and two adjacent R ⁴ groups together with two adjacent carbon atoms each have a substituent. May form an aromatic ring that may have
X represents a carbon atom, a sulfur atom, a nitrogen atom or an oxygen atom (provided that when X is a sulfur atom or an oxygen atom, R ¹ and R ² are not present, and when X is a nitrogen atom, R ² is not exist.),
R ⁵ and R ⁶ are the same or different and have a hydrogen atom, a hydroxyl group, a halogen atom, an amino group which may have a substituent, an alkyl group which may have a substituent, or a substituent. Represents an optionally substituted alkoxyl group, an optionally substituted aralkyl group, an optionally substituted aryl group, a nitro group, a cyano group, or an optionally substituted heterocyclic group. ,
Y represents a nitrogen atom or an oxygen atom (provided that when Y is an oxygen atom, R ⁵ does not exist);
A represents an acidic group,
m represents an integer of 1 to 4,
Here, when m is 2 to 4, each A may be the same or different. ]
A squarylium compound represented by:   The squarylium compound according to claim 1, wherein X is a carbon atom and Y is a nitrogen atom.   A metal complex of the squarylium compound according to claim 1.   The metal complex of a squarylium compound according to claim 3, wherein X is a carbon atom and Y is a nitrogen atom.   A photoelectric conversion material comprising the squarylium compound according to claim 1 or 2 and a semiconductor.   The photoelectric conversion material containing the metal complex of the squarylium compound of Claim 3 or 4, and a semiconductor.   A photoelectric conversion element using the photoelectric conversion material according to claim 5.   A photoelectric conversion element using the photoelectric conversion material according to claim 6.   A photoelectrochemical cell comprising the photoelectric conversion element according to claim 7. The photoelectrochemical cell containing the photoelectric conversion element of Claim 8.