JP2005197115A - Photoelectric conversion device and solar cell using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion device which is lower in price and higher in photoelectric conversion efficiency. <P>SOLUTION: The photoelectric conversion device comprises a semiconductor electrode sensitized by organic dye which is expressed by a general formula (1) (wherein (A) shows a bivalent heterocyclic group, Z shows a bivalent aromatic cyclic group, R<SB>1</SB>is a hydrogen atom or an alkyl group, and R<SB>2</SB>is a hydrogen atom, an alkyl group, a hydroxyl group, an alkoxy group, an aryl group, and a styryl group, and R<SB>1</SB>and R<SB>2</SB>may combine each other to form a carbocyclic compound of 5 cycles or 6 cycles. R<SB>3</SB>, R<SB>4</SB>, R<SB>5</SB>and R<SB>6</SB>show identically or distinctly a hydrogen atom, a halogen atom, an alkyl group, and an alkoxy group. L is a hydrogen atom or an electronic suctional group, while M is a hydrogen atom or a salt forming cation. m is an integer of 0 to 3, and n is an integer of 0 to 4). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photoelectric conversion element comprising a semiconductor electrode using a specific organic sensitizing dye and a solar cell using the photoelectric conversion element. More specifically, the present invention relates to a high-efficiency dye-sensitized photoelectric conversion device comprising a semiconductor electrode containing a polymethine dye having a 4H-pyran-4-one (γ-pyrone) skeleton as a sensitizer, and the element. Related to solar cells.

  Solar power generation is known to be possible with single crystal silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, and compound solar cells such as cadmium telluride and indium selenide. Batteries are being developed vigorously. Some of these solar cells have already been put into practical use. In the practical application, it is desired to overcome problems such as further reduction in manufacturing cost, securing of stable raw materials, and shortening the period of energy payback time.

  On the other hand, as a solar cell other than the above, a solar cell using a phthalocyanine pigment aimed at increasing the area and reducing the price has been proposed. However, this solar cell has a problem of low photoelectric conversion efficiency.

  Further, Photoelectric conversion using a metal oxide sensitized with an organic dye as a semiconductor electrode in Nature (737-740P 353 (1991)) (Non-patent Document 1) and USP 4,927,721 (Patent Document 1), etc. An element, a solar cell, a material for manufacturing the element, and a manufacturing technique thereof are disclosed. The disclosed content relates to a photoelectric conversion element and a solar cell using semiconductor fine particles made of titanium oxide sensitized with an organic dye having a ruthenium complex structure. The features of the solar cell disclosed here are (1) that an inexpensive raw material such as titanium oxide can be used, and (2) that the conversion wavelength can be used up to a long wavelength depending on the dye used, so that a wider range of visible light can be obtained. It can be converted into electricity, (3) there is a possibility that a new action may be produced by blending the dyes, and (4) there is a possibility that a new sensitizing dye can be discovered. In these features, the above-described solar cell has created a new point of view that was difficult to think of with conventional solar cells. However, there is still a problem that the photoelectric conversion efficiency is still low for practical use as a solar cell.

USP 4,927,721 Nature (737-740P 353 (1991))

  The subject of this invention is providing the highly efficient photoelectric conversion element and solar cell using the semiconductor electrode sensitized with the pigment | dye excellent in photoelectric conversion efficiency.

As a result of various studies to solve the above problems, the present invention has been achieved.
Thus, according to the present invention, the following general formula (1)

(In the formula, A represents a divalent heterocyclic group having 4 or 5 carbon atoms which may have a substituent, and Z represents a divalent divalent having 6 to 24 carbon atoms which may have a substituent. R ₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₂ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a substituent. An aryl group having 6 to 12 carbon atoms which may have a styryl group which may have a substituent, and R ₁ and R ₂ are bonded to each other to form a 5-membered or 6-membered carbocyclic ring R ₃ , R ₄ , R ₅ and R ₆ may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. L is a hydrogen atom or an electron-withdrawing group, M is a hydrogen atom or a salt-forming cation, m is an integer of 0 to 3, and n is To 4 of an integer.)
The photoelectric conversion element characterized by comprising the semiconductor electrode sensitized with the organic pigment | dye represented by these is provided.

  Furthermore, according to this invention, the solar cell which contains the said photoelectric conversion element as a component is provided.

  According to the present invention, by using a specific organic dye (hereinafter simply referred to as a dye) as a photosensitizer, a dye-sensitized photoelectric conversion element that is inexpensive and has high photoelectric conversion efficiency is provided. Moreover, a solar cell with high photoelectric conversion efficiency can be easily provided by using this.

  In the present invention, the dye-sensitized semiconductor electrode plays a role similar to that of a photoreceptor in electrophotography. Specifically, the dye-sensitized semiconductor electrode plays a role of charge separation of electrons and holes by absorbing light. In the dye-sensitized semiconductor electrode, light is absorbed by the dye portion, and electrons and holes are generated. In the semiconductor portion, generated electrons are transmitted.

Examples of the semiconductor that can be used in the present invention include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), iron oxide (Fe ₂ O ₃ ), niobium oxide (Nb ₂ O ₅ ), cadmium sulfide ( CdS), lead sulfide (PbS), zinc sulfide (ZnS), indium phosphide (InP), copper-indium sulfide (CuInS ₂ ), and the like. Of these, titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), and niobium oxide (Nb ₂ O ₅ ) are preferable.

  The semiconductor may have a single crystal system or a polycrystalline system. Among these, a polycrystalline semiconductor is preferable from the viewpoint of easy crystal growth and low manufacturing cost. Further, the semiconductor is preferably in the form of particles, and a nano- to micro-scale fine powder polycrystalline semiconductor is particularly preferable. Further, two or more kinds of particles having different particle sizes may be mixed and used. Further, particles made of different materials may be mixed.

  When semiconductor particles having different particle sizes are used, it is preferable that the average particle size of the semiconductor particles having a large particle size and the semiconductor particles having a small particle size have a difference of 10 times or more. Specifically, it is preferable to use semiconductor particles having an average particle diameter of 100 to 500 nm and semiconductor particles having an average particle diameter of 5 to 50 nm. Particles with a large average particle size are mainly for the purpose of increasing the light capture rate, and particles with a small average particle size have the purpose of mainly improving the dye adsorption property by increasing the number of dye adsorption points. ing. Further, when mixing semiconductor particles made of different materials, it is more effective to make the material having a strong adsorption action a small particle size.

  The semiconductor particles can be produced according to methods described in various documents. For example, a method described in “New Synthesis Method: Synthesis of Monodispersed Particles by Sol-Gel Method and Size Form Control” Vol. 35, No. 9, pages 1012 to 1018 (1995) and the like can be mentioned as a representative example. Moreover, the method of obtaining a semiconductor particle by hydrolyzing the chloride (brand name P25) which the Degussa company developed is also mentioned.

  In particular, titanium oxide has two types of crystal systems, anatase type and rutile type, and can take either form depending on its production method and thermal history. Generally available are mixtures of these. Anatase type titanium oxide has a shorter wavelength of light absorption than rutile type, has a lower degree of decrease in photoelectric conversion efficiency due to ultraviolet light, and more easily sensitizes a dye. Therefore, titanium oxide with high anatase type content is preferred. In particular, anatase type titanium oxide is preferably 80% by weight or more.

Next, the dye of the general formula (1) that can be used in the present invention will be described.
In the general formula (1), R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms may be linear or branched, and is a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, A tert-butyl group is mentioned. Among these, a hydrogen atom or a methyl group is preferable.

R ₂ has a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 to 12 carbon atoms which may have a substituent, and a substituent. It may be a styryl group. Examples of the alkyl group having 1 to 4 carbon atoms include the same alkyl groups as those described for R ₁ above. Examples of the alkoxy group having 1 to 4 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a naphthyl group. Examples of the substituent that can be bonded to the aryl group and styryl group include lower alkyl groups such as a methyl group and an ethyl group, and halogen atoms such as a fluorine atom, a chlorine atom, and a bromine atom.

Further, R ₁ and R ₂ may be bonded to each other to form a 5-membered ring or a 6-membered ring. Specifically, when R ₁ and R ₂ are alkyl groups, a 5-membered or 6-membered ring such as a benzene ring or cyclopentanediene may be formed together with the carbon atom to which they are bonded.

  L is a hydrogen atom or an electron-withdrawing group. Examples of the electron attractive group include those generally described in organic chemistry texts. Specific examples include a cyano group, a halogen atom such as chlorine, a trifluoromethyl group, a nitro group, a phenyl group, an alkoxycarboxyl group, a carboxyl group, an alkoxycarboxyl group, or an esterified carboxyl group. Among them, a substituent having a strong electron-withdrawing property such as a cyano group, a trifluoromethyl group, or an ester body containing a trifluoromethyl group (for example, α, α, α-trifluoroalkyloxycarbonyl group) is preferable. It is done.

  M is a hydrogen atom or a salt-forming cation. Specific examples include ammonium ions, sodium ions, potassium ions, and the like.

R ₃ , R ₄ , R ₅ and R ₆ are the same or different and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, and tert-butyl group. Examples of the alkoxy group having 1 to 4 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a naphthyl group.

  A represents a divalent heterocyclic group having 4 or 5 carbon atoms that may have a substituent, and Z represents a divalent aromatic ring group having 6 to 24 carbon atoms that may have a substituent. Show.

  Z is a condensed benzene ring such as benzene, naphthalene, anthracene or pyrene, or a heterocyclic ring containing a cyclic structure such as thiazoline, thiazole, benzothiazole, oxazole, benzoxazole, selenazole, benzoselenazole, quinoline, indolenine or benzimidazole. Examples thereof include a derived divalent group.

A includes a divalent group derived from a heterocyclic ring such as thiophene and furan.
Examples of the substituent that can be bonded to Z and A include an alkyl group having 1 to 6 carbon atoms. Specifically, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group and structural isomers thereof, n-hexyl Groups and structural isomers thereof. These substituents may be substituted in plural places where Z and A can be substituted.

m is an integer of 0 to 3, and n is an integer of 0 to 4.
Specific structures of typical examples of these dyes are described below.

In the compounds 1, 3-6, 7, 9-11, 13, 15-17, -COOH may be an alkali metal salt or an ammonium salt. In compounds 2, 8, and 12, -COONa or -COO ^- NH ₄ ⁺ may be -COOH.

  Further, the dye may be a hydrate.

  In addition, the said pigment | dye can be manufactured by a well-known method. As an example, there is a production method shown in the following reaction formula.

  The synthesis of intermediate (C) as an intermediate is E. Carter, Org. React. 3 (1932) 198, L.M. F. Tietze and U. Beifuss, Comp. Org. Syn. 2 (1991) 341.

  First, an active methylene derivative represented by the formula (A) and a γ-pyran derivative are dissolved in an organic solvent such as alcohol, an amine is added as a catalyst, and then heated for several hours at a temperature of about 100 ° C. (C) is obtained.

  The intermediate formula (D) can then be synthesized by the dianyl method. Compound (E) is obtained by adding acetic anhydride to Formula (D) and heating. The compound (C) and trialkylamine are added to the obtained compound (E), and reflux is performed while blowing an inert gas. After the reaction is complete, the reaction is cooled to room temperature and stirred overnight. A compound represented by the general formula (1) can be obtained by isolating the reaction product. This reaction formula is shown below.

  A semiconductor electrode is obtained by adsorbing the dye to a semiconductor. The adsorption method is generally a method in which a dye is dissolved in an organic solvent to obtain a solution, and well-dried semiconductor particles are immersed in the solution for several hours at room temperature. Examples of the method for improving the solubility of the dye include a method of slightly increasing the dissolution temperature, a method of mixing two or more different solvents, and the like.

  When the semiconductor particles are applied to the conductive support, the dye adsorption may be performed before or after the semiconductor particles are applied to the conductive support. In view of the adsorptivity of the dye, it is preferable to adsorb the dye after coating the semiconductor particles. As a method of adsorbing the dye on the film made of semiconductor particles coated on the conductive support, a method of immersing a well-dried film in the dye solution or applying the dye solution on the film and adsorbing is used. be able to.

  Since the unadsorbed dye causes disorder of the element function, it is preferable to remove it by washing immediately after the adsorption process. A cleaning solvent having a relatively low dye solubility is preferably used. It is also preferable to use a solvent that is relatively easy to dry, such as acetone.

  If the amount of dye adsorbed is small, the sensitizing effect becomes insufficient. On the other hand, when the amount is large, the dye not adsorbed on the semiconductor floats, which reduces the sensitization effect and, as a result, causes a decrease in photoelectric conversion efficiency.

  In order to prevent the association between the dyes and to provide a certain direction to the dye, a coadsorbing relatively low molecular weight compound may be added. Examples of the co-adsorbing compound include steroid compounds such as cholic acid having a carboxyl group and a carboxylic anhydride group.

  In addition, after removing the extra dye, the surface of the semiconductor may be treated with an organic basic compound to remove the remaining unadsorbed dye in order to make the adsorption state more stable. Examples of the organic basic compound include pyridine, quinoline, and derivatives thereof. When the organic basic compound is liquid, it may be used as it is, but when it is solid, it may be dissolved in a solvent. This solvent is preferably the same as the solvent used for dissolving the dye.

Although depending on the dye used, the adsorption amount of the dye is preferably in the range of 1 × 10 ⁻¹⁰ to 1 × 10 ⁻⁸ mol / mm ² . When it is less than 1 × 10 ⁻¹⁰ mol / mm ^2, it is not preferable because it is difficult to obtain sufficient photoelectric conversion efficiency, and when it is more than 1 × 10 ⁻⁸ mol / mm ² , unadsorbed dye remains. This is not preferable.

The semiconductor electrode is usually formed on a conductive support. As the conductive support, there can be used a support made of a material that itself has conductivity, such as a metal, or a support such as glass or plastic having a conductive layer formed on the surface. As a preferable conductive layer, a layer made of a metal such as platinum, silver, copper, aluminum, or indium, conductive carbon, indium tin composite oxide, fluorine-doped tin oxide, or the like can be given. The thickness of these conductive layers is preferably about 0.02 to 2 μm. The lower the surface resistance of the conductive support, the better. A preferable surface resistance is 40 Ω / cm ² or less.

  The conductive support is preferably substantially transparent. In consideration of this point and mechanical strength, it is preferable to laminate a conductive layer made of tin oxide doped with fluorine on a transparent substrate made of soda-lime float glass.

  In consideration of cost reduction and improvement in flexibility, the conductive layer may be provided on a support made of a transparent polymer sheet. Examples of the transparent polymer sheet include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PA), polyetherimide (PEI), and phenoxy resin. .

  Metal leads may be formed above or below the conductive layer to reduce the resistance of the conductive support. As the material of the metal lead wire, platinum, silver, copper, aluminum, indium, nickel and the like are preferable. For example, a metal lead wire may be installed on the support by sputtering or vapor deposition, and a conductive layer such as tin oxide or ITO may be provided thereon. It is preferable to form the metal lead wire so that the amount of incident light does not decrease.

  The photoelectric conversion element of this invention contains the said semiconductor electrode as a component. The photoelectric change element usually comprises a semiconductor electrode, an electrolyte layer, and a counter electrode facing the semiconductor electrode via the electrolyte layer.

  Examples of the counter electrode include platinum, rhodium, ruthenium, and carbon electrodes coated with a thin film on a conductive substrate, and oxide semiconductor electrodes. Preferably, the electrode is made of platinum or carbon.

  As the electrolyte layer, there is a layer made of a solidified electrolyte that is gelled by adding a gelling agent to a redox electrolytic solution composed of an electrolyte such as lithium iodide, tetraalkylammonium iodide, imidazolium iodide and a solvent. Can be mentioned. Here, the solvent is basically preferably a non-hydrophilic solvent (particularly a solvent having no hydroxyl group) that is stable to heat, pH and the like and dissolves the electrolyte. In general, acetonitrile having electron withdrawing property is preferable. The electrolyte concentration of this redox electrolytic solution is suitably about 0.1 to 2.0 mol / L.

  Further, instead of the redox electrolytic solution, a solid polymer such as a polyethylene oxide derivative or a polyvinylidene fluoride derivative may be melted by heat and solidified at room temperature to form an electrolyte layer having a desired shape. Furthermore, a P-type semiconductor resin such as a polythiophene derivative or a polypyrrole derivative may be used as the electrolyte layer. Furthermore, these constituent resins of the electrolyte layer may be mixed as appropriate.

  Furthermore, a spacer may be interposed in order to prevent contact between the semiconductor thin film electrode and the counter electrode. Examples of the spacer include a polymer film such as polyethylene. The thickness of the spacer is suitably about 10 to 100 μm.

  According to this invention, the solar cell which contains the photoelectric conversion element which consists of the said semiconductor electrode as a component is provided.

Synthesis example The synthesis example of the said compound-2 is shown.

  First, 0.462 g (3 mmol) of an active methylene derivative (A) and 0.414 g (3 mmol) of a 2-methyl-γ-pyran derivative (B) were dissolved in ethanol. Piperidine was added to the obtained solution as a catalyst, and the mixture was stirred at 100 ° C. for about 5 hours to obtain compound (C).

  This can be represented by the following reaction formula.

  Next, 1-ethyl-2-methylbenzothiazolium iodide obtained from 2-methyl-benzothiazole and methyl iodide is added with diphenylformamidine and heated to give 2-anilinovinyl-3ethyl-benzothiazo. Lithium iodide (D) was obtained. Compound (E) was obtained by adding 0.13 g (1.25 mmol) of acetic anhydride to 1.021 g (2.5 mmol) of 2-anilinovinyl-3-ethyl-benzothiazole iodide (D) and heating. To the obtained compound (E), 0.488 g (2.0 mmol) of compound (C) and triethylamine were added and refluxed while blowing argon gas. After completion of the reaction, the reaction mixture was cooled to room temperature and stirred overnight. The reaction mixture was filtered and the solvent in the filtrate was evaporated to give a solid. This solid was purified by column chromatography to obtain 0.597 g of compound-2 (yield 72%).

Compound 2 was identified by elemental analysis.
Elemental analysis: C22H19N2NaO3S
Calculated (%) C, 63.76; H, 4.62; N, 6.76
Found (%) C, 63.25; H, 4.82; N, 6.88
Compound-1 and compound-3 to compound-14 were synthesized in the same manner. The results of elemental analysis are shown below.

Compound-1
Elemental analysis: C20H16N2O4
Calculated (%) C, 68.96; H, 4.63; N, 8.04
Found (%) C, 69.42; H, 4.40; N, 7.89
Compound-3
Elemental analysis: C23H23NO6
Calculated (%) C, 67.47; H, 5.66; N, 3.42
Found (%) C, 68.22; H, 5.43; N, 3.19

Compound-4
Elemental analysis: C28H22N2O3Se
Calculated (%) C, 65.50; H, 4.32; N, 5.46
Found (%) C, 64.21; H, 4.63; N, 5.99
Compound-5
Elemental analysis: C26H28N2O4
Calculated (%) C, 72.20; H, 6.53; N, 6.48
Found (%) C, 72.54; H, 6.44; N, 6.33

Compound-6
Elemental analysis: C25H23N2NaO4
Calculated (%) C, 68.48; H, 5.29; N, 6.39
Found (%) C, 67.98; H, 5.49; N, 6.48
Compound-7
Elemental analysis: C25H24N2O3S
Calculated (%) C, 69.42; H, 5.59; N, 6.48
Found (%) C, 68.45; H, 5.73; N, 6.91

Compound-8
Elemental analysis: C24H29N3O7
Calculated (%) C, 61.14; H, 6.20; N, 8.91
Found (%) C, 60.65; H, 6.37; N, 9.56
Compound-9
Elemental analysis: C33H30F3NO3Se
Calculated (%) C, 63.46; H, 4.84; N, 2.24
Found (%) C, 63.34; H, 5.01; N, 2.20

Compound-10
Elemental analysis: C35H36F3NO5
Calculated (%) C, 69.18; H, 5.97; N, 2.31
Found (%) C, 69.34; H, 5.31; N, 2.43
Compound-11
Elemental analysis: C27H24N2O3S2
Calculated (%) C, 66.37; H, 4.95; N, 5.73
Found (%) C, 66.00; H, 5.34; N, 5.88

Compound-12
Elemental analysis: C25H24N2O8
Calculated (%) C, 62.49; H, 5.03; N, 5.83
Found (%) C, 62.22; H, 5.14; N, 5.97
Compound-13
Elemental analysis: C33H30F3NO3S
Calculated (%) C, 68.61; H, 5.23; N, 2.42
Found (%) C, 68.40; H, 5.66; N, 2.69

Compound-14
Elemental analysis: C33H30N2O3S3
Calculated (%) C, 66.19; H, 5.05; N, 4.68
Found (%) C, 66.88; H, 4.81; N, 4.44
Compound-15
Elemental analysis: C21H18N2O4
Calculated (%) C, 69.60; H, 5.01; N, 7.73
Found (%) C, 69.42; H, 4.40; N, 7.89

Compound-16
Elemental analysis: C24H25NO6
Calculated (%) C, 68.07; H, 5.95; N, 3.31
Found (%) C, 68.22; H, 5.43; N, 3.19
Compound-17
Elemental analysis: C37H40F3NO5
Calculated (%) C, 69.91; H, 6.34; N, 2.20
Found (%) C, 69.34; H, 5.31; N, 2.43

Examples 1-8 and Comparative Examples 1-2
(Production of organic solar cells)
Nanoporous titanium oxide thin film electrode (thickness: 14 μm) adsorbed as sensitizing dyes, 8 kinds of the above compounds and compounds 18 and 19 (Comparative Examples 1 and 2) shown below, iodine ion redox electrolytic solution (0. 3 mol tetraalkylammonium iodide + 0.03 mol iodine dissolved in propylene carbonate: acetonitrile volume ratio = 1: 1 mixed solvent), polyethylene spacer (thickness 30 μm), and dye-sensitized solar cell made of platinum counter electrode did.

Each of these steps will be described more specifically.
・ Production method of titanium oxide thin film electrode (Preparation of titanium oxide dispersion)
Titanium oxide SSP-M (manufactured by Sakai Chemical Co., Ltd .: Anatase type) was washed several times with pure water, and the inside was put into a stainless steel vessel lined with Teflon (registered trademark). About 1% by weight of a dispersant TORITONN X-100 (ALDRICH) was added. Next, glass beads having a diameter of 0.5 mm were added and dispersed for about 1 hour by a paint shaker (made by RED-DEVIL). Glass beads were removed by filtration from the resulting dispersion. In this way, a titanium oxide dispersion containing particles having an average particle size of 0.3 μm was prepared. Moreover, as a result of calculating | requiring the anataseization rate of the titanium oxide SSP-M from each peak intensity ratio of anatase and a rutile using the X ray diffraction apparatus, it was 100% of anatase conversion rate.

(Preparation of titanium oxide thin film electrode)
The dispersion was applied to the conductive film side of conductive glass (size: 25 mm × 100 mm) provided with a conductive film made of fluorine-doped tin oxide using an applicator having a clearance of 150 μm. After the coating, it was air-dried at room temperature for about 1 hour, and then baked at 450 ° C. for 30 minutes in an electric furnace (manufactured by Yamato Scientific Co., Ltd.) to obtain a TiO ₂ electrode. The electrode was taken out and cooled to room temperature, and then a nanoporous titanium oxide thin film electrode (thickness: 14 μm) was prepared by adsorbing 8 kinds of the above compounds as sensitizing dyes on a TiO ₂ electrode.

  Each dye was dissolved in ethanol / DMF (1/1 volume ratio), and further immersed in these dye solutions for 5 hours or more using a solution in which 0.4 mol of cholic acid was added at a dye mol ratio, and then the humidity was 30%. Dried naturally.

The produced solar cell was irradiated with light of AM1.5 (100 mW / cm ² ), which has almost the same light intensity as sunlight, and the amount of electricity generated at that time and the photoelectric conversion efficiency were measured and listed in Table 1. . Table 1 also shows the maximum absorption wavelength of these dyes in an alcohol solution. In addition, the photoelectric conversion rate calculated | required the electric quantity produced as a result of light irradiation with the electric current-voltage measuring apparatus, and calculated | required the photoelectric conversion ratio from the electric quantity.

  From Table 1 above, it can be seen that the solar cell provided with the semiconductor electrode containing the pigment of Example 1 has high photoelectric conversion efficiency.

Claims (6)

The following general formula (1)

(In the formula, A represents a divalent heterocyclic group having 4 or 5 carbon atoms which may have a substituent, and Z represents a divalent divalent having 6 to 24 carbon atoms which may have a substituent. R ₁ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₂ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a substituent. An aryl group having 6 to 12 carbon atoms which may have a styryl group which may have a substituent, and R ₁ and R ₂ are bonded to each other to form a 5-membered or 6-membered carbocyclic ring R ₃ , R ₄ , R ₅ and R ₆ may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. L is a hydrogen atom or an electron-withdrawing group, M is a hydrogen atom or a salt-forming cation, m is an integer of 0 to 3, and n is To 4 of an integer.)
A photoelectric conversion element comprising a semiconductor electrode sensitized by an organic dye represented by the formula:   The photoelectric conversion element according to claim 1, wherein L is a cyano group, a trifluoromethyl group, a carboxyl group, or an esterified carboxyl group.   The photoelectric conversion element according to claim 2, wherein the esterified carboxyl group is an α, α, α-trifluoroalkyloxycarbonyl group.   The photoelectric conversion element according to claim 1, wherein A is a divalent group derived from thiophene or furan.   The photoelectric conversion element according to claim 1, wherein the semiconductor includes fine particles made of at least a metal oxide.   The solar cell which contains the photoelectric conversion element as described in any one of Claims 1-5 as a component.