JP2009129652A - Photoelectric conversion element and photochemical battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion element having high photoelectric conversion efficiency, and a photochemical battery. <P>SOLUTION: The photoelectric conversion element contains an asymmetric dinuclear metal complex pigment represented by the general formula: (L<SP>1</SP>)<SB>2</SB>M<SP>1</SP>(BL)M<SP>2</SP>(L<SP>2</SP>)<SB>2</SB>(X)<SB>n</SB>(where M<SP>1</SP>and M<SP>2</SP>denote transition metals and are identical with or different from each other, L<SP>1</SP>and L<SP>2</SP>denote chelate ligands capable of multidentate coordination and are different from each other, two L<SP>1</SP>may be different from each other and two L<SP>2</SP>may be different from each other, X denotes a paired ion, n denotes the number of paired ions necessary for neutralizing a charge of a complex, and BL denotes a bridging ligand having at least two cyclic structures containing heteroatoms that are coordination atoms coordinated to M<SP>1</SP>and M<SP>2</SP>), a steroid-based compound having a steroid skeletal structure and a carboxyl group, and a semiconductor fine grains. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion element and a photochemical battery using the photoelectric conversion element.

  Solar cells are highly expected as a clean renewable energy source. Practical use of single-crystal silicon-based, polycrystalline silicon-based, amorphous silicon-based solar cells and solar cells composed of compounds such as cadmium telluride and indium copper selenide Research has been conducted with the aim of making it easier. However, in order to disseminate it as a household power source, many of the batteries that must be overcome, such as high manufacturing costs, difficulty in securing raw materials, recycling problems, and difficulty in increasing the area. I have a problem. Thus, solar cells using organic materials have been proposed with the aim of increasing the area and reducing the price, but all of them have a conversion efficiency of about 1% and are far from practical use.

  Under such circumstances, in 1991, Gretzel et al. Disclosed a photoelectric conversion element and a solar cell using semiconductor fine particles sensitized with a dye in Nature, and materials and manufacturing techniques necessary for the production of the solar cell. (For example, Nature, Volume 353, page 737, 1991 (Non-Patent Document 1), JP-A-1-220380 (Patent Document 1), etc.). This battery is a wet solar cell using a porous titania thin film sensitized with a ruthenium dye as a working electrode. The advantage of this solar cell is that it can be used as an inexpensive photoelectric conversion element because it is not necessary to purify an inexpensive material with high purity, and further, the absorption of the dye used is broad, and over a wide visible light wavelength range. It can convert sunlight into electricity. However, further improvement in conversion efficiency is necessary for practical use, and development of a dye having a higher extinction coefficient and absorbing light up to a higher wavelength region is desired.

  JP 2003-261536 (Patent Document 2) by the present applicant discloses a dipyridyl ligand-containing metal mononuclear complex which is a metal complex dye useful as a photoelectric conversion element.

  In addition, the latest technology of dye-sensitized solar cells (CMC Co., Ltd., issued on May 25, 2001, page 117) (Non-Patent Document 2) discloses polynuclear β-diketonate complex dyes.

  In addition, Japanese Patent Application Laid-Open No. 2004-359677 (Patent Document 3) describes a plurality of metals and a plurality of coordinations as a novel multinuclear complex having an excellent photoelectric conversion function for extracting electrons by receiving the energy of actinic rays such as light. A binuclear complex having a coordination structure in which a bridging ligand (BL) having a conjugated group and a metal coordinated to a plurality of metals has a heteroconjugated ring and a coordination structure not having a heteroconjugated ring is disclosed.

Furthermore, WO2006 / 038587 (Patent Document 4) discloses a binuclear metal complex having a coordination structure having a heteroconjugated ring as a metal complex dye that can provide a photoelectric conversion element having high photoelectric conversion efficiency.
Japanese Patent Laid-Open No. 1-220380 JP 2003-261536 A Japanese Patent Application Laid-Open No. 2004-359677 WO2006 / 038587 Nature, 353, 737, 1991 The latest technology of dye-sensitized solar cells (CMC Corporation, issued on May 25, 2001, page 117)

  An object of the present invention is to provide a photoelectric conversion element and a photochemical battery having high photoelectric conversion efficiency.

  The present invention relates to the following matters.

  1. Asymmetric binuclear metal complex dye represented by the following general formula (1) and a steroid compound having a steroid skeleton and a carboxyl group (provided that the proton of the carboxyl group (—COOH) is substituted with a monovalent cation) And a semiconductor fine particle.

（式中、Ｍ^１及びＭ^２は、遷移金属であって、同一でも異なっていてもよく、Ｌ^１及びＬ^２は、多座配位可能なキレート型配位子であって、Ｌ^１とＬ^２は異なるものであり、二つのＬ^１は異なるものであってもよく、二つのＬ^２も異なるものであってもよく、Ｘは対イオンであり、ｎは錯体の電荷を中和するのに必要な対イオンの数を表し、ＢＬはヘテロ原子を含む環状構造を少なくとも二つ有する架橋配位子であって、Ｍ^１及びＭ^２に配位する配位原子がこの環状構造に含まれるヘテロ原子であり、Ｌ^１が半導体微粒子に固定され得る置換基を有する。）
２． 前記二核金属錯体色素が、主に（Ｌ^１）_２Ｍ^１にＬＵＭＯが分布する構造であることを特徴とする上記１記載の光電変換素子。

(Wherein, M ¹ and M ^2, a transition metal, may be the same or different, L ¹ and L ² is a capable of multidentate coordination chelate ligand, and L ¹ L ² is different, two L ¹ may be different, two L ² may be different, X is a counter ion, and n neutralizes the charge of the complex. Represents the number of counter ions necessary for the above, BL is a bridging ligand having at least two cyclic structures containing heteroatoms, and the coordination atoms coordinated to M ¹ and M ² are included in this cyclic structure And L ¹ has a substituent that can be fixed to the semiconductor fine particles.)
2. _{2. The} photoelectric conversion element as described in 1 above, wherein the binuclear metal complex dye has a structure in which LUMO is distributed mainly in (L ¹ ) ₂ M ¹ .

  3. 3. The photoelectric conversion element as described in 1 or 2 above, wherein the steroidal compound is at least one selected from the group consisting of cholic acid, deoxycholic acid and chenodeoxycholic acid.

  4). 4. The photoelectric conversion element as described in any one of 1 to 3 above, wherein the semiconductor fine particles are titanium oxide, zinc oxide, or tin oxide.

  5). 5. The photoelectric conversion element as described in any one of 1 to 4 above, wherein the binuclear metal complex dye and the steroidal compound are adsorbed on semiconductor fine particles.

  6). 6. The photoelectric conversion element as described in 5 above, wherein a semiconductor layer containing semiconductor fine particles adsorbing the binuclear metal complex dye and the steroidal compound is formed on a conductive support.

  7. A photochemical battery comprising the photoelectric conversion element according to any one of 1 to 6 above.

  8). A photochemical battery comprising the photoelectric conversion element according to any one of the above 1 to 6 and a counter electrode as an electrode, and an electrolyte layer therebetween.

  9. The asymmetric binuclear metal complex dye represented by the general formula (1) and a steroid compound having a steroid skeleton and a carboxyl group (provided that the proton of the carboxyl group (—COOH) is substituted with a monovalent cation) And a step of immersing the semiconductor fine particles in a solution containing the photoelectric conversion element.

10. Forming a semiconductor layer containing semiconductor fine particles on a conductive support;
The semiconductor layer is composed of an asymmetric binuclear metal complex dye represented by the above general formula (1) and a steroid compound having a steroid skeleton and a carboxyl group (provided that the carboxyl group (—COOH) has a monovalent proton. And a step of immersing in a solution containing a cation.

  11. 11. The photoelectric according to the above 9 or 10, wherein the solution containing the binuclear metal complex dye and the steroid compound contains 0.1 to 15 mol of the steroid compound with respect to 1 mol of the dinuclear metal complex dye. A method for manufacturing a conversion element.

  The photoelectric conversion element of the present invention has a steroid compound having a steroid skeleton and a carboxyl group together with the binuclear metal complex dye represented by the general formula (1) (provided that the carboxyl group (—COOH) has 1 proton). Which may be substituted with a valent cation) is adsorbed on the semiconductor fine particles. A photochemical battery using this photoelectric conversion element has a high initial photoelectric conversion efficiency compared to a cell not containing a steroidal compound.

  The photoelectric conversion element of the present invention includes an asymmetric binuclear metal complex dye represented by the above general formula (1), a steroid compound having a steroid skeleton and a carboxyl group (provided that a proton of a carboxyl group (—COOH)) May be substituted with a monovalent cation) and semiconductor fine particles.

  First, the binuclear metal complex dye used in the present invention will be described.

In the asymmetric binuclear metal complex represented by the general formula: (L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ (X) _n , M ¹ and M ² are transition metals, Preferably, it is a transition metal of Group VIII to Group XI, specifically, ruthenium (Ru), osmium (Os), cobalt (Co), nickel (Ni), copper (Cu) or iron (Fe). preferable. Among these, ruthenium (Ru) and osmium (Os) are preferable, and ruthenium (Ru) is particularly preferable.

M ¹ and M ² may be the same metal or different metals.

L ¹ and L ² are chelate type ligands capable of multidentate coordination, preferably chelate type ligands capable of bidentate, tridentate or tetradentate coordination, more preferably chelate capable of bidentate coordination. Type ligand. Specific examples include derivatives such as 2,2′-bipyridine, 1,10-phenanthroline, 2- (2-pyridinyl) quinoline, or 2,2′-biquinoline. L ¹ and L ² are different. Further, the two L ¹ may be different, and the two L ² may be different.

L ¹ has at least one substituent that can be fixed to the semiconductor fine particles.

Examples of the substituent that can be fixed to the semiconductor fine particles of L ¹ include a carboxyl group (—COOH), an amino group (—NH ₂ ), a hydroxyl group (—OH), a sulfate group (—SO ₃ H), and a phosphate group (—PO ₃ H ₂ ), nitro group (—NO ₂ ) and the like. Among these, a carboxyl group (—COOH) is preferable. The hydrogen of the carboxyl group may be exchanged with a cation such as quaternary ammonium such as tetrabutylammonium or an alkali metal ion such as sodium ion. Further, hydrogen may be eliminated.

Further, L ¹ may or may not have a substituent other than the substituent that can be fixed to the semiconductor fine particles. Examples of such a substituent include an alkyl group (such as a methyl group and an ethyl group) and an alkoxy group (such as a methoxy group and an ethoxy group).

In the binuclear metal complex dye of the present invention, L ¹ is preferably a ligand such that LUMO is distributed mainly in the (L ¹ ) ₂ M ¹ portion. “Mainly, LUMO is distributed in the (L ¹ ) ₂ M ¹ portion” means that more LUMO is distributed in the (L ¹ ) ₂ M ¹ portion than in the (L ² ) ₂ M ² portion. . By using a photoelectric conversion element including semiconductor fine particles sensitized by this binuclear metal complex mainly because (L ¹ ) ₂ M ¹ has a LUMO structure in which electrons are excited by light irradiation such as sunlight. When a photochemical battery is manufactured, smooth electron transfer from the electrolyte to the photoelectric conversion element (negative electrode) can be caused, and an efficient photochemical battery can be configured.

For the calculation of LUMO, the software used was Cerius ² or Material Studio. In this method, the structure of the metal complex was optimized by DFT (density functional method) using a DMol ³ module. The exchange correlation function at that time is not particularly limited, but the VWN method or the BLYP method is preferably used. The basis function is not particularly limited, but DNP is preferably used.

  The energy state calculation uses the obtained structure, and although there is no particular limitation on the exchange correlation function, BLYP and PBE are used, and the basis function system is not particularly limited, but DNP is preferably used.

L ¹ includes a ligand represented by the following formula (L ¹ -A).

In the formula, H of —COOH may be eliminated, and R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ represent a hydrogen atom, an alkoxy group or a substituted or unsubstituted hydrocarbon group. Or two or more of these together form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aliphatic hydrocarbon ring with the carbon atom to which they are attached.

R ^{1 to} R ⁶ are preferably a hydrogen atom, an alkyl group, or an alkoxy group, and more preferably a hydrogen atom or an alkyl group. As an alkyl group, a C6 or less thing is preferable and a methyl group and an ethyl group are more preferable. Moreover, as an alkoxy group, a C6 or less thing is preferable and a methoxy group and an ethoxy group are more preferable.

In addition, R ² and R ³ , R ⁴ and R ⁵ , R ¹ and R ⁶ are combined together and a carbon atom to which they are bonded together with a 6-membered aromatic hydrocarbon ring (which may have a substituent) It is also preferable to form. Examples of the substituent of the aromatic hydrocarbon ring include an alkyl group (such as a methyl group and an ethyl group) and an alkoxy group (such as a methoxy group and an ethoxy group).

R ^{1 to} R ⁶ are particularly preferably a hydrogen atom.

Specific examples of L ¹ include ligands represented by the following formulas (L ¹ -1) to (L ¹ -4), but the present invention is not limited to these.

２，２’−ビピリジン−４，４’−ジカルボン酸（Ｈ_２ｄｃｂｐｙ）

2,2′-bipyridine-4,4′-dicarboxylic acid (H ₂ dcbpy)

１，１０−フェナントロリン−４，７−ジカルボン酸（Ｈ_２ｄｃｐｈｅｎ）

1,10-phenanthroline-4,7-dicarboxylic acid (H ₂ dcphen)

２−（２−（４−カルボキシピリジル））−４−カルボキシキノリン（Ｈ_２ｄｃｐｑ）

2- (2- (4-carboxy-pyridyl)) - 4-carboxy quinoline _(H 2 _dcpq)

２，２’−ビキノリン−４，４’−ジカルボン酸（Ｈ_２ｄｃｂｉｑ）

2,2′-biquinoline-4,4′-dicarboxylic acid (H ₂ dcbiq)

However, the heterocyclic ring and the benzene ring in the formulas (L ¹ -1) to (L ¹ -4) may have a substituent, and H of —COOH may be eliminated. Examples of the substituent include an alkyl group having 6 or less carbon atoms such as a methyl group and an ethyl group, and an alkoxy group having 6 or less carbon atoms such as a methoxy group and an ethoxy group.

As described above, L ² is a chelate ligand capable of multidentate coordination, preferably a chelate ligand capable of bidentate, tridentate or tetradentate coordination, more preferably bidentate coordination. It is a chelate type ligand. Specific examples include derivatives such as 2,2′-bipyridine, 1,10-phenanthroline, 2- (2-pyridinyl) quinoline, or 2,2′-biquinoline.

L ² may or may not have a substituent. Examples of the substituent for L ² include an alkyl group (such as a methyl group and an ethyl group), an aryl group (such as a phenyl group and a tolyl group), an alkoxy group (such as a methoxy group and an ethoxy group), and a hydroxyl group (—OH). It is done. In particular, a group showing an electron donating property is preferable.

L ² includes a ligand represented by the following formula (L ² -A).

In the formula, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ represent a hydrogen atom, an alkoxy group, a hydroxyl group or a substituted or unsubstituted hydrocarbon group, or these Two or more together form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aliphatic hydrocarbon ring with the carbon atom to which they are attached.

R ^{11 to} R ¹⁸ are preferably a hydrogen atom, an alkyl group, or an alkoxy group, and more preferably a hydrogen atom or an alkyl group. As an alkyl group, a C6 or less thing is preferable and a methyl group and an ethyl group are more preferable. Moreover, as an alkoxy group, a C6 or less thing is preferable and a methoxy group and an ethoxy group are more preferable.

Further, (which may have a substituent) two adjacent, or R ¹¹ and R ¹⁸ together aromatic 6-membered together with the carbon atoms to which they are bonded hydrocarbon ring R ¹¹ to R ¹⁸ It is also preferable to form. Examples of the substituent of the aromatic hydrocarbon ring include an alkyl group (such as a methyl group and an ethyl group) and an alkoxy group (such as a methoxy group and an ethoxy group).

R ^{11 to} R ¹⁸ are particularly preferably a hydrogen atom or a methyl group. R ¹¹ and R ¹⁸ are combined to form a 6-membered aromatic hydrocarbon ring (which may have a substituent such as a methyl group) together with the carbon atom to which they are bonded, and R ¹² It is particularly preferred that R ¹⁷ is a hydrogen atom or a methyl group, more preferably a hydrogen atom.

Specific examples of L ² include ligands represented by the following formulas (L ² -1) to (L ² -4), but the present invention is not limited to these.

２，２’−ビピリジン（ｂｐｙ）

2,2'-bipyridine (bpy)

１，１０−フェナントロリン（ｐｈｅｎ）

1,10-phenanthroline (phen)

２−（２−ピリジニル）キノリン（ｐｑ）

2- (2-Pyridinyl) quinoline (pq)

２，２’−ビキノリン（ｂｉｑ）

2,2'-biquinoline (biq)

However, the heterocyclic ring and the benzene ring in the formulas (L ² -1) to (L ² -4) may have a substituent. Examples of the substituent include an alkyl group having 6 or less carbon atoms, an alkoxy group having 6 or less carbon atoms, a phenyl group which may have a substituent such as a methyl group, and a hydroxyl group.

BL is a bridging ligand and has a cyclic structure containing a hetero atom. And the hetero atom contained in this cyclic structure (heteroconjugate ring) is a coordination atom coordinated to M ¹ and M ² . Heteroatoms include nitrogen, oxygen, sulfur, phosphorus and the like.

  BL is preferably a tetradentate ligand, more preferably anionic. Further, BL may or may not have a substituent on the cyclic structure (heteroconjugate ring).

  Examples of BL include those represented by the following formula (BL-A).

In the formula, R ³¹ , R ³² and R ³³ represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group, or two or more of these together are substituted or unsubstituted with the carbon atom to which they are bonded. An aromatic hydrocarbon ring or a substituted or unsubstituted aliphatic hydrocarbon ring, and R ³⁴ , R ³⁵ and R ³⁶ represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group, or Two or more together form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aliphatic hydrocarbon ring with the carbon atom to which they are attached.

R ^{31 to} R ³⁶ are preferably a hydrogen atom, an alkyl group, or an alkoxy group, and more preferably a hydrogen atom or an alkyl group. As an alkyl group, a C6 or less thing is preferable and a methyl group and an ethyl group are more preferable. Moreover, as an alkoxy group, a C6 or less thing is preferable and a methoxy group and an ethoxy group are more preferable.

It is also preferable that two adjacent R ^{31 to} R ³⁶ are joined together to form a 6-membered aromatic hydrocarbon ring (which may have a substituent) together with the carbon atom to which they are bonded. . Examples of the substituent of the aromatic hydrocarbon ring include an alkyl group (such as a methyl group and an ethyl group) and an alkoxy group (such as a methoxy group and an ethoxy group).

R ^{31 to} R ³⁶ are particularly preferably a hydrogen atom or a methyl group, and R ^{31 to} R ³⁶ are more preferably a hydrogen atom.

  Moreover, as BL, what is represented by the following Formula (BL-B) is also mentioned.

In the formula, R ⁴¹ and R ⁴² represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group, or a substituted or unsubstituted aromatic hydrocarbon ring together with a carbon atom to which they are bonded together, or Forming a substituted or unsubstituted aliphatic hydrocarbon ring, wherein R ⁴³ and R ⁴⁴ represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group, or the carbon to which they are bonded together; A substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aliphatic hydrocarbon ring is formed together with the atoms.

R ^{41 to} R ⁴⁴ are preferably a hydrogen atom, an alkyl group, or an alkoxy group, and more preferably a hydrogen atom or an alkyl group. As an alkyl group, a C6 or less thing is preferable and a methyl group and an ethyl group are more preferable. Moreover, as an alkoxy group, a C6 or less thing is preferable and a methoxy group and an ethoxy group are more preferable.

R ⁴¹ and R ⁴² , R ⁴³ and R ⁴⁴ together form a 6-membered aromatic hydrocarbon ring (which may have a substituent) together with the carbon atom to which they are bonded. Is also preferable. Examples of the substituent of the aromatic hydrocarbon ring include an alkyl group (such as a methyl group and an ethyl group) and an alkoxy group (such as a methoxy group and an ethoxy group).

R ^{41 to} R ⁴⁴ are particularly preferably a hydrogen atom or a methyl group, and R ^{41 to} R ⁴⁴ are more preferably a hydrogen atom. R ⁴¹ and R ⁴² , R ⁴³ and R ⁴⁴ together form a 6-membered aromatic hydrocarbon ring (which may have a substituent such as a methyl group) together with the carbon atom to which they are bonded. It is also particularly preferable.

  Among those represented by the above formula (BL-B), those represented by the following formula (BL-C) are preferable.

In the formula, R ⁵¹ , R ⁵² , R ⁵³ and R ⁵⁴ represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group, or two or more of these together are substituted with a carbon atom to which they are bonded. Or an unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aliphatic hydrocarbon ring, and R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ are each a hydrogen atom or a substituted or unsubstituted hydrocarbon group. Or two or more of these together form a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aliphatic hydrocarbon ring with the carbon atom to which they are attached.

R ^{51 to} R ⁵⁸ are preferably a hydrogen atom, an alkyl group, or an alkoxy group, and more preferably a hydrogen atom or an alkyl group. As an alkyl group, a C6 or less thing is preferable and a methyl group and an ethyl group are more preferable. Moreover, as an alkoxy group, a C6 or less thing is preferable and a methoxy group and an ethoxy group are more preferable.

It is also preferable that two adjacent R ^{51 to} R ⁵⁸ are joined together to form a 6-membered aromatic hydrocarbon ring (which may have a substituent) together with the carbon atom to which they are bonded. . Examples of the substituent of the aromatic hydrocarbon ring include an alkyl group (such as a methyl group and an ethyl group) and an alkoxy group (such as a methoxy group and an ethoxy group).

R ^{51 to} R ⁵⁸ are particularly preferably a hydrogen atom or a methyl group, and R ^{51 to} R ⁵⁸ are more preferably a hydrogen atom.

  Specific examples of BL include those represented by the following formulas (BL-1) to (BL-4), but the present invention is not limited to these.

２，２’−ビピリミジン（ｂｐｍ）

2,2'-bipyrimidine (bpm)

テトラチアフルバレン（ＴＴＦ）

Tetrathiafulvalene (TTF)

２，２’−ビイミダゾラト（ＢｉＩｍ）

2,2'-biimidazolate (BiIm)

２，２’−ビベンズイミダゾラト（ＢｉＢｚＩｍ）

2,2'-bibenzimidazolate (BiBzIm)

  However, the heterocyclic ring and the benzene ring in formulas (BL-1) to (BL-4) may have a substituent. Examples of the substituent include an alkyl group having 6 or less carbon atoms and an alkoxy group having 6 or less carbon atoms, and two adjacent carbon atoms on the benzene ring in the formula (BL-4) are joined together. A new benzene ring (which may have a substituent) may be formed.

  In the case of a metal complex dye used for a photoelectric conversion element, BL is preferably a ligand represented by the above formula (BL-3) or (BL-4).

Further, (L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ (X) _n may contain water or an organic solvent as a crystal solvent. Examples of the organic solvent include DMSO, acetonitrile, DMF, DMAC, methanol and the like. The number of crystal solvents is not particularly specified.

X is a counter ion, and if the complex [(L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ ] is a cation, the counter ion is an anion, and the complex [(L ¹ ) ₂ M ¹ (BL) M ^{If 2} (L ² ) ₂ ] is an anion, the counter ion is a cation. Here, n represents the number of counter ions necessary to neutralize the charge of the complex.

  As specific examples of X, when the counter ion is an anion, hexafluorophosphate ion, perchlorate ion, tetraphenylborate ion, tetrafluoroborate ion, trifluoromethanesulfonate ion, thiocyanate ion, sulfate ion, nitric acid Ions, and halide ions such as chloride ions and iodide ions.

  Specific examples of X include, when the counter ion is a cation, ammonium metal, tetrabutylammonium ion, alkali metal ions such as sodium ion, and proton.

As the metal complex dye, in particular, L ¹ is a ligand represented by the above formula (L ¹ -1) ( ^one from which H of —COOH is eliminated, a heterocyclic ring and a benzene ring further having a substituent. And L ² is a ligand represented by the above formula (L ² -1) or (L ² -2) (a heterocycle and a benzene ring having a substituent) BL is a ligand represented by the above formula (BL-3) or (BL-4) (including those having a heterocyclic ring and a benzene ring having a substituent), and M ¹ And M ² is preferably ruthenium (Ru), osmium (Os), cobalt (Co), nickel (Ni), copper (Cu) or iron (Fe).

Specific examples of the asymmetric binuclear metal complex represented by (L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ (X) _n of the present invention include the following formulas (D-1) to (D- Although what is represented by 16) is mentioned, this invention is not limited to these. Moreover, H of —COOH in formulas (D-1) to (D-16) may be eliminated.

［（Ｈ_２ｄｃｂｐｙ）_２Ｒｕ（ＢｉＩｍ）Ｒｕ（ｂｐｙ）_２］（ＣｌＯ_４）_２

[(H ₂ dcbpy) ₂ Ru (BiIm) Ru (bpy) ₂ ] (ClO ₄ ) ₂

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＩｍ）Ｒｕ（ｂｐｙ）_２］（ＰＦ_６）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiIm) Ru (bpy) ₂ ] (PF ₆ )

［（Ｈ_２ｄｃｂｉｑ）（Ｈｄｃｂｉｑ）Ｒｕ（ＢｉＩｍ）Ｒｕ（ｂｐｙ）_２］（ＰＦ_６）

[(H ₂ dcbiq) (Hdcbiq) Ru (BiIm) Ru (bpy) ₂ ] (PF ₆ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（ＰＦ_６）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (PF ₆ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（ＢＦ_４）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (BF ₄ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（ＢＰｈ_４）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (BPh ₄ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（ＯＳＯ_２ＣＦ_３）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (OSO ₂ CF ₃ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（ＣｌＯ_４）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (ClO ₄ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（ＮＯ_３）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (NO ₃ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（Ｉ）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (I)

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｐｈｅｎ）_２］（ＰＦ_６）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (phen) ₂ ] (PF ₆ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｂｉｑ）_２］（ＰＦ_６）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (biq) ₂ ] (PF ₆ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｒｕ（ｄｍｂｐｙ）_２］（ＰＦ_６）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (dmbpy) ₂ ] (PF ₆ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＴＭＢｉＢｚＩｍ）Ｒｕ（ｂｐｙ）_２］（ＰＦ_６）

[(H ₂ dcbpy) (Hdcbpy) Ru (TMBiBzIm) Ru (bpy) ₂ ] (PF ₆ )

［（Ｈ_２ｄｃｂｐｙ）（Ｈｄｃｂｐｙ）Ｒｕ（ＢｉＢｚＩｍ）Ｏｓ（ｂｐｙ）_２］（ＰＦ_６）

[(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Os (bpy) ₂ ] (PF ₆ )

［（Ｈｄｃｂｐｙ）_２Ｒｕ（ｂｐｍ）Ｒｕ（ｂｐｙ）_２］（ＰＦ₆）_２

[(Hdcbpy) ₂ Ru (bpm) Ru (bpy) ₂ ] (PF ₆ ) ₂

  The metal complex dye used in the present invention may be a known method such as WO2006 / 038587, Inorganic Chemistry, Vol. 17, No. 9, pp. 2660-2666, 1978, Journal of the American Chemical Society, Vol. 115, Vol. 6382-6390 pages, 1993 etc. can be manufactured with reference to the method quoted in literature.

The metal complex (L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ (X) _n of the present invention is, for example, two mononuclear metal complexes (L ¹ ) ₂ M ¹ Cl ₂ as follows. And (BL) M ² (L ² ) ₂ can be synthesized and reacted.

A mononuclear metal complex (L ¹ ) ₂ M ¹ Cl ₂ (M ¹ C-1) in which L ¹ is the above formula (L ¹ -1) and M ¹ is Ru can be synthesized according to the following synthesis scheme. it can.

In the above formula, those in which L ¹ has a substituent other than a carboxyl group and those in which M ¹ is a transition metal other than Ru can be synthesized in the same manner.

A mononuclear metal complex (L ¹ ) ₂ M ¹ Cl ₂ (M ¹ C-2) in which L ¹ is the above formula (L ¹ -4) and M ¹ is Ru is synthesized according to the following synthesis scheme. be able to.

In the above formula, those in which L ¹ has a substituent other than a carboxyl group and those in which M ¹ is a transition metal other than Ru can be synthesized in the same manner.

On the other hand, the mononuclear metal complex (BL) M ² (L ² ) ₂ can be synthesized according to the following synthesis scheme.

H ₂ BL in the scheme indicates a state in which two heteroatoms (such as a nitrogen atom) in BL are protonated.

Incidentally, BL (also including those having a substituent) represented by those in the above formula (BL-1) ~ (BL -4), L 2 is the above formula ^{(L 2 -1) ~ (L} 2 -4) (including those having a substituent) can be synthesized according to this synthesis scheme. However, for those in which BL is represented by the above formula (BL-1) (including those having a substituent), a reaction step with a base in the subsequent stage is unnecessary, and M ² (L ² ) ₂ Cl ₂ And BL are reacted to give (BL) M ² (L ² ) ₂ .

  The base used in this reaction is preferably a base containing no sodium, for example, a base containing potassium, magnesium, calcium or iron, or an organic base, and particularly a base containing lithium. Among these, lithium alkoxide is preferable, lithium methoxide, lithium ethoxide, and lithium-t-butoxide are more preferable, and lithium methoxide is particularly preferable. The amount of base used can be determined as appropriate.

The (L ¹ ) ₂ M ¹ Cl ₂ (M ¹ C) synthesized in this way and (BL) M ² (L ² ) ₂ (M ² C) are reacted according to the following synthetic scheme, and (L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ (X) _n can be synthesized.

  The base used in this reaction is preferably a base containing no sodium, for example, a base containing potassium, magnesium, calcium or iron, or an organic base, and particularly a base containing lithium. Among these, lithium hydroxide and lithium alkoxide are preferable, lithium hydroxide, lithium methoxide, lithium ethoxide, and lithium-t-butoxide are more preferable, and lithium hydroxide is particularly preferable. The amount of base used can be determined as appropriate.

(L ¹ ) ₂ M ¹ Cl ₂ (M ¹ C) is reacted with (BL) M ² (L ² ) ₂ (M ² C) in the presence of a base, and then acid (HX) is added (L _{^{1) 2 M 1 (BL)}} M 2 (L 2) 2 (X) to the binuclear metal complex represented by _n isolated. At this time, the solution is cooled as necessary. Further, a salt containing lithium such as lithium nitrate (LiX) may be added before or simultaneously with the addition of the acid.

  Moreover, in this invention, it is preferable to adjust pH when isolating a binuclear metal complex exceeding 2.5, Preferably it is 2.7 or more from the point of initial stage photoelectric conversion efficiency. The pH is preferably 2.8 or more, and from the viewpoint of the durability of the obtained photochemical battery, the pH is preferably 3.3 or more, more preferably 3.5 or more, particularly preferably 3.7 or more, 3.8 or more. Is more preferable. Further, in order to sufficiently support the binuclear metal complex dye of the present invention on the semiconductor fine particles, the pH is preferably 5 or less, more preferably 4.5 or less, and particularly preferably 4.2 or less.

In the present invention, a binuclear metal complex represented by (L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ (X) _n is obtained by isolation at an appropriate pH, and then this is dissolved in water. The solution is suspended in solution, adjusted to pH about 10 by adding a base and redissolved, acid is added to this solution to bring the pH to the above range, and (L ¹ ) ₂ M ¹ (BL) M ² (L ² ) ₂ (X) The binuclear metal complex represented by _n can also be isolated.

  In the present invention, the above-described metal complex is used as a metal complex dye, and a photochemical battery is produced using semiconductor fine particles sensitized with the metal complex dye.

  In the present invention, a steroidal compound is used together with the binuclear metal complex dye represented by the general formula (1). Steroidal compounds may be used alone or in combination of two or more.

  The steroidal compound used in the present invention has a steroid skeleton represented by the following formula (A) and a carboxyl group.

  However, the steroid skeleton represented by the formula (A) may have a substituent such as a substituted or unsubstituted hydrocarbon group (side chain) having about 1 to 10 carbon atoms or a hydroxyl group (—OH). Good. In addition, the steroid skeleton may contain an unsaturated bond.

  The position substituted with the carboxyl group may be any position in the steroid skeleton, and the side chain may have a carboxyl group. The proton of the carboxyl group (—COOH) may be exchanged with a monovalent cation such as sodium ion.

  As the steroidal compound used in the present invention, those having a structure represented by the following formula (A-1) are preferable.

  Among these, cholic acid represented by the following formula (A-2), deoxycholic acid represented by the following formula (A-3), chenodeoxycholic acid represented by the following formula (A-4) are preferable, and chenodeoxycholic acid is particularly preferable.

  The photoelectric conversion element of the present invention comprises the above binuclear metal complex dye, a steroidal compound, and semiconductor fine particles. The binuclear metal complex dye and the steroidal compound are adsorbed on the surface of the semiconductor fine particles, and the semiconductor fine particles are sensitized with the metal complex dye.

  More specifically, the photoelectric conversion element of the present invention is obtained by fixing semiconductor fine particles sensitized with the metal complex dye on a conductive support (electrode).

  The conductive electrode is preferably a transparent electrode formed on a transparent substrate. Examples of the conductive agent include metals such as gold, silver, copper, platinum, and palladium, indium oxide compounds typified by tin-doped indium oxide (ITO), and oxidation typified by fluorine-doped tin oxide (FTO). Examples thereof include tin compounds and zinc oxide compounds.

  Examples of the semiconductor fine particles include titanium oxide, zinc oxide, and tin oxide. In addition, indium oxide, niobium oxide, tungsten oxide, vanadium oxide, composite oxide semiconductors such as strontium titanate, calcium titanate, barium titanate, potassium niobate, cadmium or bismuth sulfide, cadmium selenide or tellurium And gallium phosphide or arsenide. As the semiconductor fine particles, oxides are preferable, and titanium oxide, zinc oxide, or tin oxide, and a mixture containing any one or more of these are particularly preferable.

  The primary particle diameter of the semiconductor fine particles is not particularly limited, but is usually 1 to 5000 nm, preferably 2 to 500 nm, and particularly preferably 5 to 300 nm.

  As a method for adsorbing a binuclear metal complex dye and a steroidal compound to semiconductor fine particles, after forming a semiconductor layer (semiconductor fine particle film) containing semiconductor fine particles on a conductive support, The method of immersing in the solution containing a steroid type compound is mentioned. The semiconductor layer can be formed by applying a paste of semiconductor fine particles on a conductive support and heating and baking. And after immersing in a pigment | dye solution, the electroconductive support body in which this semiconductor layer was formed is wash | cleaned and dried.

  Examples of the solvent for the dye solution include alcohols such as methanol, ethanol, isopropyl alcohol, t-butyl alcohol, and ethylene glycol; nitriles such as acetonitrile and propionitrile; N, N-dimethylacetamide, N, N-dimethylformamide, and the like Amides; ureas such as N-methylpyrrolidone; sulfoxides such as dimethyl sulfoxide, and the like, preferably isopropyl alcohol, t-butanol, and acetonitrile. These organic solvents may be used alone or in combination of two or more.

  The concentration of the dye in the solution can be determined as appropriate, but since the dye can be adsorbed in a short time, a higher concentration is preferable, and a saturated solution is preferable.

  The concentration of the steroidal compound in the solution is preferably from 0.1 to 15 mol, and more preferably from 2 to 12 mol, per 1 mol of the binuclear metal complex dye. When the content of the steroid compound is within the above range, higher photoelectric conversion efficiency can be obtained. In addition, the amount of dye adsorbed can be reduced while maintaining high photoelectric conversion efficiency.

  The temperature at which the dye is adsorbed is usually 0 to 80 ° C, preferably 20 to 40 ° C. The time for adsorbing the dye (dipping time in the dye solution) can be determined as appropriate, and is, for example, about 4 to 10 hours, preferably about 5 to 8 hours. If the adsorption time is longer than this, the amount of dye adsorbed will not change much, while the photoelectric conversion efficiency may decrease.

  Instead of immersing in a solution containing a binuclear metal complex dye and a steroid compound, immerse in a dinuclear metal complex dye solution and then immerse in a steroid compound solution, or immerse in a steroid compound solution. Then, it can be immersed in a solution of a binuclear metal complex dye.

  The photochemical battery of the present invention uses the photoelectric conversion element of the present invention as described above. More specifically, the photoelectric conversion element of the present invention and a counter electrode are provided as electrodes, and an electrolyte layer is provided therebetween. At least one of the electrode using the photoelectric conversion element of the present invention and the counter electrode is a transparent electrode.

  The counter electrode functions as a positive electrode when combined with a photoelectric conversion element to form a photochemical battery. As the counter electrode, a substrate having a conductive layer can be used as in the case of the conductive electrode. However, if the metal plate itself is used, the substrate is not necessarily required. Examples of the conductive agent used for the counter electrode include metals such as platinum and carbon, and conductive metal oxides such as tin oxide doped with fluorine.

  The electrolyte (redox couple) is not particularly limited, and any known one can be used. For example, iodine and iodide (for example, metal iodides such as lithium iodide and potassium iodide, or quaternary ammonium compounds such as tetrabutylammonium iodide, tetrapropylammonium iodide, pyridinium iodide, imidazolium iodide) Iodide), bromine and bromide, chlorine and chloride, alkyl viologen and its reduced form, quinone / hydroquinone, iron (II) ion / iron (III) ion, copper (I) ion / Transition metal ion pairs such as copper (II) ion, manganese (II) ion / manganese (III) ion, cobalt ion (II) / cobalt ion (III), ferrocyan / ferricyan, cobalt tetrachloride (II) / four Cobalt (III) chloride, cobalt (II) tetrabromide / four odors Cobalt (III), iridium hexachloride (II) / iridium hexachloride (III), ruthenium hexacyanide (II) / ruthenium hexacyanide (III), rhodium hexachloride (II) / rhodium hexachloride (III), six Rhenium chloride (III) / rhenium chloride (IV), rhenium hexachloride (IV) / rhenium hexachloride (V), osmium hexachloride (III) / osmium hexachloride (IV), osmium hexachloride (IV) / hexachloride It is formed by a combination of complex ions such as osmium (V), transition metals such as cobalt, iron, ruthenium, manganese, nickel, rhenium and biconjugated rings and derivatives thereof, terpyridine and derivatives thereof, heteroconjugated rings such as phenanthroline and derivatives thereof, and derivatives thereof. Complexes, ferrocene / ferrocenium ions, cobalt On / cobalt-ion-, ruthenocene / lutein placed um cyclopentadiene and its derivatives and metal complexes such as an ion, porphyrin compounds and the like can be used. A preferable electrolyte is an electrolyte in which iodine and lithium iodide or iodide of a quaternary ammonium compound are combined. The state of the electrolyte may be a liquid dissolved in an organic solvent, a molten salt, a so-called gel electrolyte immersed in a polymer matrix, or a solid electrolyte.

  The photochemical cell of the present invention can be produced by a conventionally applied method.

  For example, as described above, a semiconductor fine particle paste such as an oxide is applied on a transparent electrode and heated and fired to produce a thin film of semiconductor fine particles. When the thin film of semiconductor fine particles is titania, it is fired at a temperature of 450 ° C. and a reaction time of 30 minutes. The transparent electrode with the thin film is immersed in a dye solution (a solution containing the binuclear metal complex dye of the present invention and a steroid compound), and the dye is supported to produce a photoelectric conversion element. Furthermore, the photochemical cell of the present invention can be manufactured by combining this photoelectric conversion element and a transparent electrode on which platinum or carbon is deposited as a counter electrode, and putting an electrolyte solution therebetween.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Reference Example 1)
Synthesis of Binuclear Metal Complex Dye [(H ₂ dcbpy) (Hdcbpy) Ru (BiBzIm) Ru (bpy) ₂ ] (PF ₆ ) (D-4) Synthesis of mononuclear metal complex (H ₂ dcbpy) ₂ RuCl ₂ (M ¹ C-1) In a 500 ml three-necked flask under a nitrogen atmosphere, commercially available RuCl ₃ .3H ₂ O (2.53 g, 9.68 mmol), H ₂ dcbpy (4.50 g, 18.4 mmol) and 300 ml of N, N-dimethylformamide were added and refluxed for 45 minutes under microwave irradiation of 2.45 GHz. The mixture was allowed to cool and then filtered, and the obtained filtrate was dried under reduced pressure. The obtained residue was washed with acetone / diethyl ether (1: 4), 300 ml of 2 mol / l hydrochloric acid was added, ultrasonic stirring was continued for 20 minutes, and further, stirring was stopped for 2 hours. After completion of the stirring, the insoluble material was collected by filtration and washed with 2 mol / l hydrochloric acid, acetone / diethyl ether (1: 4) and diethyl ether. After vacuum drying, 5.75 g of M ¹ C-1 was obtained.

2. Synthesis of mononuclear metal complex (BiBzIm) Ru (bpy) ₂ (M ² C-2) In a nitrogen atmosphere, Ru (bpy) ₂ Cl ₂ (4.02 g, 7.7 mmol), Inorg. Chem. , 34, 5979 (1995), and 100 ml of 2,2′-bibenzimidazole (BiBzImH ₂ ) (2.18 g, 9.3 mmol) and ethylene glycol were added under microwave irradiation at 2.45 GHz. Refluxed for 5 minutes. After allowing to cool, 35 ml of a 10% lithium methoxide methanol solution was added and irradiated with a microwave of 2.45 GHz at 60 ° C. for 10 minutes. After allowing to cool, 200 ml of water was added and stirred, and the precipitate was filtered. The precipitate was washed with water, cold methanol, and diethyl ether, and dried under vacuum to obtain 5.7708 g of M ² C-2. Further, 5.77 g of this precipitate was added to 200 ml of methanol under nitrogen, and further 10 ml of a 10% lithium methoxide methanol solution was added thereto and refluxed for 1 hour. After allowing to cool, the precipitate was filtered, washed with cold methanol, water and diethyl ether, and vacuum dried to obtain 5.02 g of M ² C-2.

3. Synthesis of D-4 Under a nitrogen atmosphere, 300 ml of M ¹ C-1 (1.50 g, 2.16 mmol) and ethanol / water (1: 1) was added to a 500 ml three-necked flask, and a 1 mol / l sodium hydroxide aqueous solution was added. 8.7 ml was dropped and dissolved. M ² C-2 (1.55 g, 2.27 mmol) was added to this solution and refluxed for 30 minutes under microwave irradiation at 2.45 GHz. After allowing to cool, a small amount of insoluble matter was filtered off, and ethanol in the filtrate was distilled off under reduced pressure. The obtained suspension was filtered, and a 0.5 mol / l hexafluorophosphoric acid aqueous solution was added dropwise to the filtrate until the pH reached 2.8. After cooling at 4 ° C. overnight, the precipitated complex was collected by filtration and washed with a pH 2.8 aqueous hexafluorophosphoric acid solution, acetone / diethyl ether (4: 1), and diethyl ether. After vacuum drying, 2.61 g of a binuclear metal complex dye (D-4) was obtained.

Example 1
1. Production of Porous Titania Electrode A titania paste PST-18NR made by Catalytic Chemical was used as a transparent layer, PST-400C was used as a diffusion layer, and coated on a transparent conductive glass electrode manufactured by Asahi Glass Co., Ltd. using a screen printer. The obtained film was aged at 25 ° C. in an atmosphere of 60% for 5 minutes, and the aged film was baked at 450 ° C. for 30 minutes. The same operation was repeated on the cooled membrane until a predetermined thickness was obtained, thereby producing a 16 mm ² porous titania electrode.

2. Preparation of Porous Titania Electrode Adsorbed with Dye Saturated dye solution of binuclear metal complex dye (D-4) to which a predetermined amount of chenodeoxycholic acid (CDCA) was added (solvent: 1: 1 mixed solvent of t-butanol / acetonitrile) The porous titania electrode was dipped in 30 ° C. for a predetermined time and dried to obtain a dye-adsorbing porous titania electrode.

3. Production of Photochemical Battery The dye-adsorbed porous titania electrode obtained as described above and a platinum plate (counter electrode) were superposed. Next, an electrolyte solution (3-methoxypropionitrile and lithium iodide, iodine, 4-t-butylpyridine, and 1,2-dimethyl-3-propylimidazolium iodide, 0.1, 0.05, A photochemical battery was prepared by soaking a gap between the two electrodes using a capillary phenomenon. FIG. 3 shows the structure of the photochemical battery produced in this example.

4). Measurement of Conversion Efficiency The photoelectric conversion efficiency of the obtained photochemical battery was measured by irradiating 100 mW / cm ² of pseudo-sunlight using a solar simulator manufactured by Eihiro Seiki Co., Ltd.

5). Measurement of dye adsorption amount The dye adsorption amount of the dye-adsorbing porous titania electrode was measured as follows.

The dye was desorbed by immersing the dye-adsorbed porous titania electrode in an ethanol / water (1: 1) solution of 0.01 mol / l sodium hydroxide overnight. And the absorption spectrum of this desorption liquid was measured using JASCO Corporation V-570, and the pigment | dye adsorption amount per 1 cm < ² > was computed from the measurement result.

  FIG. 1 shows the measurement results of the conversion efficiency and the dye adsorption amount, although the adsorption time (time of immersion in the dye solution) is 20 hours and the addition amount of chenodeoxycholic acid is different. FIG. 2 shows the measurement results of the conversion efficiency and the dye adsorption amount when the addition amount of chenodeoxycholic acid is 2 moles per mole of the dye (chenodeoxycholic acid / dye molar ratio is 2) and the adsorption time is different.

  From the results in FIG. 1, it is clear that the addition of chenodeoxycholic acid increases the photoelectric conversion efficiency and improves the performance of the photochemical cell. In addition, as can be seen from the results in FIG. 2, the highest photoelectric conversion efficiency was exhibited at an adsorption time of 7 hours.

  As described above, according to the present invention, a photoelectric conversion element and a photochemical battery having high photoelectric conversion efficiency can be obtained. In addition, while maintaining high photoelectric conversion efficiency, the amount of the dye used can be reduced, and the time for adsorbing the dye can also be shortened.

FIG. 1 is a graph showing changes in photoelectric conversion efficiency and dye adsorption amount with respect to the addition amount of chenodeoxycholic acid (the molar ratio of chenodeoxycholic acid and dye). FIG. 2 is a graph showing changes in photoelectric conversion efficiency and dye adsorption amount with respect to dye adsorption time. FIG. 3 is a cross-sectional view showing the configuration of the photochemical battery produced in the present invention.

Explanation of symbols

(1) Glass (2) Transparent conductive layer (3) Platinum layer (4) Electrolytic solution (5) Dye-adsorbing porous oxide semiconductor film

Claims (11)

Asymmetric binuclear metal complex dye represented by the following general formula (1) and a steroid compound having a steroid skeleton and a carboxyl group (provided that the proton of the carboxyl group (—COOH) is substituted with a monovalent cation) And a semiconductor fine particle.

(Wherein, M ¹ and M ^2, a transition metal, may be the same or different, L ¹ and L ² is a capable of multidentate coordination chelate ligand, and L ¹ L ² is different, two L ¹ may be different, two L ² may be different, X is a counter ion, and n neutralizes the charge of the complex. Represents the number of counter ions necessary for the above, BL is a bridging ligand having at least two cyclic structures containing heteroatoms, and the coordination atoms coordinated to M ¹ and M ² are included in this cyclic structure And L ¹ has a substituent that can be fixed to the semiconductor fine particles.) The photoelectric conversion element according to claim 1, wherein the binuclear metal complex dye has a structure in which LUMO is distributed mainly in (L ¹ ) ₂ M ¹ .   The photoelectric conversion element according to claim 1 or 2, wherein the steroidal compound is at least one selected from the group consisting of cholic acid, deoxycholic acid, and chenodeoxycholic acid.   The photoelectric conversion element according to claim 1, wherein the semiconductor fine particles are titanium oxide, zinc oxide, or tin oxide.   The photoelectric conversion element according to claim 1, wherein the binuclear metal complex dye and the steroidal compound are adsorbed on semiconductor fine particles.   6. The photoelectric conversion element according to claim 5, wherein a semiconductor layer containing semiconductor fine particles on which the binuclear metal complex dye and the steroidal compound are adsorbed is formed on a conductive support.   A photochemical battery comprising the photoelectric conversion element according to claim 1.   A photochemical battery comprising the photoelectric conversion element according to any one of claims 1 to 6 as an electrode and a counter electrode, and an electrolyte layer therebetween.   The asymmetric binuclear metal complex dye represented by the general formula (1) and a steroid compound having a steroid skeleton and a carboxyl group (provided that the proton of the carboxyl group (—COOH) is substituted with a monovalent cation) And a step of immersing the semiconductor fine particles in a solution containing the photoelectric conversion element. Forming a semiconductor layer containing semiconductor fine particles on a conductive support;
The semiconductor layer is composed of an asymmetric binuclear metal complex dye represented by the above general formula (1) and a steroid compound having a steroid skeleton and a carboxyl group (provided that the carboxyl group (—COOH) has a monovalent proton. And a step of immersing in a solution containing a cation.   The solution containing the binuclear metal complex dye and the steroid compound contains 0.1 to 15 mol of the steroid compound with respect to 1 mol of the dinuclear metal complex dye. A method for producing a photoelectric conversion element.

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