GB2505093B

GB2505093B - Photoelectric converter and photoelectrochemical cell

Info

Publication number: GB2505093B
Application number: GB1317100.4A
Authority: GB
Inventors: Hamada Kazuhiro; Susuki Tatsuya; Kobayashi Katsumi; Kimura Keizo
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2011-03-30
Filing date: 2012-03-12
Publication date: 2019-10-23
Anticipated expiration: 2032-03-12
Also published as: JP5756772B2; KR20140027168A; KR101505767B1; JP2012216506A; GB201317100D0; GB2505093A; WO2012132855A1

Description

DESCRIPTION

TITLE OF INVENTION: PHOTOELECTRIC CONVERSION ELEMENT AND

PHOTOELECTROCHEMICAL CELL

TECHNICAL FIELD {0001}

The present invention relates to a photoelectric conversion element and a photoelectiOchemical cell, which have high conversion efficiency and are excellent in durability.

BACKGROUND ART {0002}

Photoelectric conversion elements are used in various photosensors, copying machines, photoelectrochemical cells (for example, solar cells), and the like. These photoelectric conversion elements have adopted various systems to be put into use, such as elements utilizing metais, elements utilizing semiconductors, elements utilizing organic pigments or dyes, or combinations of these elements. Among them, solar cells that make use of non-exhaustive solar energy do not necessitate fuels, and full-íledged practicalization of solar cells as an inexhaustible clean energy is being highly expected. Among these, research and development of silicon-based solar cells have long been in progress. Many countries also support policy-wise considerations, and thus dissemination of silicon-based solar cells is still in progress. However, Silicon is an inorganic material, and has limitations per se in terms of throughput and molecular modification. {0003}

Under such circumstances, research is being vigorously carried out on dye-sensitized solar cells. Particularly, Graetzel et al. at 1'Ecole Polytechnique de 1'Universite de Lausanne in Switzerland have developed a dye-sensitized solar cell in which a dye formed from a ruthenium complex is fixed at the surface of a porous titanium oxide thin film, and have realized a conversion efficiency that is comparable to that of amorphous Silicon. Thus, the dye-sensitized solar cells instantly attracted the attention of researchers all over the world. {0004}

Patent Literature 1 describes a dye-sensitized photoelectric conversion element making use of semiconductor fine particles sensitized by a ruthenium complex dye, to which the foregoing technology has been applied. Moreover, a photoelectric conversion element using an inexpensive organic dye as a sensitizer has been reported.

Patent Literature 2 proposes a photosensitized solar cell in which sunlight is effectively absorbed by using a dye having a specific structure to improve photoelectric conversion efficiency.

Moreover, a photoelectric cell is proposed in which a dopant is incorporated into at least one of a core and a shell of multi-structure titanium oxide fine particles having the core being a central part and the shell being an outer shell part to improve photoelectric conversion efficiency (for example, refer to Patent Literature 3).

The present inventors produced photoelectric conversion elements using the dye and the semiconductor fine particles described in these Patent Literatures, and evaluated the resultant elements. As a result, it is found that the elements are insufficient in some cases in view of durability. The photoelectric conversion element is required to have high initial conversion efficiency and a small decrease in conversion efficiency even after use and be excellent in durability. Therefore, the photoelectric conversion elements described in these Patent Literatures are unsatisfactory.

CITATION LIST

Patent Literatures {0005}

Patent Literature 1: U.S. Patent No. 5,463,057

Patent Literature 2: JP-A-2009-200028 ("JP-A" means unexamined published Japanese patent application)

Patent Literature 3: JP-A-2004-10403

DISCLOSURE OF INVENTION

TECHNICAL PROBLEM

The present invention provides a photoelectrochemical cell and a photoelectrochemical cell which have high conversion efficiency and are excellent in durability.

SOLUTION TO PROBLEM

The present inventors diligently conducted research on photoelectric conversion efficiency and durability by producing photoelectric conversion elements using various semiconductor fine particles and dyes. As a result, the present inventors found that durability cannot be significantly improved by simply mixing different kinds of semiconductor fine particles, and that a simple use of, as semiconductor fine particles, those prepared by coating tin oxide with aluminum oxide or magnesium oxide is difficult to improve durability.

Thus, the present inventors diligently conducted research on semiconductor fine particles and a dye. As a result, the present inventors found that a photoelectric conversion element and a photoelectrochemical cell, in which semiconductor fine particles have two or more kinds of metais or metallic compounds, and a metal complex dye having a specific substituent in a ligand is used, are excellent not only in initial photoelecüic conversion efficiency but also in durability.

According to a first aspect, the present invention provides a photoelectric conversion element comprising: an electrically conductive support; a photoconductor layer having semiconductor fine particles containing a dye represented by Formula (1); a charge transfer layer; and a counter electrode; wherein the semiconductor fine particles locally have two or more kinds of metais or metallic compounds;

Ru(LL1)(LL2)(X)2*(CI)m4 Formula (1) wherein LL1 is a bidentate ligand represented by Formula (2); LL is a bidentate ligand represented by Formula (5-1); X represents an isothiocyanate group;

Cl represents a counter ion for neutralizing a charge of the compound represented by Formula (1); and m4 represents an integer of 0 to 3; when m4 is an integer of 2 or more, CFs may be the same or different from each other;

wherein R101 and R102 each independently represent a heterocyclic group, a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group; R103 and R104 each independently represent a substituent; R105 and R106 each independently represent a group composed of at least one kind of group selected from the group consisting of an alkyl group, an aryl group and a heterocyclic group; L and L each independently represent a conjugated chain composed of an ethenylene group and/or ethynylene group; al and a2 each independently represent an integer of 0 to 3; when al is an integer of 2 or more, R501 ’s may be the same or different from each other; when a2 is an integer of 2 or more, R ’s may be the same or different from each other; bl and b2 each independently 103 represent an integer of 0 to 3; when bl is an integer of 2 or more, R ’S may be the same or different from each other, or R ’s may be bonded to each other to form a ring; when b2 is an integer of 2 or more, R104’s may be the same or different from each other, or R104’s may be bonded to each other to form a ring; when bl and b2 each are an integer of 1 or more, R103 and R104 may be bonded to each other to form a ring; dl and d2 each independently represent an integer of 0 to 5; d3 represents 0 or 1; and

wherein:

R151 represents an acidic group, R159 represents a substituent, el represents an integer of 0 to 4, e9 represents an integer of 0 to 6, each R151 and R159 may bind to any site of the rings, and when el is 2 or more, each R151 is the same or different from each other, or may be bonded with each other to form a ring, and when e9 is 2 or more, each of R159 is the same or different from each other, or may be bonded with each other to form a ring.

Preferably the two or more kinds of metais or metallic compounds in the semiconductor fine particles are a metal atom, metal chalcogenide, metal carbonate or metal nitrate.

Preferably the metal atom is at least one kind of atom selected from the group consisting of Ti, Sn, Au, Ag, Cu, Al, Zr, Nb, V and Ta.

Preferably the metal chalcogenide is cadmium sulfide, cadmium selenide or a metal oxide of at least one kind of metal selected from the group consisting of Ti, Sn, Zn, Mg,

Al, W, Zr, Hf, Sr, In, Ce, Y, La, V and Ta.

Preferably the metal carbonate is at least one kind of metal carbonate selected from the group consisting of calcium carbonate, potassium carbonate and barium carbonate.

Preferably the metal nitrate is lanthanum nitrate.

Preferably the semiconductor fine particles have the metal atom, the metal chalcogenide, the metal carbonate and/or the metal nitrate, according to a core-shell structure. In this case, preferably the semiconductor fine particles have the metal chalcogenide as a core part, and have the metal chalcogenide or the metal carbonate as a shell part. In this case, it is further preferred that the semiconductor fine particles have metal chalcogenide selected from the group consisting of titanium oxide and tin oxide as the core part, and have metal chalcogenide or metal carbonate selected from the group

consisting of aluminum oxide, magnesium oxide, calcium carbonate, titanium oxide, and titanium oxide/magnesium oxide as the shell part.

Preferably the semiconductor fine particles have the two or more kinds of metal atoms by doping a metal atom. In this case, the semiconductor fine particles are preferably obtainable by doping a metal atom into metal chalcogenide. In this case it is further preferred that the semiconductor fine particles are obtainable by doping at least one kind of metal atom selected from the group consisting of Nb, V and Ta into metal chalcogenide selected from the group consisting of titanium oxide and tin oxide.

Preferably the particle diameter of the semiconductor fine particles is 1 to 1,000 nm.

Preferably the semiconductor fine particles contain an additive composed of an electrically conductive material. In this case, the electrically conductive material is graphene.

Preferably LL1 in Formula (1) is represented by any one of Formulae (4-1), (4-2) and (4-3):

wherein R101 to R104, al, a2, bl, b2 and d3 have the same meaning as those in 107

Formula (2), respectively; R represents an acidic group; a3 represents an integer of 0 to 3; R represents a substituent; b3 represents an integer of 0 to 3; R to R each independently represent a hydrogen atom, an alkyl group, an alkenyl group or an aryl group; R , R , R and R each independently represent a substituent; and d4 and d5 each independently represent an integer of 0 to 4.

Preferably R in Formula (4-2) is a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic group, a phosphoryl group or a phosphonyl group.

Preferably R in Formula (4-2) is an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, or an acylamino group.

Preferably R125, R126, R127 and R128 in Formulae (4-1) to (4-3) each independently represent an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, an acylamino group or a hydroxyl group.

Preferably R103 and R104 in Formula (2) each independently represent an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an amino group, a sulfonamide group, an acyloxy group, a carbamoyl group, an acylamino group, a cyano group, or a halogen atom.

According to a second aspect, the present invention provides a photoelectric Chemical cell comprising the photoelectric conversion element in accordance with the above first aspect.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a photoelectric conversion element and a photoelectrochemical cell which exhibit high conversion efficiency and excellent durability.

Other and further features and advantages of the invention will appear more fully from the following description, appropriately referring to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING {FIG. 1}

Fig. 1 is a cross-sectional view schematically showing an exemplary embodiment of the photoelectric conversion element according to the present invention.

MODE FOR CARRYING OUT THE INVENTION

The present inventors diligently conducted research, and as a result, found that a photoelectric conversion element and a photoelectrochemical cell comprising an electrically conductive support, a photoconductor layer having a semiconductor fine particle layer containing a dye of a specific compound, a charge transfer layer and a counter electrode, in which the semiconductor fine particles locally have two or more kinds of metais or metallic compounds, have high conversion efficiency and are excellent in durability. The present invention is achieved based on these findings. A preferred exemplary embodiment of the photoelectric conversion element of the present invention will be explained with reference to the schematically cross- sectional view shown in Fig. 1.

As shown in Fig. 1, a photoelectric conversion element 10 contains an electrically conductive support 1; and a photo conductor layer 2, a charge transfer layer 3 and a counter electrode 4, all provided on the electrically conductive support 1 in this order. The electrically conductive support 1 and the photoconductor layer 2 constitute a light-receiving electrode 5.

The photoconductor layer 2 has semiconductor fine particles 22 and a sensitizing dye (hereinafter, also simply referred to as “dye”) 21. The sensitizing dye 21 is at least partially adsorbed on the semiconductor fine particles 22 (the sensitizing dye 21 is in an adsorption equilibrium State, and may partially exist in the charge transfer layer 3.). The charge transfer layer 3 functions, for example, as a hole-transporting layer for transporting positive holes (holes). The electrically conductive support 1 having a photoconductor layer 2 provided thereon functions as a working electrode in the photoelectric conversion element 10. This photoelectric conversion element 10 canbe operated as a photoelectrochemical cell 100 by making the photoelectric conversion element 10 usable in a cell application where the cell is made to work with an externai circuit 6.

The light-receiving electrode 5 is an electrode comprising an electrically conductive support 1; and a photoconductor layer 2 (photosensitive layer or semiconductor fdm) coated on the electrically conductive support 1, the layer containing semiconductor fine particles 22 to which a sensitizing dye 21 has been adsorbed. A light incident to the photoconductor layer 2 (semiconductor film) excites the dye. The excited dye has elections with high energy, and these electrons are transported from the sensitizing dye 21 to the conduction band of the semiconductor fine particles 22 and further reach the electrically conductive support 1 by diffusion. At this time, the molecules of the sensitizing dye 21 are in an oxide form. In the photoelectrochemical cell 100, the electrons on the electrode return to the oxide of the dye while working in the externai circuit 6, while the light-receiving electrode 5 works as a negative electrode of this cell.

The photoconductor layer 2 comprises a porous semiconductor layer constituted of a layer of the semiconductor fine particles 22 on which the dye described later is adsorbed. This dye may be partially dissociated in an electrolyte. The photoconductor layer 2 is designed for any purpose, and may form a multilayer structure.

As described above, the photoconductor layer 2 contains the semiconductor fine particles 22 on which a specific dye is adsorbed, and thus has a high light-receiving sensitivity. When it is used for the photoelectrochemical cell 100, a high photoelectric conversion efficiency and higher durability can be obtained. (A) Dye

In the photoconductor layer 2, a porous semiconductor layer is sensitized with at least one kind of dye 21 represented by Formula (1).

(A2) Ligand LL1

The ligand LL1 is a bidentate ligand represented by Formula (2).

In Formula (2), R101 and R102 each independently represent any one of a heterocyclic group, a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic group (preferably having 1 to 20 carbon atoms; for example, -CONHOH, -CONCH3OH, and the like), a phosphoryl group (for example, -OP(O)(OH)2, and the like) and a phosphonyl group (for example, -P(O)(OH)2, and the like). The heterocyclic group may be unsubstituted or substituted with a substituent described below. R101 and R102 each are preferably a carboxyl group or a phosphonyl group, and more preferably a carboxyl group. R101 and R102 may be substituted at any site of the pyridine-ring-forming carbon atoms. al and a2 each independently represent an integer of 0 to 3. When al is an integer of 2 or more, R101’s may be the same or different from each other. When a2 is an integer of 2 or more, R ’s may be the same or different from each other. al is preferably 0 or 1, and a2 is preferably an integer of 0 to 2. The total of al and a2 is preferably an integer of 0 to 2.

In Formula (2), R103 and R104 each independently represent a substituent. Preferred examples thereof include an alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, e.g. methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, or 1-carboxymethyl), an alkenyl group (preferably an alkenyl group having 2 to 20 carbon atoms, e.g. vinyl, allyl, or oleyl), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms, e.g. ethynyl, butadiynyl, or phenylethynyl), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, e.g. cyclopropyl, cyclopentyl, cyclohexyl, or 4-methylcyclohexyl), an aryl group (preferably an aryl group having 6 to 26 carbon atoms, e.g. phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, or 3-methylphenyl), a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, e.g. 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, or 2-oxazolyl), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, e.g. methoxy, ethoxy, isopropyloxy, or benzyloxy), an aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, e.g. phenoxy, 1-naphthyloxy, 3-methylphenoxy, or 4-methoxyphenoxy), an alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 20 carbon atoms, e.g.ethoxycarbonyl, or 2-ethylhexyloxycarbonyl), an amino group (preferably an amino group having 0 to 20 carbon atoms, e.g. amino, N,N-dimethylamino, Ν,Ν-diethylamino, N-ethylamino, or anilino), a sulfonamide group (preferably a sulfonamide group having 0 to 20 carbon atoms, e.g. N,N- dimethylsulfonamide, or N-phenylsulfonamide), an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms, e.g. acetyloxy, or benzoyloxy), a carbamoyl group (preferably a carbamoyl group having 1 to 20 carbon atoms, e.g. N,N-dimethylcarbamoyl, or N-phenylcarbamoyl), an acylamino group (preferably an acylamino group having 1 to 20 carbon atoms, e.g. acetylamino, or benzoylamino), a cyano group, and a halogen atom (e.g. a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom). Among these, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an amino group, an acylamino group, a cyano group and a halogen atom are more preferable; and an alkyl group, an alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group and a cyano group are particularly preferable. bl and b2 each independently represent an integer of 0 to 3, preferably an integer of 0 to 2. When bl is an integer of 2 or more, R ’s may be the same or different from each other, or R ’s may be bonded with each other to form a ring. When b2 is an integer of 2 or more, R104’s may be the same or different from each other, or R104’s may be bonded with each other to form a ring. When bl and b2 each are an integer of 1 or more, R and R104 may be bonded with each other to form a ring. The ring to be formed is not particularly limited. Preferred examples of the ring include a benzene ring, a pyridine ring, a thiophene ring, a pyrrole ring, a cyclohexane ring, and a cyclopentane ring.

In Formula (2), R105 and R106 each independently represent a group composed of at least one kind of group selected from the group consisting of an alkyl group, an aryl group and a heterocyclic group. R105 and R106 each independently are preferably an aromatic group (preferably an aromatic group having 6 to 30 carbon atoms, for example, phenyl, a substituted phenyl group, naphthyl, or a substituted naphthyl group), or a heterocyclic group (preferably a heterocyclic group having 1 to 30 carbon atoms, for example, a 2-thienyl group, a 2-pyrrolyl group, a 2-imidazolyl group, a 1-imidazolyl group, a 4-pyridyl group, or a 3-indolyl group), more preferably a heterocyclic group having 1 to 3 electron donative groups, and further preferably a thienyl group. The electron donative group is preferably an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, an acylamino group (preferable examples of each of the above-described groups are the same as R101 and R102 in Formula (2)) or a hydroxyl group; more preferably an alkyl group, an alkoxy group, an amino group or a hydroxyl group; and particularly preferably an alkyl group. R105 and R106 may be the same or different from each other. However, it is preferable that R105 and R106 are the same.

In Formula (2), L and L each independently represent a conjugated chain composed of an ethenylene group and/or ethynylene group. When the ethenylene group has a substituent, examples of the substituent include those represented as specific examples of the substituent of R103 and R104. In the case where the ethenylene group has a substituent, the substituent is preferably an alkyl group, and more preferably a methyl group. Preferably L and L each independently stand for a conjugated chain having 2 to 6 carbon atoms, more preferably an ethenylene group, a butadienylene group, an ethynylene group, a butadiynylene group, a methylethenylene group, or a dimethylethenylene group; especially preferably an ethenylene group, or a butadienylene group; and most preferably an ethenylene group. L and L may be the same or different from each other. However, it is preferable that L and L are the same. Herein, when the conjugated chain contains a carbon-carbon double bond, each carbon-carbon double bond may be a trans form or a cis form, or a mixture thereof. dl and d2 each independently represent an integer of 0 to 5. When dl and d2 are 0, R105 and R106 are directly bonded to the benzene ring, respectively. When dl and d2 are an integer of 1 or more, R105 and R106 are bonded to the benzene ring via L1 or L2, respectively. dl and d2 each are preferably 0 or 1. d3 is 0 or 1. When d3 is 0, a2 is preferably 1 or 2. When d3 is 1, a2 is preferably 0 or 1.

In the case where the ligand LL1 contains an alkyl group, an alkenyl group or the like, these groups may be linear or branched, and may be substituted or unsubstituted. Likewise, in the case where the ligand LL1 contains an aromatic group, such as an aryl group, a heterocyclic group or the like, these groups may be a single ring or a condensed ring, and may be substituted or unsubstituted. Examples of the substituent include those represented as specific examples of the substituent of R103 and R104.

The ligand LL1 in Formula (1) is preferably represented by Formula (4-1), (4-2) or (4-3).

In Formulae (4-1) to (4-3), R101 to R104, al, a2, bl, b2 and d3 have the same meaning as those in Formula (2), respectively, and preferable ranges thereof are also the same.

In Formula (4-2), R represents an acidic group. R is preferably a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic group, a phosphoryl group or a phosphonyl group; more preferably a carboxyl group or a phosphoryl group; and further preferably a carboxyl group.

In Formula (4-2), a3 represents an integer of 0 to 3, preferably an integer of 0 to 2. When d3 is 0, a3 is preferably 1 or 2. When d3 is 1, a3 is preferably 0 or 1. When a3 is an integer of 2 or more, R ’ s may be the same or different from each other.

In Formula (4-2), R represents a substituent; preferably an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, or an acylamino group (preferable examples of each of the above- described groups are the same as R103 and R104 in Formula (2)); more preferably an alkyl group, an

alkoxy group, an amino group or an acylamino group.

In Formula (4-2), b3 represents an integer of 0 to 3, preferably an integer of 0 to 2. 108

When b3 is an integer of 2 or more, R ’s may be the same or different from each other.

In Formulae (4-1) and (4-2), R to R each independently represent a hydrogen atom, an alkyl group, an alkenyl group, or an aryl group (preferable examples of the above groups are the same as R103 and R104 in Formula (2)). R121 to R124 each are preferably an alkyl group or an aryl group; and more preferably an alkyl group. When R to R are an alkyl group, the alkyl group may additionally have a substituent. As for the substituent, an alkoxy group, a cyano group, an alkoxycarbonyl group, or a carbonamide group is preferable, and an alkoxy group is especially preferable. R121 and R122, and R123 and R124 are each bonded with each other to form a ring. Preferable examples of the ring to be formed include a pyrrolidine ring, a pyrrolidine ring, a piperazine ring, and a morpholine ring.

In Formulae (4-1) to (4-3), R125, R126, R127 and R128 each independently represent a substituent; preferably an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, an acylamino group (preferable examples of each of the above-described groups are the same as R103 and R104 in Formula (2)) or a hydroxyl group; more preferably an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group or an acylamino group; and particularly preferably an alkyl group or an alkynyl group.

In Formulae (4-1) and (4-2), d4 and d5 each independently represent an integer of 0 to 4. When d4 is 1 or more, R125 may be bonded with R121 and/or R122 to form a ring. The formed ring is preferably a piperidine ring or a pyrrolidine ring. When d4 is 2 or more, R ’s may be the same or different from each other, or may be bonded with each other to form a ring. When d5 is 1 or more, R may be bonded with R and/or R to form a ring. The formed ring is preferably a piperidine ring or a pyrrolidine ring. When d5 is 2 or more, R s may be the same or different from each other, or may be bonded with each other to form a ring. (A3) Ligand LL2

The ligand LL is a bidentate ligand represented by Formula (5-1).

Herein R151 and R159 in Formula (5-1) are represented to be substituted on a single ring for convenience of illustration, but may be on the ring or may be substituted on a ring different from one illustrated.

In Formula (5-1), R151 represents an acidic group. R151 is, for example, a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic group (preferably having 1 to 20 carbon atoms; for example, -CONHOH, -CONCH3OH, and the like), a phosphoryl group (for example, -OP(O)(OH)2, and the like) or a phosphonyl group (for example, -P(O)(OH)2, and the like); preferably a carboxyl group, a phosphoryl group or a phosphonyl group; more preferably a carboxyl group or a phosphonyl group; and most preferably a carboxyl group.

In Formula (5-1), R159 represents a substituent. R159 is preferably an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an amino group, an acyl group, a sulfonamide group, an acyloxy group, a carbamoyl group, an acylamino group, a cyano group, or a halogen atom (preferable examples of each of the above-described groups are the same as R103 and R104 in Formula (2)); more preferably an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group, or a halogen atom; and especially preferably an alkyl group, an alkenyl group, an alkoxy group, an alkoxycarbonyl group, an amino group, or an acylamino group.

In Formula (5-1), R151 may bind to any site of the rings.

In Formula (5-1), el represents an integer of 0 to 4, preferably an integer of 1 to 2. e9 represents an integer of 0 to 6. e9 is preferably an integer of 0 to 3.

When el is 2 or more, each of the R151’s is the same or different from each other, or may be bonded with each other to form a ring. When e9 is 2 or more, each of the R159’s is the same or different from each other, or may be bonded with each other to form a ring.

When the ligand LL contains an alkyl group, an alkenyl group or the like, these groups may be linear or branched, and may be substituted or unsubstituted. Meanwhile, when the ligand LL contains an aromatic group, such as an aryl group, a heterocyclic group or the like, these groups may be a single ring or a condensed ring, and may be substituted or unsubstituted.

(A4) Ligand X

In Formula (1), the ligand X represents an isothiocyanate group. (A5) Counter ion Cl

Cl in Formula (1) represents a counter ion in the case where the counter ion is necessary to neutralize a charge. Generally, whether the dye is cationic or anionic, or has a net ionic charge depends on the metal, the ligand and the substituent in the dye.

In the case where the substituent has a dissociative group or the like, the dye represented by Formula (1) may have a negative charge arising from dissociation. In this case, an electric charge of the dye represented by Formula (1) as a whole is electrically neutralized by the counter ion Cl. m4 that represents the number of counter ions represented by Cl is an integer of 0 to 3.

When the counter ion Cl is a positive counter ion, examples of the counter ion Cl include an inorganic or organic ammonium ion (for example, tetraalkyl ammonium ion, pyridinium ion and the like), an alkali metal ion and a proton.

When the counter ion Cl is a negative counter ion, the negative counter ion may be an inorganic negative ion or an organic negative ion. Examples thereof include a halogen negative ion (for example, fluoride ion, chloride ion, bromide ion, iodide ion and the like), a substituted arylsulfonate ion (for example, p-toluene sulfonate ion, p-chlorobenzene sulfonate ion and the like), an aryldisulfonate ion (for example, 1,3- benzene disulfonate ion, 1,5-naphthalene disulfonate ion, 2,6-naphthalene disulfonate ion and the like), an alkylsulfate ion (for example, methylsulfate ion and the like), a sulfate ion, a thiocyanate ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a picrate ion, an acetate ion and a trifluoromethane sulfonate ion. Altematively, as a charge balance counter ion, an ionic polymer or another dye with the opposite charge from the primary dye may be used. Altematively, a metal complex ion (for example, bisbenzene-l,2-dithiolatonickel (III) and the like) may be used. {0070} (Α6) Anchoring group (Interlocking group)

The dye having the structure represented by Formula (1) preferably has at least one acidic group (interlocking group) that is suitable for a surface of semiconductor fine particles, further preferably from 1 to 6 interlocking groups, and particularly preferably from 1 to 4 interlocking groups. The dye preferably has an acidic group (a substituent having a dissociable proton) such as a carboxyl group, a sulfonate group, a hydroxyl group, a hydroxamic acid group (for example, -CONHOH), a phosphoryl group (for example, -OP(O)(OH)2) and a phosphonyl group (for example, -P(O)(OH)2). Above all, the dye preferable has a carboxyl group (COOH group) on the ligand. The acidic group herein means a substituent that emits a proton. An expression “to have a substituent of specific functionality” such as “to have an acidic group” means that the substituent of specific functionality is interlocked directly with a scaffold, and also that the substituent is interlocked (linked) through a predetermined linking group, within the range in which advantageous effects of the present invention are not adversely affected. {0071}

The substituent herein can represent, for example, a substituent W described below, otherwise than as specifically described: a halogen atom (e.g. a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom); an alkyl group [which represents a substituted or unsubstituted linear, branched, or cyclic alkyl group, and which includes an alkyl group (preferably an alkyl group having 1 to 30 carbon atoms, e.g. methyl, ethyl, n-propyl, isopropyl, t-butyl, n-octyl, eicosyl, 2-chloroethyl, 2-cyanoethyl, or 2-ethylhexyl), a cycloalkyl group (preferably a substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, e.g. cyclohexyl, cyclopentyl, or 4-n-dodecylcyclohexyl), a bicycloalkyl group (preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, i.e. a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms, e.g. bicyclo[1.2.2Jheptan-2-yl or bicyclo[2.2.2Joctan-3-yl), and a tricyclo or higher structure having three or more ring struetures; and an alkyl group in substituents described below (e.g. an alkyl group in an alkylthio group) represents such an alkyl group of the above concept]; an alkenyl group [which represents a substituted or unsubstituted linear, branched, or cyclic alkenyl group, and which includes an alkenyl group (preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, e.g. vinyl, allyl, prenyl, geranyl, or oleyl), a cycloalkenyl group (preferably a substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms, i.e. a monovalent group obtained by removing one hydrogen atom from a cycloalkene having 3 to 30 carbon atoms, e.g. 2-cyclopenten-l-yl group or 2-cyclohexen-1 -yl), and a bicycloalkenyl group (which represents a substituted or unsubstituted bicycloalkenyl group, preferably a substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms, i.e. a monovalent group obtained by removing one hydrogen atom from a bicycloalkene having one double bond, e.g. bicyclo[2.2.1]hept-2-en-l-yl or bicyclo[2.2.2]oct-2-en-4-yl)]; an alkynyl group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, e.g. ethynyl, propargyl, or a trimethylsilylethynyl group); an aryl group (preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, e.g. phenyl, p-tolyl, naphthyl, m-chlorophenyl, or o-hexadecanoylaminophenyl); an aromatic group (e.g. a benzene ring, a furan ring, a pyrrole ring, a pyridine ring, a thiophene ring, an imidazole ring, an oxazole ring, a thiazole ring, a pyrazole ring, an isoxazole ring, an isothiazole ring, a pyrimidine ring, a pyrazine ring, or rings formed by condensation of the foregoing rings); a heterocyclic group (preferably a monovalent group obtained by removing one hydrogen atom from a substituted or unsubstituted 5- or 6-membered aromatic or nonaromatic heterocyclic compound; more preferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms, e.g. 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl); a cyano group; a hydroxyl group; a nitro group; a carboxyl group; an alkoxy group (preferably a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, e.g. methoxy, ethoxy, isopropoxy, t-butoxy, n-octyloxy, or 2- methoxyethoxy); an aryloxy group (preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, e.g. phenoxy, 2-methylphenoxy, 4-t-butylphenoxy, 3- nitrophenoxy, or 2-tetradecanoylaminophenoxy); a silyloxy group (preferably a silyloxy group having 3 to 20 carbon atoms, e.g. trimethylsilyloxy or t-butyldimethylsilyloxy); a heterocyclic oxy group (preferably a substituted or unsubstituted heterocyclic oxy group having 2 to 30 carbon atoms, e.g. 1- phenyltetrazol-5-oxy or 2-tetrahydropyranyloxy); an acyloxy group (preferably a formyloxy group, a substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, or a substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms, e.g. formyloxy, acetyloxy, pivaloyloxy, stearoyloxy, benzoyloxy, or p-methoxyphenylcarbonyloxy); a carbamoyloxy group (preferably a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms, e.g. N,N-dimethylcarbamoyloxy, Ν,Ν-diethylcarbamoyloxy, morpholinocarbonyloxy, N,N-di-n-octylaminocarbonyloxy, or N-n-octylcarbamoyloxy); an alkoxycarbonyloxy group (preferably a substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, e.g. methoxycarbonyloxy, ethoxycarbonyloxy, t-butoxycarbonyloxy, or n-octylcarbonyloxy); an aryloxycarbonyloxy group (preferably a substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, e.g. phenoxycarbonyloxy, p-methoxyphenoxycarbonyloxy, orp-n- hexadecyloxyphenoxycarbonyloxy); an amino group (preferably an amino group, a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, or a substituted or unsubstituted anilino group having 6 to 30 carbon atoms, e.g. amino, methylamino, dimethylamino, anilino, N-methyl-anilino, or diphenylamino); an acylamino group (preferably a foimylamino group, a substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, or a substituted or unsubstituted arylcarbonylamino group having 6 to 30 carbon atoms, e.g. formylamino, acetylamino, pivaloylamino, lauroylamino, benzoylamino, or 3,4,5-tri-n-octyloxyphenylcarbonylamino); an aminocarbonylamino group (preferably a substituted or unsubstituted aminocarbonylamino group having 1 to 30 carbon atoms, e.g. carbamoylamino, N,N-dimethylaminocarbonylamino, Ν,Ν-diethyl aminocarbonylamino, or morpholinocarbonylamino); an alkoxycarbonylamino group (preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, e.g. methoxycarbonylamino, ethoxycarbonylamino, t-butoxycarbonylamino, n-octadecyloxycarbonylamino, or N-methyl-methoxycarbonylamino); an aryloxycarbonylamino group (preferably a substituted or unsubstituted aryloxycarbonylamino group having 7 to 30 carbon atoms, e.g. phenoxycarbonylamino, p-chlorophenoxycarbonylamino, or m-n-octyloxyphenoxycarbonylamino); a sulfamoylamino group (preferably a substituted or unsubstituted sulfamoylamino group having 0 to 30 carbon atoms, e.g. sulfamoylamino, N,N-dimethylaminosulfonylamino, or N-n-octylaminosulfonylamino); an alkyl- or aryl-sulfonylamino group (preferably a substituted or unsubstituted alkylsulfonylamino group having 1 to 30 carbon atoms, or a substituted or unsubstituted arylsulfonylamino group having 6 to 30 carbon atoms, e.g. methylsulfonylamino, butylsulfonylamino, phenylsulfonylamino, 2,3,5- trichlorophenylsulfonylamino, or p-methylphenylsulfonylamino); a mercapto group; an alkylthio group (preferably a substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms, e.g. methylthio, ethylthio, or n-hexadecylthio); an arylthio group (preferably a substituted or unsubstituted arylthio group having 6 to 30 carbon atoms, e.g. phenylthio, p-chlorophenylthio, or m-methoxyphenylthio); a heterocyclic thio group (preferably a substituted or unsubstituted heteiOcyclic thio group having 2 to 30 carbon atoms, e.g. 2-benzothiazolylthio or l-phenyltetrazol-5-ylthio); a sulfamoyl group (preferably a substituted or unsubstituted sulfamoyl group having 0 to 30 carbon atoms, e.g. N-ethylsulfamoyl, N-(3-dodecyloxypropyl)sulfamoyl, Ν,Ν-dimethylsulfamoyl, N-acetyl sul famoyl, N-benzoyl sul famoyl, or N-(N’-phenylcarbamoyl)sulfamoyl); a sulfo group; an alkyl- or aryl-sulfinyl group (preferably a substituted or unsubstituted alkylsulfmyl group having 1 to 30 carbon atoms, or a substituted or unsubstituted arylsulfinyl group having 6 to 30 carbon atoms, e.g. methylsulfinyl, ethylsulfinyl, phenyl sul finyl, or p-methylphenylsulfinyl); an alkyl- or aryl-sulfonyl group (preferably a substituted or unsubstituted alkylsulfonyl group having 1 to 30 carbon atoms, or a substituted or unsubstituted arylsulfonyl group having 6 to 30 carbon atoms, e.g. methylsulfonyl, ethylsulfonyl, phenylsulfonyl, or p-methylphenylsulfonyl); an acyl group (preferably a formyl group, a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyl group having 7 to 30 carbon atoms, or a substituted or unsubstituted heterocyclic carbonyl group having 4 to 30 carbon atoms, which is bonded to said carbonyl group through a carbon atom, e.g. acetyl, pivaloyl, 2-chloroacetyl, stearoyl, benzoyl, p-n-octyloxyphenylcarbonyl, 2-pyridylcarbonyl, or 2-furylcarbonyl); an aryloxycarbonyl group (preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms, e.g. phenoxycarbonyl, o-chlorophenoxycarbonyl, m-nitrophenoxycarbonyl, or p-t- butylphenoxycarbonyl); an alkoxycarbonyl group (preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, e.g. methoxycarbonyl, ethoxycarbonyl, t-butoxycarbonyl, or n-octadecyloxycarbonyl); a carbamoyl group (preferably a substituted or unsubstituted carbamoyl group having 1 to 30 carbon atoms, e.g. carbamoyl, N-methylcarbamoyl, Ν,Ν-dimethylcarbamoyl, N,N-di-n-octylcarbamoyl, or N- (methylsulfonyl)carbamoyl); an aryl- or heterocyclic-azo group (preferably a substituted or unsubstituted aryl azo group having 6 to 30 carbon atoms, or a substituted or unsubstituted heterocyclic azo group having 3 to 30 carbon atoms, e.g. phenylazo, p-chlorophenylazo, or 5-ethylthio-l,3,4-thiadiazol-2-ylazo); an imido group (preferably N-succinimido or N-phthalimido); a phosphino group (preferably a substituted or unsubstituted phosphino group having 2 to 30 carbon atoms, e.g. dimethylphosphino, diphenylphosphino, or methylphenoxyphosphino); a phosphinyl group (preferably a substituted or unsubstituted phosphinyl group having 2 to 30 carbon atoms, e.g. phosphinyl, dioctyloxyphosphinyl, or diethoxyphosphinyl); a phosphinyloxy group (preferably a substituted or unsubstituted phosphinyloxy group having 2 to 30 carbon atoms, e.g. diphenoxyphosphinyloxy or dioctyloxyphosphinyloxy); a phosphinylamino group (preferably a substituted or unsubstituted phosphinylamino group having 2 to 30 carbon atoms, e.g. dimethoxyphosphinylamino or dimethylaminophosphinylamino); and a silyl group (preferably a substituted or unsubstituted silyl group having 3 to 30 carbon atoms, e.g. trimethylsilyl, t-butyldimethylsilyl, or phenyldimethylsilyl).

The substituent may be further substituted. In that case, examples of the substituent include the substituent mentioned above.

Specific examples of the dye having the structure represented by Formula (1) used in the present invention are shown below. However, the present invention is not limited thereto. In the case where the dye in the following specific examples thereof contains a ligand having a proton-dissociable group, the ligand may release a proton with dissociation as needed. {0074}

{0075}

{0078}

As a method for synthesizing the dye represented by Formula (1), the methods disclosed in EXAMPLES as described later can be referred to, and the dye can be synthesized by appropriately applying an ordinary method based on them. Further, the dye can be synthesized with reference to the methods in the literatures of J. Am. Chem. Soc., vol. 121, p. 4047 (1997), Can. J. Chem., vol. 75, p. 318 (1997), Inorg. Chem., vol. 27, p. 4007 (1988) or the like, and the methods cited in the literatures. The dye and the methods described above are incorporated herein by reference. Moreover, the Information disclosed in JP-A-2001-291534 and WO 2007/091525 can also be referred to, and the dye and the methods described above are incorporated herein by reference. {0079}

The dye represented by Formula (1) has a maximum absorption wavelength in a solution in a range of preferably from 300 nm to 1,000 nm, more preferably from 350 nm to 950 nm, and especially still more preferably from 370 nm to 900 nm. {0080}

The content of the dye represented by Formula (1) herein is not particularly limited, but is preferably 0.001 to 1 millimole, and further preferably 0.1 to 0.5 millimole, based on 1 g of the semiconductor fine particles. When the content is adjusted to be equal to or more than the lower limit, a sensitizing effect in the semiconductor can be sufficiently achieved. When the content is adjusted to be equal to or less than the upper limit, reduction of the sensitizing effect as caused by desorption of the dye can be suppressed. Moreover, two or more kinds of dyes represented by Formula (1) may be used in the present invention.

{0081} (B) Charge transfer layer A layer formed of an electrolyte composition can be applied to the charge transfer layer used for the photoelectric conversion element according to the present embodiment. Examples of the redox pair include a combination of iodine and an iodide (for example, lithium iodide, tetrabutylammonium iodide, or tetrapropylammonium iodide), a combination of an alkylviologen (for example, methylviologen chloride, hexylviologen bromide, or benzylviologen tetrafluoroborate) and a reductant thereof, a combination of polyhydroxybenzenes (for example, hydroquinone or naphthohydroquinone) and an oxidant thereof, and a combination of a divalent iron complex and a trivalent iron complex (for example, potassium ferricyanide and potassium ferrocyanide). Among these, a combination of iodine and an iodide is preferred. A cation of iodine salt is preferably a 5- or 6-membered nitrogen-containing aromatic cation. In particular, when the compound represented by Formula (1) is not the iodine salt, an iodine salt such as the pyridinium salt, the imidazolium salt, and the triazolium salt as described in WO 95/18456, JP-A-8-259543, and Electrochemistry, vol. 65, No. 11, p. 923 (1997), is preferably used in combination.

In the electrolyte composition used for the photoelectric conversion element, iodine is preferably contained with a heterocyclic quatemary salt compound. The content of iodine is preferably 0.1 to 20% by mass, and further preferably 0.5 to 5% by mass, based on the total of the electrolyte composition. {0082}

The electrolyte composition may contain a solvent. The content of the solvent in the electrolyte composition is preferably 50% by mass or less, further preferably 30% by mass or less, and particularly preferably 10% by mass or less, based on the total of the composition.

The solvent preferably can develop excellent ion conductivity due to low viscosity to have high ionic mobility, or high permittivity to allow an increase in an effective carrier concentration, or due to satisfying both properties. Specific examples of such solvents include a carbonate compound (e.g. ethylene carbonate and propylene carbonate), a heterocyclic compound (e.g. 3-methyl-2-oxazolidinone), an ether compound (e.g. dioxane and diethyl ether), chain ethers (e.g. ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, and polypropylene glycol dialkyl ether), alcohols (e.g. methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, and polypropylene glycol monoalkyl ether), polyhydric alcohols (e.g. ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, and glycerol), a nitrile compound (e.g. acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, benzonitrile, and biscyanoethyl ether), esters (e.g. carboxylate, phosphate, and phosphonate), an aprotic polar solvent (e.g. dimethyl sulfoxide (DMSO) and sulfolane), water, a water-containing electrolytic liquid as described in JP-A-2002-110262, and an electrolytic solvent as described in JP-A-2000-36332, JP-A-2000-243134 and WO 00/54361. These solvents may be used by mixing two or more kinds. {0083}

Moreover, as the electrolytic solvent, an electrochemically inert salt that is in a liquid State at room temperature and/or has a melting point lower than room temperature may also be used. Specific examples include an imidazolium salt such as 1 -ethyl-3-methylimidazolium trifluoromethanesulfonate and l-butyl-3-methylimidazolium triíluoromethanesulfonate, a nitrogen-containing heterocyclic quatemary salt compound such as a pyridinium salt, and a tetraalkylammonium salt. {0084}

The electrolyte composition may also be allowed to gelate (solidified) by adding a polymer or an oil-gelling agent, or by applying a technique such as polymerization of polyfunctional monomers or a polymer crosslinking reaction. {0085}

In the case where the electrolyte composition is allowed to gelate by adding a polymer, compounds described in "Polymer Electrolyte Reviews 1 and 2" (edited by J. R. MacCallum and C. A. Vincent, ELSEV1ER APPLIED SCIENCE), can be used as the polymer. Of these compounds, polyacrylonitrile or poly(vinylidene fluoride) is preferably used. {0086}

In the case where the electrolyte composition is allowed to gelate by adding an oil-gelling agent, compounds described in J. Chem. Soc. Japan, Ind. Chem. Soe., 1943, p. 46779; J. Am. Chem. Soc., 1989, vol. 111, p. 5542; J. Chem. Soc., Chem. Commun., 1993, p. 390; Angew. Chem. Int. Ed. Engl., 1996, vol. 35, p. 1949; Chem. Lett., 1996, p. 885; J. Chem. Soc., Chem. Commun., 1997, p. 545; or the like can be used as the oil-gelling agent. Of these compounds, a compound having an amide structure is preferably used. {0087}

In the case where the electrolyte composition is allowed to gelate by polymerization of polyfunctional monomers, a method is preferably applied in which a solution is prepared from polyfunctional monomers, a polymerization initiator, an electrolyte, and a solvent, a sol electrolyte layer is formed on a dye-supported electrode by a method such as a cast method, an application method, an immersion method, and an impregnation method, and then the electrolyte layer is allowed to gelate by radical polymerization of the polyfunctional monomer. The polyfunctional monomer is preferably a compound having two or more ethylenically unsaturated groups. Preferred examples thereof include divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate. {0088}

The gel electrolyte may also be formed by polymerization of a mixture containing a monofunctional monomer in addition to the polyfunctional monomers. Examples of the monofunctional monomer include acrylic acid or a-alkylacrylic acid (e.g. acrylic acid, methacrylic acid, and itaconic acid) or ester or amide thereof (e.g. methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-pentyl acrylate, 3-pentyl acrylate, t-pentyl acrylate, n-hexyl acrylate, 2,2-dimethylbutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 4-methyl-2-propylpentyl acrylate, cetyl acrylate, n-octadecyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate, benzyl acrylate, hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, phenoxyethyl acrylate, 3-methoxybutyl acrylate, ethylcarbitol acrylate, 2-methyl-2-nitropropyl acrylate, 2,2,2-trifluoroethyl acrylate, octafluoropentyl acrylate, heptadecafluorodecyl acrylate, methyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, t-pentyl methacrylate, n-octadecyl methacrylate, benzyl methacrylate, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-methoxyethoxyethyl methacrylate, dimethylaminoethyl methacrylate, 2,2,2-trifluoroethyl methacrylate, tetrafluoropropyl methacrylate, hexafluoropropyl methacrylate, heptadecafluorodecyl methacrylate, ethyleneglycolethyl carbonate methacrylate, 2-isobomyl methacrylate, 2-norbomylmethyl methacrylate, 5-norbomen-2-ylmethyl methacrylate, 3-methyl-2-norbomylmethyl methacrylate, acrylamide, N-i-propylacrylamide, N-n-butylacrylamide, N-t-butyl-acrylamide, Ν,Ν-dimethylacrylamide, N-methylolacrylamide, diacetonacrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylamide propyltrimethylammonium chloride, methacrylamide, N-methylmethacrylamide, N-methylolmethacrylamide), vinyl esters (e.g. vinyl acetate), maleic acid or fumaric acid, or esters derived from maleic acid or fumaric acid (e.g. dimethyl maleate, dibutyl maleate, and diethyl fumarate), a sodium salt of p-styrenesulfonic acid, acrylonitrile, methacrylonitrile, dienes (e.g. butadiene, cyclopentadiene, and isoprene), an aromatic vinyl compound (e.g. styrene, p-chlorostyrene, t-butylstyrene, α-methylstyrene, and sodium styrenesulfonate), N-vinylformamide, N-vinyl-N-methylfoimamide, N-vinylacetamide, N-vinyl-N-methylacetamide, vinylsulfonic acid, sodium vinylsulfonate, sodium allylsulfonate, sodium methacrylsulfonate, vinylidene fluoride , vinylidene chloride, vinyl alkyl ethers (e.g. methyl vinyl ether), ethylene, propylene, butane, isobutene, and N-phenylmaleimide. {0089}

The amount of the polyfunctional monomer component is preferably 0.5 to 70% by mass, and further preferably 1.0 to 50% by mass, based on the total of monomers. The monomer can be polymerized according to radical polymerization being an ordinary macromolecule synthesis method described in “Kobunshi Gosei no Jikken Hou (Experimental methods of polymer synthesis),” co-edited by Takayuki OTSU and Masayoshi KINOSHITA (Kagaku-Dojin Publishing Company, Inc.), and “Koza Jugo Hannou Ron 1 (Polymerization reaction theory course 1), Radical polymerization (I))” by Takayuki OTSU (Kagaku-Dojin Publishing Company, Inc.).

The monomer for the gel electrolyte used in the present invention can be radically polymerized by heating, light or an electron beam, or electrochemically, but particularly preferably polymerized by heating. In this case, examples of the polymerization initiator that can be preferably used includes an azo initiator such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), and dimethyl-2,2'-azobisisobutyrate; and a peroxide initiator such as lauryl peroxide, benzoyl peroxide and t-butyl peroxyoctoate. A preferred amount of polymerization initiator addition is 0.01 to 20% by mass, and a further preferred amount is 0.1 to 10% by mass, based on the total amount of monomer.

The weight composition of the monomer in the gel electrolyte is preferably in the range of 0.5 to 70% by mass, and further preferably in the range of 1.0 to 50% by mass. In the case where the gel electrolyte composition is prepared by the polymer crosslinking reaction, a polymer having a crosslinkable reactive group and a crosslinking agent are preferably added to the composition. A preferred reactive group includes a nitrogen-containing heterocyclic ring such as a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring, a morpholine ring, a piperidine ring and a piperazine ring. A preferred crosslinking agent includes a compound (electrophile) having two or more functional groups to which the nitrogen atom can make a nucleophilic attack. Specific examples include alkyl halide, aralkyl halide, sulfonate, acid anhydride, acid chloride and isocyanate having two or more functional groups. {0090}

To the electrolyte composition, metal iodide (e.g. Lil, NaI, Kl, Csl and Cal2), metal bromide (e.g. LiBr, NaBr, KBr, CsBr and CaBr2), quatemary ammonium bromide (e.g. tetraalkylammonium bromide and pyridinium bromide), a metal complex (e.g. ferrocyanate-ferricyanate and ferrocene-ferricinium ion), a sulfur compound (e.g. poly(sodium sulfíde) and alkyl thiol-alkyl disulfide), a viologen dye, hydroquinone-quinone, or the like may be added. These may be used by mixing with each other. {0091}

In the present invention, moreover, a basic compound such as t-butylpyridine, 2-picoline, and 2,6-lutidin described in J. Am. Ceram. Soc., 1997, vol. 80, No. 12, p. 3157-3171 may also be added. A preferred concentration in the case of adding the basic compound is in the range of 0.05 to 2 M. As the electrolyte, a charge transport layer containing a hole conductor material may also be used. As the hole conductor material, a 9,9'-spirobiíluorene derivative or the like can be used. {0092} (C) Electrically conductive support

As the electrically conductive support, a support having electroconductivity per se, such as a metal, or a glass or polymeric material having an electrically conductive layer on the surface can be used. It is preferable that the electrically conductive support is substantially transparent. The terms ”substantially transparent” means that the transmittance of light is 10% or more, preferably 50% or more, particularly preferably 80% or more. As the electrically conductive support, a support formed from glass or a polymeric material and coated with an electrically conductive metal oxide can be used. In this case, the amount of coating of the conductive metal oxide is preferably 0.1 to 100 g per square meter of the support made of glass or a polymeric material. In the case of using a transparent conductive support, it is preferable that light is incident from the support side. Examples of the polymeric material that may be preferably used include tetraacetylcellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAR), polysulfone (PSF), polyester sulfone (PES), polyether imide (PEI), cyclic polyolefm, and phenoxy bromide. The electrically conductive support may be provided with a light management function at the surface, and for example, the anti-reílective film having a high refractive index film and a low refractive index oxide film altemately laminated as described in ,ΙΡ-Α-2003-l23859, and the light guide function as described in JP-A-2002-260746 may be mentioned.

In addition to the above, a metallic support can also be preferably used. Examples thereof include titanium, aluminum, copper, nickel, iron, stainless Steel and copper. These metais may be alloys. Among these, titanium, aluminum and copper are further preferable; and titanium and aluminum are particularly preferable. {0093}

It is preferable to provide the electrically conductive support with a function of blocking ultraviolet light. For instance, there may be mentioned a method of adopting a fluorescent material that is capable of changing ultraviolet light to visible light, within the polymeric material layer or on the surface of the polymeric material layer. As another preferred method, a method of using an ultraviolet absorbent may also be used.

The conductive support may also be imparted with the functions described in JP-A-11-250944. {0094}

Preferred examples of the electrically conductive fdm include films of metais (for example, platinum, gold, silver, copper, aluminum, rhodium, and indium), carbon, and electrically conductive metal oxides (for example, indium-tin composite oxide, and fluorine-doped tin oxide).

The thickness of the conductive film layer is preferably 0.01 to 30 pm, more preferably 0.03 to 25 pm, and particularly preferably 0.05 to 20 pm.

In the present invention, an electrically conductive support having lower surface resistance is preferred. The surface resistance is preferably in the range of 50 Ω/cm2 or less, and more preferably 10 Ω/cm2 or less. The lower limit of the surface ·-) resistance is not particularly limited, but the lower limit is usually about 0.1 Ω/cm-. {0095}

Since the resistance value of the electrically conductive film is increased as the cell area increases, a collecting electrode may be disposed. A gas barrier film and/or an ion diffusion preventing film may be disposed between the support and the transparent conductive film. As the gas barrier layer, any of a resin film or an inorganic film can be used.

Furthermore, a transparent electrode and a porous semiconductor electrode photocatalyst-containing layer may also be provided. The transparent conductive layer may have a laminate structure, and preferred examples of the production method include the method of laminating FTO on ITO. {0096} (D) Semiconductor fine particles

The semiconductor fme particles locally have two or more kinds of metais or metallic compounds. In the present invention, the metallic compound means an inorganic compound containing a metal and at least one kind of atom other than the metal in a molecule. Specific examples include metal chalcogenide, metal carbonate, or metal nitrate. In the present invention, the semiconductor fme particles locally having two or more kinds of metais or metallic compounds mean those in which two or more kinds of metais or metallic compounds locally exist in the fme particles by treating the fine particles with two or more kinds of metais or metallic compounds. Specific examples of the semiconductor fme particles locally having two or more kinds of metais or metallic compounds include, as described later, those in which a core-shell structure is formed by two or more kinds of metais or metallic compounds, or those in which part of the surface and other parts are foimed of different metais or metallic compounds. Therefore, a simple mixture of two or more kinds of semiconductor fme particles is not included. When a dye having a specific substituent is used for the semiconductor fme particles locally having two or more kinds of metais or metallic compounds, the dye can be effectively adhered on the semiconductor fine particles, and thus a highly durable photoelectric conversion element can be realized. {0097}

The semiconductor fme particles preferably have a metal atom, metal chalcogenide, metal carbonate and/or metal nitrate.

The metal atom is preferably at least one kind selected from the group consisting of Ti (titanium), Sn (tin), Au (gold), Ag (silver), Cu (copper), Al (aluminum), Zr (zirconium), Nb (niobium), V (vanadium), and Ta (tantalum). The metal atom is further preferably Ti, Sn, Zr, Nb, V or Ta; and particularly preferably Nb, V or Ta.

The metal chalcogenide is preferably cadmium sulfide, cadmium selenide, or an oxide of at least one kind of metal selected from the group consisting of Ti (titanium), Sn (tin), Zn (zinc), Mg (magnesium), Al (aluminum), W (tungsten), Zr (zirconium), Hf (hafnium), Sr (strontium), In (indium), Ce (cerium), Y (yttrium), La (lanthanum), V (vanadium), and Ta (tantalum); further preferably an oxide of at least one kind of metal selected from the group consisting of Ti, Sn, Zn, Mg and Al; still further preferably an oxide of at least one kind of metal selected from the group consisting of Ti, Sn, Mg and

Al; and particularly preferably an oxide of at least one kind of metal selected from the group consisting of Ti, Sn and Al.

The metal carbonate is preferably at least one kind selected from the group consisting of calcium carbonate, potassium carbonate, and barium carbonate. The metal carbonate is further preferably calcium carbonate or barium carbonate, and particularly preferably calcium carbonate.

The metal nitrate is preferably lanthanum nitrate. {0098}

The semiconductor fine particles locally having two or more kinds of metais or metallic compounds preferably have the core-shell structure, and further preferably have the metal atom, the metal chalcogenide, the metal carbonate, and/or the metal nitrate by the core-shell structure. “Core-shell structure” herein means one having a shell (outer shell) part so as to cover the core part being the core. The core part does not need to be wholly covered with the shell part, but preferably 50% or more, further preferably 80% or more, and particularly preferably 90% of a surface area of the core part is covered with the shell part. The semiconductor fine particles having the core-shell structure can produce an effect of improving open circuit voltage by action of suppressing electrons injected from an excited dye from retuming to I3' in the electrolytic liquid. {0099}

The semiconductor fme particles having the core-shell structure can be obtained by adding semiconductor fme particles to be formed as the core into a solution of the metal atom or the metallic compound to be formed as the shell, and allowing the semiconductor fine particles to appropriately react with the metal atom or the metallic compound. The semiconductor fme particles to be formed as the core may be used in one kind or two or more kinds thereof, and the metal atom and the metallic compound to be formed as the shell can be used in one kind or two or more kinds thereof.

As the semiconductor fme particles having the core-shell structure, for example, semiconductor fine particles having a core-shell structure in which titanium oxide is contained as the core and calcium carbonate is contained as the shell can be prepared by the method described below, but preparation is not limited to this method and the conditions. First, 12 g (0.2 mol) of acetic acid is added dropwise to 58.6 g (0. 2 mol) of titanium tetraisopropoxide while stirring the resultant mixture with a stirrer. The mixture obtained is stirred for 15 minutes, and added to 290 mL of distilled water.

After stirring for 1 hour, 4 mL of 65% nitric acid is added, the resultant mixture is heated to 78°C over 40 minutes to keep a constant temperature for 75 minutes. A reaction vessel is removed from a heater, and 370 mL of water is added thereto. The liquid obtained is transíerre d into an autoclave made from titanium, and heated at 250°C for 12 hours. Then, 2.4 mL of 65% nitric acid is added, the resultant mixture is stirred by means of an ultrasonic homogenizer, and then a dispersion liquid is concentrated until the amount of titanium oxide reaches 13 to 15%. The concentrated solution is centrifugally separated, supematant distilled water is removed, and an amount of ethanol same with the amount of distilled water is added. Then, the resultant mixture is stirred by means of an ultrasonic homogenizer, and thus the dispersion liquid of titanium oxide as the core is obtained. Next, the titanium oxide particles being the core are added to an aqueous solution of 1 to 3% by mass of calcium acetate, and the resultant mixture is slirred for 30 minutes to 3 hours. After stirring, the calcium acetate aqueous solution is removed by centrifugai separation, and the remaining solid is washed with distilled water to perform centrifugai separation, and the resultant solid is calcined at 525°C for 1 hour. Thus, the semiconductor fine particles having the core-shell structure in which titanium oxide is contained as the core and calcium carbonate is contained as the shell can be obtained.

The semiconductor fine particles obtained can be judged to have the core-shell structure by observation by means of a transmission electron microscope (TEM). A volume ratio of the core part to the shell part is not particularly limited, but the volume ratio is preferably 50:50 to 98:2, and further preferably 70:30 to 95:5. The volume ratio can be determined by observation by means of TEM. {0100}

The semiconductor fine particles having the core-shell-structure preferably have, as the core part, a metal atom, metal chalcogenide or metal nitrate. The core part is further preferably a metal atom or metal chalcogenide, and particularly preferably metal chalcogenide. The shell part preferably has metal chalcogenide or metal carbonate.

When the metal atom is used as the core part, the metal atom is preferably at least one kind of metal atom selected from the group consisting of Ti, Nb, Sn, Zn and La; further preferably Ti, Sn or Zn; and particularly preferably Ti or Sn. When the metal chalcogenide is used as the core part, the metal chalcogenide is preferably at least one kind of metal oxide selected from oxides of Ti, Sn, Zn, Mg and Al; further preferably an oxide of Ti, an oxide of Sn, or an oxide of Zn; and particularly preferably an oxide of Ti or an oxide of Sn. When the metal nitrate is used as the core part, the metal nitrate is preferably lanthanum nitrate.

When the metal chalcogenide is used as the shell part, the metal chalcogenide is preferably oxides of Ti, Mg and Al. When the metal carbonate is used as the shell part, the metal carbonate is preferably calcium carbonate. {0101} A particle diameter of the semiconductor fine particles is preferably from 1 nm to 1,000 nm, further preferably from 2 nm to 100 nm in an average particle diameter of primary particles for the purpose of keeping high viscosity of semiconductor fine particle dispersion liquid. The particle diameter herein is a value measured by means of a laser diffraction-type particle diameter distribution analyzer, for example, Mastersizer (trade name) manufactured by Malvem Instruments Ltd. Two or more kinds of fine particles having different particle diameter distributions may be used in mixture, and in this case, it is preferable that the average size of the smaller particles is 5 nm or less. Moreover, for the purpose of enhancing a light trapping rate by scattering incident light, large particles having an average particle diameter exceeding 50 nm can also be added or applied as a separate layer at a low content based on the ultrafine particles described above. In this case, the content of the large particles is preferably 50% or less, and more preferably 20% or less, by mass of the content of the particles having an average particle diameter of 50 nm or less. The average particle diameter of the large particles that are added and mixed for the purpose described above is preferably 100 nm or more, and more preferably 250 nm or more. {0102}

In regard to the method for producing semiconductor fine particles, sol-gel methods described in, for example, SAKKA, Sumio, "Science of Sol-Gel Processes",

Agne Shofu Publishing, Inc. (1998) are preferred. It is also preferable to use a method developed by Degussa GmbH, in which a chloride is hydrolyzed at high temperature in an acid hydride salt to produce an oxide. When the semiconductor fine particles are titanium oxide, the sol-gel method, the gel-sol method, and the method of hydrolyzing a chloride in an acid hydride salt at high temperature, are all preferred, and the sulfuric acid method and chlorine method described in SEINO Manabu, "Titanium Oxide: Material Properties and Application Technologies", Gihodo Shuppan Co., Ltd. (1997) may also be used. Other preferred examples of the sol-gel method include the method described in Barbe et al., Journal of American Ceramic Society, Vol. 80, No. 12, pp. 3157-3171 (1997), and the method described in Bumside et al., Chemistry of Materials, Vol. 10, No. 9, pp. 2419-2425.

Upon manufacturing the semiconductor fine particles having the core-shell structure, as described above, the semiconductor fine particles to be formed as the core part can be first manufactured by the conventional method. For example, when titanium oxide (titania) is used for the core, the semiconductor fine particles to be formed as the core part are manufactured according to a method for manufacturing titania nanoparticles, preferably, a method by flame hydrolysis of titanium tetrachloride, a method of titanium tetrachloride combustion, hydrolysis of a stable chalcogenide complex, hydrolysis of orthotitanic acid, a method for dissolving and removing a soluble part, after forming semiconductor fine particles, from the soluble part and an insoluble part, and hydrotheimal synthesis of a peroxide aqueous solution. Then, the semiconductor fine particles of the core-shell structure are obtained by adding, to the solution of the metal atom or metallic compound to be served as the shell, the semiconductor fine particles to be served as the core by the method described above and allowing a suitable reaction.

Examples of the crystal structure of titania being the core part include anatase type, brookite type, and rutile type, and anatase type and brookite type structures are preferred in the present invention. It is also acceptable to mix a titania nanotube/nanowire/nanorod with the titania fine particles. {0103}

The semiconductor fine particles locally having two or more kinds of metais or metallic compounds, to be used in the present invention, may be semiconductor fine particles prepared so as to have two or more kinds of metal atoms by doping the metal atom into semiconductor fine particles. When the metal atom is doped, an effect of an increase of short-circuit current can be produced by action of improving electric charge injection efficiency due to a positive shift of flat band potential.

Specific examples of the metal atom to be doped include Nb, V and Ta. Nb or V is further preferred. For example, Nb powder and tetrabutyl titanate are added to an aqueous solution containing hydrogen peroxide and ammonia (v/v = 5/1), and the resultant mixture is stin ed. After stirring, excess hydrogen peroxide and ammonia are removed by heating to 80°C. The solution obtained is transferred into an autoclave made from Teflon (registered trade name), and stirred at 180°C for 20 hours. The precipitate obtained is washed with distilled water having pH = 7 and dried at 100°C for 6 hours, and thus the metal atom can be doped. {0104}

The semiconductor fine particles may include an additive other than the metal atom, the metal chalcogenide, the metal carbonate, and the metal nitrate. As the additive, an electrically conductive material is preferred. Specific examples of the electrically conductive material include an application-type electrically conductive material. Specific examples include a carbon material such as a carbon nanotube, graphene and graphite; a π-conjugated polymer being an electrically conductive polymer; and a silver nanowire. These materiais can be formed by applying a thin film to develop electrical conductivity, and thus the semiconductor fine particles can be manufactured at a low cost. Among the materiais, a carbon material such as graphite, graphene and a carbon nanotube is preferred, and graphene is further preferred. When the electrically conductive material is added to the semiconductor fine particles, the above-described dye excited by light irradiation can be held as it is, a reaction of returning the dye to a ground state can be suppressed, and thus cell performance, particularly photoelectric conversion efficiency, can be improved. Graphite or graphene having a planar structure is further preferred. The additives such as the electrically conductive material can be added to the semiconductor fine particles by adding the additive to a paste of semiconductor fine particles and then applying a method for dispersing the resultant mixture by means of the ultrasonic homogenizer. As the electrically conductive material, one having a value of electric resistance of 107 Ω-cm or less is preferred, and one having a value of 103 Ω-cm or less is further preferred.

In addition thereto, a binder for improving necking of the semiconductor fine particles with each other may be used, or an additive may also be used on the surface for preventing reverse electron transfer, for the semiconductor fine particles. Preferred examples of the additive include ITO or SnO particles, whiskers, a fibrous graphite/carbon nanotube, a zinc oxide necking coupler, fibrous materiais such as celluloses, metais, organosilicon, dodecyl benzenesulfonate, charge transfer coupling molecules of silane compounds or the like, and a potential gradient type dendrimer. For the purpose of eliminating surface defects of semiconductor fme particles, the semiconductor fine particles may be subjected to an acid base treatment or an oxidation reduction treatment before the adsorption of a dye. Furthermore, the semiconductor fine particles may also be subjected to etching, an oxidation treatment, a hydrogen peroxide treatment, a dehydrogenation treatment, UV-ozone, oxygen plasma or the like. {0105}

The semiconductor fine particles locally having two or more kinds of metais or metallic compounds, to be used in the present invention, are preferably semiconductor fme particles having a core-shell structure that has metal chalcogenide as the core part and metal chalcogenide or metal carbonate as the shell part, or semiconductor fme particles obtained by doping the metal atom into metal chalcogenide; and more preferably semiconductor fme particles having a core-shell structure that has metal chalcogenide selected from the group consisting of titanium oxide (TiO2) and tin oxide (SnO2) as the core part and metal chalcogenide or metal carbonate selected from the group consisting of aluminum oxide (A12O3), magnesium oxide (MgO), calcium carbonate (CaCCb), titanium oxide (TiO2), and titanium oxide/magnesium oxide (TiO2/MgO) as the shell part, or semiconductor fme particles obtained by doping at least one kind of metal atom selected from the group consisting of Nb, V and Ta into metal chalcogenide selected from the group consisting of titanium oxide and tin oxide. {0106} (E) Preparation of semiconductor fme particle dispersion liquid and production of semiconductor fme particles-coated layer A semiconductor fme particles-coated layer can be obtained by applying a semiconductor fine particle dispersion liquid on the electrically conductive support mentioned above, and appropriately heating the coated support. In the semiconductor fme particle dispersion liquid, it is preferable that the content of solids excluding the semiconductor fine particles is 10% by mass or less of the total amount of the semiconductor fine particle dispersion liquid.

Examples of the method of producing a semiconductor fme particle dispersion liquid include, in addition to the sol-gel method described above, a method of precipitating the semiconductor in the foim of fme particles in a solvent upon synthesis and directly using the fine particles; a method of ultrasonicating fme particles, and thereby pulverizing the fme particles into ultrafine particles; a method of mechanically grinding a semiconductor using a mill or a mortar, and pulverizing the ground semiconductor; and the like. As a dispersion solvent, water and/or various organic solvents can be used. Examples of the organic solvent include alcohols such as methanol, ethanol, isopropyl alcohol, citronellol and α-terpineol; ketones such as acetone; esters such as ethyl acetate; dichloromethane, and acetonitrile.

At the time of dispersing the fme particles, for example, a polymer such as polyethylene glycol, butylcellulose, ethylcellulose, hydroxyethylcellulose or carboxymethylcellulose; a surfactant; an acid; or a chelating agent may be used in a small amount as a dispersing aid, as necessary. It is preferable that such a dispersing aid is mostly eliminated before the step of forming a film on the electrically conductive support, by a filtration method, a method of using a separating membrane, or a centrifugation method. The semiconductor fme particle dispersion liquid is such that the content of solids excluding semiconductor fme particles is 10% by mass or less based on the total amount of the dispersion liquid. This concentration is preferably 5% or less, further preferably 3% or less, further preferably 1% or less, further preferably 0.5% or less, and particularly preferably 0.2% or less. In other words, the semiconductor fine particle dispersion liquid may contain a solvent and solids excluding semiconductor fine particles in an amount of 10% by mass or less based on the total amount of the semiconductor fme particle dispersion liquid. In the present, it is preferable that the semiconductor fine particle dispersion liquid is substantially composed of semiconductor fine particles and a dispersion solvent.

If the viscosity of the semiconductor fine particle dispersion liquid is too high, the dispersion liquid undergoes aggregation, and film formation cannot be achieved.

On the other hand, if the viscosity of the semiconductor fine particle dispersion liquid is too low, the liquid flows out, and film formation cannot be achieved in some cases. Therefore, the viscosity of the dispersion liquid is preferably 10 to 300 N-s/m2 at 25°C, and more preferably 50 to 200 N-s/m2 at 25°C. {0107}

In regard to the method of applying the semiconductor fine particle dispersion liquid, a roller method, a dipping method or the like can be used as a method involving application. Furthermore, an air knife method, a blade method or the like can be used as a method involving metering. As a method that can equally utilize a method involving application and a method involving metering, a wire bar method disclosed in JP-B-58-4589 (“JP-B” means examined Japanese patent publication), an extrusion method, a curtain method and a slide hopper method described in U.S. Patent No. 2,681,294 and the like are preferred. It is also preferable to apply the dispersion liquid by a spinning method or a spray method, using a versatile machine. Preferred examples of a wet printing method include the three major printing methods of relief printing, offset printing and gravure printing, as well as intaglio printing, rubber plate printing, screen printing and the like. Among these, a preferable film forming method is selected in accordance with the liquid viscosity or the wet thickness. Furthermore, since the semiconductor fine particle dispersion liquid used in the present invention has high viscosity and has viscidity, the fine particle dispersion liquid often has a strong cohesive power, and may not have good affinity to the support upon coating. Under such circumstances, when surface cleaning and hydrophilization are carried out through a UV-ozone treatment, the affinity between the applied semiconductor fine particle dispersion liquid and the surface of the electrically conductive support increases, and thus it becomes easier to apply the semiconductor fine particle dispersion liquid.

The thickness of the entire semiconductor fine particle layer is preferably 0.1 to 100 pm, more preferably 1 to 30 pm, and even more preferably 2 to 25 pm. The amount of the coated semiconductor fme particles per square meter of the support is preferably 0.5 to 400 g, and more preferably 5 to 100 g. {0108}

The applied layer of semiconductor fme particles is subjected to a heating treatment, for the purpose of reinforcing the electronic contact between semiconductor fme particles and enhancing the adhesiveness of the semiconductor fme particles to the support, and also in order to dry the applied semiconductor fme particle dispersion liquid. The porous semiconductor fme particle layer can be formed by this heating treatment. In addition thereto, according to characteristics and an application of a member, the semiconductor fme particle layer may be appropriately formed by a known method. For example, a material, a preparation method, and a production method disclosed in JP-A-2001-291534 can be referred to, and are incorporated herein by reference.

Furthermore, light energy can also be used in addition to the heating treatment. For example, when titanium oxide is used for the semiconductor fme particles, the surface may be activated by providing the light that is absorbed by the semiconductor fme particles, such as ultraviolet light, or only the surface of the semiconductor fme particles can be activated with a laser light or the like. When the semiconductor fme particles are irradiated with a light that is absorbed by the fme particles, the impurities adsorbed to the particle surfaces are decomposed as a result of activation of the particle surfaces, and a State preferable for the purpose described above can be attained. In the case of using the heating treatment and ultraviolet light in combination, the heating is carried out at a temperature of preferably 100°C or more and 250°C or less, more preferably 100°C or more and 150°C or less, while the semiconductor fme particles are irradiated with the light that is absorbed by the fine particles. As such, by inducing photoexcitation of the semiconductor fine particles, the impurities incorporated in the fme particle layer can be washed away by photodecomposition, and the physical bonding between the fme particles can be reinforced. {0109}

In addition to the processes of applying the semiconductor fme particle dispersion liquid on the electrically conductive support and subjecting the semiconductor fme particles to heating or light irradiation, other treatments may also be carried out. Preferred examples of such treatments include the passage of electric current, Chemical treatment, and the like.

It is also acceptable to apply pressure after coating, and examples of the method of applying pressure include the methods described in JP-T-2003-500857 (“JP-T” means searched and published International patent publication) and the like.

Examples of the light irradiation method include the methods described in JP-A-2001 -357896 and the like. Examples of the methods utilizing plasma, microwaves or electric current include the methods described in JP-A-2002-353453 and the like. Examples of the Chemical treatment include the methods described in JP-A-2001 -357896 and the like. {0110}

The method of coating the semiconductor fme particles on the electrically conductive support is included in the above-described method, such as a method of applying a semiconductor fme particle dispersion liquid on an electrically conductive support; and a method of applying a precursor of the semiconductor fme particles on an electrically conductive support, hydrolyzing the precursor under the action of the moisture in air, and thereby obtaining a semiconductor fme particle film, as described in Japanese Patent No. 2664194.

Examples of the precursor include (NH4)2TiF6, titanium peroxide, a metal alkoxide, a metal complex and an organic acid metal salt.

Examples thereof include a method of applying a slurry additionally containing a metal organic oxide (alkoxide or the like), and forming a semiconductor film by a heating treatment, a light treatment or the like; and a method of characterizing the pH of the slurry additionally containing an inorganic precursor, and the slurry, and the properties and State of the dispersed titania particles. These slurries may be added with a small amount of binder. Examples of the binder include celluloses, fluoropolymers, a crosslinked rubber, polybutyl titanate, and carboxymethylcellulose.

Examples of the technique related to the formation of a layer of semiconductor fine particles or a precursor layer thereof include a method of hydrophilizing the layer by a physical method using corona discharge, plasma, UV or the like; a Chemical treatment based on an alkali or on polyethylene dioxythiophene and polystyrenesulfonic acid or the like; formation of an intermediate film for bonding of polyaniline or the like. {0111}

As the method of coating semiconductor fine particles on an electrically conductive support, (2) dry methods or (3) other methods may be used together with the (1) wet methods described above. Preferred examples of the (2) dry methods include the methods described in JP-A-2000-231943 and the like. Preferred examples of the (3) other methods include the methods described in JP-A-2002-134435 and the like. {0112}

Examples of the dry method include deposition, sputtering, an aerosol deposition method, and the like. Furthermore, the electrophoresis method and the electrocrystallization method may also be used.

Furthermore, a method of first preparing a coating film on a heat resistant base, and then transferring the film to a film made of plastic or the like, may be used. Preferably, a method of transferring a layer through EVA as described in JP-A-2002-184475; a method of forming a semiconductor layer and a conductive layer on a sacrificing base containing an inorganic salt that can be removed by ultraviolet rays or a water-based solvent, subsequently transferring the layers to an organic base, and removing the sacrificing base as described in JP-A-2003-98977; and the like may be used. {0113}

It is preferable for the semiconductor fine particles to have a large surface area, so that a large amount of dye can adsorb to the surface. For example, while the semiconductor fine particles have been coated on the support, the surface area is preferably 10 times or more, and more preferably 100 times or more, relative to the projected surface area. The upper limit of this value is not particularly limited, but the upper limit is usually about 5000 times. Preferred examples of the structure of the semiconductor fine particles include the structures disclosed in JP-A-2001-93591 and the like. {0114}

In general, as the thickness of the semiconductor fine particle layer increases, the amount of dye that can be supported per unit area increases, and therefore, the light absorption efficiency is increased. However, since the diffusion distance of generated electrons increases along, the loss due to charge recombination is also increased. Although a preferred thickness of the semiconductor fine particle layer may vary with the utility of the element, the thickness is typically 0.1 to 100 pm. In the case of using it in the photoelectric conversion element for a photoelectrochemical cell, the thickness of the semiconductor fine particle layer is preferably 1 to 50 pm, and more preferably 3 to 30 pm. The semiconductor fme particles may be calcined after being applied on the support, at a temperature of 100 to 800°C for 10 minutes to 10 hours, so as to bring about cohesion of the particles. When a glass support is used, the film forming temperature is preferably 400 to 600°C.

When a polymer material is used as the support, it is preferable that the formed film is heated at 250°C or less. The method of forming a film in this case may be any of (1) a wet method, (2) a dry method, and (3) an electrophoresis method (including an electrocrystallization method); preferably (1) a wet method or (2) a dry method; and further preferably (1) a wet method.

The amount of coating of the semiconductor fine particles per square meter of the support is preferably 0.5 to 500 g, and more preferably 5 to 100 g. {0115} (F) Photoconductor layer

When a dye is adsorbed onto the semiconductor fine particle layer produced as described above, a photoconductor layer can be formed.

In order to adsorb the dye onto the semiconductor fme particles, well-dried semiconductor fine particles are preferably immersed into a dye solution for dye adsorption formed of a solvent and the dye for a long time. In regard to the solvent that is used in the dye solution for dye adsorption, any solvent capable of dissolving the dye for use in the present invention can be used without any particular limitation. For example, ethanol, methanol, isopropanol, toluene, t-butanol, acetonitrile, acetone or n-butanol can be used. Among them, ethanol and toluene can be preferably used.

The dye solution for dye adsorption formed from a solvent and the dye may be heated if necessary, at 50°C to 100°C. Adsorption of the dye may be carried out before or after the process of applying the semiconductor fme particles. Adsorption of the dye may also be conducted by simultaneously applying the semiconductor fme particles and the dye. Any unadsorbed dye is removed by washing. In the case of performing calcination of the coating film, it is preferable to carry out the adsorption of the dye after calcination. After calcination has been performed, it is particularly preferable to perfoim the adsoiption of the dye rapidly before water adsorbs to the surface of the coating film. The dyes are selected so that the wavelength region for photoelectric conversion can be made as broad as possible when the dyes are mixed. In the case of using a mixture of dyes, it is preferable to prepare a dye solution for dye adsorption by dissolving all of the dyes used therein. {0116}

The overall amount of use of the dye is preferably 0.01 to 100 millimoles, more preferably 0.1 to 50 millimoles, and particularly preferably 0.1 to 10 millimoles, per square meter of the support. In this case, the amount of use of the dye is preferably adjusted to 5% by mole or more.

The amount of the dye adsorbed to the semiconductor fme particles is preferably 0.001 to 1 millimole, and more preferably 0.1 to 0.5 millimoles, based on 1 g of the semiconductor fme particles. When the amount of the dye is adjusted to such a range, the sensitization effect for the semiconductor can be sufficiently obtained. {0117}

For the purpose of reducing the interaction between dye molecules such as association, a colorless compound may be co-adsorbed. Examples of the hydrophobic compound that is co-adsorbed include steroid compounds having a carboxyl group (for example, cholic acid and pivaloyl acid).

After the dye has been adsorbed, the surface of the semiconductor fme particles may be treated using amines. Preferred examples of the amines include 4-tert-butylpyridine, and polyvinylpyridine. These may be used directly when the compounds are liquids, or may be used in a state of being dissolved in an organic solvent. {0118} (G) Counter electrode

The counter electrode is an electrode working as a positive electrode in the photoelectiOchemical cell. The counter electrode usually has the same meaning as the electrically conductive support described above, but in a construction which is likely to maintain a sufficient strength, a support is not necessarily required. However, a construction having a support is advantageous in terms of sealability. Examples of the material for the counter electrode include platinum, carbon, and electrically conductive polymers. Preferred examples include platinum, carbon, and electrically conductive polymers. {0119} A preferred structure of the counter electrode is a structure having a high charge collecting effect. Preferred examples thereof include those described in JP-T-10-505192 and the like.

In regard to the light-receiving electrode, a composite electrode of titanium oxide and tin oxide (TiCb/SnCb) or the like may be used. Examples of mixed electrodes of titania include those described in JP-A-2000-113913 and the like. Examples of mixed electrodes of materiais other than titania include those described in JP-A-2001-185243, JP-A-2003-282164 and the like. {0120} (H) Constitution of photoelectric conversion element

As a constitution of the photoelectric conversion element, an eclectically conductive support (electrode layer), a photoelectric conversion layer (a photoconductor layer and a charge transfer layer), a hole transport layer, a conductive layer, and a counter electrode layer can be sequentially laminated. A hole transport material functioning as a p-type semiconductor can also be used as the hole transport layer. For the hole transport layer, for example, an inorganic or an organic hole transport material can be used. Examples of the inorganic hole transport material include Cul, CuO, NiO and the like. Moreover, specific examples of the organic hole transport material include a polymer material and a low-molecular-weight material. Examples of the polymer material include polyvinyl carbazole, polyamine, organic polysilane and the like. Examples of the low-molecular-weight material include triphenylamine derivatives, stilbene derivatives, hydrazone derivatives, phenamine derivatives and the like. Among these, an organic polysilane is preferable since it is different from conventional carbon polymers, and a polymer having a Si main chain and δ electrons delocalized along the main chain contribute to the photoconduction, so that high hole mobility is exhibited (Phys. Rev. B, 1987, vol. 35, p. 2818). {0121}

The conductive layer is not particularly limited as long as it is highly conductive. Examples thereof include one formed of an inorganic conductive material, an organic conductive material, a conductive polymer, an intermolecular charge-transfer complex or the like. Among them, the intermolecular charge-transfer complex composed of a donor material and an acceptor material is preferable. Among these, one formed of an organic donor and an organic acceptor is preferably used. The donor material is preferably rich in electrons in a molecular structure thereof. Examples thereof include an organic donor material, such as a substance having a substituted or non-substituted amine group, a hydroxyl group, an ether group, a selen atom or a sulfur atom in π electrons of its molecule. More specifically, phenylamine-series materiais, triphenylmethane-series materiais, carbazole-series materiais, phenol-series materiais and tetrathiafulvalene-series materiais can be exemplified. The acceptor material is preferably poor in electrons in a molecular structure thereof. Examples thereof include fullerene, and an organic acceptor material, such as a substance having a substituent, e.g. a nitro group, a cyano group, a carboxyl group or a halogen group, in π electrons of its molecule. More specifically, PCBM; quinone-series materiais such as benzoquinone-series materiais, naphthoquinone-series materiais and the like; fluorenone-series materiais; chloranils-series materiais; bromanil-series materiais; tetracyanoquinodimethane-series materiais; tetracyanoneethylene-series materiais; and the like can be exemplified.

The thickness of the conductive layer is not particularly limited, but a thickness with which the pores of the photovoltaic layer are entirely filled is preferable. {0122}

As a constitution of the element, the element may have a structure formed by sequentially laminating a first electrode layer, a first photoconductor layer, an electrically conductive layer, a second photoconductor layer, and a second electrode layer. In this case, the dyes used for the first photoconductor layer and the second photoconductor layer may be identical or different. When the dyes are different, absorption spectra are preferably different. In addition thereto, a structure and a member that are applied to this kind of electrochemical element can be appropriately applied. {0123}

The light-receiving electrode may be a tandem type electrode so as to increase the utility ratio of the incident light, or the like. Preferred examples of the tandem type construction include those described in JP-A-2000-90989, JP-A-2002-90989 and the like.

The light-receiving electrode may be provided with the photo management function by which light scattering and reflection are efficiently achieved inside the light-receiving electrode layer. Preferred examples thereof include those described in JP-A-2002-93476 and the like. {0124}

It is preferable to form a short circuit preventing layer between the electrically conductive support and the photoconductor layer, so as to prevent reverse current due to a direct contact between the electrolyte liquid and the electrode. Preferred examples thereof include those described in JP-T-6-507999 and the like.

It is preferable to employ a spacer or a separator so as to prevent the contact between the light-receiving electrode and the counter electrode. Preferred examples thereof include those described in JP-A-2001-283941 and the like. {0125}

Methods for sealing a cell or a module preferably include a method using a polyisobutylene thermosetting resin, a novolak resin, a photocuring (meth)acrylate resin, an epoxy resin, an ionomer resin, glass frit, or alkoxide for alumina; and a method for laser fusing of low-melting point glass paste. When the glass frit is used, a mixture prepared by mixing powder glass with an acrylic resin being a binder may be used.

EXAMPLES {0126}

The present invention will be described in more detail based on examples given below, but the invention is not meant to be limited by these. {0127}

Synthesis Example 1 (Preparation of Exemplified Dye (X-26))

The exemplified dye (X-26) was prepared according to the method shown in the following scheme. {0128}

{0129} (i) Preparation of Compound (d-1-2)

To mixed solution of 70 mL of triethylamine and 50 mL of tetrahydrofuran (THF), 25 g of Compound (d-1-1), 33.8 g of Pd(dba), 8.6 g of triphenyl phosphine, 2.5 g of copper iodide, and 25.2 g of 1-heptyne were added. The resultant mixture was

stirred at room temperature, and stirred at 8O°C for 4.5 hours. After concentration, purification was performed by means of column chromatography, and thus 26,4 g of Compound (d-1-2) was obtained. {0130} (ii) Preparation of Compound (d-1-4)

Under a nitrogen atmosphere at -15°C, 6.7 g of Compound (d-1-3) was dissolved in 200 mL of terahydrofuran, and LDA (lithium diisopropylamide) that was separately prepared was added dropwise in an amount of 2.5 equivalents of Compound (d-1-3), and the resultant mixture was stirred for 75 minutes. Then, a solution in which 15 g of Compound (d-1 -2) was dissolved in 30 mL of terahydrofuran was added dropwise, and the resultant mixture was stirred at 0°C for 1 hour, and stirred at room temperature for 17 hours. After concentration, 150 mL of water was added, and the resultant liquid was separated and extracted with 150 mL of methylene chloride, the resultant organic layer was washed with salt water, and the organic layer was concentrated. The crystal obtained was recrystallized with methanol, and then 18.9 g of Compound (d-1-4) was obtained. {0131} (iii) Preparation of Compound (d-1-5)

To 1,000 mL of toluene, 13.2 g of Compound (d-1-4) and 1.7 g of PPTS (pyridinium para-toluenesulfonate) were added, and the resultant mixture was subjected to heating reflux for 5 hours under a nitrogen atmosphere. After concentration, the resultant liquid was separated with a saturated aqueous solution of sodium hydrogencarbonate and methylene chloride, and the resultant organic layer was concentrated. The crystal obtained was recrystallized with methanol and methylene chloride, and thus 11.7 g of Compound (d-1-5) was obtained. {0132} (iv) Preparation of Exemplified Dye (X-26)

To 60 mL of DME (dimethylformamide), 4.0 g of Compound (d-1-5) and 2.2 g of Compound (d-1-6) were added, and the resultant mixture was sti rred at 70°C for 4 hours. Then, 2.1 g of Compound (d-1-7) was added, and the resultant mixture was stirred under heating at 160°C for 3.5 hours. Then, 19.0 g of ammonium thiocyanate was added, and the resultant mixture was stirred at 130°C for 5 hours. After concentration, 1.3 mL of water was added, the resultant mixture was filtered, and the resultant cake was washed with diethyl ether. A crude purified product was dissolved in a methanol solution together with TBAOH (tetrabutylammonium hydroxide) and purified by means of a Sephadex LH-20 column. A fraction in the main layer was recovered, and after concentration, a 0.2 M nitric acid solution was added, precipitates were filtered, washed with water and diethyl ether, and thus 600 mg of a crude purified product was obtained. The crude purified product was dissolved in a methanol solution, and 1 M of nitric acid was added, precipitates were filtered, and then washed with water and diethyl ether, and thus 570 mg of the exemplified dye (X-26) was obtained. {0133}

The structure of the exemplified dye (X-26) obtained was confirmed by NMR measurement. 'H-NMR (DMSO-dô, 400MHz): ô(ppm) in aromatic regions: 9.37 (1H, d), 9.11 (1H, d), 9.04 (1H, s), 8.89 (2H), 8.74 (1H, s), 8.26 (1H, d), 8.10-7.98 (2H), 7.85-7.73 (2H), 7.60 (1H, d), 7.45-7.33 (2H), 7.33-7.12 (5H, m), 6.92 (1H, d) {0134}

When the exemplified dye (X-26) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absorption measurement was carried out, the absorption maximum wavelength was 568 nm. {0135}

Synthesis Example 2 (Preparation of Exemplified Dye (X-30))

Compound (d-2-4) was prepared according to the method shown in the following scheme, and the exemplified dye (X-30) was prepared in a manner similar to the exemplified dye (X-26), except that the compound (d-1-2) was replaced with the compound (d-2-4). {0136}

{0137}

When the exemplified dye (X-30) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absoiption measurement was carried out, the absorption maximum wavelength was 570 nm. {0138}

Synthesis Example 3 (Preparation of Exemplified Dye (X-32))

Compound (d-3-2) was prepared according to the method shown in the following scheme, and the exemplified dye (X-32) was prepared in a manner similar to the exemplified dye (X-26), except that the compound (d-1-2) was replaced with the compound (d-3-2). {0139}

{0140}

When the exemplified dye (X-32) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absorption measurement was carried out, the absorption maximum wavelength was 574 nm. {0141}

Synthesis Example 4 (Preparation of Exemplified Dye (X-31))

Compound (d-4-2) was prepared according to the method shown in the following scheme, and the exemplified dye (X-31) was prepared in a manner similar to the exemplified dye (X-26), except that the compound (d-1-2) was replaced with the compound (d-4-2). {0142}

{0143}

When the exemplified dye (X-31) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absorption measurement was carried out, the absorption maximum wavelength was 588 nm. {0144}

Synthesis Example 5 (Preparation of Exemplified Dye (X-33))

Compound (d-5-6) was prepared according to the method shown in the following scheme, and the exemplified dye (X-33) was prepared in a manner similar to the exemplified dye (X-26), except that the compound (d-1-5) was replaced with the compound (d-5-6). {0145}

{0146}

When the exemplified dye (X-33) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absorption measurement was carried out, the absorption maximum wavelength was 570 nm. {0147}

Synthesis Example 6 (Preparation of Exemplified Dye (X-34))

Compound (d-6-3) was prepared according to the method shown in the following scheme, and the exemplified dye (X-34) was prepared in a manner similar to

the exemplified dye (X-26), except that the compound (d-1-5) was replaced with the compound (d-6-3). {0148}

{0149}

When the exemplified dye (X-34) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absoiption measurement was carried out, the absorption maximum wavelength was 571 nm. {0150}

Synthesis Example 7 (Preparation of Exemplified Dye (X-3 5))

The exemplified dye (X-35) was prepared in a manner similar to the exemplified dye (X-30), except that the compound (d-2-2) was replaced with the compound (d-7-1) described below. {0151}

{0152}

When the exemplified dye (X-35) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absoiption measurement was carried out, the absorption maximum wavelength was 574 nm. {0153}

Synthesis Example 8 (Preparation of Exemplified Dye (X-36))

The exemplified dye (X-36) was prepared in a manner similar to the exemplified dye (X-26) according to the method shown in the following scheme. {0154}

{0155}

When the exemplified dye (X-36) obtained was prepared to be 8.5 pmol/L in the dye concentration with ethanol solvent and spectral absorption measurement was carried out, the absorption maximum wavelength was 580 nm. {0156}

The exemplified dye (X-22), the exemplified dye (X-23), the exemplified dye (X-24), the exemplified dye (X-25), the exemplified dye (X-27), and the exemplified dye (X-28) were also prepared in a similar manner.

Moreover, the following dyes (X-19), (X-20) and (X-21) were also prepared as comparative dyes with reference to the method described in J. Am. Chem. Soc., 2001, vol. 123, p. 1613-1624. {0157}

{0158}

{0159} <Evaluation of Dyes>

The maximum absorption wavelengths of the above-described dyes (X-19) to (X-36) were measured. The results are shown in Table 1. The measurement was conducted using a spectrophotometer U-4100 (trade name, manufactured by Hitachi High-Technologies Corp.). A solution was adjusted to have a concentration of 2 μΜ using THF:ethanol =1:1. {0160}

Table 1

{0161} <Preparation of dispersion liquid of semiconductor fme particles (II) locally having two or more kinds of metais or metallic compounds>

Semiconductor fine particles (I ) were prepared and, using the same, semiconductor fine particles (II) locally having two or more kinds of metais or metallic compounds were prepared. 1. Preparation of semiconductor fine particles (I) (1) Tin oxide (SnO2)

Puratronic (trade name) manufactured by Alfa Aesar Company was used without purification. When a particle diameter of the tin oxide was measured using a laser diffraction-type particle diameter distribution analyzer (Mastersizer (trade name), manufactured by Malvem Instruments Ltd.), the particle diameter was 20 to 30 nm. (2) Titanium oxide (TiO2)

Acetic acid (0.2 mol) was added dropwise to titanium isopropoxide (0.2 mol) at room temperature, and the resultant mixture was stirred for 15 minutes. Then, 290 mL of distilled water was added, and the resultant mixture was stirred for 1 hour. After 1 hour, a 65% HNO3 aqueous solution was added, the resultant mixture was heated to 78°C over 40 minutes, and stirred for 75 minutes. After stimng, 290 mL of distilled water was added, and thus a titanium oxide sol solution (crystal system: amorphous) was produced. When the titanium oxide sol solution was stirred at 250°C for 12 hours using an autoclave, an aqueous solution dispersed with titanium oxide particles was obtained.

Titanium oxide was obtained by filtering the aqueous solution. The crystal system of titanium oxide obtained was an anatase type. When a particle diameter of the tin oxide was measured using a laser diffraction-type particle diameter distribution analyzer (Mastersizer (trade name), manufactured by Malvern Instruments Ltd.), the particle diameter was 10 to 30 nm. {0162} 2. Preparation of semiconductor fine particles (II) locally having two or more kinds of metais or metallic compounds (1) Preparation of core-shell semiconductor fine particles (a) Preparation of semiconductor fine particles (II ) having aluminum oxide (AI2O3) as a shell part

The semiconductor fine particles (I) were dispersed into 2 to 150 mM of trimethylaluminum aqueous solution, allowed to react for 8 seconds under a 200°C atmosphere, and thus semiconductor fme particles (II) were obtained. When the semiconductor fine particles obtained were observed by means of a transmission electron microscope (TEM), the semiconductor fme particles (II) were found to have a core-shell structure in which tin oxide or titanium oxide was contained as a core part, and aluminum oxide was contained as a shell part. When a volume ratio of core:shell was observed by means of TEM, the volume was from 90:10 to 98:2. When a particle diameter of the obtained semiconductor fme particles was measured using a laser diffraction-type particle diameter distribution analyzer (Mastersizer (trade name), manufactured by Malvem Instruments Ltd.), the particle diameter was 20 to 30 nm. {0163} (b) Preparation of semiconductor fme particles (II) having magnesium oxide (MgO) as a shell part

The semiconductor fme particles (I) were immersed for 1 minute into an ethanol solution (60 to 70°C) into which 2 to 150 mM of magnesium acetate was dissolved, and the resultant fme particles were washed and then calcined at 500°C, and thus semiconductor fine particles (II) were obtained. When the semiconductor fme particles obtained were observed by means of a transmission electron microscope (TEM), semiconductor fme particles (II) were found to have a core-shell structure in which tin oxide or titanium oxide was contained as a core part, and magnesium oxide was contained as a shell part. When a volume ratio of core:shell was observed by means of TEM in a similar manner as described above, the volume ratio was from 90:10 to 98:2. When a particle diameter of the semiconductor fme particles was measured in a similar manner as described above, the particle diameter was 20 to 30 nm. {0164} (c) Preparation of semiconductor fine particles (II) having titanium oxide (TiO2) as a shell part

The semiconductor fme particles (1) were immersed for 1 hour into an TiCfi solution (70°C) of from 2 to 20 mM, and the resultant fine particles were washed and then calcined at 500°C, and thus semiconductor fme particles (II) were obtained. When the semiconductor fme particles obtained were observed by means of a transmission electron microscope (TEM), semiconductor fme particles (II) were found to have a core-shell structure in which tin oxide or titanium oxide was contained as a core part, and titanium oxide was contained as a shell part. When a volume ratio of core:shell was observed by means of TEM in a similar manner as described above, the volume ratio was from 90:10 to 98:2. When a particle diameter ofthe semiconductor fme particles was measured in a similar manner as described above, the particle diameter was 20 to 30 nm. {0165} (d) Preparation of semiconductor fme particles (II) having calcium carbonate ( CaCCb) as a shell part

The semiconductor fme particles (I) were immersed for a predetermined period of time into an aqueous solution of 1 to 3% by mass of calcium acetate, and the resultant fme particles were calcined at 525°C, and thus semiconductor fine particles (II) were obtained. When the semiconductor fme particles obtained were observed by means of a transmission electron microscope (TEM), semiconductor fme particles (II) were found to have a core-shell structure in which tin oxide or titanium oxide was contained as a core part, and calcium carbonate was contained as a shell part. When a volume ratio of core:shell was observed by means of TEM in a similar manner as described above, the volume ratio was from 90:10 to 98:2. When a particle diameter of the semiconductor fme particles was measured in a similar manner as described above, the particle diameter was 20 to 30 nm. {0166} (e) Preparation of semiconductor fme particles (II) having two or more kinds of materiais as a shell part

Semiconductor fme particles having two or more kinds of materiais as a shell part were prepared by repeating the methods described in (a) to (d). When the semiconductor fine particles obtained were observed by means of a transmission electron microscope (TEM), semiconductor fme particles (II) are found to have a core-shell structure in which two or more kinds of materiais used were contained as a shell part relative to a core part. When a volume ratio of core:shell was observed by means of TEM in a similar manner as described above, the volume ratio was from 90:10 to 98:2. When a particle diameter of the semiconductor fine particles was measured in a similar manner as described above, the particle diameter was 20 to 40 nm. {0167} (f) Addition of electrically conductive material

Graphene was used as an electrically conductive material. Graphene was prepared by the following methods from flake graphite (average particle diameter: 4 pm, purity 99.95%, Qingdao (trade name) manufactured by Qingdao Tianhe Graphite Co., Ltd. (People’s Republic of China)).

First, 5 g of graphite described above and 3.75 g of NaNCrt were added to a flask, 375 mL of H2SO4 was added, and the resultant mixture was stirred under ice cooling. Then, 22.5 g of KM 116)4 was added over about 1 hour. The resultant mixture was stirred for 2 hours under ice cooling, and then stirred for five days at room temperature. Then, 700 mL of a 5 wt% sulfuric acid aqueous solution was added, and the resultant mixture was stirred for 1 hour at a temperature maintained at 98°C. The mixture obtained was further stirred at 98CC for 2 hours. After a temperature was decreased to 60°C, 15 mL of a hydrogen peroxide aqueous solution was added, and the resultant mixture was stirred at room temperature for 2 hours. In order to remove impurity ions, the mixture obtained was purified by performing the following operations 15 times. (Purification method)

Centrifugai separation was performed to remove a supematant. Then, 2 L of mixed aqueous solution of 3 wt% H2SO4/O.5 wt% H2O2 was added, and the resultant mixture was subjected to ultrasonication for 30 minutes while strongly stirring the mixture. Then, the resultant mixture was washed three times with 2 L of 3 wt% HC1 aqueous solution, and once with distilled water. The aqueous solution obtained was purified by allowing the solution to pass through an ion exchange resin (D301T, Nankai University Chemical Plant).

When purification was performed by the method described above and distilled water was removed, grapheme was obtained. The purified substance was confirmed to be graphene according to X-ray photoelectron spectroscopy and by means of a scanning electron microscope. A material in which graphene was added to the semiconductor fine particles was prepared by compounding 1 % by mass based on the semiconductor fme particles. {0168} (2) Preparation of metal-doped semiconductor fme particles

Titanium oxide semiconductor fme particles doped with Nb were produced by the following method. A precursor was prepared by adding Nb powder (0.002 mol) and tetrabutyl titanate (0.018 mol) to a H2O2/NH3 mixed solution (v/v = 5/1), and stirring the resultant mixture. The precursor was heated to 80°C to remove excess H2O2 and NH3, and then heated at 180°C for 20 hours using an autoclave. The dispersion obtained was washed with deionized water having pH = 7 or less, and the resultant material was dried at 100°C for 6 hours, to obtain Nb-doped titanium oxide semiconductor fine particles. The semiconductor fine particles being doped with Nb was confirmed by XRD or STEM. When a particle diameter of the semiconductor fme particles was measured in a manner as described above, the particle diameter was 10 to 30 nm. {0169} 3. Preparation of dispersion liquid of semiconductor fme particle (II)

The semiconductor fme particles (II) were dispersed into an a-terpineol solution containing 5% by mass of ethyl cellulose, and thus a dispersion liquid containing 15% by mass of the semiconductor fme particles (II ) was obtained. The dispersion liquid was uniformly dispersed and mixed using a mixing conditioner of rotation/revolution combination type. {0170} 4. Preparation of other semiconductor fme particle dispersion liquids

In Comparative Examples 50 to 105 shown in the following tables, mixtures of two kinds of fine particles 1 and fine particles 2 in a mass ratio of 1 : 1 shown in the following tables were used. Herein, among the fme particles 2 shown in the following tables, “TiCb/Mgü” represents fme particles prepared by immersing TiO2 fine particles for 1 minute into an ethanol solution (60 to 70°C) into which 2 to 150 mM of magnesium acetate was dissolved, and the resultant fine particles were washed, and then calcined at 500°C. {0171} <Evaluation of adsorption property>

On a glass substrate, as a transparent electrically conductive film, fluorine-doped tin oxide was formed by sputtering. Next, the semiconductor fine particle dispersion liquid described above was applied to the transparent electrically conductive film and heated at 500°C, and thus a semiconductor fine particle layer was formed. A thickness of the semiconductor fine particle layer thus obtained was 10 pm, and an application amount of the semiconductor fme particles was 20 g/nr.

The glass substrate with the semiconductor fme particle layer foimed thereon was immersed into a 10% ethanol solution of a dye shown in the following tables at 40°C for 3 hours in a dark place. The dye was desorbed using a 10% TBAOE1 methanol solution from a light-receiving electrode obtained by adsoiption of the dye, and an amount of initial adsorption of each dye was quantitatively deteimined by measuring an absorption spectrum. One having the amount of adsorption of less than 2.0 x 10'4 mM/cm was rated as “B”, and one having the amount of 2.0 χ 10'4 mM/cm or more was rated as “A”. {0172} <Evaluation of photoelectric conversion efficiency> (Production of photoelectric conversion element) A light-receiving electrode was produced in a manner similar to the method for evaluating the adsorption property described above. Then, the same semiconductor fine particle dispersion liquid was applied to this light-receiving electrode and heated at 500°C, and thus an insulating porous body was formed. Next, the glass substrate having the insulating porous body formed thereon was immersed for 12 hours in a 10% ethanol solution of each of the dyes indicated in the following Tables 2 to 9. The glass dyed with the dye was immersed for 30 minutes in a 10% ethanol solution of 4-tert-butylpyridine, and then the glass was washed with ethanol and naturally dried. The photoconductor layer thus obtained had a thickness of 10 pm, and the application amount of the semiconductor fme particles was 20 g/m2.

Then, the semiconductor fme particle electrode was arranged, through a 50 micrometer-thick theimoplastic polyolefin resin sheet, on a position opposite to a platinum-sputtered FTO substrate, a resin sheet part was thermally fused, and thus both electrode plates were fixed.

Herein, an electrolytic liquid was injected from an electrolytic liquid injection port opened beforehand on a side of the platinum sputter electrode, and a space between the electrodes was filled. Further, a peripheral part and the electrolytic liquid injection port were firmly sealed using an epoxy sealing resin, silver paste was applied to a current collecting terminal section, and thus a photoelectric conversion element was formed.

For the electrolytic liquid, a methoxypropionitrile solution of dimethylpropylimidazolium iodide (0.5 mol/L) and iodine (0.1 mol/L) was used. {0173} (Measurement of photoelectric conversion efficiency)

Pseudo-sunlight which did not include ultraviolet radiation was generated by passing the light of a 500-W xenon lamp (manufactured by Ushio, Inc.) through an AM1.5G filter (manufactured by Oriel Instruments Corp.) and a sharp cutoff filter (Kenko L-42, trade name). The intensity of this light was 89 mW/cm2. The produced photoelectric conversion element was irradiated with this light, and the electricity thus generated was measured with a current-voltage measurement device (Keithley-238 type, trade name). The results of measuring the initial value of the conversion efficiency of the photoelectrochemical cell thus determined are shown in Tables 2 to 9. The results were evaluated such that one having a conversion efficiency of 4% or more and less than 5% was rated as “E”; one having a conversion efficiency of 5% or more and less than 6% was rated as “D”; one having a conversion efficiency of 6% or more and less than 7% was rated as “C”; one having a conversion efficiency of 7% or more and less than 8% was rated as “B”; and one having a conversion efficiency of 8% or more and less than 9% was rated as “A”. One having a conversion efficiency rated as “A”, “B” or “C” was deemed to be passable. Moreover, as durability, based on the initial value of the conversion efficiency, one having a conversion efficiency of 90% or more after 500 hours was rated as “A”; one having a conversion efficiency of 80% or more and less than 90% after 500 hours was rated as “B”; and one having a conversion efficiency of less than 80% after 500 hours was rated as “C”. One rated as “A” or “B” was deemed to be passable. {0174}

Table 2

"Ex" means Example according to this invention. * 1: Semiconductor fine particles

{0175}

Table 3

{0181}

Table 9

"C Ex" means Comparative Example. * 1: Semiconductor fine particles {0182}

As shown in Tables 4 and 7, it is found that in Comparative Examples 1 to 21 and 26 to 46, in which the dye represented by Formula (1) was not used or the semiconductor fine particles were not composed of two or more kinds of metais or metallic compounds, the initial value of conversion efficiency was insufficient in many cases, and durability was not passable in any of cases. Moreover, Tables 8 and 9 showed that either of the initial value of photoelectric conversion efficiency or durability was not passable for one obtained by merely mixing two kinds of semiconductor fine particles, and both were not passable for most of the ones.

In contrast, when the semiconductor fine particles locally having two or more

kinds of metais or metallic compounds were used and the dye represented by Formula (1) was employed, the initial value of photoelectric conversion efficiency and durability are found to be excellent. {0183}

Having described our invention as related to the present embodiments, it is our intention that the invention not be limited by any of the details of the description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims. {0184}

This non-provisional application claims priority on Patent Application No. 2011-076724 filed in Japan on March 30, 2011, and Patent Application No. 2012-052699 filed in Japan on March 9, 2012, each of which is entirely herein incoiporated by reference.

REFERENCE SIGNS LIST {0185} 1 Electrically conductive support 2 Photoconductor layer 21 Sensitizing dye 22 Semiconductor fine particle 3 Charge transfer layer 4 Counter electrode 5 Light-receiving electrode 6 Externai circuit 10 Photoelectric conversion element 100 PhotoelectiOchemical cell

Claims

CLAIMS:

1. A photoelectric conversion element comprising: an electrically conductive support; a photoconductor layer having semiconductor fine particles containing a dye represented by Formula (1); a charge transfer layer; and a counter electrode; wherein the semiconductor fine particles locally have two or more kinds of metais or metallic compounds; Ru(LL1)(LL2)(X)2*(CI)m4 Formula (1) wherein LL1 is a bidentate ligand represented by Formula (2); LL is a bidentate ligand represented by Formula (5-1); X represents an isothiocyanate group; Cl represents a counter ion for neutralizing a charge of the compound represented by Formula (1); and m4 represents an integer of 0 to 3; when m4 is an integer of 2 or more, CI’s may be the same or different from each other;

wherein R101 and R102 each independently represent a heterocyclic group, a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic acid group, a phosphoryl group or a phosphonyl group; R103 and R104 each independently represent a substituent; R105 and R106 each independently represent a group composed of at least one kind of group selected from

the group consisting of an alkyl group, an aryl group and a heterocyclic group; L and L each independently represent a conjugated chain composed of an ethenylene group and/or ethynylene group; al and a2 each independently represent an integer of 0 to 3; when al is an integer of 2 or more, R501 ’s may be the same or different from each other; when a2 is an integer of 2 or more, R ’s may be the same or different from each other; bl and b2 each independently represent an integer of 0 to 3; when bl is an integer of 2 or more, R103’s may be the same or different from each other, or R ’s may be bonded to each other to form a ring; when b2 is an integer of 2 or more, R104’s may be the same or different from each other, or R104’s may be bonded to each other to form a ring; when bl and b2 each are an integer of 1 or more, R103 and R104 may be bonded to each other to form a ring; dl and d2 each independently represent an integer of 0 to 5; d3 represents 0 or 1; and

wherein: R151 represents an acidic group, R159 represents a substituent, el represents an integer of 0 to 4, e9 represents an integer of 0 to 6, each R151 and R159 may bind to any site of the rings, and when el is 2 or more, each R151 is the same or different from each other, or may be bonded with each other to form a ring, and when e9 is 2 or more, each of R159 is the same or different from each other, or may be bonded with each other to form a ring.
2. The photoelectric conversion element according to Claim 1, wherein the two or more kinds of metais or metallic compounds in the semiconductor fine particles are a metal atom, metal chalcogenide, metal carbonate or metal nitrate.
3. The photoelectric conversion element according to Claim 2, wherein the metal atom is at least one kind of atom selected from the group consisting of Ti, Sn, Au, Ag, Cu, Al, Zr, Nb, V and Ta.
4. The photoelectric conversion element according to Claim 2 or Claim 3, wherein the metal chalcogenide is cadmium sulfide, cadmium selenide or a metal oxide of at least one kind of metal selected from the group consisting of Ti, Sn, Zn, Mg, Al, W, Zr, Hf, Sr, In, Ce, Y, La, V and Ta.
5. The photoelectric conversion element according to any of Claims 2 to 4, wherein the metal carbonate is at least one kind of metal carbonate selected from the group consisting of calcium carbonate, potassium carbonate and barium carbonate.
6. The photoelectric conversion element according to any of Claims 2 to 5, wherein the metal nitrate is lanthanum nitrate.
7. The photoelectric conversion element according to any of Claims 2 to 6, wherein the semiconductor fine particles have the metal atom, the metal chalcogenide, the metal carbonate and/or the metal nitrate, according to a core-shell structure.
8. The photoelectric conversion element according to Claim 7, wherein the semiconductor fine particles have the metal chalcogenide as a core part, and have the metal chalcogenide or the metal carbonate as a shell part.
9. The photoelectric conversion element according to Claim 8, wherein the semiconductor fine particles have metal chalcogenide selected from the group consisting of titanium oxide and tin oxide as the core part, and have metal chalcogenide or metal carbonate selected from the group consisting of aluminum oxide, magnesium oxide, calcium carbonate, titanium oxide, and titanium oxide/magnesium oxide as the shell part.
10. The photoelectric conversion element according to any of Claims 1 to 6, wherein the semiconductor fine particles have the two or more kinds of metal atoms by doping a metal atom.
11. The photoelectric conversion element according to Claim 10, wherein the semiconductor fine particles are obtainable by doping a metal atom into metal chalcogenide.
12. The photoelectric conversion element according to Claim 11, wherein the semiconductor fine particles are semiconductor fine particles obtainable by doping at least one kind of metal atom selected from the group consisting of Nb, V and Ta into metal chalcogenide selected from the group consisting of titanium oxide and tin oxide.
13. The photoelectric conversion element according to any preceding Claim, wherein the particle diameter of the semiconductor fine particles is 1 to 1,000 nm.
14. The photoelectric conversion element according to any preceding Claim, wherein the semiconductor fine particles contain an additive composed of an electrically conductive material.
15. The photoelectric conversion element according to Claim 14, wherein the electrically conductive material is graphene.
16. The photoelectric conversion element according to any preceding Claim, wherein LL1 in Formula (1) is represented by any one of Formulae (4-1), (4-2) and (4-3):

wherein R101 to R104, al, a2, bl, b2 and d3 have the same meaning as those in 107 Formula (2), respectively; R represents an acidic group; a3 represents an integer of 0 to 3; R represents a substituent; b3 represents an integer of 0 to 3; R to R each independently represent a hydrogen atom, an alkyl group, an alkenyl group or an aryl group; R , R , R and R each independently represent a substituent; and d4 and d5 each independently represent an integer of 0 to 4.
17. The photoelectric conversion element according to Claim 16, wherein R in Formula (4-2) is a carboxyl group, a sulfonic acid group, a hydroxyl group, a hydroxamic group, a phosphoryl group or a phosphonyl group.
18. The photoelectric conversion element according to Claim 16, wherein R in Formula (4-2) is an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, or an acylamino group.

125 126
19. The photoelectric conversion element according to Claim 16, wherein R ,R , R and R in Formulae (4-1) to (4-3) each independently represent an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an amino group, an acylamino group or a hydroxyl group.
20. The photoelectric conversion element according to Claim 16, wherein R103 and R104 in Formula (2) each independently represent an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an amino group, a sulfonamide group, an acyloxy group, a carbamoyl group, an acylamino group, a cyano group, or a halogen atom.
21. A photoelectrochemical cell comprising the photoelectric conversion element as defined in any preceding Claim.