JP2000285978A - Coloring agent, photoelectric conversion element, and photoelectrochemical battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase transfer efficiency at a low cost by containing semiconductor micro particles sensitized by polymethine coloring matter. SOLUTION: A coloring matter for sensitizing semiconductor micro particles is represented by the formula. In the formula, R1 and R2 are each independently a substituted group; R3 is O-, S-, Se-, Te-, or -NR4-; R4 is a hydrogen atom, an alkyl group, or an aryl group. R1 and R2 may be interconnected to form a ring. P1 and P2 are each independently nonmetal atom group required for forming a polymethine coloring matter. W1 is a counter ion when the counter ion is required for neutralizing a charge. This coloring matter preferably has an acidic group, and the acidic group is a carboxy group, phosphate group, or a phosphate group, more preferably, is contained in R1 and R2. As the semiconductor micro particles to be used, titanium oxide micro particles are suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device, a dye used therefor, and a photoelectrochemical cell using the same, and more particularly, to a photoelectric conversion device and a photoelectrochemical device using semiconductor fine particles sensitized with a dye. Batteries and dyes.

[0002]

2. Description of the Related Art Photovoltaic power generation is a single-crystal silicon solar cell,
Polycrystalline silicon solar cells, amorphous silicon solar cells, and compound solar cells such as cadmium telluride and indium copper selenide have been put into practical use or subject to major research and development.
It is necessary to overcome problems such as a long energy payback time. On the other hand, there have been proposed many solar cells using an organic material intended to have a large area and a low price, but have a problem that conversion efficiency is low and durability is poor.

Under these circumstances, Nature (Vol. 353,
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. The first 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. Since the absorption of the dye is broad, it is possible to convert light in almost all wavelength regions of visible light into electricity.

One of the demands for improvement of dye-sensitized photoelectric conversion elements is to use expensive ruthenium complex dyes as sensitizing dyes, and the development of photoelectric conversion elements sensitized by inexpensive organic dyes has been developed. Was desired. As such examples, Japanese Patent Application No. 10-219774 and Japanese Patent Application No.
Although a method using a compound described in No. 19775 is known, high photoelectric conversion efficiency in near infrared to infrared light has not been obtained.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dye having an inexpensive and high conversion efficiency by using an organic dye having absorption in the near infrared to infrared region and capable of efficiently sensitizing semiconductor fine particles. An object is to provide a sensitized photoelectric conversion element. It is another object of the present invention to provide a novel dye used for this and a photoelectrochemical cell using the same.

[0006]

The above objects have been attained by the following items which specify the present invention and preferable items. (1) A photoelectric conversion element comprising semiconductor fine particles sensitized by a dye represented by the following formula (I).

[0007]

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[0008] represents [In formula (I), R ₁ and R ₂ each independently represent a substituent, R ₃ is ^{O -, S -, Se -} , Te - or -NR ₄ ^- represents, R ₄ is hydrogen , An alkyl group or an aryl group. R ₁ and R ₂ may be linked to each other to form a ring. P ₁ and P ₂ each independently represent a nonmetallic atomic group necessary for forming a polymethine dye. W ₁ represents a counter ion when a counter ion is required to neutralize the charge. (2) The polymethine dye represented by the formula (I), wherein the polymethine dye is any one of a cyanine dye, a merocyanine dye, a rhodocyanine dye, a trinuclear merocyanine dye, an allopolar dye, a hemicyanine dye and a styryl dye. Photoelectric conversion element. (3) The photoelectric conversion device according to the above (2), wherein the polymethine dye represented by the formula (I) is a cyanine dye or a merocyanine dye. (4) The photoelectric conversion device according to the above (3), wherein the polymethine dye represented by the formula (I) is a cyanine dye. (5) The photoelectric conversion element according to any one of the above (1) to (4), wherein the dye represented by the formula (I) is a cyanine dye represented by the following formula (II).

[0009]

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[In the formula (II), R ₁ , R ₂ , R ₃ , R ₄ and W ₁ have the same meaning as in the formula (I). R _{11 to} R ₁₄ each independently represent hydrogen, an alkyl group, an aryl group or a heterocyclic group, and Y ₁ and Y ₂ each independently represent oxygen, sulfur, selenium, tellurium, —CR ₅ R ₆ — or —NR ₇ Represents-
R ₅ , R ₆ and R ₇ each independently represent hydrogen, an alkyl group or an aryl group. R ₁₅ and R ₁₆ each independently represent a substituent, and a and b each independently represent 0 to 4
Represents an integer. When a or b is 2 or more, R ₁₅ or R
₁₆ may be connected to each other to form a ring. (6) In the dye represented by the formula (I) or (II), R
₁ and R ₂ are each independently a cyano group, alkoxycarbonyl group, carboxyl group, acyl group, alkylsulfonyl group, arylsulfonyl group, sulfonic acid group, carbamoyl group, acylamino group, alkyl group, alkenyl group, aryl group, alkoxy group The photoelectric conversion device according to any one of the above (1) to (5), which is an alkylthio group, an aryloxy group, a heterocyclic group, a phosphonyl group or a phosphoryl group. (7) The photoelectric conversion element according to any one of the above (1) to (6), wherein R ₃ is O ⁻ in the polymethine dye represented by the formula (I) or (II). (8) The photoelectric conversion device according to any one of the above (1) to (7), wherein R ₁₂ and R ₁₃ are both hydrogen in the cyanine dye represented by the formula (II). (9) The cyanine dye represented by the formula (II) is represented by the following formula (II)
The dye represented by I), or the photoelectric conversion element according to any one of the above (1) to (8).

[0011]

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[In the formula (III), R ₁ , R ₂ , R ₁₁ , R ₁₄ ,
Y ₁ , Y ₂ and W ₁ have the same meanings as in formula (II). R _{17 to} R ₂₀ each independently represent an alkyl group, an aryl group, an alkoxy group, a hydroxyl group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an acylamino group, a phosphonyl group, a phosphoryl group, a sulfonic acid group, a cyano group or a halogen atom. Represent. c and d each independently represent 0 or 1, and e, f, g and h each independently represent 0 to
Represents an integer of 4. (10) The dye of the above (9), wherein R ₁₁ and R ₁₄ are the same or different alkyl groups in the cyanine dye represented by the formula (II) or (III), or the above (1) to
The photoelectric conversion element according to any one of (9). (11) In the polymethine dyes represented by the formulas (I) to (III), R ₁ and R ₂ are each independently a cyano group, an alkoxycarbonyl group, a carboxyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfone. Acid groups,
The dye of the above (9) or (10), which is a carbamoyl group, a heterocyclic group or a phosphonyl group, or the above (1)
To (10). (12) The dye of the above (11), wherein R ₁ and R ₂ are each independently a cyano group, an alkoxycarbonyl group, a carboxyl group or a phosphonyl group, or the photoelectric conversion element of the above (11). (13) In the dye represented by the formula (I) or (II), R ₁ and R ₂ are connected to each other to form a ring, or the dye of the above (9) or (10), or the above (1) to (10) Any one of the photoelectric conversion elements. (14) The ring formed by linking R ₁ and R ₂ is 5 or 6
The dye of the above (13), which is a membered ring, or the above (13) a photoelectric conversion element. (15) The dye according to any one of the above (9) to (14), wherein Y ₁ and Y _{2 in the} formula (II) or (III) are oxygen, sulfur, —CR ₅ R ₆ — or —NR ₇ — Or the above (1)
The photoelectric conversion element of any one of (14) to (14). (16) The dye according to (15), wherein Y ₁ and Y ₂ are —CR ₅ R ₆ —, and both R ₅ and R ₆ are alkyl groups, or the photoelectric conversion element according to (15). (17) The dye represented by any one of the above (9) to (16), wherein the dye represented by the formula (I) to (III) has at least one acidic group, or any of the above (1) to (16) Photoelectric conversion element. (18) The dye of the above (17), wherein the acidic group is a carboxyl group, a phosphoric acid group, a phosphonic acid group, a sulfonic acid group or a hydroxyl group, or the photoelectric conversion element of the above (17). (19) The photoelectric conversion device according to any one of (1) to (18), wherein the semiconductor fine particles sensitized by the dye are titanium oxide fine particles. (20) A photoelectrochemical cell using the photoelectric conversion element according to (19).

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. Hereinafter, the dye of the present invention represented by the formula (I) will be described in detail. When the compound of the present invention contains an alkyl group, an alkenyl group, an alkynyl group, an alkylene group, etc., they may be linear or branched, and may be substituted or unsubstituted.

When the compound of the present invention contains an aryl group, a heterocyclic group, a cycloalkyl group, etc., they may be substituted or unsubstituted, and may be monocyclic or condensed.

In the formula (I), P ₁ and P ₂ each independently represent a nonmetallic atom group necessary for forming a polymethine dye. Although any methine dye can be formed by P ₁ and P ₂ , a cyanine dye, a merocyanine dye, a rhodacyanine dye, a trinuclear merocyanine dye,
Examples include allopolar dyes, hemicyanine dyes, styryl dyes, and the like, preferably cyanine dyes and merocyanine dyes, and more preferably cyanine dyes. At this time, the cyanine dyes include those in which a squarium ring or a croconium ring is further formed as a substituent on the methine chain forming the dye. For a detailed description of these dyes, see FM Harmer, Heterocyclic Compounds-Cysteine and Related Compounds.
anine Dyes and Related Compounds), John Wiley & Sons, New York, London, 1964, Heterocyclic Compound Special Topics by DMSturmer. In Heterocyclic Compounds-Special
topics in heterocyclicchemistry) ", Chapter 18, Chapter 1
Section 4, pages 482 to 515 and the like. The general formulas of the cyanine dye, merocyanine dye and rhodacyanine dye are preferably those shown in (XI), (XII) and (XIII) on pages 21 and 22 of US Pat. No. 5,340,694.

In the formula (I), W ₁ represents a counter ion when a counter ion is required to neutralize the charge.

Whether a certain dye is a cation or an anion,
Alternatively, the presence or absence of a net ionic charge depends on the auxiliary chromophore and the substituent. 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 ₁ . 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.

[0019] Formula in (I) R ₃ is ^{O -, S -, Se -} , Te
^— , —NR ₄ ^— , wherein R ₄ is hydrogen, an alkyl group (preferably having 1 to 12 carbon atoms (hereinafter referred to as C number), for example, methyl, ethyl, i-propyl, t-butyl, n-butyl), Represents an aryl group (preferably having 6 to 20 carbon atoms, such as phenyl and 2-naphthyl). R ₃ is preferably O ⁻ , S ⁻ , and —NR ₄ ^— , and more preferably O ⁻ .

In the formula (I), R ₁ and R ₂ each independently represent a substituent, preferably a cyano group or an alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, for example, ethoxycarbonyl, butoxycarbonyl, 2-ethylhexyl) Oxycarbonyl, hexadecyloxycarbonyl, octadecyloxycarbonyl, cyclohexyloxycarbonyl), carboxyl group, acyl group (preferably having 1 to 1 carbon atoms)
20, for example, acetyl, t-valeryl, benzoyl),
An alkylsulfonyl group (preferably having 1 to 20 carbon atoms, such as methanesulfonyl, i-butanesulfonyl), an arylsulfonyl group (preferably having 6 to 26 carbon atoms, such as benzenesulfonyl, 4-methoxybenzenesulfonyl),
A sulfonic acid group (—SO ₃ H), a carbamoyl group (preferably having 1 to 20, for example, N, N-dimethylcarbamoyl, N-phenylcarbamoyl), an acylamino group (preferably having 1 to 20, for example, acetylamino) Benzoylamino), an alkyl group (preferably having a C number of 1 to 20,
For example, methyl, ethyl, i-propyl, t-butyl),
Alkenyl group (preferably having 2 to 20 carbon atoms, for example, vinyl, allyl, oleyl), aryl group (preferably having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl ), An alkoxy group (preferably having 1 to 20, for example, methoxy, i-propoxy), an alkylthio group (preferably having 1 to 20, for example, methylthio), an aryloxy group (preferably having 6 to 26, for example, phenoxy) , 2
-Naphthyloxy), a heterocyclic group (preferably having 2 to 2 carbon atoms)
20, for example 2-thiazolyl, 2-benzothiazolyl,
2-oxazolyl), a phosphonyl group (for example, C number 0 to 2)
0, for example, _{-PO (OH) 2, -PO (} OC 2 H 5) 2),
A phosphoryl group (preferably having 0 to 20 carbon atoms, such as -OP
O (OH) _2, represents _{-OPO (OC 2 H 5) 2} ), preferably a cyano group, an alkoxycarbonyl group, a carboxyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfonic acid group, a carbamoyl group, an acylamino Group, alkyl group, alkenyl group, aryl group, alkoxy group, alkylthio group, aryloxy group, heterocyclic group, phosphonyl group or phosphoryl group, more preferably cyano group, alkoxycarbonyl group, carboxyl group, acyl group, alkyl group Represents a sulfonyl group, an arylsulfonyl group, a sulfonic acid group, a carbamoyl group, a heterocyclic group, a phosphonyl group, more preferably a cyano group,
Represents an alkoxycarbonyl group, a carboxyl group, or a phosphonyl group. Note that R ₁ and R ₂ may be the same or different.

R ₁ and R ₂ may be linked to each other to form a ring. In that case, it is preferable to form a 5- or 6-membered ring, and a pyrazolidinedione ring, a barbituric acid ring, a thiobarbituric acid ring, an isoxazolone ring, a pyrazolone ring,
It is preferable to form a pyridone ring, a rhodanin ring, a pyrrolotriazole ring, a pyrazolotriazole ring or the like. More preferably, it is a pyrazolidinedione ring or a rhodanin ring.

Preferred examples of the ring formed by linking R ₁ and R _{2 of} R ₁ C (=) R ₂ are specifically described below.

[0023]

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The dye represented by the formula (I) is preferably a cyanine dye represented by the formula (II). In equation (II),
R ₁ , R ₂ , R ₃ and R ₄ have the same meanings as in formula (I).

R _{11 to} R ₁₄ each independently represent hydrogen, an alkyl group, an aryl group, or a heterocyclic group (preferred examples are R
Same as ₁ ). R ₁₁ and R ₁₄ may be the same or different and are preferably an alkyl group. R ₁₂ and R ₁₃ may be the same or different, but both are preferably hydrogen.

[0026] Y _1, Y ₂ are each independently oxygen, sulfur, selenium, _{tellurium, -CR 5 R 6 -, -} NR 7 - represents, R _5,
R ₆ and R ₇ each independently represent hydrogen, an alkyl group, or an aryl group (preferable examples are the same as R ₄ ). Y ₁ and Y ₂ may be the same or different, and are preferably oxygen, sulfur, and —CR ₅ R ₆ —, and more preferably —CR ₅ R ₆ —. At that time, R ₅ ,
Preferably, both R ₆ are alkyl groups.

R ₁₅ and R ₁₆ each independently represent a substituent, preferably an alkyl group, an aryl group, an alkoxy group, a hydroxyl group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an acylamino group, a phosphonyl group, a phosphoryl group, A sulfonic acid group, a cyano group (the preferred examples are the same as R ₁ ), and a halogen atom (preferably fluorine, chlorine, bromine, iodine), and more preferably an alkyl group, an alkoxy group, a hydroxyl group, a carboxyl group, or an alkoxycarbonyl group. Group, phosphonyl group, phosphoryl group and halogen atom.

A and b each independently represent an integer of 0 to 4, preferably 0 to 2. When a or b is 2 or more, R ₁₅ or R ₁₆ may be linked to each other to form a ring, and the ring formed at that time is preferably a benzene ring.

Further, the cyanine dye represented by the formula (II) is preferably represented by the following formula (III).

In the formula (III), R ₁ , R ₂ , R ₁₁ , R ₁₄ ,
Y ₁ and Y ₂ have the same meanings as in formula (II). R _{1 7} to R ₂₀ each independently represent an alkyl group, an aryl group, an alkoxy group, a hydroxyl group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an acylamino group, a phosphonyl group,
Represents a phosphoryl group, a sulfonic acid group, a cyano group, or a halogen atom. c and d each independently represent 0 or 1.
e, f, g, and h each independently represent an integer of 0 to 4,
0 to 2 is preferred.

The dyes represented by the formulas (I) to (III) are suitable for interlocking with the surface of the semiconductor fine particles.
group) is preferable. Preferred linking groups include carboxyl (COOH)
Group, sulfonic acid (SO ₃ H) group, phosphonic acid (-P (O) (OH) ₂ )
An acid group (substituent having a dissociable proton) such as a phosphoric acid (-OP (O) (OH) ₂ ) group or a hydroxyl group, or an oxime, dioxime, hydroxyquinoline, salicylate and α-keto enolate Chelating groups having such π conductivity are exemplified. These groups may form a salt with an alkali metal or the like, or may form an intramolecular salt.

The dyes represented by formulas (I) to (III) more preferably have an acidic group, and more preferably have a carboxyl group, a phosphoric acid group or a phosphonic acid group. These acidic groups are represented by R ₁ , R ₂ , R ₁₁ , R ₁₄ , R
It is preferably contained in any one of ₁₅ to R _20.

Specific examples of the compound represented by the formula (I) of the present invention are shown below, but the present invention is not limited thereto. In addition, the structural formula of the dye described herein is only the ultimate structure of one of many possible resonance structures.

[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[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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The synthesis of the compound represented by the formula (I) used in the present invention is carried out according to Ukrainskii Khimicheskii Zhurnal No. 40.
Volume 3, pages 253-258 and Japanese Patent Application No. 10-2780
No. 22 and the references cited in these documents can be referred to.

The general method for synthesizing the dye of the present invention is shown below, but the present invention is not limited thereto.

[0049]

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When synthesizing the dye represented by the formula (I) of the present invention, it is preferable to use R ₁ CH ₂ R ₂ as a raw material, which is generally called an active methylene compound and has a wide variety of raw materials. Yes and preferred. Further, a so-called "4-equivalent coupler" known in silver salt photography can also be used, which is preferable.

The dye of the present invention generally has a terminal squaric acid 3 synthesized by reacting a quaternary salt 1 with diethyl squarate 2 in a solvent such as ethanol in the presence of a base such as triethylamine, and an active methylene compound R ₁ CH _2. R ₂ 4
Is reacted in a solvent such as butanol or ethanol in the presence of a base such as sodium methoxide, potassium t-butoxide, triethylamine, potassium carbonate or the like in an equivalent amount or more to obtain 5 in a high yield, thereby converting 5 to a quaternary salt. 6
Alternatively, it can be easily obtained by reacting with methylene base 7. X ₁ and X _{2 each} represent a counter anion.

The maximum absorption wavelength λmax (in methanol) of the dye of the present invention is preferably from 300 to 1,000 nm, more preferably from 400 to 900 nm.

Hereinafter, the constitution and materials of the photoelectric conversion element and the photoelectrochemical cell of the present invention will be described in detail.

In the present invention, the dye-sensitized photoelectric conversion element comprises a conductive support, a semiconductor film (photosensitive layer) sensitized by a dye 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 the dye. The excited dye has high-energy electrons, which are transferred from the dye to the conduction band of the semiconductor fine particles and reach the conductive support by diffusion. At this time, the dye molecule is in an oxidized form. In a photoelectrochemical cell, the electrons on the conductive support return to the oxidized dye via the counter electrode and the charge transfer layer while working in an external circuit, and the dye is regenerated. The semiconductor film functions as a negative electrode of this battery. In the present invention, at the boundary of each layer (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.), these components are They may be mutually diffused and mixed.

In the present invention, the semiconductor is a so-called photoreceptor, and plays a role of absorbing light to separate electric charges to 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, a so-called compound semiconductor represented by a metal chalcogenide (eg, oxide, sulfide, selenide, etc.) or a compound having a perovskite structure is used in addition to a simple semiconductor such as silicon and germanium. be able to. Preferably as a metal chalcogenide titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium,
Examples include 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.

The compound having a perovskite structure is preferably strontium titanate, calcium titanate, sodium titanate, barium titanate, or potassium niobate.

More preferably, the semiconductor used in the present invention is specifically Si, TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , Zn
O, Nb ₂ O ₅ , CdS, ZnS, PbS, Bi ₂ S ₃ , CdSe, CdTe, GaP, I
nP, GaAs, 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 , most preferably TiO ₂ .

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 preferably 5 to 200 nm as primary particles, and particularly preferably 8 to 1 nm, as an average particle diameter using a diameter when the projected area is converted into a circle.
Preferably it is 00 nm. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is 0.01 to 10
It is preferably 0 μm.

Further, two or more kinds of fine particles having different particle size distributions may be mixed and used. In this case, the average size of the small particles is preferably 5 nm or less. Also, in order to improve the light capture rate by scattering incident light,
Semiconductor particles having a large particle size, for example, about 300 nm may be mixed.

As the conductive support, a support such as metal having conductivity can be used, or a glass or plastic support having a conductive agent layer on its surface can be used. In the latter case, preferred conductive agents include metals (eg, 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 light transmittance is 10%
The above means that it is preferably at least 50%, particularly preferably at least 70%. 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.
Transparent polymer films include tetraacetyl cellulose (TAC), polyethylene terephthalate (PET),
Polyethylene naphthalate (PEN), syndioctatic polysterene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyacrylate (PAr), polysulfone (PSF), polyester sulfone (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 a glass or plastic support 1.
m ² per 0.01~100g are preferred.

As a method for coating semiconductor fine particles on a conductive support (or on the conductive layer side in the case of a support having a conductive layer), a dispersion or colloid solution of semiconductor fine particles is coated on the conductive support. And a method in which a precursor of semiconductor fine particles is coated on a conductive support and hydrolyzed by moisture in the air to obtain a semiconductor fine particle film (sol-gel method). In addition to the sol-gel method described above, a method of preparing a dispersion of semiconductor fine particles, a method of grinding in a mortar, a method of dispersing while crushing using a mill, or a method of depositing fine particles in a solvent when synthesizing a semiconductor. And a method of using it as it is. Examples of the dispersion medium include water and various organic solvents (eg, methanol, ethanol, isopropyl alcohol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.). At the time of dispersion, a polymer, a surfactant, an acid, a chelating agent, or the like may be used as a dispersing aid, if necessary.

Generally, as the thickness of the layer containing semiconductor fine particles 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, so that the loss due to charge recombination also increases. growing. Therefore, the semiconductor fine particle 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,
More preferably, it is 2 to 25 μm. The coating amount per support 1 m ² of the semiconductor fine particles 0.5～400G, more 5~100g is preferred.

The semiconductor fine particles are preferably subjected to a heat treatment in order to bring the particles into electronic contact 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.

After the heat treatment, chemical plating using, for example, an aqueous solution of titanium tetrachloride for the purpose of increasing the surface area of the semiconductor particles, increasing the purity near the semiconductor particles, and increasing the efficiency of injecting electrons from the dye into the semiconductor particles. Alternatively, electrochemical plating using an aqueous solution of titanium trichloride may be performed.

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. The upper limit is not particularly limited, but is usually about 1000 times.

For adsorbing a dye on a semiconductor, a method of immersing well-dried semiconductor fine particles in a dye solution for several hours is generally used. The dye may be adsorbed at room temperature or may be heated and refluxed as described in JP-A-7-249790. The adsorption of the dye may be performed before or after the application of the semiconductor fine particles, or the semiconductor fine particles and the dye may be simultaneously applied and adsorbed. preferable. The dye adsorption in the heat treatment of the semiconductor fine particle film is preferably performed after the heat treatment, and it is particularly preferable that the dye is quickly adsorbed after the heat treatment and before water is adsorbed on the surface of the coating film. It is desirable that unadsorbed dye be removed by washing. The dye to be adsorbed may be one kind or a mixture of several kinds.
Further, the polymethine dye of the present invention may be used in combination with a known dye such as a ruthenium complex dye. When the application is a photoelectrochemical cell, a dye to be mixed can be selected so as to make the wavelength range of photoelectric conversion as wide as possible.

The amount of the dye used is preferably 0.01 to 100 mmol per 1 m ² of the support. 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.

By using such a dye amount, a sufficient sensitizing effect in a semiconductor can be 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.

A colorless compound may be co-adsorbed for the purpose of reducing interaction between dyes such as association. Examples of the hydrophobic compound to be co-adsorbed include steroid compounds having a carboxyl group (for example, cholic acid).

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.

Hereinafter, the charge transfer layer and the counter electrode will be described in detail. The charge transfer layer is a layer having a function of replenishing the oxidized dye with electrons. Typical examples are a liquid (electrolytic solution) in which a redox couple is dissolved in an organic solvent, a so-called gel electrolyte in which a liquid in which a redox couple is dissolved in an organic solvent is impregnated in a polymer matrix, and a molten salt containing a redox couple. Is mentioned. Further, a solid electrolyte or a hole transport material can be used.

The electrolyte used in the electrolytic solution of the present invention is I ₂
And various iodides (eg, LiI, NaI, KI, Cs
Metal iodides such as I and CaI ₂ , iodine salts of quaternary imidazolium compounds, iodine salts of quaternary pyridinium compounds, iodine salts of tetraalkylammonium compounds, etc., Br ₂ and various bromides (eg, LiBr, NaB)
metal bromides such as r, KBr, CsBr, CaBr ₂ ,
Bromine salts of quaternary ammonium compounds such as tetraalkylammonium bromide and pyridinium bromide), combinations of metal complexes such as ferrocyanate-ferricyanate and ferrocene-ferricinium ions, sodium polysulfide, alkylthiol-alkyldisulfide, etc. Combinations of sulfur compounds, alkyl viologens (eg methyl viologen chloride,
Hexyl viologen bromide, benzyl viologen tetrafluoroborate) and its reduced form in combination,
A combination of polyhydroxybenzenes (eg, hydroquinone, naphthohydroquinone, etc.) and oxidized products thereof can be used. Among them, LiI, NaI,
KI, CsI, the metal iodide CaI _2, iodine salt of a quaternary imidazolium compound, a combination of iodine salt and I ₂ of the iodide salt or a tetraalkyl ammonium compound of the quaternary pyridinium compound.

As long as the organic solvent used for the electrolytic solution has a high boiling point, deterioration due to volatilization of the electrolytic solution can be prevented. In addition, from the viewpoint of the short-circuit current density and the conversion efficiency of the photoelectric conversion element,
Preferably, the viscosity of the organic solvent is low and the dielectric constant is high. That is, if the viscosity is low, an effect of improving the ion mobility can be obtained, and if the dielectric constant is large, an effect of improving the effective carrier concentration can be obtained. Specific organic solvents include aprotic polar solvents (for example, acetonitrile, propylene carbonate, ethylene carbonate, dimethylformamide, dimethyl sulfoxide, sulfolane, 1,3-dimethylimidazolinone, N
-Methyl-2-oxazolidinone). Examples of the polymer used for the matrix of the gel electrolyte include polyacrylonitrile and polyvinylidene fluoride.

The redox couple needs to have a certain concentration since it becomes an electron carrier. When used as a liquid or gel electrolyte, the total concentration in the solution is preferably at least 0.01 mol / l, more preferably at least 0.1 mol / l, particularly preferably at least 0.3 mol / l. It is. The upper limit in this case is not particularly limited, but is usually 5
It is about mol / l.

As the molten salt, for example, 1-butyl-3-
Methylpyridinium iodide, 1-butyl-3-methylimidazolium iodide, lithium iodide and at least one other lithium salt (eg, lithium acetate, lithium perchlorate, etc.), and polyethylene oxide and the like , The fluidity at room temperature may be increased. In this case, the amount of the polymer to be added is 1 to 5
0 wt%.

Examples of the hole (hole) transporting material include aromatic amines, polypyrrole, polythiophene and the like.

The counter electrode functions as a positive electrode of the photoelectrochemical cell when the photoelectric conversion element is a photoelectrochemical cell. The counter electrode is usually synonymous with the conductive support described above, but the support is not necessarily required in a configuration that maintains sufficient strength. However, having a support is advantageous in terms of hermeticity.

In order for light to reach the photosensitive layer, at least one of the conductive support and the counter electrode 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.

As the counter electrode of the photoelectrochemical cell, glass or plastic on which a metal or a conductive oxide is deposited can be used, and the metal thin film is formed so as to have a thickness of 5 μm or less, preferably 5 nm to 3 μm. It can also be formed by forming by a method such as vapor deposition or sputtering. In the present invention, it is preferable to use glass on which platinum is deposited or a metal thin film formed by deposition or sputtering as a counter 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.

[0085]

The present invention will be specifically described below with reference to examples. Example 1: Synthesis example of D-1, D-2, and D-54

[0086]

Embedded image

[0087]

Embedded image

(1) Synthesis of D-1 Indolenine quaternary salt 11, 7.92 g (20 mmol)
l), 3.44 g of diethyl squarate (20 mmol)
1) 4.2 g (40 mmol) of triethylamine was dissolved in 50 ml of ethanol and refluxed for 4 hours. After cooling, the crystals were separated by filtration and washed with ethanol to obtain 5.7 g (yield 82%) of yellow crystals of terminal squaric acid 12.

Terminal squaric acid 12, 1.04 g (3 m
mol), 0.22 g of malononitrile (3.3 mmol)
l), 0.69 g (3.6 mmol) of a 28% solution of sodium methoxide / methanol was dissolved in 20 ml of butanol and refluxed for 2 hours. The pH was adjusted to 3 by adding hydrochloric acid, and the mixture was cooled. The crystals were separated by filtration and washed with ethanol to obtain 13 orange crystals (0.66 g, yield 60%).

13, 0.18 g (0.5 mmol), indolenine quaternary salt 14, 0.21 g (0.5 mmol)
Was dissolved in 10 ml of butanol and refluxed for 8 hours.

After concentration, silica gel column chromatography (developing solvent: methylene chloride: ethyl acetate = 4: 1 →
1: 1 → 10% methanol addition), and further recrystallized from methanol to obtain the target green crystal of D-1 0.1
1 g (35% yield) was obtained. The structure was confirmed by NMR spectrum and MS (mass) spectrum.

(2) Synthesis of D-2 15 yellow crystals were obtained in exactly the same manner as in the synthesis of 13, except that equimolar butyl cyanoacetate was used instead of malononitrile. Yield 1.09 g (82% yield).

Further, in the synthesis of D-1, 1 was used instead of 13.
Except for using an equimolar 5, 0.10 g (yield 29%) of green crystals of D-2 was obtained in the same manner. The structure was confirmed by NMR spectrum and MS spectrum.

Synthesis of D-54 In the same manner as in the synthesis of 13, except that pyrazolidinedione 16 was used instead of malononitrile, 1.00 g (yield: 60%) of orange crystals of 17 was obtained.

17, 0.28 g (0.5 mmol) and 0.40 g (10 mmol) of indolenine quaternary salt were dissolved in 10 ml of butanol and refluxed for 30 minutes. After adding water, the mixture is concentrated, purified by silica gel column chromatography (developing solvent: methylene chloride: ethyl acetate = 4: 1 → 1: 1 → addition of methanol 25%), and recrystallized from methanol to obtain the desired D 0.094 g (yield 24%) of green crystals of -54 was obtained. Structure is NMR spectrum and MS
The spectrum was confirmed.

Example 2: Measurement of absorption spectrum D-1, D-2, D-4, D-18, D-19, D-2
2, D-34, D-35, D-54, D-55, and Comparative Dye 1 were measured for absorption spectra in methanol. Table 1 shows the absorption maximum wavelength.

[0097]

[Table 1]

In any case, the wavelength is longer than that of Comparative Dye 1, and when used as a photochemical battery, it is very preferable because light of longer wavelength can be spectrally sensitized and converted into a photocurrent.

Example 3 Preparation of Titanium Dioxide Dispersion Internal Volume 2 Teflon Coated Inside
15 g of titanium dioxide (Degussa P-25, Nippon Aerosil Co., Ltd.) and water 4 in a 00 ml stainless steel vessel
5 g, dispersant (Triton X-, manufactured by Aldrich)
100) 1 g and 30 g of zirconia beads having a diameter of 0.5 mm (manufactured by Nikkato Co., Ltd.) were added, and dispersed at 1500 rpm for 2 hours using a sand grinder mill (manufactured by Imex). The zirconia beads were removed by filtration from the dispersion. The average particle size of titanium dioxide in this case is 2.5 μm
Met. The particle size at this time was measured with a master sizer manufactured by MALVERN.

Example 4 Preparation of Titanium Dioxide Electrode Adsorbing Dye Transparent conductive glass coated with fluorine-doped tin oxide (manufactured by Nippon Sheet Glass, surface resistance is about 10 Ω / cm ² )
This coating solution was applied to the conductive surface side of the sample with a doctor blade to a thickness of 140 μm, dried at 25 ° C. for 30 minutes, and then dried at 450 ° C. for 30 minutes in an electric furnace (Yamato Scientific muffle furnace FP-32).
Bake for a minute. The coating amount of titanium dioxide is 15 g / m ^2,
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 (3 × 10 ^-4 mol / l) for 3 hours. The glass on which the dye was dyed was immersed in 4-tert-butylpyridine for 15 minutes, washed with ethanol and air-dried. The coating amount of the dye was appropriately selected from the range of 0.1 to 10 mmol / m ² according to the type of the dye.

Example 5: Preparation of a photoelectrochemical cell The color-sensitized TiO ₂ electrode substrate (2 cm × 2 cm) prepared as described above was superimposed on a platinum-deposited glass of the same size as that shown in FIG. 1). Next, the supporting electrolyte (1) was added to the electrolytic solution (acetonitrile: N-methyl 2-oxazolidinone = 8: 2) by utilizing the capillary phenomenon in the gap between the two glasses.
-Butyl-3-methylimidazolium iodide) 0.6
5 mol / l and iodine 0.05 mol / l) were impregnated and introduced into a TiO2 electrode to obtain a photoelectrochemical cell. This step was performed with the dyes modified as described in Table 2.

According to the present embodiment, as shown in FIG. 1, conductive glass 1 (a conductive agent layer 2 is provided on glass), TiO ₂ electrode 3, dye layer 4, electrolytic solution 5, platinum layer 6
Thus, a photoelectrochemical cell in which the glass and the glass 7 were sequentially laminated was produced.

Example 6: Measurement of Photoelectric Conversion Wavelength and Photoelectric Conversion Efficiency The photoelectric conversion capability of the photoelectric conversion element of the present invention was measured using an Optel IP.
CE (Incident Photon to Current Conversion Efficienc
y) Measured by a measuring device. Table 2 summarizes the wavelength at which the photochemical cell using each dye exhibits the maximum conversion capability and the photoelectric conversion efficiency of the monochromatic light.

[0105]

[Table 2]

All of the dyes of the present invention have high photoelectric conversion characteristics in the near infrared to infrared region. Further, it can have high photoelectric conversion ability even in an infrared region longer than 700 nm.

[0107]

According to the present invention, a dye-sensitized photoelectric conversion device having high photoelectric conversion characteristics in the near infrared to infrared region is provided.
Thereby, a photoelectrochemical cell can be configured.

[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

Continued on the front page F term (reference) 4H056 CA03 CA05 CB01 CC05 CC08 CE03 CE06 DD03 5F051 AA14 AA20 GA03 5H032 AA06 AS16 CC11 EE16 EE17 EE20

Claims (9)

[Claims] 1. A photoelectric conversion element comprising semiconductor fine particles sensitized by a dye represented by the following formula (I). Embedded image [In the formula (I), R ₁ and R ₂ each independently represent a substituent, R ₃ represents O ⁻ , S ⁻ , Se ⁻ , Te ⁻ or —NR ₄ ⁻ , and R ₄ represents hydrogen or an alkyl group. Or an aryl group. R ₁ and R ₂ may be linked to each other to form a ring.
P ₁ and P ₂ each independently represent a nonmetallic atomic group necessary for forming a polymethine dye. W ₁ represents a counter ion when a counter ion is required to neutralize the charge. ] 2. The dye represented by the formula (I) is represented by the following formula (II):
The photoelectric conversion device according to claim 1, which is a cyanine dye represented by the following formula: Embedded image [In the formula (II), R ₁ and R ₂ each independently represent a substituent, R ₃ represents O ⁻ , S ⁻ , Se ⁻ , Te ⁻ or —NR ₄ ^— , and R ₄ represents a hydrogen or an alkyl group. Or an aryl group. R ₁ and R ₂ may be linked to each other to form a ring.
R _{11 to} R ₁₄ each independently represent hydrogen, an alkyl group, an aryl group or a heterocyclic group, and Y ₁ and Y ₂ each independently represent oxygen, sulfur, selenium, tellurium, —CR ₅ R ₆ — or —NR ₇ And R ₅ , R ₆ and R ₇ each independently represent hydrogen, an alkyl group or an aryl group. R ₁₅ and R ₁₆ each independently represent a substituent, and a and b each independently represent an integer of 0 to 4. When a or b is 2 or more, R ₁₅ or R ₁₆ may be linked to each other to form a ring. W ₁ represents a counter ion when a counter ion is required to neutralize the charge. ] 3. R ₁ and R _{2 in} formula (I) or (II) each independently represent a cyano group, an alkoxycarbonyl group, a carboxyl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfonic acid group. The photoelectric conversion device according to claim 1, wherein the compound is a carbamoyl group, an acylamino group, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, an alkylthio group, an aryloxy group, a heterocyclic group, a phosphonyl group, or a phosphoryl group. 4. The photoelectric conversion device according to claim 1, wherein the dye represented by the formula (I) or the formula (II) has at least one acidic group. 5. A dye represented by the following formula (III): Embedded image [In formula (III), R ₁ and R ₂ each independently represents a substituent, R ₁₁ and R _{1 4} are each independently hydrogen, an alkyl group, an aryl group or a heterocyclic group, Y ₁ and Y ₂ Is independently oxygen, sulfur, selenium, tellurium,-
CR ₅ R ₆ — or —NR ₇ —, and R ₅ , R ₆ and R ₇ each independently represent hydrogen, an alkyl group or an aryl group. R _{17 to} R ₂₀ each independently represent an alkyl group, an aryl group, an alkoxy group, a hydroxyl group, a carboxyl group, an alkoxycarbonyl group, a carbamoyl group, an acylamino group, a phosphonyl group, a phosphoryl group, a sulfonic acid group, a cyano group or a halogen atom. Represent. c and d each independently represent 0 or 1, and e, f, g and h
Each independently represents an integer of 0 to 4; W ₁ represents a counter ion when a counter ion is required to neutralize the charge. ] 6. The dye according to claim 5, wherein the dye represented by the formula (III) has at least one acidic group. 7. A photoelectric conversion element comprising semiconductor fine particles sensitized by the dye of claim 5 or 6. 8. The fine particles of semiconductor sensitized by a dye are fine particles of titanium oxide.
3. The photoelectric conversion element according to item 1. 9. A photoelectrochemical cell using the photoelectric conversion element according to claim 8.