JP2000228233A - Pigment adsorbing semiconductor fine grain, pigment adsorbing method to semiconductor fine grain, optoelectronic transducer element and optoelectronic chemical cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve optoelectronic transducing efficiency and to prevent cohesion of a pigment by adsorbing a pigment and a compound having a hetero ring to a semiconductor fine grain. SOLUTION: A pigment and a compound expressed by formula I such as a compound of formula II are used. To adsorb a pigment in a semiconductor fine grain, a well dried semiconductor fine grain is dipped in a pigment solution for several hours. The compound by formula I is coexistent in a pigment adsorbing liquid or a pigment is adsorbed to the semiconductor fine grain and then washed with a solution of the compound expressed by formula I. As a color sensitizing pigment, a ruthenium complex pigment, a phthalocyanine pigment, and a polymethyne are preferable. In formula I, Q is a hetero ring, L is a single bond or a bivalent coupling group, Z is an acid group, and W is paired ions for neutralizing charges of a molecule. Preferably, Q is a pyrrole ring, a thiazole ring, an oxazole ring, a cerenazo cerenazole ring, an imidazole ring, a 2-quinoline ring, a 4-quinoline ring, and Z is carboxylic acid or solufonic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor fine particle having a dye adsorbed thereon and a method of adsorbing the same. In particular, the present invention relates to a dye-adsorbed semiconductor fine particle used for a dye-sensitized photoelectric conversion element or a photoelectrochemical cell and a method for adsorbing the dye.

[0002]

2. Description of the Related Art Nature (Vol. 353, pp. 737-740, 1991)
And U.S. Pat. No. 4,492,721 disclose a photoelectric conversion element and a solar cell using semiconductor fine particles sensitized with a dye, and materials and manufacturing techniques for producing the same. The proposed battery is a wet solar battery using a titanium dioxide porous thin film spectrally sensitized by a ruthenium complex as a working electrode. An advantage of this method is that an inexpensive oxide semiconductor such as titanium dioxide can be used without purification to a high degree of purity, so that an inexpensive photoelectric conversion element can be provided.

As a sensitizing dye for such a dye-sensitized photoelectric conversion element, various complex dyes and organic dyes can be used in addition to the ruthenium complex dye. When the dye is adsorbed on the fine particles, the dye may undesirably aggregate, and the performance (particularly, the photoelectric conversion efficiency) of the obtained photoelectric conversion element may be reduced. To prevent this aggregation between dyes, a method of mixing steroid compounds into the dye adsorption solution is known as Chemic.
Although described in alCommunication (pp. 719-720, 1998), the effect was not sufficient, and the steroid compound was expensive.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide dye-sensitized semiconductor fine particles having excellent photoelectric conversion efficiency and to provide a method for effectively preventing dye aggregation. . It is still another object of the present invention to provide a photoelectric conversion element and a photoelectrochemical cell using semiconductor fine particles produced by such a method.

[0005]

The object of the present invention has been attained by the following items which specify the present invention and preferred embodiments thereof. (1) Semiconductor fine particles on which a dye and a compound represented by the following formula (I) are adsorbed.

[0006]

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[In the formula (I), Q represents a heterocyclic ring, and Q may be condensed or may have a substituent. L represents a single bond or a divalent linking group. Z represents an acidic group having a dissociable proton, and W represents a counter ion necessary for neutralizing the charge of the molecule. (2) The semiconductor fine particles according to the above (1), wherein Q is a nitrogen-containing heterocycle. (3) Q is a pyrrole ring, thiazole ring, oxazole ring, selenazole ring, imidazole ring, 2-quinoline ring,
The semiconductor fine particles of the above (2), which are rings selected from a 4-quinoline ring and a nucleus derived from these benzo-fused rings. (4) The semiconductor fine particles according to any one of the above (1) to (3), wherein Z is a carboxylic acid or a sulfonic acid. (5) The above (1) to (4), wherein L is a single bond, a divalent linking group having 1 to 5 carbon atoms or a linking group containing one sulfur, oxygen or nitrogen atom and 0 to 5 carbon atoms. Any semiconductor fine particles. (6) The semiconductor fine particles according to any one of (1) to (5), wherein the compound represented by the formula (I) is a compound having substantially no absorption in the visible region. (7) The semiconductor fine particles according to any one of (1) to (6), wherein the dye is at least one dye selected from a ruthenium complex dye, a polymethine dye, and a phthalocyanine dye. (8) The molar ratio of the adsorbed compound represented by the formula (I) to the adsorbed dye is 1/10 or less (1) to (7).
Semiconductor fine particles of any of the above. (9) The semiconductor particles according to any one of the above (1) to (8), wherein the semiconductor particles are a metal oxide. (10) The semiconductor particles according to any one of (1) to (9), wherein the semiconductor particles are titanium oxide or niobium oxide. (11) A photoelectric conversion element using the semiconductor fine particles according to any of (1) to (10). (12) A method of adsorbing a dye on semiconductor fine particles, wherein the method is performed by at least one of the following a) and b). a) A compound represented by the formula (I) coexists in a solution of a dye to be adsorbed, and semiconductor fine particles are immersed in this solution. b) After adsorbing the dye on the semiconductor fine particles, the semiconductor fine particles are immersed in a solution containing the compound represented by the formula (I).

[0008]

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[In the formula (I), Q represents a heterocyclic ring, and Q represents
It may be condensed or may have a substituent. L is a single bond
Or a divalent linking group. Z has a dissociable proton
Represents an acidic group, and W is necessary to neutralize the molecular charge.
Represents a key counter ion. (13) In the above a), the compound represented by the formula (I)
The concentration of the dye in the solution is 10 to 100
The dye adsorption method according to the above (12), which is 0-fold. (14) In the above b), the compound represented by the formula (I) in the solution
The concentration of the compound to be ^-3More than mol / l 10mol
The color of (12) or (13) above which is not more than / liter
Element adsorption method. (15) Any of the above methods (11) to (13)
Conversion element using dye-adsorbed semiconductor fine particles prepared from
Child. (16) The photoelectric conversion element according to the above (11) or (15).
A photoelectrochemical battery using.

Hereinafter, the formula (I) used in the present invention will be described in detail. In the formula (I), Q represents a heterocyclic ring;
May be further condensed or may have a substituent. Q
Preferred examples of the heterocyclic ring completed in are a pyrrole ring, a thiazole ring, an oxazole ring, a selenazole ring,
Imidazole ring, tellurazole ring, 2-quinoline ring, 4-quinoline ring, thiazoline ring, oxadiazole ring and these benzo-condensed ring-derived rings, and particularly preferably a pyrrole ring, a thiazole ring, an oxazole ring, They are a selenazole ring, an imidazole ring, a 2-quinoline ring, a 4-quinoline ring and a ring derived from a benzo-fused product thereof. Examples of the substituent on the ring include carboxylic acid, phosphonic acid, sulfonic acid, halogen (F, Cl, Br, I), cyano, alkoxy (eg, methoxy, ethoxy, methoxyethoxy), aryloxy (eg, phenoxy), alkyl (Eg, methyl, ethyl, cyclopropyl, cyclohexyl, trifluoromethyl, methoxyethyl, allyl, benzyl, etc.), alkylthio (eg, methylthio, ethylthio, etc.), alkenyl (eg, vinyl,
-Propenyl, etc.), aryl (eg, phenyl, thienyl, toluyl, chlorophenyl, etc.) and the like.

L represents a single bond or a divalent linking group. L
Is not particularly limited as long as it is a linear group having two or more functionalities, and may not be present when Q and Z are directly bonded. It is preferably formed of a single bond or a group of atoms selected from carbon, oxygen, sulfur, nitrogen, silicon, phosphorus and a halogen atom. The number of carbon atoms is preferably 0 to 15, more preferably 0 to 8. Particularly preferably, a single bond and 1 carbon atom
To 5 divalent linking groups or a linking group containing one sulfur, oxygen or nitrogen atom and 0 to 5 carbon atoms. In this case, the nitrogen atom may have an alkyl substituent different from the above carbon number.

Z represents an acidic group having a dissociable proton. Preferred examples of the acidic group having a dissociable proton include carboxylic acid, sulfonic acid, phosphonic acid, boric acid, a dissociable phenol group, and a hydroxyl group. Particularly preferred is a carboxylic acid or a sulfonic acid.

W represents a counter ion when a counter ion is required to neutralize the charge. Whether a compound of formula (I) is a cation, anion, or has a net ionic charge depends on the substituents. When the substituent has a dissociable group, it may dissociate and have a negative charge, and in this case also, the charge of the entire molecule is neutralized by W. Typical cations are inorganic or organic ammonium ions (eg, tetraalkylammonium ions, pyridinium ions) and alkali metal ions, while the anions are specifically either inorganic or organic anions. Well, for example, halogen anions (eg, fluoride, chloride, bromide, iodide), substituted arylsulfonates (eg, p-toluenesulfonate, p-chlorobenzenesulfonate), Aryl disulfonate ion (for example, 1,3-benzenedisulfonate ion, 1,
5-naphthalenedisulfonic acid ion, 2,6-naphthalenedisulfonic acid ion), alkyl sulfate ion (for example, methyl sulfate ion), sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion,
Picric acid ion, acetate ion, and trifluoromethanesulfonic acid ion. Further, an ionic polymer or another dye having a charge opposite to that of the dye may be used as the charge balancing counter ion, or a metal complex ion (for example,
Bisbenzene-1,2-dithiolatonickel (III)) is also possible

The compound of the formula (I) is added for the purpose of preventing undesired aggregation of the dye, and is substantially colorless from the viewpoint of effective use of light, that is, substantially absorbed in the visible region. It is preferable not to have. Hereinafter, specific examples of the compound represented by the formula (I) of the present invention are shown, but the present invention is not limited thereto.

[0015]

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[0016]

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[0017]

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[0018]

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In the present invention, the semiconductor to which the dye is adsorbed and sensitized is a so-called photoreceptor, which plays a role of absorbing light to separate electric charges and generate electrons and holes. In a dye-sensitized semiconductor, light absorption and the resulting generation of electrons and holes mainly occur in the dye, and the semiconductor is responsible for receiving and transmitting the electrons. As the semiconductor, besides a simple semiconductor such as silicon or germanium, a so-called compound semiconductor represented by a metal chalcogenide (for example, oxide, sulfide, selenide, or the like) or a compound having a perovskite structure can be used. .
Preferably as a metal chalcogenide titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium,
Examples include lanthanum, vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony, bismuth sulfide, cadmium, selenide of lead, and telluride of cadmium. Other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium, gallium arsenide, copper-indium-selenide, copper-
Indium-sulfide and the like. Further, as the compound having a perovskite structure, strontium titanate, calcium titanate, sodium titanate, barium titanate, and potassium niobate are preferably exemplified. More preferably as the semiconductor used in the present invention,
Specifically, Si, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O
_{5, CdS, ZnS, PbS,} Bi 2 S 3, CdSe, CdTe, GaP, InP, G
aAs, CuInS ₂ and CuInSe ₂ are mentioned. More preferably _{TiO 2, ZnO, SnO 2,} Fe 2 O 3, WO 3, Nb 2 O 5, CdS, Pb
S, CdSe, InP, GaAs, CuInS ₂ , CuInSe ₂ , particularly preferably TiO ₂ or Nb ₂ O ₅ , most preferably TiO ₂
It is.

The semiconductor used in the present invention may be single crystal or polycrystal. Although a single crystal is preferable as the conversion efficiency, a polycrystal is preferable in terms of manufacturing cost, securing of raw materials, energy payback time, and the like, and a fine particle semiconductor having a nanometer to micrometer size is particularly preferable. The particle diameter of these semiconductor fine particles is an average particle diameter using the diameter when the projected area is converted into a circle, and is 5% as a primary particle.
It is preferably from 200 to 200 nm, particularly preferably from 8 to 100 nm. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is 0.01 to 100 μm.
It is preferred that Further, two or more kinds of fine particles having different particle size distributions may be mixed and used, and in this case, the average size of the small particles is preferably 5 nm or less. In addition, semiconductor particles having a large particle size, for example, about 300 nm may be mixed for the purpose of improving the light capture rate by scattering incident light.

The method for producing the semiconductor fine particles is described in "Sol-Gel Method Science" by Agaku Shofusha (1988) by Shuo Sakuhana, "Thin Film Coating Technology by Sol-Gel Method" (1995) by Technical Information Association, etc. Tadao Sugimoto, "Synthesis of Monodisperse Particles and Size Morphology Control by New Synthetic Gel-Sol Method", Materia, Vol. 35, No. 9, 1012
The gel-sol method described on pages 10 to 1018 (1996) is preferred. Further, a method of producing an oxide by hydrolyzing a chloride in an oxyhydrogen flame at a high temperature developed by Degussa is also preferable. In the case of titanium oxide, the above sol-gel method,
The gel-sol method and the high-temperature hydrolysis method of chloride in an oxyhydrogen flame are all preferable. However, the sulfuric acid method described in Manabu Kiyono's "Titanium oxide properties and applied technology" Gihodo Shuppan (1997).
The chlorine method can also be used. In the case of titanium oxide, among the sol-gel methods described above, in particular, Barb et al., Journal of American Ceramic Society No. 80
Vol. 12, No. 3, pp. 3157 to 3171 (1
997) ”and Burnside et al.,“ Chemical Materials, Vol. 10, No. 9, pages 2419 to 2425 ”.

The dye used in the present invention may be any dye that adsorbs to the above-mentioned semiconductor fine particles and sensitizes it, but a metal complex dye, a phthalocyanine dye or a polymethine dye is preferable, and a phthalocyanine dye or polymethine dye is more preferable. It is a dye, particularly preferably a polymethine dye. In the present invention, two or more kinds of dyes can be mixed in order to widen the wavelength range of photoelectric conversion as much as possible and to increase the conversion efficiency. Dyes to be mixed and their proportions can be selected so as to match the wavelength range and intensity distribution of the target light source. Such a dye preferably has an appropriate interlocking group for the surface of the semiconductor fine particles. Preferred linking groups include
COOH group, SO ₃ H group, a cyano group, -P (O) (OH) 2 group, -OP (O) (OH)
_Two groups or chelating groups having π conductivity such as oximes, dioximes, hydroxyquinolines, salicylates and α-keto enolates. Among them, a COOH group, a —P (O) (OH) ₂ group, and a —OP (O) (OH) ₂ group are particularly preferable. These groups may form a salt with an alkali metal or the like, or may form an intramolecular salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case of forming a squarylium ring or a croconium ring, this portion may be used as a bonding group.

Preferred of the metal complex dye used in the present invention
The form includes a ruthenium complex dye,
The Ru complex dye represented by the formula (II) is preferable. Formula (II) (A₁)_pRuB_aB_bB_c In the formula, p is 0 to 2, preferably 2. Ru is
Represents ruthenium. A ₁Is Cl, SCN, H_TwoO, B
r, I, CN, NCO and SeCN
It is a child. B_a, B_b, B_cAre each independently
It is an organic ligand selected from B-1 to B-8.

[0024]

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[0025]

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Here, _Ra is a hydrogen atom, a halogen atom,
A substituted or unsubstituted alkyl group having 1 to 12 carbon atoms (hereinafter referred to as C number), an aralkyl group substituted or unsubstituted with 7 to 12 carbon atoms, or a substituted or unsubstituted with 6 to 12 carbon atoms Represents an aryl group. The above alkyl group,
The alkyl portion of the aralkyl group may be linear or branched, and the aryl portion of the aralkyl group may be monocyclic or polycyclic (condensed ring, ring assembly). . Examples of the ruthenium complex dye used in the present invention include, for example, U.S. Pat.Nos. 4,492,721, 4,684,537 and 5,084.
And complex dyes described in JP-A Nos. 365, 5350644, 5463057, 5525440 and JP-A-7-249790.

The phthalocyanine dye which can be used in the present invention may be in the form of a metal complex.
Phthalocyanine dyes and naphthalocyanine dyes described in JP-A-188446, JP-A-9-199744 and WO94 / 05025.

Preferred specific examples of the metal complex dye used in the present invention are shown below, but the present invention is not limited to these.

[0029]

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[0030]

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[0031]

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When the dye used in the present invention is a polymethine dye, a dye represented by the following formula (III) or (IV) is preferred.

[0033]

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In the formula, R _b and R _f each represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, and R _{c to} R _e
Represents a hydrogen atom or a substituent. R _{b to} R _f may combine with each other to form a ring. X ₁₁ and X ₁₂ each represent nitrogen, oxygen, sulfur, selenium, or tellurium. m ₁₁ and m
₁₃ represents an integer of 0 to 2, and m ₁₂ represents an integer of 1 to 6. The compound represented by the formula (III) may have a counter ion depending on the charge of the whole molecule. The alkyl group in the above,
The aryl group and the heterocyclic group may have a substituent.
The alkyl group may be linear or branched, and the aryl group and the heterocyclic group may be monocyclic or polycyclic (condensed ring, ring assembly). The ring formed by R _{b to} R _f may have a substituent and may be a single ring or a condensed ring.

[0035]

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[0036] In the formula, the Z _a represents a non-metallic atomic group necessary for forming a nitrogen-containing heterocyclic ring. R _g is an alkyl group or an aryl group. Q _a represents a methine group or a polymethine group necessary for the compound represented by the formula (IV) to form a methine dye. X ₁₃ represents a charge balancing counter ion, and m ₁₄ represents an integer of 0 or more and 10 or less necessary for neutralizing the charge of the molecule. Nitrogen-containing heterocyclic ring formed by the above Z _a may have a substituent, it may be a condensed ring may be a single ring. Further, the alkyl group and the aryl group may have a substituent, the alkyl group may be linear or branched, and the aryl group may be monocyclic or polycyclic (condensed ring, Ring set). The dye represented by the formula (IV) is preferably a dye represented by the following formulas (IV-a) to (IV-d).

[0037]

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In the formulas (IV-a) to (IV-d), R _a1 to
R _a5 , R _{b1 to} R _b4 , R _{c1 to} R _c3 , and R _{d1 to} R _d3 each independently represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, and Y ₁₁ , Y ₁₂ , Y ₂₁ , Y _22, Y ₃₁ ~Y
₃₅ and Y ₄₁ to Y ₄₆ each independently represent oxygen, sulfur, selenium, tellurium, -CR _e1 R _e2 - represents a -, or -NR _e3. Y ₂₃ represents O ⁻ , S ⁻ , Se ⁻ , Te ⁻ , or NR _e4 ⁻ . R _{e1 to} R _e4 each independently represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. V _11, V _12,
V ₂₁ , V ₂₂ , V ₃₁ and V ₄₁ each independently represent a substituent, and m ₁₅ , m ₃₁ and m ₄₁ each independently represent an integer of 1 to 6. The alkyl group, aryl group and heterocyclic group in the above may have a substituent, the alkyl group may be linear or branched, and the aryl group and heterocyclic group may be monocyclic. Or polycyclic (condensed ring, ring assembly). Specific examples of such polymethine dyes are described in M. Okawar
a, T.Kitao, T.Hirasima, M.Matuoka by Organic Colorants
(Elsevier) et al. The formula (II
Preferred specific examples of the polymethine dye represented by I) or (IV) are shown below, but the present invention is not limited thereto.

[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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The compounds represented by the formulas (III) and (IV) are described in FM Harmer, "Heterocyclic Compounds-Cysteine Soybean and Related Compounds (Heterocyclic Compounds-Cy)".
anine Dyes and Related Compounds), John Wiley & Sons, New York, London, 1964, DMSturmer, Heterogeneous Cyclic Compounds Special Topics・ In ・ Complex Cyclic Chemistry (Heterocyclic Compounds-Special
topics in heterocyclic chemistry), Chapter 18, Section 14, 482-515, John Wiley & Sons, Inc.-New York,
London, 1977, "Rodd's Chemistry of Car Compounds
bon Compounds) "2nd.Ed.vol.IV, partB, 1977, Chapter 15, Chapters 369-422, Elsevier Scienc Inc.
e Publishing Company Inc.), New York, UK Patent No. 1,077,611, and the like.

For adsorbing the dye on the semiconductor fine particles, a method of immersing well-dried semiconductor fine particles in a dye solution for several hours is general. Any solvent can be used as long as it dissolves the dye. The dye may be adsorbed at room temperature or may be heated and refluxed as described in JP-A-7-249790. It is desirable that unadsorbed dye be removed by washing. The amount of the dye adsorbed on the semiconductor fine particles is preferably 0.01 to 1 mmol per 1 g of the semiconductor fine particles. With such an amount of the dye, a sensitizing effect in the semiconductor can be sufficiently obtained. In contrast,
If the amount of the dye is small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not adhering to the semiconductor floats and causes a reduction in the sensitizing effect.

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

The compound of the formula (I) of the present invention may be allowed to coexist with a dye adsorbing solution when the dye is adsorbed on the semiconductor fine particles, or a solution of the compound of the formula (I) after adsorbing the dye on the semiconductor fine particles. May be used to wash the semiconductor fine particles. The concentration of the compound of the formula (I) when it is dissolved in the dye adsorption solution is 0.1 to 10000 times, preferably 10 to 1000 times, most preferably 10 to 100 times the concentration of the dye. When washing after dye adsorption, the solvent for dissolving the compound of the formula (I) is not particularly limited as long as the compound is soluble, but is preferably an alcohol or a nitrile, and the concentration of the compound is preferably 10 or more. ^-3 mol / L or more and 10 mol / L or less. The compound of the formula (I) is for preventing undesired aggregation of the dye, and the amount of adsorption to the semiconductor fine particles is preferably small. Specifically, the amount is preferably equal to or less than the dye adsorption amount, and more preferably 1/10 or less. The lower limit is not particularly limited, but is about 1/1000.

Next, the structure and material when the semiconductor fine particles of the present invention are used for a photoelectric conversion element and a photoelectrochemical cell will be described in detail. In the present invention, the dye-sensitized photoelectric conversion element comprises a conductive support, a semiconductor fine particle film (photosensitive layer) sensitized by a dye or the like provided on the conductive support, a charge transfer layer, and a counter electrode. A photoelectrochemical cell that can use this photoelectric conversion element for a battery that works in an external circuit is used. The photosensitive layer is designed according to the purpose, and may have a single-layer structure or a multilayer structure. Light incident on the photosensitive layer excites dyes and the like. The excited dye or the like has high-energy electrons, which are transferred from the dye or the like to the conduction band of the semiconductor fine particles and reach the conductive support by diffusion. At this time, molecules such as dyes are oxidized.
In a photoelectrochemical cell, electrons on a conductive support return to an oxidant such as a dye via a counter electrode and a charge transfer layer while working in an external circuit, and the dye or the like is regenerated. The semiconductor film functions as a negative electrode of this battery. In the present invention, at the boundaries between the layers (for example, the boundary between the conductive layer and the photosensitive layer of the conductive support, the boundary between the photosensitive layer and the charge transfer layer, the boundary between the charge transfer layer and the counter electrode, etc.) They may be mutually diffused and mixed.

As the conductive support, use is made of a support such as metal, which has conductivity, or a glass or plastic support having a conductive layer (conductive agent layer) containing a conductive agent on the surface. Can be. In the latter case, a preferable conductive agent is a metal (for example, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, or a conductive metal oxide (indium-tin composite oxide, tin oxide doped with fluorine). And the like). The conductive agent layer preferably has a thickness of about 0.02 to 10 μm. The lower the surface resistance of the conductive support, the better.
The preferred range of the surface resistance is 100 Ω / cm ² or less, and more preferably 40 Ω / cm ² or less. The lower limit is not particularly limited, but is usually about 0.1 Ω / cm ² . Preferably, the conductive support is substantially transparent. Substantially transparent means that the light transmittance is 10% or more, preferably 50% or more,
70% or more is particularly preferred. As the transparent conductive support, glass or plastic coated with a conductive metal oxide is preferable. Among them, conductive glass in which a conductive layer made of tin dioxide doped with fluorine is deposited on a transparent substrate made of low-cost soda-lime float glass is particularly preferable. In addition, for a low-cost and flexible photoelectric conversion element or solar cell, a transparent polymer film provided with the above conductive layer is preferably used. For the transparent polymer film, tetraacetyl cellulose (TA
C), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndioctatic polysterene (SPS), polyphenylene sulfide (P
PS), polycarbonate (PC), polyacrylate (PAr), polysulfone (PSF), polyestersulfone (PES), polyetherimide (PE)
I), cyclic polyolefins, brominated phenoxy and the like. When a transparent conductive support is used, it is preferable that light be incident from the support side. In this case, the coating amount of the conductive metal oxide is preferably 0.01 to 100 g per 1 m ² of a glass or plastic support.

Examples of the method of applying the semiconductor fine particles on the conductive support include a method of applying a dispersion or a colloid solution of the semiconductor fine particles on the conductive support, and the above-mentioned sol-gel method. In consideration of mass production of photoelectric conversion elements, liquid physical properties, and flexibility of a support, a wet film forming method is relatively advantageous. As a wet type film applying method, a coating method and a printing method are typical. Application methods include a roller method, a dipping method as an application system, an air knife method, a blade method, and the like as a metering system, and a method in which application and metering can be performed in the same portion. Wire bar method, U.S. Pat. Nos. 2,681,294 and 2,761,419.
No. 2761791 and the slide hopper method described in
An extrusion method, a curtain method and the like are preferred. As a general-purpose machine, a spin method or a spray method is also preferably used. As a wet printing method, intaglio, rubber printing, screen printing, and the like are conventionally preferable, including three major printing methods of letterpress, offset, and gravure. From the above methods, a preferable film-forming method is selected according to the liquid viscosity and the wet thickness.

In general, as the thickness of the semiconductor fine particle-containing layer increases, the amount of dye carried per unit projected area increases, so that the light capture rate increases. However, the diffusion distance of generated electrons increases, and the loss due to charge recombination also increases. growing. Therefore, the semiconductor fine particle-containing layer has a preferable thickness, but typically has a thickness of 0.1 to 100 μm. When used as a photoelectrochemical cell, the thickness is preferably 1 to 30 μm, and more preferably 2 to 25 μm. The coating amount of the semiconductor fine particles per 1 m ² of the support is 0.5 to 400.
g, more preferably 5 to 100 g.

The semiconductor fine particles are preferably subjected to a heat treatment in order to make the particles electronically contact each other after being applied to the conductive support, and to improve the strength of the coating film and the adhesion to the support. A preferred range of the heat treatment temperature is 40 ° C. or more and less than 700 ° C., more preferably 1 ° C.
It is not less than 00 ° C and not more than 600 ° C. The heat treatment time is 1
It is about 0 minutes to 10 hours. When a support having a low melting point or softening point, such as a polymer film, is used, high-temperature treatment is not preferable because the support is deteriorated. Further, it is preferable that the temperature is as low as possible from the viewpoint of cost. The lowering of the temperature can be achieved by the above-mentioned combination of small semiconductor particles having a size of 5 nm or less, heat treatment in the presence of a mineral acid, and the like. Also,
After the heat treatment, for example, chemical plating using an aqueous solution of titanium tetrachloride or an aqueous solution of titanium trichloride for the purpose of increasing the surface area of the semiconductor particles, increasing the purity near the semiconductor particles, and increasing the efficiency of electron injection from the dye to the semiconductor particles. May be used for electrochemical plating. The semiconductor fine particles preferably have a large surface area so that many dyes can be adsorbed. For this reason, the surface area in the state where the semiconductor fine particle layer is coated on the support is preferably at least 10 times, more preferably at least 100 times the projected area. There is no particular upper limit, but usually 100
It is about 0 times.

Hereinafter, the charge transfer layer and the counter electrode will be described. The charge transfer layer is a layer having a function of replenishing the oxidized dye with electrons. Examples of typical charge transfer layers that can be used in the present invention include a liquid (electrolytic solution) in which a redox couple is dissolved in an organic solvent, and a so-called gel in which a liquid in which a redox couple is dissolved in an organic solvent is impregnated in a polymer matrix. Examples include an electrolyte and a molten salt containing a redox couple. Further, a solid electrolyte or a hole transporting material can be used.

The electrolyte used in the present invention comprises an electrolyte, a solvent,
And additives. The electrolyte of the present invention is a combination of I ₂ and iodide (for the iodide, a metal iodide such as LiI, NaI, KI, CsI, or CaI ₂ , or a tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide or the like). Iodine salts of secondary ammonium compounds), B
Combination of r ₂ and bromide (bromide is LiBr,
NaBr, KBr, CsBr, metal bromide such as CaBr _2, or tetraalkylammonium bromide, pyridinium bromine salts of di-bromide and quaternary ammonium compounds). In addition, ferrocyanate - ferricyanide or ferrocene - ferricinium ion such as Metal complex, sodium polysulfide, sulfur compounds such as alkylthiol-alkyldisulfide, viologen dyes, hydroquinone-quinone, and the like.
I ₂ and LiI or pyridinium iodide Among these, an electrolyte that combines iodine salt of imidazolium iodide and quaternary ammonium compounds are preferred in the present invention.
The above-mentioned electrolytes may be used as a mixture. The electrolyte is EP-718288, WO95 / 18456, J. Electrochem.Soc.,
Vol.143, No. 10, 3099 (1996), Inorg. Chem. 1996, 35, 11
A salt in a molten state at room temperature (molten salt) described in 68-1178 can also be used. When a molten salt is used as an electrolyte, a solvent need not be used.

The preferred electrolyte concentration is 0.1M or more and 15M or less, more preferably 0.2M or more and 10M or less. When iodine is added to the electrolyte, a preferable concentration of iodine is 0.01 M or more and 0.5 M or less.

The solvent used for the electrolyte in the present invention is a compound capable of exhibiting excellent ionic conductivity by decreasing the viscosity and improving the ionic mobility or increasing the dielectric constant and improving the effective carrier concentration. Desirably. Such solvents include carbonate compounds, 3-methyl-
Heterocyclic compounds such as 2-oxazolidinone, ether compounds, alcohols, nitrile compounds, aprotic polar substances such as dimethyl sulfoxide (DMSO) and sulfolane, and water can be used.

Further, in the present invention, J. Am. Ceram. Soc., 8
0 (12) Basic compounds such as ter-butylpyridine, 2-picoline and 2,6-lutidine as described in 3157-3171 (1997) can also be added. A preferred concentration range when a basic compound is added is 0.05M or more and 2M or less.

In the present invention, the electrolyte may be gelled (solidified) by a technique such as addition of a polymer, addition of an oil gelling agent, polymerization containing a polyfunctional monomer, or crosslinking reaction of the polymer. In the case of gelation by adding a polymer, "Polymer Electrolyte Reviews-1 and 2" (J.
R.MacCallum and CA Vincent co-edited, ELSEVIER APPLIEDS
CIENCE), and polyacrylonitrile and polyvinylidene fluoride can be particularly preferably used. When gelling by adding an oil gelling agent, use J. Chem Soc. Japan, Ind. C
hem. Soc., 46779 (1943), J. Am. Chem. Soc., 111,5542.
(1989), J. Chem. Soc., Chem. Commun., 1993, 390, An
gew. Chem. Int. Ed. Engl., 35, 1949 (1996), Chem. Le
tt., 1996, 885, J. Chm. Soc., Chem. Commun., 1997,
Although the compounds described in 545 can be used, preferred compounds are compounds having an amide structure in the molecular structure.

When the gel electrolyte is formed by polymerization of polyfunctional monomers, a solution is prepared from the polyfunctional monomers, a polymerization initiator, an electrolyte, and a solvent, and the solution is prepared by a method such as a casting method, a coating method, a dipping method, or an impregnation method. A method in which a sol-like electrolyte layer is formed on an electrode supporting a dye and then gelled by radical polymerization is preferable. The polyfunctional monomer is preferably a compound having two or more ethylenically unsaturated groups. The monomers constituting the gel electrolyte may further contain a monofunctional monomer.

The above-mentioned monomers are generally described in Takatsu Otsu and Masayoshi Kinoshita: Experimental Method for Polymer Synthesis (Chemical Doujin) and Takatsu Otsu: Lecture Polymerization Reaction Theory 1 Radical Polymerization (I) (Chemical Doujin) It can be polymerized by radical polymerization, which is a simple polymer synthesis method. When the electrolyte is gelled by a crosslinking reaction of the polymer, it is preferable to use a polymer containing a crosslinkable reactive group and a crosslinking agent together. In this case, a preferable crosslinkable reactive group is a nitrogen-containing heterocyclic ring (for example, a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring, a morpholine ring, a piperidine ring, a piperazine ring, etc.), and a preferable crosslinking agent. Is a bifunctional or higher functional reagent capable of electrophilic reaction with a nitrogen atom (for example, alkyl halide, aralkyl halide, sulfonic acid ester, acid anhydride, acid chloride, isocyanate, etc.).

In the present invention, an organic or inorganic hole transporting material or a combination thereof can be used in place of the electrolyte. Organic hole transport materials applicable to the present invention include N, N'-diphenyl-N, N'-bis (4-methoxyphenyl)-(1,1'-biphenyl) -4,4'-diamine, 2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenylamine) 9,9'-spirobifluorene, 1,1-bis ｛4-
(Di-P-tolylamino) phenyl｝ cyclohexane 3
Diamine compound linked with a secondary aromatic amine unit, including two or more tertiary amines represented by 4,4, -bis [(N-1-naphthyl) -N-phenylamino] biphenyl and two or more Aromatic amines in which the condensed aromatic ring is substituted with a nitrogen atom, aromatic amines such as an aromatic triamine having a starburst structure in a derivative of triphenylbenzene, α-octylthiophene and α, ω-dihexyl-α
Oligothiophene compounds such as -octylthiophene, hexadodecyldodecithiophene, 2,8-dihexylanthra [2,3-b: 6,7-b '] dithiophene, polypyrrole, "Ha
ndbook of Organic Conductive Molecules and Polymer
s Vol. 1, 2, 3, 4 "(by NALWA, published by WILEY) polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-phenylenevinylene)
And its derivatives, polythienylenevinylene and its derivatives, polythiophene and its derivatives, polyaniline and its derivatives, polytoluidine and its derivatives, and other conductive polymers can be preferably used. The organic hole transporting material can be introduced into the electrode by a method such as a vacuum evaporation method, a casting method, a coating method, a spin coating method, a dipping method, an electrolytic polymerization method, and a photoelectrolytic polymerization method. When a hole transporting material is used instead of the electrolyte, a titanium dioxide thin layer is formed by using a technique such as spray pyrolysis described in Electorochim. Acta 40, 643-652 (1995) to prevent a short circuit. It is preferable to apply as an undercoat layer.

When an inorganic solid compound is used in place of the electrolyte, copper iodide (p-CuI), copper thiocyanate, or the like is used to form an electrode by a method such as a casting method, a coating method, a spin coating method, a dipping method, and an electrolytic plating method. Can be introduced inside.

There are two methods for forming the charge transfer layer. One is a method in which a counter electrode is first adhered to a semiconductor fine particle-containing layer carrying a sensitizing dye, and a liquid charge transfer layer is sandwiched between the counter electrodes. Another one
The first is a method in which the charge transfer layer is directly provided on the semiconductor fine particle-containing layer, and the counter electrode is subsequently provided. As the method of sandwiching the charge transfer layer in the former case, a normal pressure process utilizing a capillary phenomenon due to immersion or the like and a vacuum process of replacing the gas phase with a liquid phase at a pressure lower than normal pressure can be used. In the latter case, the wet charge transfer layer is provided with a counter electrode in an undried state, and measures are taken to prevent liquid leakage at the edge. In the case of a gel electrolyte, there is also a method of solidifying by a method such as polymerization by coating in a wet manner, in which case drying,
A counter electrode may be provided after immobilization. As a method for applying a wet organic hole transport material or a gel electrolyte in addition to the electrolytic solution, as in the case of providing a semiconductor fine particle-containing layer or a dye,
An immersion method, a roller method, a dip method, an air knife method, an extrusion method, a slide hopper method, a wire bar method, a spin method, a spray method, a casting method, various printing methods, and the like can be considered. In the case of a solid electrolyte or a solid hole transport material, the charge transfer layer can be formed by a dry film forming process such as a vacuum evaporation method or a CVD method, and then a counter electrode can be provided.

The water content in the charge transfer layer was 10,
2,000 ppm or less, more preferably 2,0 ppm
It is at most 00 ppm, particularly preferably at most 100 ppm.

The counter electrode functions as a positive electrode of the photoelectrochemical cell when the photoelectric conversion element is a photoelectrochemical cell. As the counter electrode, a support having a conductive layer can be used as in the case of the above-described conductive support. However, the support is not necessarily required in a configuration in which the strength and the sealing property are sufficiently maintained. Specifically, as the conductive material used for the counter electrode, a metal (for example, platinum, gold, silver, copper, aluminum, rhodium,
Indium, etc.), carbon, or a conductive metal oxide (indium-tin composite oxide, tin oxide doped with fluorine, or the like). The thickness of the counter electrode is not particularly limited, but is preferably 3 nm or more and 10 μm or less. If it is a metal material, its thickness is preferably 5 μm.
m, more preferably 5 nm or more and 3 μm or less. In order for light to reach the photosensitive layer, at least one of the conductive support and the counter electrode described above must be substantially transparent. In the photoelectrochemical cell of the present invention, it is preferable that the conductive support is transparent and sunlight is incident from the support side. In this case, it is more preferable that the counter electrode has a property of reflecting light. In the present invention, as the counter electrode, glass or plastic on which a metal or a conductive oxide is deposited, or a metal thin film can be used.

As described in the description of the application of the charge transfer layer, the counter electrode is applied on the charge transfer layer or first on the semiconductor fine particle containing layer. In either case, depending on the type of counter electrode material and the type of charge transfer layer,
The counter electrode material can be appropriately formed on the charge transfer layer or the semiconductor fine particle-containing layer by a method such as coating, laminating, vapor deposition, or bonding. For example, in the case of attaching a counter electrode, a substrate provided as a conductive layer can be attached by a method such as application, evaporation, or CVD of the above conductive material. When the charge transfer layer is solid, the above-mentioned conductive material is directly applied thereon, plated, PVD, CV
The counter electrode can be formed by a technique such as D.

Further, a layer having other necessary functions such as a protective layer and an antireflection film may be provided on the conductive support or the counter electrode of the working electrode. In the photoelectrochemical cell of the present invention, it is preferable to seal the side surface of the cell with a polymer, an adhesive or the like in order to prevent deterioration of components and volatilization of contents.

[0074]

[Example 1]

1. Preparation of Coating Solution Containing Titanium Dioxide Particles Titanium dioxide having a titanium dioxide concentration of 11% by weight was prepared in the same manner as that described in Journal of American Ceramic Society, Vol. 80, p. 3157, except that the autoclave temperature was changed to 230 ° C. A dispersion was obtained. The average size of the resulting titanium dioxide particles was about 10 nm. To this dispersion was added 30% by weight of polyethylene glycol (molecular weight: 20,000, manufactured by Wako Pure Chemical Industries) based on titanium dioxide, and mixed to obtain a coating solution.

2. Fabrication of dye-adsorbed titanium dioxide electrode
Transparent conductive coated with fluorine-doped tin oxide
Electric glass (made by Nippon Sheet Glass, surface resistance is about 10Ω / cm^Two)
140 μm of this coating solution with a doctor blade on the conductive surface side of
After applying with a thickness and drying at 25 ° C for 30 minutes,
30 ° C at 450 ° C in a muffle furnace FP-32 manufactured by Kagaku Kagaku)
Bake for a minute. The application amount of titanium dioxide is 15g / m^TwoAnd
The film thickness was 10 μm. After taking out the glass and cooling,
3 hours immersion in ethanol solution of dyes and additives shown in Table 1
(The structure of the dye used is shown below). Dyeing dye
Immersed glass in 4-tert-butylpyridine for 15 minutes
After that, it was washed with acetonitrile and dried naturally. In addition,
The concentration of the additive in the immersion liquid depends on the combination of the additive and the dye.
Depending on the combination, the ratio was 10 to 100 times that of the dye. Ma
The dye concentration depends on the type of the dye and the amount of adsorption is 0.
1 to 10 mmol / m ^TwoIt was set to be within the range.

[0076]

Embedded image

3. Preparation of Photoelectrochemical Cell The sensitized TiO ₂ electrode substrate (2 cm × 2 cm) prepared as described above was overlaid with a platinum-deposited glass of the same size (see FIG. 1). Next, an electrolytic solution (0.05 mol / liter of iodine using a mixture of acetonitrile and N-methyl-2-oxazolidinone in a volume ratio of 90:10 as a solvent, lithium iodide 0 (0.5 mol / liter solution) and introduced into a TiO ₂ electrode to obtain a photoelectrochemical cell. According to this embodiment,
As shown in FIG. 1, a conductive glass 1 (having a conductive agent layer 2 provided on the glass), a TiO ₂ electrode 3, a dye layer 4, an electrolytic solution 5, a platinum layer 6, and a glass 7 are sequentially laminated. A photoelectrochemical cell was created.

4. Measurement of Photoelectric Conversion Wavelength and Photoelectric Conversion Efficiency
CE (Incident Photonto Current Conversion Efficienc
y) Measured by a measuring device. Table 1 summarizes the photoelectric conversion efficiencies at the wavelengths at which the photochemical cells using the respective dyes exhibit the maximum conversion ability.

[0079]

[Table 1]

The batteries to which any additive having the structure of the formula (I) of the present invention was added were the batteries without any additives (1-1 and 1-).
Higher photoelectric conversion characteristics are observed as compared to 11).

[Embodiment 2] 1. Preparation of Coating Solution Containing Titanium Dioxide Particles Titanium dioxide having a titanium dioxide concentration of 11% by weight was prepared in the same manner as that described in Journal of American Ceramic Society, Vol. 80, p. 3157, except that the autoclave temperature was changed to 230 ° C. A dispersion was obtained. The average size of the resulting titanium dioxide particles was about 10 nm. To this dispersion was added 30% by weight of polyethylene glycol (molecular weight: 20,000, manufactured by Wako Pure Chemical Industries) based on titanium dioxide, and mixed to obtain a coating solution.

2. Preparation of Titanium Dioxide Electrode Adsorbing Dye A 140 μm doctor blade is used to apply this coating solution to the conductive surface side of a transparent conductive glass coated with fluorine-doped tin oxide (manufactured by Nippon Sheet Glass, surface resistance is about 10 Ω / cm ² ). After applying with a thickness and drying at 25 ° C. for 30 minutes, it was baked at 450 ° C. for 30 minutes in an electric furnace (muffle furnace FP-32 manufactured by Yamato Scientific). The coating amount of titanium dioxide was 15 g / m ² , and the film thickness was 10 μm. After the glass was taken out and cooled, it was immersed in an ethanol solution of the dye shown in Table 2 for 3 hours. The glass to which the dye was dyed was immersed in 4-tert-butylpyridine for 15 minutes, washed with acetonitrile, and air-dried. The dye-adsorbed titanium dioxide electrode was washed with a 1 mol / L methanol solution of the additives shown in Table 2. The amount of the dye adsorbed was appropriately selected from the range of 0.1 to 10 mmol / m ² according to the type of the dye.

3. Preparation of Photoelectrochemical Cell The sensitized TiO ₂ electrode substrate (2 cm × 2 cm) prepared as described above was overlaid with a platinum-deposited glass of the same size (see FIG. 1). Next, an electrolytic solution (0.05 mol / liter of iodine using a mixture of acetonitrile and N-methyl-2-oxazolidinone in a volume ratio of 90:10 as a solvent, lithium iodide 0 (0.5 mol / liter solution) and introduced into a TiO ₂ electrode to obtain a photoelectrochemical cell. According to this embodiment,
As shown in FIG. 1, a conductive glass 1 (having a conductive agent layer 2 provided on the glass), a TiO ₂ electrode 3, a dye layer 4, an electrolytic solution 5, a platinum layer 6, and a glass 7 are sequentially laminated. A photoelectrochemical cell was created.

4. Measurement of Photoelectric Conversion Wavelength and Photoelectric Conversion Efficiency
CE (Incident Photonto Current Conversion Efficienc
y) Measured by a measuring device. Table 2 summarizes the photoelectric conversion efficiencies at the wavelengths at which the photochemical cells using the respective dyes show the maximum conversion ability.

[0085]

[Table 2]

Batteries washed with the solution of any additive having the structure of the formula (I) of the present invention show higher photoelectric conversion characteristics as compared with those washed without any additive.

[0087]

According to the present invention, a dye-sensitized photoelectric conversion element having high photoelectric conversion characteristics is provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a photoelectrochemical cell prepared in an example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conductive glass 2 Conductive agent layer 3 TiO ₂ electrode 4 Dye layer 5 Electrolyte 6 Platinum layer 7 Glass

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Reyuki Inoue 210, Nakanuma, Minamiashigara, Kanagawa Prefecture Fuji Photo Film Co., Ltd. F-term (reference) 4H056 CA01 CA02 CA03 CA05 CB01 CB06 CC02 CC08 CD07 CD08 CE03 CE06 DD03 DD04 DD06 DD07 DD19 DD23 DD28 DD29 FA05 5F051 AA14 5H032 AA06 AS16 BB05 BB10 EE16 EE20

Claims (10)

[Claims] 1. Semiconductor fine particles having a dye and a compound represented by the following formula (I) adsorbed thereon. Embedded image [In the formula (I), Q represents a heterocyclic ring, and Q may be condensed or may have a substituent. L represents a single bond or a divalent linking group. Z represents an acidic group having a dissociable proton, and W represents a counter ion necessary for neutralizing the charge of the molecule. ] 2. The semiconductor fine particles according to claim 1, wherein Q is a nitrogen-containing heterocyclic ring. 3. The method according to claim 2, wherein Q is a ring selected from a pyrrole ring, a thiazole ring, an oxazole ring, a selenazole ring, an imidazole ring, a 2-quinoline ring, a 4-quinoline ring and a nucleus derived from a benzo-fused ring thereof. Semiconductor fine particles. 4. The semiconductor fine particle according to claim 1, wherein Z is a carboxylic acid or a sulfonic acid. 5. The semiconductor fine particles according to claim 1, wherein said dye is a dye selected from a ruthenium complex dye, a phthalocyanine dye, and a polymethine dye. 6. The semiconductor fine particles according to claim 1, wherein said semiconductor fine particles are metal oxide fine particles. 7. A photoelectric conversion element using the semiconductor fine particles according to claim 1. 8. A method for adsorbing a dye on semiconductor fine particles, wherein the method is performed by at least one of the following a) and b). a) A compound represented by the formula (I) coexists in a solution of a dye to be adsorbed, and semiconductor fine particles are immersed in this solution. b) After adsorbing the dye on the semiconductor fine particles, the semiconductor fine particles are immersed in a solution containing the compound represented by the formula (I). Embedded image [In the formula (I), Q represents a heterocyclic ring, and Q may be condensed or may have a substituent. L represents a single bond or a divalent linking group. Z represents an acidic group having a dissociable proton, and W represents a counter ion necessary for neutralizing the charge of the molecule. ] 9. A photoelectric conversion element using the dye-adsorbed semiconductor fine particles produced by the method of claim 8. 10. A photoelectrochemical cell using the photoelectric conversion element according to claim 7.