GB2507661A

GB2507661A - Pigment, photoelectric converter, and photoelectrochemical cell

Info

Publication number: GB2507661A
Application number: GB1319073.1A
Authority: GB
Inventors: Kouji Oomori; Katsumi Kobayashi; Hirotaka Satou
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2011-03-31
Filing date: 2012-02-29
Publication date: 2014-05-07
Also published as: GB2507661A8; JP2012214671A; GB201319073D0; JP5771092B2; WO2012132735A1

Abstract

Provided is a pigment obtained from a compound represented by formula (1) or (2). (1) (2) [Where A is a group having acidic groups; Ar is an aromatic ring; Ra and Rb are a hydrogen atom, aliphatic group, aromatic group, or heterocyclic group bonded by carbon atoms; n, L, and m are integers between 1 and 5; and d and a are predetermined linking groups.]

Description

DESCRIPTION

TITLE OF INVENTION: DYE, PHOTOELECTRIC CONVERSION ELEMENT AND

PHOTOELECTROCHEMICAL CELL

S

TECHNICAL FIELD

The present invention relates to a dye, a photoelectric conversion element and a photoelecfrochemical cell.

BACKGROUND ART

Photoelectric conversion elements are used in various photosensors, copying machines, photoelectrochemical cells (for example, solar cells), and the like. These photoelecfric conversion elements have adopted various systems to be put into use, such as elements utilizing metals, 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-fledged 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 l'Ecole Polytechnique de l'Univcrsite dc Lausannc 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.

Patent Literature I 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. However, each of these photoelectric conversion elements is not in itself entirely sufficient to obtain a photoelectric conversion element having high conversion efficiency.

In view of the above, a technique of improving photoelectric conversion efficiency by adsorbing a photosensitizing dye having a particular structure onto semiconductor fine particles is proposed (for example, Non-Patent Literature 1).

CITATION LIST

Patent Literatures Patent Literature 1: U.S. Patent No. 5,463,057 Non-Patent Literatures Non-Patent Literature 1: J. Am. Chcm. Soc., 128, 14256-14257 (2006)

DISCLOSURE OF INVENTION

TECHNICAL PROBLEM

Non-Patent Literature I discloses a photosensitizing dye which achieves higher value than the traditional one in terms of initial photoelectric conversion characteristics.

However, this photosensitizing dye is not sufficient to absorb light having a long wavelength, thereby improving the photoelectric conversion efficiency. Further, this photosensitizing dye is not sufficient in terms of element durability, that is to say, properties that a photoelectric conversion element can be used without any troubles even after leaving it in an environment of receiving light and heat over a long period of time.

A problem of the present invention to be solved is to provide a photoelectric conversion element and aphotoelectrochemical cell, of which initial photoelectric conversion efficiency is high and durability is also excellent, since light having a long S wavelength can be used sufficiently, and also to provide a dye which is used for them.

SOLUTTON TO PROBLEM

As a result of intensive and repeated investigation, the present inventors have found that it is possible to provide a photoelectric conversion element and a photoclectrochemical cell, of which conversion efficiency is high and durability is also excellent since light having a long wavelength can be absorbed by the use of a dye in which a donor site and an acceptor site are bound to one another via a linking group having a particular structure. The present invention is achieved based on these findings.

{OO1O} The problems of the present invention can be solved by the following means.

<1> A dye composed of a compound represented by formula (1) or (2): {OO11} Ra Ra Rb7 "(2) wherein, in formula (1) or (2), A represents a group having an acidic group; Ar represents an aromatic ring; Ra and Rb each represent a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group which is bonded through a carbon atom; n, Land m each represent an integer of I to 5; and d and a each represent a linking group represented by any one of formulae (3) to (6): {0012} * s1;,* (Rx)ox_ * (3) (4) (5) (6) (R)0 wherein, in formulae (3) to (6), R and R each represent a substituent; R7 represents a hydrogen atom, an aliphatic group, an aromatic group, or a hctcrocyclic group which is bonded through a carbon atom; X6 and X1 each represent an aromatic ring; X2 represents a heterocycle; OX and OY each represent an integer of 0 to 3; and "k" represents a binding site; wherein each of formulae (3) to (5) may have a substituent on the hetero ring thereof, and when there are a plurality of substituents, these may bind to one another to form a condensed ring structure; the condensed ring structure also may have a substituent and they may further bind to one another to form a condensed ring structure.

<2> The dye described in the above item <1>, wherein d and a of the dye are such that LIJMO is from -3.0 to 0eV and HOMO is from -9.5 to -6.0eV, each of which is a value obtained by molecular orbital calculation using Winmostar computation software.

<3> The dye described in the above item <1> or <2>, wherein in formula (1) or (2), of the d and a, the group giving higher energy level of I-IOMO, which is a value obtained by molecular orbital calculation using Winmostar computation software, is designated as d while the other is designated as a, and the difference in the energy level of HOMO is from 0.01 to 1.0eV.

<4> The dye described in any one of the above items <I> to <3>, wherein "RaRbN-Ar-" in formula (1) or (2) is represented by formula (7): {0013) Fl X (7) wherein, in formula (7), X3 represents a group of atoms for forming the nitrogen-containing heterocycle; "k" represents a binding site; and R' represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group which is bonded through a carbon atom.

<5> The dye described in any one of the above items <1> to <4>, wherein "RaRbN-Ar-" in formula (1) or (2) is represented by formula (8): {0014} (z'1)01 (z12) CS) wherein, in formula (8), X4 represents a group of atoms for forming the nitrogen-containing heterocycle; "p" represents a binding site; 01 and 02 each independently represent an integer of 0 or greater; Z' andZ'2 each represent a substituent; and R' represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group which is bonded through a carbon atom.

<6> The dye described in any one of the above items <1> to <5>, wherein "RaRbN-Ar-" in formula (1) or (2) is represented by formula (9): R'8 R1 R12 wherein, in formula (9), X5 represents a group of atoms for forming the nitrogen-containing heterocycle; R' represents a hydrogen atom, an aliphatic group, or an aromatic group; to R18 each represent a hydrogen atom or a substituent; and "*" represents a binding site, and wherein d and a in formula (1) or (2) each arc represented by any one of formulae (10-1) to (10-6): 4 R29RS' R31 E° * tr \4 14 5 _ R23 * ___ * * * (10-1) (10-2) (10-3) (10-4) (Rx)0 Rz (Rx)0 Rz *oY (10-6) wherein, in formulae (10-1) to (10-6), E° represents a nitrogen atom, an oxygen atom or a sulfur atom for forming the 5-membered heterocyele; E' to E and E5 to each represent an atom for forming the 5-membered heterocycle; at least one of E' to and E5 to E1° represents a nitrogen atom, an oxygen atom or a sulfur atom, and the others represent CRw; R represents a hydrogen atom or a substituent; E4 represents a nitrogen atom, an oxygen atom or a sulfur atom for forming the 5-membered heterocycle; Rx, Ry, Rz, OX and OY each have the same meaning as those in formula (6), respectively; R21 to R32 each represent a hydrogen atom or a substituent; and represents a binding site.

<7> The dye described in any one of the above items <1> to <6>, wherein A is represented by any one of formulae (11-1) to (11-5): 9021-1° COOH R * NC NK _7j-COOH * .__rL__s/=' *

COOH COOH

(11-1) (11-2) (11-3) (1l4) (11-5) wherein, in formulae (11-1) to (11-5), "s" represents a binding site; and R represents a hydrogen atom or a substituent.

<8> The dye described in any one of the above items <1> to <7>, wherein "RaRbN-Ar-" in formula (1) or (2) is represented by any one of formulae (12-1) to (12-5): (R41)kl R1 kl 44)k2 (R) 46 42)k25 5cR) (12-1) (12-2) (12-3) (12-4) (12-5) wherein, in formulae (12-1) to (12-5), R1 represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group which is bonded through a carbon atom; to R5° each represent a hydrogen atom or a substituent; "" represents a binding site; kI represents an integer of Ito 4; and k2 represents an integer of I to 3, and wherein d and a in formula (1) or (2) each are represented by any one of formulae (13-1) to (13-9): F * S * S * R1? * * *

N

OC ROOC /L<R$5 (13-I) (13-2) 3-5) R6° R°3 (R62)k3 * S * P56 61)ka \ I

ROOC

S57 13-6) (13-7) * (13-8) (13-9) wherein, in formulae (13-1) to (13-9), R5' to RM each represent a hydrogen atom or a substituent; k3 represents an integer of Ito 3; and "*" represents a binding site.

<9> A photoelectric conversion element comprising, in the following order: an electrically conductive support, a photoconductor layer comprising semiconductor fine particles and a sensitizing dye, a charge transfer object layer comprising an electrolyte, and a counter electrode, the dye described in any one of the above items <1> to <8> being used as the photosensitizing dye in the photoconductor layer.

<10> A photoelectrochemical cell comprising the photoelectric conversion element described in the above item <9>.

<11> The photoelectric conversion element described in the above item <9>, wherein the electrolyte in the charge transfer object layer is a cobalt complex.

<12> The photoelectric conversion element described in the above item <11>, wherein the cobalt complex is represented by formula (14): Co(LL2)&(X)1j.Cl formula (14) wherein, in formula (14), LL2 represents a bidentate or terdentate ligand represented by formula LL2; X represents a monodentate or bidentate ligand; m2 represents an integer of 0 to 3; m3 represents an integer of 0 to 6; and CI represents a counter ion for neutralizing a charge of the compound represented by formula (14): LL2: ,-Za-,-Zb-NNN Ic wherein, in formula LL2, Za, Zb and Zc each independently represent a group of atoms for forming a 5-or 6-membered ring; and c represents 0 or 1.

<13> The photoelectric conversion element described in the above item <11> or <12>, wherein X is a halogen atom.

<14> The photoelectric conversion element described in any one of the above items <11> to <13>, wherein LL2 in formula (14)is represented by any one of formulae (14-1) to (14-3): {0021} (R'd)nd (R'a)fla(R'b)flb (R1c)flc (R'e)ne (R'f)nfJ{Jl (14-1) (14-2) (14-3) wherein R'a to R'i each represent a substituent; nato nb each represent an integer of 0 to 4; nc and ne each represent an integer of 0 to 3; nd represents an integer of 0 to 2; and nf and nj each represent an integer of 0 to 4.

{0022} In the present specification, the aromatic ring is used in a sense including an aromatic ring and a hetero ring (an aliphatic hetero ring and an aromatic hetero ring).

The carbon-carbon double bond may be either E-form or Z-form. The structural formula and the linking of each site just have to be construed so that a resonance structure thereof is consistently formed, even if it is different from the structure represented by the above-described formula. When a plurality of substituents or ligands are alternatively defined all together, each of the substituents or the ligands may be the same or different from one another. This is also applied to the definition of the number of the substituent. When the plurality of substituents, ligands or linking groups are close to one another, they maybe linked to one another, or maybe ring-fused to form a ring. An acidic nucleus is incorporated in a group having an acidic group.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a photoelectric conversion clement and a photoclectrochemical cell which exhibit high conversion efficiency and excellent durability, and a dye for use in these.

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. I is a cross-sectional view schematically showing an exemplary embodiment of the photoelectric conversion clement prepared by the present invention.

MODE FOR CARRYING OUT THE INVENTION

As a result of intensive and repeated investigations, the present inventors have found that it is possible to provide a photoelectric conversion element and a photoelectrochemical cell, of which conversion efficiency is high and durability is also excellent since light is effectively utilized by employing a dye having a particular structure that can absorb light having a long wavelength. 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 contains an electrically conductive support 1; and a photoconductor layer 2, a charge transfer object 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 object layer 3.). The charge transfer object layer 3 functions, for example, as a hole-transporting layer for transporting positive holes (holes). The electrically conductive support I having a photoconductor layer 2 provided thereon functions as a working electrode in the photoelectric conversion element 10. This photoelectric conversion element 10 can be 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 external circuit 6.

The light-receiving electrodeS is an electrode comprising an electrically conductive support I; and a photoconductor layer 2 (semiconductor film) 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 electrons 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 I by diffusion. At this time, the molecules of the sensitizing dye 21 are in an oxide form. In the photoelectroehemieal cell 100, the electrons on the electrode return to the oxide of the dye while working in the external circuit 6, while the light-receiving electrode 5 works as a negative electrode of this cell. {OO2}

The photoconduetor 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.

It is noted that the top and bottom of the photoelectric conversion element is not needed to specify in particular. In the present specification, however, when described on the basis of the graphically-illustrated embodiment, the counter electrode 4 side that corresponds to the light-receiving side is designated as the upside (top) direction, while the support 1 side is designated as the underside (bottom) direction. It is noted that the light-receiving electrodes may be defined as incorporating therein a part of the charge transfer object layer 3.

As described above, since the photoconductor layer 2 incorporates therein semiconductor fine particles 22 on which the particular dye is adsorbed, high light-receiving sensitivity can be obtained, and when used as the photoelectric conversion element 10, high photoelectric conversion efficiency can be obtained, and further it has high durability. [Dye]

The dye of the present invention is composed of a compound represented by formula(1)or(2). Ra Ra

RbA+ ---(1) Rb' -t A ***(2) Herein, A represents a group having an acidic group. Ar represents an aromatic ring. Ra and Rb each represent a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclie group which is bonded through a carbon atom. n, L and m each are an integer of I to 5. d and a each are a specific linking group shown below.

That is, the dye of the present invention has, at the both ends thereoL a donor group URaRbN-Ar) (hereinafter, this group may be referred to as the site D) and an acceptor site A which includes a group having at least one acidic group or a group having an acidic nucleus. Each of the donor site D and the acceptor site A independently binds to a linking group, thereby constituting a dye composed of the compound represented by formula (1) or (2). The linking group is a donor linking- group d and/or an acceptor linking-group a. In formula (1) or (2), the donor linking-group d and the acceptor linking-group a are represented by any one of the following formulae (3) to (6).

{0033) In the dye of the present invention, since the linking group thereof does not only connect the donor site (D) with the acceptor site (A), but also has a donor linking-group (d) and/or an acceptor linking-group (a), electron transfer can be done intensively and promptly upon light irradiation, and photoelectric conversion efficiency can be improved due to absorption of light having a long wavelength.

Donor site (D) The dye of the present invention has the site D in formulae (1) and (2) in order to introduce a donor site with a wide-conjugated system, thereby stabilizing one-electron oxidation state of the dye. In the site D, each of Ra and Rb binds to a nitrogen S atom, and frirther the nitrogen atom binds to the linking group described below via Ar.

A conjugated system is broadened by this structure, so that both of the effect of stabilizing electron oxidation state and the effect on which the wavelength to be absorbed is made longer can be achieved. Each of Ra and Rb represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group which binds through a carbon atom thereof Examples of the aliphatic group of Ra and Rb include an alkyl group, an alkenyl group, an alkynyl group, and the like. Examples of the aromatic group of Ra and Rb include a benzyl group, a naphthyl group, an anthracenyl group, and the like. Examples of the hetcrocyclic group of Ra and Rb include a thiophene group, a pyrrole group, and the like. Among these, a benzyl group, a thiophene group, and the 111cc are preferred. Ra and Rb may be coupled to one another to form a ring. Further, at least one of Ra or Rb may bind to or may be condensed with Ar to form a ring structure.

The site D binds to the linking group described below via Ar which represents an aromatic ring. As the aromatic ring, abenzyl group, a naphthyl group, an anthracenyl group, and the like are preferred and a benzyl group is more preferred. As the hetero ring, a thiophene group, a pyrrole group, and the like are preferred and a thiophene group is more preferred. Since the conjugated system is lengthened by the configuration that the site D binds to the linking group described below via Ar which represents an aromatic ring, together with the structure of the linking group described below, the effects that light having a long wavelength can be absorbed and one electron oxidation state can be stabilized can be achieved.

The site D is preferably represented by formula (7). / 31 X (7)

Herein, X3 represents a group of atoms for forming the nitrogen-containing heterocycle. "" represents a binding site. R1 represents a hydrogen atom, an aliphatic group, an aromatic group, or a hetcrocyclic group which is bondcd through a carbon atom.

The group of atoms X3 necessary for forming the nitrogen-containing hetero ring with thc linking bcnzcnc ring is preferably a group of atoms to which at least one selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom and a sulfur atom is bound. X3 is preferably a 4-to 8-membered ring which is constituted of at least a carbon atom in addition to the nitrogen atom, and more preferably a 5-to 7-membered ring. Examples of the 4-to 8-membered ring include a pyrrolidine ring, a piperidine ring, a hexamethyleneimine ring, an azacyclooctane ring, a morpholine ring, and a thiomorpholine ring. More preferred are a pyrrolidine ring, a hexamethyleneimine ring and a thiomorpholine ring.

In formula (7), R' represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group which is bonded through a carbon atom. Specific preferred examples of R' include a substituted or unsubstituted alkyl group having ito 20 carbon atoms (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodecyl, cyclohexyl or benzyl), a substituted or unsubstituted aryl group (for example, phenyl, tolyl or naphthyl), and a substituted or unsubstituted heterocyclic residue (for example, pyridyl, imidazolyl, furyl, thienyl, oxazolyl, thiazolyl, benzimidazolyl, or quinolyl). A more preferred example of R1 is a substituted or unsubstituted alkyl group having I to 20 carbon atoms (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodecyl, cyclohexyl, or benzyl).

The site D is preferably represented by formula (8). (8)

In formula (8), X4 represents a group of atoms for forming the nitrogen-containing heterocycle. "" represents a binding site to the "d". 01 and 02 each independently represent an integer of 0 or greater. Z1' and Z'2 each represent a substituent. B.' represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocycic group which is bonded through a carbon atom.

In formula (8), the group of atoms K' necessary for forming the nitrogen-containing hetero ring with the linking benzene ring is preferably a group of atoms to which at least one selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom and a sulfur atom is bound. X4 is preferably a 4-to 8-membered ring which is constituted of at least a carbon atom in addition to the nitrogen atom, and more preferably a 5-to 7-membered ring. Examples of R1 in formula (8) include the same examples of R' in formula (7).

In formula (8), Z and Z'2 each represent a substituent. Z and Z'2 maybe the same or different from each other. Examples thereof include an aliphatic group, an aromatic group, a heterocycic group or the like. Specific examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, and a heterocyclie ring. Preferred examples include an alkyl group (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodecyl, cyelohexyl, or benzyl), a substituted aryl group (for example, phenyl, tolyl, or naphthyl), and an alkoxy group (for example, methoxy, ethoxy, isopropoxy or butoxy).

The number of the substituent 01 and 02 independently represent an integer of 0 or greater. The number of the substituent is preferably from 0 to 3, and more preferably fromOto 1.

The site D is preferably represented by fonnula (9).

R'8 R' R'2 Ic'II (9) In formula (9), X5 represents a group of atoms for forming the nitrogen-containing heterocycle. R1 represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocydic group which is bonded through a carbon atom. to R'8 each represent a hydrogen atom or a substituent. "s" represents a binding site.

In formula (9), the group of atoms X5 necessary for forming the linking nitrogen-containing hetero ring is preferably a group of atoms to which at least one selectcd 11Dm the group consisting of a carbon atom, an oxygen atom, a nitrogen atom and a sulThr atom is bound. X5 is preferably a 4-to 8-membered ring which is constituted of at least a carbon atom in addition to the nilmgen atom, and more preferably a 5-to 7-membered ring. Examples of R1 include the same as those of the above-described formula (7). Preferable examples of the substituent of K'2 to K'8 include the same examples of Z" and z12 in formula (8).

The site D is preferably represented by any one of formulae (12-1) to (12-5).

n41' I I' hI ")u (R'5) 46 (R7 th3 ct& &c (12-1) (12-2) (12-3) (12-4) (12-5) {0048} In the above formulae, R' represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group which is bonded through a carbon atom. to R5° each represent a hydrogen atom or a substituent. Examples of the substituent of R.4' to R5° include the same examples of Z1' and z12 in formula (8).

"s" represents a binding site.

ki represents an integer of 1 to 4, and k2 represents an integer of 1 to 3.

(b) Acceptor site (A) The acceptor site (A) is a group having at least one acidic group (including a group having an acidic nucleus). Examples of the acidic nucleus (A) include those described in, for example, T. H. James, "The Theory of the Photographic Process, 4th edition", Macmillan publishing, 1977, p. 199.

Preferred examples of the acidic nucleus include a rhodanine nucleus, hydantoin, thiohydantoin, barbituric acid. pyrazolidinedione, pyrazolone, and indanedione. These may contain two or more acidic nuclei linked together, with each acidic nucleus having been dehydrated and condensed at the carbonyl moiety. Preferred examples include rhodaninc, hydantoin, thiohydantoin, barbituric acid and pyrazolidinedione, and rhodanine is particularly preferred among them.

{0051} The acidic group represents a proton-dissociative group having a pica of 13 or lower. Specific preferred examples of the acidic group include a carboxylic acid, a sulfonic acid, a phosphoric acid and a phosphoric acid ester. A more preferred example of the acidic group is a carboxylic acid. The carbon-carbon double bond may be any of an E-form double bond and a Z-form double bond. The acidic group may be its salt.

When the acidic nucleus has at least one acidic group, it is preferable that the acidic nucleus also has an electron-withdrawing group. The electron-withdrawing group may be a substituent having the effects described below (-I effect and -M effect).

When the acidic nucleus has an acidic group and an electron-withdrawing group at the same time, the type or bonding position of the electron-withdrawing group is appropriately selected so as to exhibit an effect that the overlap of the molecular orbital in the excited state of the dye and the light-receiving electrode seems to increase.

In general, an electron-withdrawing group attenuates the electron density at a particular position of a molecule. The electron-withdrawing property or electron-donating property cannot be explained only by the difference in the electronegativity.

That is, since an inductive effect, a mesomeric effect and the like work together in a compositive manner, the manifestation of the electron-withdrawing property or the electron-donating property can vary with the aromaticity, presence of a conjugated system, or a topological positional relationship. As an experimental rule for S quantitatively evaluating and predicting these effects on the basis of the acid dissociation constant of para-and meta-substituted benzoic acid, there is known Hammett's rule. In the ease of the inductive effect, the electron-withdrawing effect is referred to as the -I effect, while the electron-donating effect is referred to as the +1 effect, and an atom having higher electronegativity than carbon exhibits the -I effect.

Furthermore, an anion exhibits the +1 effect, while a cation exhibits the-I effect. In the ease of the mesomeric effect, the electron-withdrawing effect is referred to as the -M effect, while the electron-donating effect is referred to as the +M effect. Examples of the electron-withdrawing group arc shown below.

Inductive effect (-I effect) *-O'R2>-N R3 * -N R3 > -P R3 > * -OR2 > * -NR3 > -NO2 > -SO2R> -SOR * -SO2R> -SOR * -N'R3 > -NR * -OR2 > -OR * -SR2> -SR *-F>-Cl>-Br>-l *=O>=NR>=CR2 *=O>-OR * N> CR * N>=NR>-NR2 * -CCR> -CR=CR2 > -CR2CR Mesomeric effect (-M effect) * > =NR * =0> =NR > =CR2 *=S>=0>N 0053} The above-described A is preferably represented by any of the foflowing formulae (11-1) to (11-5). Here, in formulae, "p" represents a binding site. It is possible to achieve the effects that adsorbability onto an oxide semiconductor (for example, titanium oxide) is enhanced by A being these groups, and further light having a long wavelength is absorbed by formation of conjugate with the other site in a molecule, so that electrons become easy to be transferred from within the molecule to the oxide semiconductor.

02H 000H NC C0 OH * NC * _COOH (11-1) (11-2) (11-3) (114) (11-5) "s" represents a binding site. R represents a hydrogen atom or a substituent, preferably a substituent. Examples of the substituent include substituent T described below, and preferable embodiments are also the same as those of the substituent T. {0056} (c) Linking group The linking group may be either a single combination or a plurality of combinations of the linking-group having a donor property (d) and the linking-group having an acceptor property (a) (formula (1)), or the linking-group having a donor property (d) and!or the linking-group having an acceptor property (a) which is or are each independently involved therein (formula (2)). In formulae (1) and (2), n, Land m each are an integer of 1 to 5.

In formulae (1) and (2), d and a each are represented by any one of formulae (3) to (6).

* * * (3) (4) (5) (6) (R)0 Herein, Rx and Ry each represent a substituent. Rz represents a hydrogen atom, an aliphatic group, an aromatic group, or a hctcrocyclie group which is bonded through a carbon atom. X6 and X1 each represent an aromatic ring. X2 represents a heterocycle.

OX and OY cach reprcscnt an integer of 0 to 3. "i" represents a binding site.

{0059} R and R each represent a substituent. R and R may be the same or different from each other. Examples thereof include an aliphatic group, an aromatic group, a heterocyclic group or the like. Specific examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, and a heterocyclic ring. Preferred examples include an alkyl group (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodeeyl, cyclohexyl, or benzyl), a substituted aryl group (for example, phenyl, tolyl, or naphthyl), and an alkoxy group (for example, methoxy, ethoxy, isopropoxy or butoxy).

Rz represents a hydrogen atom, an aliphatic group, or a heterocyclic group which is bonded through a carbon atom. Preferable examples of Rz include the same examples of R' in formula (7).

In X' and X6, examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthraeene ring, and the like. Examples of the hetero ring include a thiophene ring, a pyrrol ring, a thiazole ring, an imidazole ring, and the like. Among these, a benzene ring, a naphthalene ring, a thiophene ring, and the like are preferred.

The aromatic ring of X6 may be linked via an aliphatic ring, or may be a condensed ring in which a plurality of rings are condensed.

Examples of X2 include a pyrrolidine ring, a piperidine ring, a hexamethyleneimine ring, an azacyclooctane ring, a morpholine ring, and a thiomorpholine ring. Further preferred are a pyrrolidine ring, a hexamethyleneimine nng and a thiomorpholine ring.

Examples of the above-described formula (4) include a linking group represented by the following formula (4').

{0063} Rx (4!) The substituent of Rx and Ry is preferably a bulky and hydrophobic one, and examples thereof include an alkyl group (more preferably alkyl group having Ito 20 carbon atoms, and especially preferably alkyl group having 1 to I 5 carbon atoms), an alkenyl group (for example, propenyl, heptenyl, 2-ethylhexenyl, or the 111cc), an ailcynyl group (for example, propynyl, heptynyl, 2-ethylhexynyl, or the like), an ether group (for example, methoxy, heptoxy, 2-ethylhexoxy, or the like), an ester group (for example, methoxycarbonyl, heptoxycarbonyl, 2-ethylhexoxycarbonyl, or the like), and an amino group (for example, methane amido, heptane amido, 2-ethylhexaamido, or the like).

More preferred are an alkyl group, an alkenyl group, and an ether (alkyloxy) group.

X6 has the same meaning as X6 in formula (6).

Whether the linking group is a donor one (d) or an acceptor one (a) is determined by comparison with the donor site (D) or the acceptor site (A) bound to both ends. That is, the higher energy level of HOMO is the donor one (d), while the lower is the acceptor one (a), wherein the energy level of HOMO is a value obtained by molecular orbital calculation (Hamiltonian: AM1) using Winmostar computational software (Winmostar(trade name), manufactured by Kabushiki Kaisha Tencube Kenkyusho). Further, when there are two or more linking groups, whether the linking groups have a donor property or an acceptor property is determined in the same manner S by calculating an energy level of HOMO of each of the linking groups in accordance with molecular orbital calculation (Hamiltonian: AM!) using the Winmostar computational software (Winmostar (trade name), manufactured by Kabushiki Kaisha Tencube Kenkyusho).

When explained with reference to, for example, specific example A-I described below, the donor site (D) is 9-ethylcarbazole, the acceptor site (A) is cyano acetic acid, the linking group a is thienothiophene, and the linking group d is benzodithiophene. With respect to other dyes, the donor site (D), the acceptor site (A), and the linking groups can also be identified in the same manner.

When other specific examples A-2 to A-17 described below are shown in the same manner, each of the sites and the donor and/or acceptor linldng group bind to one another in the order starting from the left at the wavy line section of each of the structural formulae as shown below.

A-I: A, a, d, D A-2: A, a, d, D A-3: A, a, d, D A-4: A, a, d, D A-5: A, a, d, D A-6: A, a, d, 13 A-7:A,a,d,d,d,D A-8: A, a, d, d, d, D A-9: A, a, a, d, d, d, D A-IO: A, a, a, d, D A-li: A, a, d, a, d, D A-13: A, a, d, D A-14: A, a, d, 13 A-iS: A, a, d, D A-16: A, a, d, D A-17: A, a, d, D S The donor linking group d and the acceptor linking group a, when the linking group having the higher energy level of HOMO is designated as d while the other is designated as a in accordance with molecular orbital calculation using the Winmostar computational software, preferably satisfy the following condition (A). Here, the Winmostar computational software is a software for molecular orbital calculation of a compound, and is provided as Winmostar (trade name) from Kabushiki Kaisha Tencube Kenkyusho.

(A) LUMO energy levels of d and a of the dye are from -3.0 to 0eV, and 1-IOMO energy levels thereof are from -9.5 to -6.0eV.

When the energy level of the dye is within the range of the above condition (A), it is possible to achieve the effect that the dye absorbs light having a longer wavelength than the conventional dyes. Further, it is preferable to satisfy the following condition (B) from the viewpoint of forming energy gradient between d and a.

It is preferable that the donor linking group d and the acceptor linking group a farther satisfy the following condition (B) in accordance with molecular orbital calculation using the Winmostar computational software.

(B) The difference in HOMO energy levels between d and a is from 0.01 to 1.0eV.

When the energy levels of d and a satisfy the above the two conditions (A) and (B) at the same time, an appropriate energy gradient between the sections d and a in a dye molecule can be formed, and light having a long wavelength can be absorbed.

Examples of such combination include combinations of (10-1) and/or (10-5) as d and (10-2) as a. Preferable examples thereof include combinations of 13-6 and/or 13-7 as d and at least anyone of 13-1 to 13-3 and 13-9 as a.

The LUMO energy levels of d and a are preferably from -2.0 to 0.1 eV, further preferably from -1.5 to 0.1 eV. The HOMO energy levels of d and a are preferably from -9.5 to -6.0 eV, further preferably from -7.0 to -9.0 eV.

The above-mentioned d and a described above each are preferably represented by any one of formulae (10-1) to (10-6).

{0070} »=73E2 iFIE7_* , ___* E,48- (10-1) (10-2) (10-3) (10-4) (Rx)0 Rz (R) c Ni (R)0 (Rx)0 R / * * * Herein, E° represents a nitrogen atom, an oxygen atom or a sulfur atom for forming the 5-membered heterocycle. E1 to E3 and E5 to E1° each represent an atom for forming the 5-membered heterocycle; and at least one of E' to E* at least one of E5 to F7, and at least one ofF5 to F'° represent a nitrogen atom, an oxygen atom or a sulfur atom, and the others represent represents a hydrogen atom or a substituent.

E4 represents a nitrogen atom, an oxygen atom or a sulfur atom for forming the 5-membered heterocycle. R, R, R, OX and OY each have the same meaning as those in formula (6), respectively. R2' to R32 each represent a hydrogen atom or a substituent; and "*" represents a binding site.

{0071) In formulae (10-1) to (10-6), when the rings having Ex are hetero ring structures capable of forming a conjugation, it is possible to achieve the effect of linking conjugated systems of each site. Further, d or a represented by formula (10), by binding to the above-described D or A via the carbon atom of the hetero ring, can achieve the effect that the conjugated system is extended and light having a long wavelength is absorbed. When any of R2' to R'2 is a substituent, preferable examples thereof include examples of Z11 and Z12 in formula (8).

Examples of the substituent of Rw include the substituent T. The above-mentioned d and a described above each are more preferably represented by any one of formulae (13-1) to (13-9).

F t & * :c: R5100C ROOC RDOd 133 -* _ 1* 5) (12-I) C2-2) (13-8 P56 (R62)K3 * S * * * * R8O R (13-7) (13-8) (13-9) In formulae (13-1) to (13-9), d and a each bind to the other dye residue via a bindable carbon atom in the hetero ring. Each of R51 to R64 represents a hydrogen atom or a substituent. Examples of the substituent of R51 to R55 and R64 include a straight chain or branched alkyl chain having I to 20 carbon atoms (for example, methyl, ethyl, 2-cthylhcxyl, 3,3,5-trimcthylhcxyl (nonyl)). "p" represents a binding site.

The substituent of R6 and R57 is preferably a builcy and hydrophobic one, and examples thereof include an alkyl group (more preferably alIcyl group having I to 20 carbon atoms, and especially preferably alkyl group having 1 to 1 5 carbon atoms), an alkenyl group (for example, propenyl, heptenyl, 2-ethylhexenyl, or the like), an alkynyl group (for example, propynyl, heptynyl, 2-ethylhexynyl, or the like), an ether group (for example, methoxy, heptoxy, 2-ethylhexoxy, or the like), an ester group (for example, methoxycarbonyl, heptoxycarbonyl, 2-ethylhexoxycarbonyl, or the like), and an amino group (for example, methane amido, heptane amido, 2-ethylhexaamido, or the like).

Examples of the substituent of R58, RD9, R61 and R62 include an aliphatic group, an aromatic group, a heterocyclic group, and the like. Specific examples of the substituent include an alkyl group, an alkyloxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, a heterocyclic group, and the like. Preferable S examples include an alkyl group (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodecyl, cyclohexyl, benzyl, or the like), a substituted aryl group (for example, phenyl, tolyl, naphthyl, or the like), and an alkoxy group (for example, methoxy, ethoxy, isopropoxy, butoxy, or the like). The number of the substituent 01 and 02 independently represents an integer of 0 or greater. The number of the substituent is preferably from 0 to 3, and more preferably from 0 to 1.

Examples of the substituent of R6° and R63 include a substituted or unsubstituted alkyl group having I to 20 carbon atoms (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodecyl, cyclohexyl, benzyl, or the like), a substituted or unsubstituted aryl group (for example, phenyl, tolyl, naphthyl, or the like), and a substituted or unsubstituted hetero ring residue (for example, pyridyl, imidazolyl, thryl, thienyl, oxazolyl, thiazolyl, benzimidazolyl, quinolyl, or the like). More preferable examples thereof include a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodecyl, cyclohexyl, benzyl, or the like).

The dye of the present embodiment is preferably represented by any of the following formulae (A1)to (A3).

csc1o)_(dm -(a)L-A (Al)

NC COOH

ç34TI/(d)m (A2) Rx NCCOOH i-ti X2, Rx and Ry each have the same meaning as those in formula (6), respectively. d, a, m and L each have the same meaning as those in formula (2), respectively.

The dye represented by formula (1) or (2) may have the maximum absorption wavelength in a solution in the range of from 550 to 7SOnm, and more preferably in the range of from 600 to 700nm. {002}

Specific examples of the dye having a structure represented by formula (1) or (2) used in the present invention are shown below. However, the present invention is not limited to these, it is noted that in case where the dye in the following specific examples includes a ligand having a proton-dissociabic group, the ligand may dissociate to release the proton, if needed.

It is noted that in the present specification, the representation of the compound (a complex and a dye are incorporated therein) is used in the sense that not only the compound itselL but also its salt and its ion are incorporated therein. Further, it is used in the sense that the compound includes a derivative thereof which is modified in a predetermined form in the range of achieving a desired effect. Further, in the present specification, a substituent (a linking group is incorporated therein) that is not specified by substitution or non-substitution means that the substituent may have an optional substituent. This is applied to the compound that is not specified by substitution or non-substitution. Further, the ligand may coordinate to a central metal as any of an anionic ligand and a neutral ligand. Preferable examples of the substituent include the Examples of the substituent T include an alkyl group (preferably an alkyl group having Ito 20 carbon atoms, e.g. methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, bcnzyl, 2-ethoxyethyl, or I -carboxymethyl), an alkenyl group (preferably an alicenyl group having 2 to 20 carbon atoms, e.g. vinyl, ally], or oleyl), an alkynyl group (prcferably 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-ehlorophenyl, 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, c.g. mcthoxy, cthoxy, 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 allcoxycarbonyl group having 2 to 20 carbon atoms, e.g. ethoxycarbonyl, or 2-ethyihexyloxycarbonyl), an amino group (preferably an amino group having 0 to 20 carbon atoms, e.g. amino, N,N-dimethylamino, N,N-diethylamino, N-ethylamino, or anilino), a sulfonamide group (preferably a sulfonamide group having o to 20 carbon atoms, e.g. N,N-dimethylsulfonamide, or N-phenylsulfonamide), an acyloxy group (preferably an acyloxy group having I 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 I 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, aheterocyclic 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 ailcoxycarbonyl group, an amino group, an acylamino group and a cyano group arc particularly preferable.

Examples of the compound represented by formula (1) or (2) are shown below.

However, the present invention is not construed to be limited to these. The wavy line in the drawing is described supplementarily in order to indicate the structural units of D, d, a, and A. R102C R1:2-ethyLhexyt OR2 R1:2-ethylhexyl A-I A-2 R7:n-oclyl :4cx:0cP OR -OR1 R1 020 R1.2ethythe,ç'l R102C R1:2cthylbexyl k-S A-4 H0r1x5cc N R1020 A-S R1:2-cthylhexyl R10 A-iS R3:2-ethylhcxyl {0087} OR1 OR1 C

N

i-102G OR1 A-7 OR1 R1c R1:2-ethylhexyl OR1 1 HO2C F OR1 OR1 R1 02C R1:2-ethylhexyL A-8

N S HO2C

C R1 02

OR1 OR1 R1O2c R1:2-ethyffie1 A-9 NC OR1 rN H026 rF R102C OR1 R.1:2-ethyllLey1 A1O OR1 K

N

HO2CJ( Rthy1hwcyL A-li OR1 c OR1 OR1)-OR1 - 1130020 R1.2-etliylhexyl c-i2co2c R1.2-ethylhexyl A-IS A-14 OR1 OR 113002C K1 2-ethyllinyl I-1SCH2002 K1 2-elkyihexyl A-IS A-16

HOOC CN OCH

0C3H17 N Herein, "R102C-" means an alkyloxycarbonyl group Ri-O-(CO)-).

[Charge transfer object] Examples of the redox pair contained in the electrolyte composition for use in the photoelectric conversion element 10 of the present invention include a combination of iodine and an iodide (for example, lithium iodide, tetrabutylammonium iodide, or tctrapropylammonium 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, a combination of a divalent iron complex and a trivalent iron complex (for example, potassium ferricyanide and potassium fcrrocyanidc), and a combination of a divalent cobalt complex and a trivalent cobalt complex. Among these, a combination of iodine and an iodide and a combination of a divalent cobalt complex and a trivalent cobalt complex are preferred.

The cobalt complex is preferably represented by formula (14).

Co(LL2)rn2(X)is.C1 formula (14) In formula (14), LL2 represents a bidentate or terdentate ligand represented by formula LL2. X represents a monodentate or bidentate ligand. m2 represents an integer of 0 to 3. m3 represents an integer of 0 to 6. CI represents a counter ion for neutralizing a charge of the compound represented by formula (14).

LL2: ,Za,Zb (-Zc..\ N'N't'N/'c In formula LL2, Za, Zb and Zc each independently represent a group of atoms for forming a 5-or 6-membered ring. Each of Za, Zb and Ze may have a substituent, and may form ring closure together with an adjacent ring through a substituent. c represents 0 or 1.

X is preferably a halogen atom.

LL2 in formula (14) is preferably represented by any one of formulae (14-1) to (14-3).

(R'd)nd (R'a)fla (R'b)flb (R')n0 (R')fl (R' )n I f\3 r( (14-1) (14-2) (14-3) Herein, R'a to R'i each represent a substituent. nato nb each represent an integer of 0 to 4. nc and ne each represent an integer of 0 to 3. nd represents an integer of 0 to 2. nf and nj each represent an integer of 0 to 4.

In formulae (14-1) to (14-3), examples of Wa to R'i include an aliphatic group, an aromatic group, a heterocyclic group or the like. Specific examples of the substituent include an alkyl group, an alkoxy group, an alkylthio group, an aryl group, an aryloxy group, an arylthio group, and a heterocyclic ring. Preferred examples include an alkyl group (for example, methyl, ethyl, n-butyl, n-hexyl, isobutyl, sec-butyl, t-butyl, n-dodecyl, cyclohexyl, or benzyl), a substituted aryl group (for example, phenyl, tolyl, or naphthyl), and an alkoxy group (for example, methoxy, ethoxy, isopropoxy or butoxy). The number of the substituent 01 and 02 independently represent an integer of 0 or greater. The number of the substituent is preferably from 0 to 3, and more preferably from 0 to I. Specific examples of the above-described cobalt complex include the followings.

2/3 2+/3÷ C5H1j C-i C-2 C-3 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.

{0100) In the electrolyte composition used for the photoelectric conversion element 10 of the present invention, 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.

The electrolyte composition for use in the photoelectric conversion element 10 of the present invention 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.

{0102} The solvent preferably can develop excellent ion conductivity due to low viscosity to havc high ionic mobility, or high permittivity to aflow 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 (c.g. dioxanc and dicthyl cther), chain cthcrs (c.g. cthylcnc glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol diallcyl ether, and polypropylene glycol dialkyl ether), alcohols (e.g. methanol, ethanol, ethylcne glyeol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, and polypropylene glycol monoalkyl ether), polyhydric alcohols (e.g. ethylene glycol, propylene glycol, polyethylene glyeol, polypropylene glyeol, 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 (DM50) and sulfolane), water, a water-containing electrolytic liquid as described in JP-A-2002-l 10262, and an electrolytic solvent as described in JP-A-2000-36332, JP-A-2000-243 134 and WO 00/54361. These solvents may be used by mixing two or more kinds.

Moreover, as the electrolytic solvent, an electrochemically inert salt that is in a liquid statc at room tcmperature and has a mclting point lowcr than room tcmpcraturc may also be used. Specific examples include an imidazolium salt such as 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and I -butyl-3-methylimidazolium trifluoromethancsulfonatc, a nitrogcn-containing hcterocyclic quaternary salt compound such as a pyridinium salt, and a tetraalkylammonium salt.

{0104} The electrolyte composition for use in the photoelectric conversion element of the present invention 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.

(0105) 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, ELSEVIER APPLTED SCTENCE), can be used as the polymer. Of these compounds, polyacrylonitrile or poly (vinylidene fluoride) is preferably used.

{0106} In the case where the electrolyte composition is allowed to gelate by adding an oil-gelling agent, compounds described in J. Chem. Soc. Japan, md. Chem. Soc., 1943, p. 46779; J. Am. Chem. Soc., 1989, vol. 111, p. 5542; J. Chem. Soc., Chem. Commun., 1993, p. 390; Angew. Chem. hit. Ed. EngL, 1996, vol. 35, p. 1949; Chem. Left., 1996, p. 885; J. Chem. Soc., Chem. Con,inun., 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.

{0 1 07} In the case where the electrolyte composition is allowed to gelate by polymerization of polyfunetional monomers, a method is preferably applied in which a solution is prepared from polyflinctional 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.

{0 1 08} 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-alkvlacrylic acid (e.g. acrylic acid, methacrylic acid, and itaconic acid) or ester or amide thereof 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 ofp-styrenesulfonic acid, acrylonitrile, mcthacrylonitrilc, dienes (e.g. butadiene, cyclopentadiene, and isoprene), an aromatic vinyl compound (e.g. styrene, p- chiorostyrene, t-butylstyrene, ct-methylstyrene, and sodium styrenesulfonate), N- vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, vinylsulfonic acid, sodium vinylsulfonate, sodium allylsulfonatc, sodium methacrylsulfonate, vinylidene fluoride, vinylidene chloride, vinyl alkyl ethers (e.g. methyl vinyl ether), ethylene, propylene, butenc, isobutcnc, and N-phenylmaleimide.

{0109} 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 Jikkcn Hou (Experimental methods of polymer synthesis)," co-edited by Takayuki OTSU and Masayoshi KINOSHITA Kagaku-Dojin Publishing Company, Inc.), and "Koza Jugo Haimou Ron 1 (Polymerization reaction theory course 1), Radical polymerization (I))" by Takayuld 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-dimethylvaleronitrilc), dimcthyl-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 additive amount of polymerization initiator 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 crosslinldng agent includes a compound (electrophile) having two or more functional groups to which the nitrogen atom can make a nueleophilic attack. Specific examples include alkyl halide, aralkyl halide, sulfonate ester, acid anhydridc, acid chloride and isocyanate having two or more functional groups.

{0111} [Electrically conductive supportj As shown in Fig. 1, in the photoelectric conversion element of the present invention, the photosensitive layer 2 in which the sensitizing dye 21 is adsorbed on the porous semiconductor fine particles 22 is formed on the electrically conductive support 1. As described below, for example, a dispersion liquid of semiconductor fine particles is coated on the above-described electrically conductive support and dried, and then the resultant support is soaked in a solution of the dye of the present invention, thereby making it possible to produce a photosensitive layer 2.

As the electrically conductive support I, a support having elcctroconductivity 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 I 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 1, 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 polyolefin, and phenoxy bromide.

The electrically conductive support 1 may be provided with a light management function at the surface, and for example, the anti-reflective film having a high refractive index film and a low refractive index oxide film alternately laminated as described in JP-A-2003-1 23859, 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 metals may be alloys. Among these, titanium, aluminum and copper are further preferable; and titanium and aluminum are particularly preferable.

{01 14} It is preferable to provide the electrically conductive support 1 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 electrically conductive support (transparent support) oron the surface of the polymeric material layer. As another preferred method, a method of using an ultraviolet absorbent may also be used.

The electrically conductive support I may also be imparted with the functions described in JP-A-l 1-250944.

Preferred examples of the electrically conductive film include metals (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).

{01 17} The thickness of the electrically conductive film is preferably 0.01 to 30 jim, more preferably 0.03 to 25 jim, and particularly preferably 0.05 to 20 jim.

An eleetricafly conductive support I having lower surface resistance is preferred. The surface resistance is preferably in the range of 50 0/cm2 or less, and more preferably 10 0/cm2 or less. The lower limit of the surface resistance is not particularly limited, but the lower limit is usually about 0.1 0/cm2.

{01 19} Since the resistance value of the electrically conductive film increases as the cell area increases, a collecting electrode may be disposed. Any one or both of a gas barrier film and an ion dififision preventing film may be disposed between the electrically conductive support 1 and the transparent conductive film. As the gas barrier layer, anyofa resin film oran 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 thereof include a method of laminating FTO on ITO.

[Semiconductor fine particlesj As shown in Fig. 1, in the photoelectric conversion element 10 of this embodiment, the photosensitive layer 2 in which the sensitizing dye 21 is adsorbed on the porous semiconductor fine particles 22 is formed on the electrically conductive support 1. As described below, for example, a dispersion liquid of semiconductor fine particles 22 is coated on the above-described electrically conductive support I and dried, and then the resultant support is soaked in a solution of the dye described above, thereby making it possible to produce the photosensitive layer 2.

Regarding the semiconductor fine particles 22, fine particles of chalcogenides of metals (for example, oxides, sulfides and selenides), or fine particles of perovskites may be used with preference. Preferred examples of the chalcogenides of metals include oxides of titanium, tin, zinc, tungsten, zirconium, hafnium, strontium, indium, S cerium, yttrium, lanthanum, vanadium, niobium or tantalum, cadmium sulfide, and cadmium selenide. Preferred examples of the perovskites include strontium titanate, and calcium titanate. Among these, titanium oxide, zinc oxide, tin oxide, and tungsten oxide are particularly preferred.

Semiconductors are classified into n-type semiconductors in which the carrier associated with conduction is electron, or p-type semiconductors in which the carrier is a hole. It is preferable to use an n-type semiconductor in the present invention, in view of the conversion efficiency. The n-type semiconductors include an intrinsic semiconductor (or true semiconductor) which does not have an impurity level, and has equal concentrations of the carriers consisting of the conduction band electrons and the valence band holes, as well as an n-type semiconductor having a higher concentration of the electron carrier due to the structural defect originating from impurities. Examples of the n-type inorganic semiconductors that may be preferably used in the present invention include Ti02, TiSrO, ZnO, Nb201, 5n02, W02, Si, CdS, CdSe, V205, ZnS, ZnSc, SnSe, KTaO-, FeS2, PbS, InP, GaAs, CuInS2, and CuInSc2. Among these, most preferred examples of the n-type semiconductors include Ti02, ZnO, 5n02, W03 and Nb203. A composite semiconductor material composed of plural kinds of these semiconductors is also used with preference.

In regard to the method for producing semiconductor fine particles 22, 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 22 are titanium oxide, the sol-gel method, the gel-sol method, and the method of hydrolyzing a chloride in an oxygen-hydrogen flame at high temperature, are all preferred, and the sulfuric acid method and chlorine method described in SEfNO Manabu, "Titanium Oxide: Material Properties and Application Technologies", Giliodo Shuppan Co., Ltd. (1997) may also be used. Other preferred examples of the sot-gel method include the method described in Barbe et at., Journal of American Ceramic Society, Vol. 80, No. 12, pp. 3157-3171(1997), and the method described in Burnside et al., Chemistry of Materials, Vol. 10, No. 9, pp. 2419-2425.

[Semiconductor fine particle dispersion liquid] In the present invention, porous semiconductor fine particles-coated layer can be obtained by applying a semiconductor fine particle dispersion liquid in which the content of solids excluding semiconductor fine particles is 10% by mass or less of the total amount of the semiconductor fine particle dispersion liquid, on the electrically conductive support 1 mentioned above, and appropriately heating the coated support.

Examples of the method of producing a semiconductor fine particle dispersion liquid include, in addition to the sol-gel method described above, a method of precipitating the semiconductor in the form of fine particles in a solvent upon synthesis and directly using the fine particles; a method of ultrasonicating fine particles, and thereby pulverizing the fine 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 a-terpineol; ketones such as acetone; esters such as ethyl acetate; dichloromethane, and acetonitrile.

{0127) At the time of dispersing the fine particles, for example, a polymer such as polyethylene glycol, 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 fine particle dispersion liquid is such that the content of solids excluding semiconductor fine 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 tIne 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 fine particle dispersion liquid. It is preferable that the semiconductor fine particle dispersion liquid is substantially composed only 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 fme 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 Ns/m2 at 25°C, and more preferably 50 to 200 Ns/m2 at 25°C.

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 an application-related method. Furthermore, an air knife method, a blade method or the like can be used as a metering-related method. As a method that can utilize an application-related method and a metering-related method on the same part, a wire bar method disclosed in JP-B-58-4589 ("JP-B" means examined Japanese patent publication), a slide hopper method described in U.S. Patent No. 2,681,294, an extrusion method, and a curtain method 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 DY-ozone treatment, the affinity between the applied semiconductor fine particle dispersion liquid and the surface of the electrically conductive support 1 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 jim, more preferably ito 30 jim, and even more preferably 2 to 25 jim. The amount of the coated semiconductor fine particles per square meter of the support is preferably 0.5 to 400g. and more preferably 5 to 100g. In this case, the amount of use of the dye for use in the present invention is preferably adjusted to 5% by mole or more.

The amount of the dye adsorbed to the semiconductor fine particles is preferably 0.00 1 to 1 millimole, and more preferably 0.1 to 0.5 millimoles, based on 1 g of the semiconductor fine particles. When the amount of the dye is adjusted to such a range, the sensitization effect for the semiconductor can be sufficiently obtained. On the other hand, if the amount of the dye is too small, the sensitization effect is insufficient, and if the amount of the dye is excessive, the portion of the dye that is not attached to the semiconductor is suspended, and causes a decrease in the sensitization effect.

In case where the above-described dye is in the form of a salt, the counter ion of the specific metal complex dye described above is not particularly limited. Examples of the counter ion include an alkali metal ion and a quaternary ammonium ion.

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

{0132} The amount of coating of the semiconductor fine particles 22 per square meter of the support is preferably 0.5 to 500 g, and more preferably 5 to 100 g.

The counter electrode 4 is an electrode working as a positive electrode in the photoclectrochemical cell. The counter electrode 4 usually has the same meaning as the electrically conductive support 1 described above, but in a construction which is likely to maintain a sufficient strength, a support of the counter electrode is not necessarily required. However, a construction having a support is advantageous in terms of sealability. Examples of the material fbr the counter electrode 4 include platinum, carbon, and electrically-conductive polymers. Preferred examples include platinum, carbon, and electrically-conductive polymers.

(0134) A preferred structure of the counter electrode 4is a structure having a high charge collecting effect. Preferred examples thereof include those described in JP-T- 10-505 192 and the like.

{0135} In regard to the light-receiving electrode 5, a composite electrode of titanium oxide and tin oxide (Ti02/Sn02) or the like may be used. Examples of mixed electrodes of titania include those described in JP-A-2000-l 13913 and the like. Examples of mixed electrodes of materials other than titania include those described in JP-A-2001 - 185243, JP-A-2003-282164 and the like.

{0 1 36} As a constitution of the photoelectric conversion element, the element may have a structure formed by sequentially laminating a first electrode layer, a first photoelectric conversion layer, an electrically-conductive layer, a second photoelectric conversion layer, and a second electrode layer. In this case, the dyes used for the first photoelectric conversion layer and the second photoelectric conversion layer may be identical or different. When the dyes are different, absorption spectra are preferably different.

(0137) The light-receiving electrodes 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 a photo management function by which light scattering and reflection are efficiently achieved inside the layer of the light-receiving electrode 5. Preferred examples thereof include those described in JP-A-2002-93476 and the like.

It is preferable to form a short circuit preventing layer between the electrically conductive support I and the porous semiconductor fine particle 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 5 and the counter electrode 4. Preferred examples thereof include those described in JP-A-2001-283941 and the like.

Methods for sealing a cell or a module preferably include a method using a polyisobutylene thermosetting resin, a novolak resin, a photocuring (meth) aerylate resin, an epoxy resin, an ionomer resin, glass frit, or aluminium 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

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.

(Example 1 and Comparative Example 1) [Preparation of dyes] A-i as the dye of the present invention was prepared according to the following method. Other dyes used in Examples were prepared in a similar maimer.

MeCH DCH2cCH3 A -Tin4 -cv1y000Me Na2S NaUll

S H AOEt

2 MeO2d HO Yield 93 % Yield 6.9 % Yield 24.6 % Yield 47.2 % PhSQNF OHC%Ø_Br n-BuU TsOR1 Sell NS

__ I -F

F

F S DMF

__________ 13

DMF

H020 AR, refkx [ Rio R102 6 Rj:2-othylhexyl R1:2-ethy[hexyl Rio -Yield 45. % S R1:2-ethylheyl Yield 33.8% Yield 56.8% Yield 74.4 % OAc OR1 0 0 NHMt'BCI 1.1 eq n-Th'Li 1.2 q lOeq, NE1⁄4 ThOR1 Seq NEt32cq Et20 / ____________ ________ CI P NMe2 _______ ZnlOeq CII1CI2,rtThS Cs,C035eq Cfl,CI, Ot-r.t.2h ci Ac Alt, reilur OR4 LI IY'C-n.t. lb 13 14 5 Yield 85.1% Yield 55.4% Yield 45.0 Yield S&9 % R1:2.ctbylhcxyl {0145}

-

Jo-BuLl 1.1 eq 2.5 OR1 OR1 2JkOBu)3 3.0 tq -Pd'Ptb)4 Meq -SOC--tr.t. lh

____

P0a31.6eq OR, OR, lOwt%Cs2CO3aq OR1 Allquat 336 Rj;2cthylhvsyl 16 tohrn,e, itt 4h Yield 433 % Yield 84.2 54

OEIC

1.mBuLi 1.1 eq ZB(OBu)3 3.0 eq OR1 2.5 eq OH TDF.50t*r.t lb \/ /-. I'd(PPh3)4 04 eq H0 -PBu3 1.6 eq 3. V 3eq

OR

I IOnt%O2CO3q OR1 Atiquat33G RiQ,C 18 totua,e, r.L4h 19 Yield 3&2% Yield 734% OR1 El N C) ORi Tolucue, 100°C 21i

A-I

Yield 53.2 % MS-EM tSz:932.24(M-LL) [Evaluation of maximum absorption wavelength of dye and long-wavelength edge (Abs/Absmax=0. 1)] Measurement of the maximum absorption wavelength of the dye and the long-wavelength edge (Abs!Absmax=0.1) was conducted. The long-wavelength edge represents a wavelength at which Abs is 10% with respect to the Abs at the 2. max of the solution absorption spectrum (Abs/Absmax=0.1). The results are shown in Table 1.

Measurement was conducted using a spcctrophotomctcr (U-41 00 (trade name), manufactured by Hitachi High-Technologies Corporation) and a mixture of THF and ethanol with a mixing ratio of 1:1 was used as the solution, and a concentration of the solution was adjusted so asto be 2MM.

[Molecular orbital calculation of dye using Winmostar computational software] With respect to the dyes shown in Table 1, which were prepared by the above-described method and similar methods, the energy levels of HOMO and LUMO of each of the section d and the section a were calculated and the difference in the energy levels of FIOMO between the section d and the section a was calculated using Winmostar computational software (Winmostar (trade name), manufactured by Kabushiki Kaisha Tencube Kenkyusho). The results are shown in Table 1.

[Preparation of photoelectric conversion clement and evaluation of photoelectric conversion efficiency] A transparent conductive film was prepared by forming an FTO film on a glass substrate. Then, a transparent electrode plate was obtained by forming a semiconductor fine particle layer on the transparent conductive film. Then, a photoelectrochemical cell was prepared using the transparent electrode plate to measure conversion efficiency.

Details of these methods are described in the following (1)to (3).

(1) Preparation of raw material compound solution for ETO (fluorine-doped tin oxide) film Was dissolved 0.70 1 g of tin (IV) chloride pentahydrate in 10 ml of ethanol, and 0.592 g of a saturated aqueous solution of ammonium fluoride was added thereto.

This mixture was completely dissolved in an ultrasonic bath over about 20 minutes, and thus a raw material compound solution for FTO film was prepared.

(2) Preparation of FTO transparent conductive film The surface of a heat resistant glass plate having a thickness of 2mm was subjected to chemical cleaning and was dried. Subsequently, this glass plate was placed in a reactor and was heated with a heater. When the heating temperature of the heater reached 450°C, the raw material compound solution for FTO film obtained in the above item (1) was sprayed over the glass plate for 25 minutes through a nozzle having an aperture diameter of 0.3 mm at a pressure of 0.06 MPa with a distance to the glass plate of 400 mm. Thus, there was obtained a transparent electrode plate in which an FTO film having a thickness of 170 nm was formed on the heat resistant glass plate. Then, the transparent electrode plate was heated in a heating frirnace at 450°C for 2 hours.

(3) Preparation of photoclcctrochcmical cell Subsequently, a photoelectrochemical cell having a structure such as shown in FIG. 2 of Japanese Patent No. 4260494 was prepared using the transparent electrode plate. The formation of an oxide semiconductor porous film was carried out by dispersing titanium oxide fine particles having an average particle size of about 7 nm in acetonitrile to prepare a paste, applying this paste on a transparent electrode 11 by a bar coating method, drying the paste, and then calcining the paste at 450°C for one hour.

Then, the formation of a semiconductor fine particle layer having a thickness of 15 tm was carried out by dispersing titanium oxide fine particles having an average particle size of about 400 nm in acetonitrile to prepare a paste, applying this paste on the transparent electrode 11 by a bar coating method, drying the paste, and then caleining the paste at 450°C for one hour.

{0150) Next, a dye described in Table 1 was dissolved in absolute ethanol at a concentration of 3 x 1o4 mol/L, and thus a dye solution for adsorption was prepared.

Here, the number of the dye is identical to the number of the dye previously indicated as the specific example thereof. This dye solution for adsorption and the transparent substrate provided with the titanium oxide film and the transparent electrically conductive film obtained as described above were put in a container, respectively, to allow the titanium oxide film to adsorb the dye by permeation for about 4 hours, thereby providing a light-receiving electrode. Then, the substrate was washed with absolute ethanol several times, and dried at 60°C for about 20 minutes.

Next, lithium iodide at a concentration of 0.5 moL'L and iodine at a concentration of 0.05 mol/L were dissolved using PC as a solvent to prepare an electrolytic solution. In this solution, the above-described light-receiving electrode was soaked for about 2 hours whereby the oxidation-reduction electrolytic solution was penetrated into the light-receiving electrode. After that, an electrically conductive substrate having a platinum film was provided and then the periphery thereof was sealed with an epoxy sealant, and then the oxidation-reduction electrolytic solution was injected without any change into space between the light-receiving electrode and a counter electrode and then sealed to prepare a photoelectric conversion element. Light having intensity of 1000 W!m2 using a solar simulator was irradiated to this element to measure conversion efficiency. The results are shown in Table 1. The conversion efficiency of 80% or higher was judged as being practically acceptable. Further, the photoelecfric conversion efficiency after 500 hour irradiation was measured whereby durability was evaluated.

A: Photoelectric conversion efficiency after 500 hour irradiation is at least 80% of the initial value.

B: Photoelectric conversion efficiency after 500 hour irradiation is from 60% or more and less than 80% of the initial value.

C: Photoelectric conversion efficiency after 500 hour irradiation is from 40% or more and less than 60% of the initial value.

D: Photoelectric conversion efficiency after 500 hour irradiation is from 20% or more and less than 40% of the initial value.

E: Photoelectric conversion efficiency after 500 hour irradiation is less than 20% of the initial value.

tcc Itt 3 9Th 0 ZZ6-I'tO ZZ6-t'ZO £-8 £13 t'09 OLt' C rc 0 868 Lt0 868 L0 ZtI Z13 19c 9f7 3 St 0 868-L0 868-CO 111 113 0L9 0cc V ______________ cco oc*s-001-ccL-cco-LI-v 011 I IL csc v 18 080 ccs-ill-ccL-cco-91-v 601 In ___________ ________ ________ __________ ________________ _____ _____ _____ _____ ____ ____ _______________ csc v rs zso LE8-£11-ccL-cco-ct-v sot 989 Lç V 8L LEO 8-160-ccL-cco-N-V LOT 89 oLc V 08 6L0 IS-V6O-ccL-cco-£LV 901 69 0Z9 V 8L IWO 98-111-ccL-cco-c-V co 189 csc V OS 181) 9E8-111 ccL-cco-P-V POT 999 csc V VL IWO 9f8-1I1 ccL-cco-£V LOT zc9 osc V 9L Z90 ZL8-160-CL-190-Z-V ZOT LOL osc V 8 181) 9L8-111-ccL-cco-1-V TOT (uLu) (iuu) (AD) (AD) (AD) (Ac) (AD) (1 o=xBtusqv/sqv) 1? uOTJDDS MTt ONOU ONf1TI OWOB ONITI Dfl TSDJ.

icit1iqiunc couDLUJjD uoncbosqi UOL4DDS LLDDM1D Ot"JOF-{ J0

UOLSJDAUOJ

1ufluhiXl1I\ jDADp,caIDuD UL DDUDJDJJLU _________ _________ _________ _________ BUOUDD5 j)U0fl035 I 1W1 (zc i o The following dyes were used for comparison (comparative example). CN1 i3 0-3

{0155} Hc2c4F Further, with respect to the above comparative dye B-i, as described above, its formula was cut into sections of the formula at wavy line positions and the energy level of each of the sections, and the difference in the energy level of HOMO between the section d and the section a were measured. With respect to B-2 and B-3, these values were also calculated in the same manner.

{0156) As is apparent from Table 1, each of the comparative dyes had a relatively shorter maximum absorption wavelength and was inferior in both initial conversion efficiency and durability. In contrast, each of the dyes of thc present invention had a relatively longer maximum absorption wavelength and was superior in both initial value of conversion efficiency and durability.

(Example 2 and Comparative Example 2) The following tests 201 to 204 and C21 to C24 were conducted in the same manner as tests 101 to 110, except that dyes shown in the following table were used and the electrolyte was changed from iodine to those shown in the following table.

{0158}

Table 2

Test Dye Electrolyte Voc Conversion efficiency (%) 201 A-17 C-i AA AA 202 A-17 C-2 AA AA 203 A-17 C-3 AA AA 204 A-17 iodine A A C21 B-3 C-i B B C22 B-3 C-2 B B C23 B-3 C-3 B B C24 B-3 iodine C B In comparative dyes, although Voc is improved by using a Co complex as an electrolyte, conversion efficiency is low. In contrast, in each of the dyes of the present invention, the conversion efficiency is improved together with a Voc-enhancing effect.

This suggests that thc cncrgy level of the dyc of the present invcntion has energy suitable for oxidation-reduction potential of the Co complex whereby a charge transfer proceeds smoothly, which results in improvement of the conversion efficiency.

The above-described results are indicated in terms of comparative assessment.

Each of the symbols has the following meaning.

AA:VeryGood A: Good B: Normal C: inferior to Normal

REFERENCE SIGNS LIST

1 Electrically conductive support 2 Photoconductor layer 21 Sensitizing dye 22 Semiconductor fine particle 3 Charge transfer object layer 4 Counter electrode Light-receiving electrode 6 External circuit 10 Photoelectric conversion element Photoelectrochemical cell system