JPH11214730A - Photoelectric conversion element and opto-electric chemical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a color element sensitizing optoelectric conversion element through the use of an organic color element by permitting the photosensitive layer of an optical conversion element having at least a conductive supporting body and a photosensitive layer to contain semiconductor fine grains which are sensitized by a polymethine color element expressed by a specified formula. SOLUTION: A photosensitive layer 3 of an optical conversion element, having at least a conductive supporting body 2 and the photosensitive layer 3, contains semiconductor fine grains sensitized by a polymethine color element expressed by a formula. Thus, a color element sensitizing optoelectric conversion element using an organic color element can be formed. In the formula, R1 and R5 represent hydrogen atoms and the like, R2 , R3 and R4 represent hydrogen atoms or a monohydric substituent, X11 and X12 respectively represents tellurium atoms of nitrogen atoms, n11 and n13 represent integers of 0-2, and n12 represents integer 1-6. Paired ions pai can be given to a compound expressed by the formula in accordance with the charge of ovrerall molecule. Thus, the infrared light of a wavelength not less than 800 nm, which is included, in sunlight, can be used by selecting the polymethine color element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photoelectric conversion element and an electrochemical cell using the same, and more particularly, to a photoelectric conversion element and an electrochemical cell using semiconductor fine particles sensitized with a dye.

[0002]

2. Description of the Related Art Photoelectric conversion elements are used in various optical sensors, copying machines, and photovoltaic devices. Various types of photoelectric conversion elements have been put into practical use, such as those using metals, those using semiconductors, those using organic pigments and dyes, and those combining these.

[0003] US Patent Nos. 4,927,721 and 46,845
No. 37, No. 5,084,365, No. 5,350,644, No. 5,463,057, No. 5,525,440 and JP-A-7-249790 describe a photoelectric conversion element using semiconductor fine particles sensitized with a dye (hereinafter, referred to as a photoelectric conversion element). Dye-sensitized photoelectric conversion elements), or materials and manufacturing techniques for producing the same. The first advantage of this method is that an inexpensive oxide semiconductor such as titanium dioxide can be used without purification to a high degree of purity, so that a relatively inexpensive photoelectric conversion element can be provided. The second advantage is that since the absorption of the dye used is broad, light in almost all visible wavelength regions can be converted into electricity. Since these features are advantageous when applied to a photoelectric conversion element (so-called solar cell) for converting solar energy into electricity, application to this area is being actively studied.

[0004] However, there are at least two points in the dye-sensitized photoelectric conversion element that require improvement. The first is to use an expensive ruthenium complex dye as the sensitizing dye, and the second is that the light that can be photoelectrically converted is visible light or 800 light.
That is, it is limited to near-infrared light having a wavelength shorter than nm. A photoelectric conversion element having sensitivity to wavelengths longer than 800 nm can be applied to various analytical instruments and is also useful for solar cells. Sunlight contains a lot of infrared light having a wavelength longer than 800 nm, and if such low-energy light can be converted into electricity, the conversion efficiency of the element can be improved.

[0005] For these reasons, development of a photoelectric conversion element sensitized by an inexpensive organic dye and capable of converting low-energy light having a wavelength of 800 nm or more into electricity has been desired.

[0006]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a dye-sensitized photoelectric conversion element using an organic dye. A second object is to provide a dye-sensitized photoelectric conversion element capable of converting low-energy light having a wavelength of 800 nm or more into electricity. A third object is to provide a photoelectrochemical cell using such a photoelectric conversion element and having improved conversion efficiency.

[0007]

As a result of research, it has been found that the following (1) to (7) are suitable for the purpose of the present invention. (1) A photoelectric conversion element having at least a conductive support and a photosensitive layer, wherein the photosensitive layer contains semiconductor fine particles sensitized by a polymethine dye. (2) The photoelectric conversion device according to (1), wherein the polymethine dye is represented by the following general formula (1).

[0008]

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[In the general formula (1), R ₁ and R ₅ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic residue, and R ₂ , R ₃ and R ₄ each represent a hydrogen atom or Represents a monovalent substituent. R _{1 to} R ₅ may combine with each other to form a ring. X ₁₁ and X ₁₂ are each a nitrogen atom,
Represents an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom. n ₁₁ and n ₁₃ each represents an integer of 0 to 2, n ₁₂ represents an integer of 1-6. The compound represented by the general formula (1) may have a counter ion depending on the charge of the whole molecule. (3) The photoelectric conversion element according to (2), wherein the polymethine dye is represented by the following general formula (2), (3) or (4).

[0010]

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[In the general formula (2), R ₁₁ , R ₁₂ and R ₁₃
Represents a hydrogen atom or a monovalent substituent, respectively. R _{11 to} R ₁₃
May combine with each other to form a ring. R ₁₄ and R ₁₅
Each represents an alkyl group. A ₁₁ and A ₁₂ each represent an atomic group for forming a 3- to 9-membered ring together with a carbon atom and a nitrogen atom, and n ₁ represents an integer of 0 to 4. The compound represented by the general formula (2) may have a counter ion depending on the charge of the whole molecule. In the general formula (3), R ₂₁ , R ₂₂ and R ₂₃ each represent a hydrogen atom or a monovalent substituent. R ₂₁
To R ₂₃ may combine with each other to form a ring. R ₂₄ and R ₂₅ each represent an alkyl group. A ₂₁ and A ₂₂ each represent an atomic group for forming a 5- to 9-membered ring together with a carbon atom and a nitrogen atom, and n ₂ represents an integer of 0 to 4.
The compound represented by the general formula (3) may have a counter ion depending on the charge of the whole molecule. In the general formula (4), R ₃₁ and R
₃₂ and R ₃₃ each represent a hydrogen atom or a monovalent substituent. R _{31 to} R ₃₃ may combine with each other to form a ring.
A ₃₁ and A ₃₂ each represent an atomic group for forming a 3- to 9-membered ring together with carbon atoms, and n ₃ represents an integer of 0 to 4. The compound represented by the general formula (4) may have a counter ion depending on the charge of the whole molecule. (4) The photoelectric conversion element according to (3), wherein the polymethine dye is represented by the following general formula (5).

[0012]

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[In the general formula (5), R ₄₁ and R ₄₂ each represent a hydrogen atom or a monovalent substituent. R ₄₃ and R ₄₄ each represent an alkyl group. A ₄₁ and A ₄₂ each represent an atomic group for forming a 3- to 9-membered ring together with a carbon atom and a nitrogen atom. The compound represented by the general formula (5) may have a counter ion depending on the charge of the whole molecule. (5) The photoelectric conversion element according to the above (4), wherein the heterocycle completed by A ₄₁ and the heterocycle completed by A ₄₂ are each benzothiazoline, indolenine, naphthothiazoline or benzoindolenine. (6) The photoelectric conversion element according to any one of (2) to (5), wherein the polymethine dye has at least one carboxyl group. (7) A photoelectrochemical cell having the photoelectric conversion element according to any one of (1) to (6), and further having at least a charge transfer layer and a counter electrode.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The photoelectric conversion element of the present invention has a photosensitive layer on a conductive support, and the photosensitive layer contains semiconductor fine particles sensitized by a polymethine dye.

As described above, by using a polymethine dye, a dye-sensitized photoelectric conversion element having excellent conversion efficiency can be obtained. In addition, by selecting a polymethine dye, it becomes possible to use infrared light having a long wavelength of 800 nm or more contained in sunlight and convert low-energy light into electricity. For this reason, the conversion efficiency of the element is improved. It is also advantageous in terms of cost.

The polymethine dye used in the present invention includes:
Polymethine dyes represented by the general formula (1) are preferred. To explain the general formula (1), in the general formula (1), R ₁
And R ₅ each represents a hydrogen atom, an alkyl group, an aryl group or a heterocyclic residue, and R ₂ , R ₃ and R ₄ each represent a hydrogen atom or a monovalent substituent. R _{1 to} R ₅ may combine with each other to form a ring. X ₁₁ and X ₁₂ are each nitrogen,
Represents oxygen, sulfur, selenium or tellurium. n ₁₁ and n
₁₃ represents an integer of 0 to 2, n ₁₂ represents an integer of 1-6.
The compound represented by the general formula (1) may have a counter ion depending on the charge of the whole molecule.

The polymethine dye represented by the general formula (1) will be described in detail.

In the general formula (1), R ₁ and R ₅ represent a hydrogen atom, an alkyl group or an alkenyl group (for example, methyl, ethyl, propyl, butyl, isobutyl, n-dodecyl,
A cyclohexyl, vinyl, allyl, benzyl, etc.), an aryl group (eg, phenyl, tolyl, naphthyl, etc.), or a heterocyclic residue (eg, pyridyl, imidazolyl, furyl, thienyl, oxazolyl, thiazolyl,
Benzimidazolyl group, quinolyl group, etc.). These may have a substituent.

Examples of the substituent include an alkyl group, an aryl group, and a heterocyclic residue. Specific examples are the same as those described above, and further, a halogen atom (for example, fluorine,
Chlorine, bromine), alkoxy groups (eg, methoxy, ethoxy, benzyloxy, etc.), aryloxy groups (eg, phenoxy, etc.), alkylthio groups (eg, methylthio, ethylthio, etc.), arylthio groups (eg, phenylthio, etc.), hydroxy groups and oxygen groups Ion, nitro group, cyano group, amide group (eg, acetylamino, benzoylamino, etc.), sulfonamide group (eg, methanesulfonylamino, benzenesulfonylamino, etc.), ureido group (eg, 3-phenylureido, etc.), urethane group ( For example, isobutoxycarbonylamino, carbamoyloxy, etc.), ester group (eg, acetoxy, benzoyloxy, methoxycarbonyl, phenoxycarbonyl, etc.), carbamoyl group (eg, N-methylcarbamoyl, N, N-diphenylca) Bamoyl, etc.), sulfamoyl group (eg, N-phenylsulfamoyl, etc.), acyl group (eg, acetyl, benzoyl, etc.), amino group (amino, methylamino, anilino, diphenylamino, etc.), sulfonyl group (eg, methylsulfonyl) , A phosphonyl group and its ester, a phosphonyloxy group and its ester, a carboxyl group, a sulfo group and the like. The above substituent may be further present on the carbon atom of the substituent.

R _{2 to} R ₄ represent a hydrogen atom or a monovalent substituent. As the monovalent substituent, those similar to the substituents at R ₁ and R ₅ can be mentioned. R _{2 to} R ₄ may further have a substituent. R _{2 to} R ₄ are preferably a hydrogen atom, a halogen atom, an oxygen anion, or a substituted or unsubstituted alkyl group.

X ₁₁ and X ₁₂ represent nitrogen, oxygen, sulfur, selenium, tellurium. n ₁₁ and n ₁₃ represents an integer of 0 to 2. n ₁₂ represents an integer of 0 to 6. However, when X ₁₁ is oxygen, sulfur, selenium, tellurium, n ₁₁ is 0 to 0 due to chemical restrictions.
Represents an integer of 1. The same is true for n _13. The length of the methine chain is related to the absorption wavelength of the dye is adjusted appropriately according to the purpose because it absorbs the long-wavelength light as the value of n ₁₂ is large.

Arbitrary groups selected from R _{1 to} R ₅ may be bonded to each other to form a ring. For example, R ₁ and R ₂ , or R ₄ and R ₅ may combine to form a _3- to 9-membered heterocycle, or R ₂ and R ₃ , or R ₃ and R ₄ may combine to form a 3 to 9-membered heterocyclic ring. 8
It may form a membered aromatic, heterocyclic, or alicyclic ring, and the rings formed thereby may be fused together. Preferred rings include cyclobutene, cyclopentene, cyclohexene, benzene, dehydrodecalin, pyridine, dihydropyridine, tetrahydropyridine, furan, dihydrofuran, thiophene, dihydrothiophene, hexahydroquinoline and the like. All of these rings may be further fused with a 3- to 8-membered aromatic ring, heterocyclic ring or alicyclic ring. For example, for a ring (including a condensed ring) formed by bonding R ₁ and R ₂ or R ₄ and R ₅ , A _{1 in} the following general formulas (2) to (4)
_{11, A 12, A 21,} A 22, A 31, can be the same as the ring formed by A _32.

When the compound represented by the general formula (1) has a charge as a whole molecule, it may have a counter ion for neutralizing the charge. The counter ion is not particularly limited and may be either organic or inorganic. Representative examples include halogen ions (fluorine ions, chloride ions, bromine ions, and iodine ions), hydroxide ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, acetate ions, and trifluoroacetate ions. Anions such as methanesulfonate ion, paratoluenesulfonate ion, trifluoromethanesulfonate ion, alkali metals (lithium, sodium, potassium, etc.), alkaline earth metals (magnesium, calcium, etc.), ammonium, alkylammonium (eg, diethyl Cations such as ammonium, tetrabutylammonium), pyridinium, alkylpyridinium (eg, methylpyridinium), guanidinium, and tetraalkylphosphonium.

It is particularly preferable that the compound represented by the general formula (1) has an acidic group, since it has excellent adsorptivity to semiconductor fine particles. As the acidic group, those having a pKa of 10 or less in a mixed solvent of water and tetrahydrofuran (volume ratio of 50 to 50) are preferable. Particularly preferred are a carboxyl group, a sulfonic acid group, a sulfinic acid group, a phosphonic acid group, a hydroxyl group, a phosphoric acid monoester and a diester group. Of these, a carboxyl group is most preferred. These groups may form a salt with an alkali metal or the like. Further, an inner salt may be formed.

A specific example of such a polymethine dye is M.Ok
Organic Colora by awara, T.Kitao, T.Hirasima, M.Matuoka
nts (Elsevier) and others.

The polymethine dye used in the present invention is more preferably represented by the following general formulas (2) to (4).

The polymethine dye represented by the general formula (2) will be described in detail. In the general formula (2), R ₁₁ and R
₁₂ and R ₁₃ each represent a hydrogen atom or a monovalent substituent. Examples of the monovalent substituent include an alkyl group or an alkenyl group (eg, methyl, ethyl, propyl, butyl, isobutyl, n-dodecyl, cyclohexyl, vinyl, allyl, benzyl, etc.), an aryl group (eg, phenyl, tolyl, naphthyl, etc.), A heterocyclic residue (for example, pyridyl group, imidazolyl group, furyl group, thienyl group, oxazolyl group, thiazolyl group, benzimidazolyl group, quinolyl group, etc.), a halogen atom (for example, fluorine, chlorine, bromine),
An alkoxy group (eg, methoxy, ethoxy, benzyloxy, etc.), an aryloxy group (eg, phenoxy, etc.),
Alkylthio group (for example, methylthio, ethylthio, etc.),
Arylthio group (eg, phenylthio etc.), hydroxy group and oxygen anion, nitro group, cyano group, amide group (eg, acetylamino, benzoylamino etc.), sulfonamide group (eg, methanesulfonylamino, benzenesulfonylamino, etc.), ureido group (Eg, 3-phenylureido), urethane group (eg, isobutoxycarbonylamino, carbamoyloxy, etc.), ester group (eg, acetoxy, benzoyloxy, methoxycarbonyl, phenoxycarbonyl, etc.), carbamoyl group (eg, N-methylcarbamoyl, N, N-diphenylcarbamoyl, etc.), a sulfamoyl group (eg, N-phenylsulfamoyl), an acyl group (eg, acetyl,
Benzoyl), an amino group (amino, methylamino, anilino, diphenylamino, etc.), a sulfonyl group (eg, methylsulfonyl, etc.), a phosphonyl group and its ester, a phosphonyloxy group and its ester, a carboxyl group, a sulfo group and the like. Can be The above substituent may be further present on the carbon atom of the substituent.

The methine chain substituents represented by R _{11 to} R ₁₃ may be bonded to each other to form a 3- to 8-membered monocyclic or polycyclic aromatic, heterocyclic or alicyclic ring. Good. Preferred rings include cyclobutene, cyclopentene, cyclohexene, benzene, dehydrodecalin, pyridine,
Examples thereof include dihydropyridine, tetrahydropyridine, furan, dihydrofuran, thiophene, dihydrothiophene, and hexahydroquinoline. All of these rings may be further fused with a 3- to 8-membered aromatic ring, heterocyclic ring or alicyclic ring. In the general formula (2), R ₁₄ and R ₁₅ each represent a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms. Examples of the alkyl group and examples of the substituent are R _{11 to} R
_The statements made in section ₁₃ apply.

In the general formula (2), A ₁₁ and A ₁₂ each represent an atomic group for forming a 3- to 9-membered monocyclic or condensed ring together with a carbon atom and a nitrogen atom. The atoms constituting the ring in the atomic group are carbon, nitrogen, oxygen, sulfur, selenium, and tellurium. Examples of the heterocycle completed by A ₁₁ or A ₁₂ include indolenine, benzoindolenine, benzimidazoline, benzoxazoline, benzothiazoline, quinoline, benzoselenazoline, benzotellrazoline, naphthoxazoline, naphthothiazoline and the like. . These may have the aforementioned substituents. n
₁ represents an integer of 0 to 4. The length of the methine chain is related to the absorption wavelength of the dye is adjusted appropriately according to the purpose because it absorbs the long-wavelength light as the value of n ₁ is larger.

The compound represented by the general formula (2) may have a counter ion depending on the charge of the whole molecule. The counter ion is not particularly limited and may be either organic or inorganic. Representative examples include halogen ions (fluorine ions, chloride ions, bromine ions, and iodine ions), hydroxide ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphate ions, acetate ions, and trifluoroacetate ions. Anions such as methanesulfonic acid ion, paratoluenesulfonic acid ion, trifluoromethanesulfonic acid ion, alkali metals (lithium, sodium, potassium, etc.), alkaline earth metals (magnesium, calcium, etc.), ammonium, alkyl ammonium (for example, Diethylammonium, tetrabutylammonium, etc.),
Examples include cations such as pyridinium, alkylpyridinium (eg, methylpyridinium), guanidinium, and tetraalkylphosphonium.

It is particularly preferable that the compound represented by the general formula (2) has an acidic group, since it has excellent adsorptivity to semiconductor fine particles. As the acidic group, those having a pKa of 10 or less in a mixed solvent of water and tetrahydrofuran (volume ratio of 50 to 50) are preferable. Particularly preferred are a carboxyl group, a sulfonic acid group, a sulfinic acid group, a phosphonic acid group, a hydroxyl group, a phosphoric acid monoester and a diester group. Of these, a carboxyl group is most preferred. These groups may form a salt with an alkali metal or the like. Further, an inner salt may be formed.

Next, the general formula (3) will be described. In the general formula (3), R _{21 to} R ₂₃ represent R ₁₁ in the general formula (2).
Is synonymous with R ₂₄ and R ₂₅ have the same meaning as R _{14 in} formula (2). A ₂₁ and A ₂₂ each represent an atomic group for forming a 5- to 9-membered monocyclic or fused ring together with a carbon atom and a nitrogen atom. The atoms constituting the ring in the atomic group are carbon, nitrogen, oxygen, sulfur, selenium, and tellurium.
As the heterocyclic ring completed by A ₂₁ or A ₂₂ , dihydroquinoline and the like are preferable. These may have the aforementioned substituents. n ₂ represents an integer of 0-4. The compound represented by the general formula (3) may have the aforementioned counter ion depending on the charge of the whole molecule. The compound represented by the general formula (3) also preferably has the above-mentioned acidic group, and as the acidic group, a carboxyl group is most preferred.

Next, the general formula (4) will be described. In the general formula (4), R _{31 to} R ₃₃ represent R ₁₁ in the general formula (2).
Is synonymous with A ₃₁ and A ₃₂ each represent an atomic group for forming a 3- to 9-membered monocyclic or fused ring together with carbon atoms. The atoms constituting the ring in the atomic group are carbon, nitrogen, oxygen, sulfur, selenium, and tellurium. A ₃₁ ,
Alternatively, as the heterocyclic ring completed by A ₃₂ , a heterocyclic cyclic ketone (including thioketone) is preferable, and pyrimidine,
Those having a heterocyclic ring such as pyridine and pyrazole are preferred. These may have the aforementioned substituents. n ₃ represents an integer of 0-4. The acidic hydroxyl group at the conjugate end may be dissociated. The compound represented by the general formula (4) may have the aforementioned counter ion depending on the charge of the whole molecule.
The compound represented by the general formula (4) also preferably has the above-mentioned acidic group, and the acid group is most preferably a carboxyl group.

In the present invention, a particularly preferred dye is a dye represented by formula (5). In the general formula (5), R ₄₁ and R ₄₂ have the same meaning as R _{11 in the} general formula (2). R
₄₃ and R ₄₄ have the same meaning as R _{14 in} formula (2). A ₄₁ , A
₄₂ has the same meaning as A _{11 in} formula (2). As the heterocycle completed by A ₄₁ or A ₄₂ , indolenine, benzothiazoline, quinoline, benzoindolenine, naphthothiazoline and the like are preferable, and benzothiazoline, indolenine, naphthothiazoline and benzoindolenine are particularly preferable. It may have the same substituents as A _11. The compound represented by the general formula (5) may have the aforementioned counter ion depending on the charge of the whole molecule. The compound represented by the general formula (5) also preferably has the above-mentioned acidic group,
A carboxyl group is most preferred as the acidic group.

Preferred specific examples of the polymethine dyes represented by formulas (2) to (4) are shown below, but the present invention is not limited thereto.

[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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The polymethine dyes represented by formulas (2) to (4) of the present invention are FM Harme (FM Harme).
r), Heterocyclic Compounds-Cyanine Soybean and Related Compounds (Hete
rocyclic Compounds-Cyanine Dyes and Related Compou
nds) ", John Willy and Sons (John W
illey & Sons), New York, London, 199
Fourth year, DMSturmer, Heterocyclic Compounds-Special Topics in Heterocyclic Chemistry (H
eterocyclic Compounds-Special Topics In Heterocy
clic Chemistry ", Chapter 18, Sections 14, 482-515, John Wiley and Sons (John Wi
lley & Sons), New York, London, 1977, "Rodd's Chemistry of Carbon Compounds" 2nd
Edition Vol.4, PartB, Chapter 15, Chapters 369-422
Clause, Eisevier Science Publishing Company Inc.
Company, New York, 1977, UK Patent No. 1077
No. 611 or the like.

Next, the method for synthesizing the polymethine dye used in the present invention will be described with reference to specific examples, but the present invention is not limited thereto.

Synthesis Example 1 Synthesis of Exemplified Compound (10) The exemplified compound (10) of the present invention was synthesized by the following synthesis route.

[0051]

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3.9 g of compound (A-1) and compound (A-
2) 0.57 g, toluene 10 ml, butanol 30 m
and heated to reflux for 4 hours with stirring. The solvent was distilled off under reduced pressure, 10 cc of a 1: 1 (volume ratio) mixed solvent of isopropyl alcohol and methanol was added, and the mixture was left at 5 ° C. overnight. The precipitated crystals were collected by filtration to obtain 0.3 g of Exemplified Compound (10).

Next, a dye-sensitized photoelectric conversion element to which the polymethine dye of the present invention is applied and a photoelectrochemical cell will be described in detail.

In the present invention, the dye-sensitized photoelectric conversion element is an electrode comprising a conductive support and a layer (photosensitive layer) of semiconductor fine particles having a polymethine dye adsorbed thereon, which is coated on the conductive support. The photosensitive layer is designed according to the purpose and may have a single-layer structure or a multilayer structure. The dye in one photosensitive layer may be one kind or a mixture of many kinds. Light incident on the photosensitive layer excites the dye. The excited dye has high-energy electrons, which are transferred from the dye to the conduction band of the semiconductor fine particles and reach the conductive support by diffusion. At this time, the dye molecules are in an oxidized form, but the photoelectrochemical cell returns electrons to the oxidized form while the electrons on the electrodes work in an external circuit, and the dye-sensitized photoelectric conversion element is the negative electrode of this battery. Work as

Hereinafter, the conductive support and the photosensitive layer will be described in detail.

The conductive support is a support such as a metal which has conductivity, or a glass or plastic support having a conductive agent layer on the surface. In the latter case, a preferred conductive agent is a metal (eg, platinum, gold,
Silver, copper, aluminum, rhodium, indium, etc.), carbon, or a conductive metal oxide (indium-tin composite oxide, tin oxide doped with fluorine, or the like). In this case, the thickness of the conductive agent layer is 0.05 to 10
μm is preferred.

The lower the surface resistance of the conductive support, the better.
The preferable range of the surface resistance is 50 Ω / cm ² or less, and more preferably 10 Ω / cm ² or less. The lower limit is not particularly limited, but is usually about 0.1 Ω / cm ² .

Preferably, the conductive support is substantially transparent. Substantially transparent means that light transmittance is 10%
It means that it is at least 50%, preferably at least 50%, particularly preferably at least 80%. As the transparent conductive support, glass or plastic coated with a conductive metal oxide is preferable. The amount of the conductive metal oxide applied at this time is preferably 0.1 to 100 g per 1 m2 of a glass or plastic support. When a transparent conductive support is used, light is preferably incident from the support side.

The semiconductor fine particles used in the photosensitive layer are metal chalcogenides (eg, oxides, sulfides, selenides, etc.).
Alternatively, it is fine particles of perovskite. The metal chalcogenide preferably includes titanium, tin, zinc, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxide, cadmium sulfide, cadmium selenide, and the like. As the perovskite, strontium titanate, calcium titanate and the like are preferably mentioned. Among these, titanium oxide, zinc oxide, tin oxide and tungsten oxide are particularly preferred.

The average particle size of these semiconductor fine particles is 0.001 to 1 μm as primary particles using the diameter when the projected area is converted into a circle, and 0.01 to 1 μm as the average particle size of the dispersion. Preferably it is 100 μm.

The method of coating the semiconductor fine particles on the conductive support includes a method of coating a dispersion or a colloidal solution of the semiconductor fine particles on the conductive support, and a method of coating the precursor of the semiconductor fine particles on the conductive support. A method of coating and hydrolyzing with water in the air to obtain a semiconductor fine particle film, and the like can be given. Examples of a method for preparing a dispersion of semiconductor fine particles include a method of grinding in a mortar, a method of dispersing while grinding using a mill, and a method of precipitating and using fine particles in a solvent when synthesizing a semiconductor. . Examples of the dispersion medium include water and various organic solvents (eg, methanol, ethanol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.). At the time of dispersion, a polymer, a surfactant, an acid, a chelating agent, or the like may be used as a dispersing aid, if necessary.

The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. For example, in a state where the semiconductor fine particles are coated on the support, the surface area is preferably 10 times or more the projected area,
More preferably, it is 100 times or more. The upper limit is not particularly limited, but is usually about 5000 times.

In general, as the thickness of the layer of semiconductor fine particles increases, the amount of dye that can be supported per unit area increases, so that the light absorption efficiency increases. However, the diffusion distance of generated electrons increases, and the loss due to charge recombination also increases. growing. The preferred thickness of the semiconductor fine particle layer (that is, the photosensitive layer) varies depending on the use of the device, but is typically 0.1 to 100 μm. When used as a photoelectrochemical cell, the thickness is preferably 1 to 50 μm, more preferably 3 to 30 μm. The semiconductor fine particles are applied at a temperature of 100 to 800 ° C. for 10 minutes to adhere the particles to each other after being applied to the support.
You may bake for 10 hours.

The coating amount of the semiconductor fine particles per 1 m ² of the support is preferably 0.5 to 500 g, more preferably 5 to 100 g.

In the present invention, the semiconductor fine particles are sensitized by the adsorption of the polymethine dye. To adsorb the dye to the semiconductor fine particles, a method of immersing well-dried semiconductor fine particles in a dye solution for a long time is generally used. It is. The dye solution may be heated to 50 ° C to 100 ° C as needed. The dye may be adsorbed before or after the application of the semiconductor fine particles. Further, the semiconductor fine particles and the dye may be simultaneously applied and adsorbed. Unadsorbed dye is removed by washing. When baking the coating film, it is preferable that the dye is adsorbed after baking. It is particularly preferable that the dye is quickly adsorbed after the firing and before the water is adsorbed on the coating film surface. The dye to be adsorbed may be one kind or a mixture of several kinds. In the case of mixing, the polymethine dyes of the present invention may be mixed with each other, or may be mixed with US Pat. Nos. 4,927,721, 4,684,537, 5,084,365, and 53506.
No. 44, No. 5463057, No. 5525440 and the complex dye described in JP-A-7-249790 may be mixed with the dye of the present invention. When the application is a photoelectrochemical cell, a dye to be mixed is selected so as to widen the wavelength range of photoelectric conversion as much as possible.

The total amount of the dye used is preferably from 0.01 to 100 mmol, more preferably from 0.1 to 50 mmol, particularly preferably from 0.5 to 10 mmol, per 1 m ² of the support. In this case, the amount of the polymethine dye of the present invention is preferably 5 mol% or more.

The amount of the dye adsorbed on the semiconductor fine particles is preferably 0.001 to 1 mmol, more preferably 0.1 to 0.5 mmol, per 1 g of the semiconductor fine particles.

By using such a dye amount, a sufficient sensitizing effect in a semiconductor can be obtained. In contrast,
If the amount of the dye is small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not adhering to the semiconductor floats and causes a reduction in the sensitizing effect.

A colorless compound may be co-adsorbed for the purpose of reducing the interaction between dyes such as association. Examples of the hydrophobic compound to be co-adsorbed include steroid compounds having a carboxyl group (for example, cholic acid).

After the dye is adsorbed, the surface of the semiconductor fine particles may be treated with amines. Preferred amines include pyridine, 4-tert-butylpyridine, polyvinylpyridine and the like. When these are liquid, they may be used as they are, or may be used by dissolving them in an organic solvent.

In the present invention, the conductive agent and the semiconductor fine particles may be mutually diffused and mixed in the vicinity of the interface between the conductive support and the photosensitive layer.

The dye-sensitized photoelectric conversion device thus prepared can be applied to various sensors and photoregeneration type photoelectrochemical cells. When applied to a photoelectrochemical cell, a charge transfer layer and a counter electrode are required as shown in FIG.

The photoelectrochemical cell 1 shown in FIG. 1 has a photosensitive layer 3 on a conductive support 2, and further has a charge transfer layer 4 and a counter electrode 5 provided on the photosensitive layer 3.

Hereinafter, the charge transfer layer and the counter electrode will be described in detail.

The charge transfer layer is a layer having a function of replenishing the oxidized dye with electrons. Representative examples include a liquid in which a redox couple is dissolved in an organic solvent, a so-called gel electrolyte in which a liquid in which a redox couple is dissolved in an organic solvent is impregnated in a polymer matrix, and a molten salt containing a redox couple.

Examples of the redox couple include a combination of iodine and iodide (eg, lithium iodide, tetrabutylammonium iodide, tetrapropylammonium iodide, etc.), an alkyl viologen (eg, methyl viologen chloride, hexyl viologen bromide, benzyl viologen) Combination of tetrafluoroborate) and its reduced form, combination of polyhydroxybenzenes (eg, hydroquinone, naphthohydroquinone, etc.) and its oxidized form, divalent and trivalent iron complexes (eg, red blood salt and yellow blood salt)
And the like. Of these, a combination of iodine and iodide is preferred. As an organic solvent for dissolving them, aprotic polar solvents (for example, acetonitrile, propylene carbonate, ethylene carbonate, dimethylformamide, dimethylsulfoxide, sulfolane, 1,3-dimethylimidazolinone, 3-methyloxazolidinone, etc.) are preferable. Examples of the polymer used for the matrix of the gel electrolyte include polyacrylonitrile and polyvinylidene fluoride. Examples of the molten salt include lithium iodide and at least one other lithium salt (eg, lithium acetate, lithium perchlorate, etc.). May be increased. In this case, the amount of the polymer added is 1 to 50% by weight.

Since the redox couple becomes a carrier of electrons, a certain concentration is required. When used as a liquid or gel electrolyte, the total concentration in the solution is preferably at least 0.01 mol / l, more preferably at least 0.1 mol / l, particularly preferably at least 0.3 mol / l. It is. The upper limit in this case is not particularly limited, but is usually 5
It is about mol / l.

The counter electrode functions as a positive electrode of the photoelectrochemical cell. The counter electrode is usually synonymous with the above-mentioned conductive support, but the support is not necessarily required in a configuration in which the strength is sufficiently maintained. However, having a support is advantageous in terms of hermeticity.

In order for light to reach the photosensitive layer, at least one of the above-described conductive support and the counter electrode must be substantially transparent. In the photoelectrochemical cell of the present invention, it is preferable that the conductive support is transparent and sunlight is incident from the support side. In this case, it is more preferable that the counter electrode has a property of reflecting light. As the counter electrode of the photoelectrochemical cell, glass or plastic on which metal or a conductive oxide is deposited is preferable, and glass on which platinum is deposited is particularly preferable.

In a photoelectrochemical cell, it is preferable to seal the side surface of the cell with a polymer, an adhesive or the like in order to prevent the components from evaporating.

The characteristics of the photoelectrochemical cell obtained as described above are as follows: when the AM 1.5 G is 100 mW / cm ² , the open-circuit voltage is 0.01 to 3 V and the short-circuit current density is 0.001 to 20 mA / c.
m ² , form factor 0.1 ~ 0.99, conversion efficiency 0.001 ~
25%.

[0082]

EXAMPLES Hereinafter, the method for producing the dye-sensitized photoelectric conversion element and the photoelectrochemical cell of the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Example 1 Preparation of Titanium Dioxide Dispersion 15 g of titanium dioxide (DegussaP-25, Nippon Aerosil Co., Ltd.), 45 g of water, and a dispersant (Triton X-100, manufactured by Aldrich Co., Ltd.) were placed in a 200 ml stainless steel vessel coated with Teflon on the inside. ) 1g,
Zirconia beads with a diameter of 0.5 mm (manufactured by Nikkato)
30 g was added and dispersed at 1500 rpm for 2 hours using a sand grinder mill (manufactured by Imex). The zirconia beads were removed from the dispersion by filtration. In this case, the average particle size of the titanium dioxide was 2.5 μm. The particle size at this time was measured with a master sizer manufactured by MALVERN.

Preparation of Photoelectric Conversion Element Conductive glass coated with fluorine-doped tin oxide (TCO glass manufactured by Asahi Glass, 20 mm × 20 mm
The above dispersion was applied using a glass rod to the conductive surface side of the substrate (which had been cut to the size of). The surface resistance of the conductive glass was about 30 Ω / cm ² .

At this time, an adhesive tape was stretched on a part (3 mm from the end) on the conductive surface side to form a spacer, and glass was lined up so that the adhesive tape came to both ends, and applied eight at a time.
After the application, it was air-dried at room temperature for one day, and the adhesive tape was peeled off (the part with the adhesive tape was used to make electrical contact with a measuring instrument during photoelectric conversion measurement). next,
This glass was placed in an electric furnace (Yamato Scientific Muffle Furnace FP-3).
(Type 2) and baked at 450 ° C. for 30 minutes. After the glass was taken out and cooled, it was immersed in an ethanol solution (3 × 10 ⁻⁴ mol / l) of the dye of the present invention shown in Table 1 for 3 hours.
The glass on which the dye was dyed was immersed in a 10 wt% ethanol solution of 4-tert-butylpyridine for 30 minutes, washed with ethanol and air-dried. The thickness of the photosensitive layer thus obtained was 10 μm, and the coating amount of the semiconductor fine particles was 20 g / m ² . The coating amount of the dye was appropriately selected from the range of 0.1 to 10 mmol / m ² according to the type of the dye.

Measurement of Reflection Spectrum A reflection spectrum of the above photoelectric conversion element was measured using a spectrophotometer (U-3500, manufactured by Hitachi, Ltd.) equipped with an integrating sphere. Table 1 shows the wavelength and the absorbance at the absorption peak on the longest wavelength side.

Preparation of Photoelectrochemical Cell As one embodiment of the photoelectrochemical cell of FIG. 1, a photoelectrochemical cell as shown in FIG. 2 was prepared. The photoelectrochemical cell 10 of FIG.
Uses the above-mentioned photoelectric conversion element having a configuration in which a photosensitive layer 13 is provided on a conductive support having a conductive agent layer 12 on a glass support 11, and is a charge transfer layer on the photosensitive layer 13. It has an electrolyte layer 14 and a platinum-deposited glass 15 as a counter electrode. In this creation,
The above-mentioned photoelectric conversion element was overlapped with platinum-deposited glass of the same size (FIG. 2, the uncoated portion of the photoelectric conversion element was shifted so as not to contact the platinum-deposited glass).
Next, an electrolytic solution (a mixture of acetonitrile and N-methyl-2-oxazolidinone at a volume ratio of 90:10, iodine 0.05
Mol / l, 0.5 mol / l of lithium iodide).

Measurement of Photoelectric Conversion Efficiency The light of a 500 W xenon lamp (manufactured by Ushio) was applied to AM1.
Simulated sunlight containing no ultraviolet light was generated by passing through a 5G filter (manufactured by Oriel) and a sharp cut filter (Kenko L-42). The intensity of this light was 50 mW / cm ² .

This light is irradiated to the photoelectric conversion element of the present invention,
The generated electricity is measured by a current-voltage measuring device (Keithley 238).
(Type). Table 1 shows the open-circuit voltage, short-circuit current, form factor, and conversion efficiency of the photochemical cell obtained in this way.
Summarized in

[0090]

[Table 1]

As is evident from Table 1, photoelectric conversion characteristics are observed for all the dyes. In addition, Exemplified Compound 12 has an absorption maximum exceeding 800 nm and has a photoelectric conversion characteristic. More specifically, dyes having a carboxyl group (exemplified compounds 6 to 10, 12, and 13) are more excellent in dyeing and dyeing than dyes having no carboxyl group (exemplified compounds 4 and 5). It can be seen that the photoelectric conversion efficiency is high. In addition, it can be seen that the exemplified compound 10 belonging to the general formula (5) exhibits particularly high photoelectric conversion characteristics.

[0092]

It has been clarified that the present invention provides a dye-sensitized photoelectric conversion element using an organic dye. In addition, it was confirmed that a dye having a longer wavelength absorption than 800 nm also performs photoelectric conversion. Therefore, a photoelectrochemical cell could be constructed using such a photoelectric conversion element.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one configuration example of a photoelectrochemical cell of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration example of a photoelectrochemical cell used in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 10 Photoelectrochemical cell 2 Conductive support 3, 13 Photosensitive layer 4 Charge transfer layer 5 Counter electrode 11 Glass support 12 Conductive agent layer 14 Electrolyte layer 15 Platinum vapor deposition glass

Claims (7)

[Claims] 1. A photoelectric conversion device having at least a conductive support and a photosensitive layer, wherein the photosensitive layer contains semiconductor fine particles sensitized by a polymethine dye. 2. The photoelectric conversion device according to claim 1, wherein the polymethine dye is represented by the following general formula (1). Embedded image [In the general formula (1), R ₁ and R ₅ each represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic residue, and R ₂ , R ₃ and R ₄ each represent a hydrogen atom or a monovalent Represents a substituent. R _{1 to} R ₅ may combine with each other to form a ring. X ₁₁ and X ₁₂ each represent a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom. n ₁₁ and n ₁₃ each represents an integer of 0 to 2, n ₁₂ represents an integer of 1-6. The compound represented by the general formula (1) may have a counter ion depending on the charge of the whole molecule. ] 3. A polymethine dye represented by the following general formula (2):
The photoelectric conversion device according to claim 2, which is represented by (3) or (4). Embedded image [In the general formula (2), R ₁₁ , R ₁₂ and R ₁₃ each represent a hydrogen atom or a monovalent substituent. R _{11 to} R ₁₃ may combine with each other to form a ring. R ₁₄ and R ₁₅ each represent an alkyl group. A ₁₁ and A ₁₂ each represent an atomic group for forming a 3- to 9-membered ring together with a carbon atom and a nitrogen atom, and n ₁ represents an integer of 0 to 4. The compound represented by the general formula (2) may have a counter ion depending on the charge of the whole molecule. In the general formula (3), R ₂₁ , R ₂₂ and R ₂₃ each represent a hydrogen atom or a monovalent substituent. R _{21 to} R ₂₃ may combine with each other to form a ring. R ₂₄ and R ₂₅ each represent an alkyl group. A ₂₁ and A ₂₂ each represent an atomic group for forming a 5- to 9-membered ring together with a carbon atom and a nitrogen atom, and n ₂ represents an integer of 0 to 4. General formula (3)
The compound represented by may have a counter ion depending on the charge of the whole molecule. In the general formula (4), R ₃₁ , R ₃₂ and R ₃₃
Represents a hydrogen atom or a monovalent substituent, respectively. R _{31 to} R ₃₃
May combine with each other to form a ring. A ₃₁ and A ₃₂
Each represent an atomic group for forming a 9-membered ring 3- to together with a carbon atom, n ₃ is an integer of 0-4. The compound represented by the general formula (4) may have a counter ion depending on the charge of the whole molecule. ] 4. The photoelectric conversion device according to claim 3, wherein the polymethine dye is represented by the following general formula (5). Embedded image [In the general formula (5), R ₄₁ and R ₄₂ each represent a hydrogen atom or a monovalent substituent. R ₄₃ and R ₄₄ each represent an alkyl group. A ₄₁ and A ₄₂ each represent an atomic group for forming a 3- to 9-membered ring together with a carbon atom and a nitrogen atom. The compound represented by the general formula (5) may have a counter ion depending on the charge of the whole molecule. ] 5. The photoelectric conversion device according to claim 4, wherein the heterocycle completed by A ₄₁ and the heterocycle completed by A ₄₂ are each benzothiazoline, indolenine, naphthothiazoline or benzoindolenine. 6. The photoelectric conversion device according to claim 2, wherein the polymethine dye has at least one carboxyl group. 7. A photoelectrochemical cell comprising the photoelectric conversion element according to claim 1 and further comprising at least a charge transfer layer and a counter electrode.