JP2003017148A - Electrolyte component, photoelectric conversion element, and photoelectric chemical cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte component having excellent durability and electric charge transmitting property, and to provide a photoelectric conversion element and a photoelectric chemical cell using above electrolyte component, having excellent durability and photoelectric conversion property. SOLUTION: The electrolyte component contains a quarternary salt electrolyte expressed by the formula (I). In the formula, Q represents an atom group forming cation of five or six-membered ring together with nitrogen atom, R1 represents a hydrogen atom or an substituent, R2 represents a substituent, n1 represents an integer of 0-5, X1 represents an ion, and n2 represents an integer of 0-4. When n1 is larger than 2, a plurality of R2 might be same with or different from each other, and at least one of R1 or R2 is a substituent expressed by the formula (II). In the formula (II), L represents a bonding group with two valence bonding the aromatic cation and V, where, V represents a carbonic acid group, a sulfonic acid group, or a carbonic acid group or a phosphonic acid group from which, proton is dissociated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte composition having excellent durability and charge transporting ability, and a photoelectric conversion device and a photoelectrochemical element having excellent durability and photoelectric conversion characteristics due to the use of the electrolyte composition. Regarding batteries.

[0002]

2. Description of the Related Art Conventionally, a liquid electrolyte composition (electrolyte solution) in which an electrolyte salt is dissolved in a solvent has been used as an electrolyte for electrochemical elements such as batteries, capacitors, sensors, display elements and recording elements. However, in an electrochemical device using such a liquid electrolyte composition, the composition may leak during long-term use or storage, which is unreliable.

Nature, 353, 737-740, 1991
In US Pat. No. 4,927,721, etc., a photoelectric conversion element using semiconductor fine particles sensitized with a dye and a photoelectrochemical cell using the same are disclosed. In these, however, an electrolyte solution is used in a charge transport layer. Therefore, the electrolyte solution may leak or be depleted during long-term use or storage, and the photoelectric conversion efficiency may be significantly reduced, or the device may not function as a device.

Under such circumstances, WO93 / 20565 has proposed a photoelectric conversion element using a solid electrolyte. The Chemical Society of Japan, 7, 484 (1997), JP-A-7-288142, Solid State
Ionics, 89, 263 (1986) and Japanese Unexamined Patent Publication No. 9-27352 have proposed a photoelectric conversion device including a solid electrolyte using a crosslinked polyethylene oxide polymer compound. However, photoelectric conversion elements using these solid electrolytes have insufficient photoelectric conversion characteristics, particularly short-circuit current density, and in addition, durability is not sufficient.

Also disclosed is a method of using a pyridinium salt, an imidazolium salt, a triazolium salt or the like in order to prevent leakage and depletion of the electrolyte composition and improve the durability of the photoelectric conversion element (WO 95/18456). No., JP 8-259
543, Electrochemistry, Vol.65, No.11, p.923 (1997)
etc). These salts are in a molten state at room temperature (around 25 ° C) and are called room temperature molten salts. This method does not require or requires a small amount of solvent such as water or organic solvent, so that the durability of the photoelectrochemical cell is improved. However, all room temperature molten salts used for conventional photoelectric conversion devices are those in which the cation and anion are not linked by a covalent bond, and the cation and anion can move independently of each other. It was disadvantageous from a viewpoint. The photoelectric conversion element using such a room temperature molten salt has poor photoelectric conversion efficiency.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an electrolyte composition having excellent durability and charge transporting ability, and a photoelectric conversion element having excellent durability and photoelectric conversion characteristics due to the use of the electrolyte composition. And to provide a photoelectrochemical cell.

[0007]

As a result of earnest research in view of the above objects, the present inventors have an aromatic cation moiety and a proton dissociation product of a carboxylic acid group, a sulfonic acid group, a phosphonic acid group or a phosphoric acid group. It was discovered that an electrolyte composition using a quaternary salt electrolyte has excellent durability and charge transporting ability, and the present invention was conceived.

That is, the electrolyte composition of the present invention has the following general formula:
It is characterized by containing a quaternary salt electrolyte represented by (I). When the electrolyte composition of the present invention contains this quaternary salt electrolyte and an iodine salt, it can be suitably used for a photoelectric conversion element or a photoelectrochemical cell. However, when the quaternary salt electrolyte is an iodine salt, it can be preferably used for the photoelectric conversion element without adding another iodine salt to the electrolyte composition.

[Chemical 3] In general formula (I), Q represents an atomic group forming a 5- or 6-membered aromatic cation together with a nitrogen atom, R ₁ represents a hydrogen atom or a substituent, R ₂ represents a substituent, and n 1 represents Represents an integer of 0 to 5, X ₁ represents a counter ion, and n 2 represents an integer of 0 to 4. n1
Is 2 or more, a plurality of R ₂ may be the same or different, and at least one of R ₁ and R ₂ is a substituent represented by the following general formula (II).

[Chemical 4] In the general formula (II), L represents a divalent linking group that links the aromatic cation and V, V is a carboxylic acid group, a sulfonic acid group,
It represents a proton dissociation product of a phosphonic acid group or a phosphoric acid group.

The photoelectric conversion device of the present invention is characterized by having a conductive support, a photosensitive layer, a charge transport layer and a counter electrode, and the charge transport layer is composed of the electrolyte composition of the present invention. The photoelectrochemical cell of the present invention uses the photoelectric conversion element.

In the present invention, by satisfying the following conditions,
An electrolyte composition having more excellent durability and charge transporting ability, and a photoelectric conversion element and a photoelectrochemical cell exhibiting more excellent durability and photoelectric conversion characteristics can be obtained. (1) The 5- or 6-membered ring formed by Q is particularly preferably an imidazole ring or a pyridine ring, and most preferably an imidazole ring. (2) R ₁ is particularly preferably a substituent represented by the general formula (II). (3) V is preferably a proton dissociation product of a carboxylic acid group or a sulfonic acid group, and more preferably a proton dissociation product of a sulfonic acid group. (4) n2 is preferably 0. (5) The melting point of the quaternary salt electrolyte represented by the general formula (I) is 100.
It is preferably at most ° C. (6) The solvent content of the electrolyte composition is 10 of the total electrolyte composition.
It is particularly preferably not more than mass%. (7) The electrolyte composition preferably contains iodine. (8) The photosensitive layer of the photoelectric conversion element preferably contains semiconductor fine particles sensitized with a dye, and the semiconductor fine particles preferably contain titanium oxide fine particles.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION [1] Electrolyte Composition The electrolyte composition of the present invention contains a quaternary salt electrolyte represented by the general formula (I) described below. This quaternary salt electrolyte may be used in combination with other iodine salt, and when the electrolyte composition of the present invention contains the quaternary salt electrolyte and iodine salt, it is suitable for a photoelectric conversion element or a photoelectrochemical cell. Can be used for When the quaternary salt electrolyte is an iodine salt, it can be preferably used for a photoelectric conversion element without adding another iodine salt to the electrolyte composition. The electrolyte composition of the present invention may further contain iodine, a solvent and the like. The electrolyte composition of the present invention can be used in chemical reactions, reaction solvents such as metal plating, CCD (charge coupled device) cameras, various photoelectric conversion devices and batteries, and used in lithium secondary batteries or photoelectrochemical batteries. Is preferable, and it is more preferable to use in a photoelectrochemical cell using a semiconductor. Hereinafter, each component of the electrolyte composition of the present invention will be described in detail.

(A) Quaternary Salt Electrolyte The electrolyte composition of the present invention contains a quaternary salt electrolyte represented by the following general formula (I). Hereinafter, in the present invention, the general formula (I)
The quaternary salt electrolyte represented by is referred to as “quaternary salt electrolyte (I)”. The quaternary salt electrolyte (I) is usually a salt having a low melting point, and its melting point is preferably 100 ° C. or lower.

[Chemical 5]

The quaternary salt electrolyte (I) and a mixture of the quaternary salt electrolyte (I) and an iodine salt can often be used as an electrolyte composition with almost no solvent, and in some cases, it is not necessary to use a solvent. Many. Quaternary salt electrolyte (I) is at room temperature (around 25 ° C)
When it is solid, it can be used as a liquid electrolyte composition by adding a solvent, an additive and the like. In addition, a method of dissolving by heating and permeating onto the electrode without adding anything, a method of permeating onto the electrode using a low boiling point solvent (methanol, acetonitrile, methylene chloride, etc.), and then removing the solvent by heating It is possible to incorporate it into the photoelectric conversion element by the above method.

In the general formula (I), Q is 5 or 6 together with the nitrogen atom.
Represents an atomic group forming an aromatic cation of a member ring. Q is preferably composed of at least one atom selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom.

The 5-membered ring formed by Q is preferably an oxazole ring, thiazole ring, imidazole ring, pyrazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring or triazole ring, and is preferably an oxazole ring, thiazole ring or imidazole ring. A ring is more preferable, and an imidazole ring is particularly preferable. The 6-membered ring formed by Q is preferably a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring or a triazine ring, and particularly preferably a pyridine ring. Among them, the 5- or 6-membered ring formed by Q together with the nitrogen atom is most preferably an imidazole ring.

In the general formula (I), R ₁ represents a hydrogen atom or a substituent, and R ₂ represents a substituent. N1 representing the number of R ₂ is an integer of 0 to 5, and when n 1 is 2 or more, a plurality of R ₂ may be the same or different. R ₁ and R ₂ may be linked to each other to form a ring.

At least one of R ₁ and R ₂ is a substituent represented by the following general formula (II). Hereinafter, the substituent represented by formula (II) is referred to as "substituent (II)". The quaternary salt electrolyte (I) preferably has 1 or 2 substituents (II), more preferably 1 substituent. In particular, R ₁
Is preferably a substituent (II).

[Chemical 6]

In the general formula (II), L is the above aromatic cation and V
Represents a divalent linking group for linking and. L is preferably composed of an atom selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom. The number of carbon atoms of L is preferably 1 to 30, more preferably 2 to 20, and particularly preferably 2 to 8. Specific examples of L include an alkylene group, an arylene group, an alkyleneoxy group, an aryleneoxy group, and combinations thereof. L is particularly preferably an alkylene group having 2 to 8 carbon atoms or an alkyleneoxy group.

In the general formula (II), V represents a proton dissociation product of a carboxylic acid group, a sulfonic acid group, a phosphonic acid group or a phosphoric acid group. V is preferably a proton dissociation product of a carboxylic acid group or a sulfonic acid group, and more preferably a proton dissociation product of a sulfonic acid group.

When R ₁ in the general formula (I) represents a substituent other than the above-mentioned substituent (II), it is preferably an alkyl group (preferably having 1 to 80 carbon atoms, even if linear). It may be branched or cyclic, for example, methyl group, ethylpropyl group, butyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-octyl group, decyl group, Dodecyl group, tetradecyl group, 2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, etc.) or alkenyl group (preferably having 2 to 80 carbon atoms, whether linear or branched) It may be cyclic, for example, vinyl group, allyl group, etc.)
And more preferably an alkyl group having 3 to 60 carbon atoms or an alkenyl group having 2 to 60 carbon atoms, and particularly preferably an alkyl group having 3 to 48 carbon atoms. R ₁ may further have a substituent, and examples of the substituent include those similar to the examples of the preferable substituent represented by R ₂ described later.

When R ₂ in the general formula (I) represents a substituent other than the above-mentioned substituent (II), preferable examples of the substituent include an alkoxy group (methoxy group, ethoxy group,-(OCH ₂ CH ₂ ) _n -OCH ₃
(N is an integer of 1 to 20),-(OCH ₂ CH ₂ ) _n -OCH ₂ CH ₃ (n is 1 to 2
0) etc.), cyano group, alkoxycarbonyl group (ethoxycarbonyl group, methoxyethoxycarbonyl group etc.), carbonic acid ester group (ethoxycarbonyloxy group etc.), amide group (acetylamino group, benzoylamino group etc.), carbamoyl Group (N, N-dimethylcarbamoyl group, N-phenylcarbamoyl group, etc.), phosphonyl group (diethylphosphonyl group, etc.), heterocyclic group (pyridyl group, imidazolyl group, furanyl group, oxazolidinonyl group, etc.),
Alkylthio group (methylthio group, ethylthio group, etc.), acyl group (acetyl group, propionyl group, benzoyl group, etc.), sulfonyl group (methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy group (acetoxy group, benzoyloxy group, etc.), Sulfonyloxy group (methanesulfonyloxy group, toluenesulfonyloxy group, etc.), aryl group (phenyl group, toluyl group, etc.), aryloxy group (phenoxy group, etc.), alkenyl group (vinyl group, 1-propenyl group, etc.), alkyl group (Methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.) and the like. Among them, an alkoxy group, a cyano group, a carbonic acid ester group, an amide group, a carbamoyl group, a phosphonyl group, a heterocyclic group, an acyl group, a sulfonyl group, an acyloxy group, a sulfonyloxy group and an alkyl group are more preferable, an alkoxy group, a cyano group, Carbonic acid ester groups, phosphonyl groups, heterocyclic groups and alkyl groups are particularly preferred.

In the general formula (I), X ₁ represents a counter ion, and n 2 representing the number of X ₁ represents an integer of 0-4. n2 is a quaternary salt electrolyte
(I) It is selected so that the entire charge is neutralized. That is,
Depending on the nature of the substituent of the quaternary salt electrolyte (I), the counter ion X ₁ may be present when the portion of the quaternary salt electrolyte (I) other than X ₁ becomes a cation or anion or has a net ionic charge. Is required. Further, even when the quaternary salt electrolyte (I) has a dissociative group capable of having a negative charge, the charge of the entire quaternary salt electrolyte (I) is neutralized by X ₁ . When X ₁ is a cation, examples thereof include inorganic or organic ammonium ions (tetraalkylammonium ion, pyridinium ion and the like), alkali metal ion and the like. When X ₁ is an anion, it may be an inorganic anion or an organic anion, and examples thereof include a halogen anion (fluoride ion, chloride ion, bromide ion, iodide ion, etc.), Substituted aryl sulfonate ion (p-toluene sulfonate ion, p-chlorobenzene sulfonate ion, etc.), aryl disulfonate ion (1,3-benzenedisulfonate ion, 1,5-naphthalene disulfonate ion, 2,6-naphthalene) Disulfonate ion, etc.), alkyl sulfate ion (methyl sulfate ion, etc.), sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, picrate ion, acetate ion, trifluoromethanesulfonic acid Examples include ions. X ₁ may be a charge-balancing counterion such as an ionic polymer, or a metal complex ion (bisbenzene-1,2-dithiolatonickel (III) etc.). In the present invention, n2 is 0 and the quaternary salt electrolyte
It is preferred that (I) does not have X ₁ . That is, it is preferable that the quaternary salt electrolyte (I) does not contain any counterion that is not covalently linked.

The quaternary salt electrolyte (I) may form a multimer via Q, R ₁ or R ₂ . This multimer is preferably a dimer to a tetramer, more preferably a dimer. Further, when the quaternary salt electrolyte (I) contains an alkyl group, an alkenyl group, an alkynyl group, an alkylene group, an aralkyl group, etc., they may be linear or branched,
It may be cyclic, and may be substituted or unsubstituted. When the quaternary salt electrolyte (I) contains an aryl group, a heterocyclic group, a cycloalkyl group, an aralkyl group, etc., they may be monocyclic or polycyclic (condensed ring, ring assembly), and It may be substituted or unsubstituted.

Quaternary salt electrolyte in the electrolyte composition of the present invention
The content of (I) is preferably 10% by mass or more, and more preferably 20 to 95% by mass, based on the whole electrolyte composition. Specific examples of the quaternary salt electrolyte (I) are shown below, but the present invention is not limited thereto.

[0025]

[Chemical 7]

[0026]

[Chemical 8]

The quaternary salt electrolyte (I) can be synthesized by a general quaternary salt synthesis method, for example, the Journal of
It can be easily synthesized by referring to the method described in Material Chemistry, 2001, (11), 1057 to 1062.

(B) Iodine Salt When the electrolyte composition of the present invention contains the quaternary salt electrolyte (I) and an iodine salt, it can be suitably used for a photoelectric conversion element or a photoelectrochemical cell. When the quaternary salt electrolyte (I) is an iodine salt, it can be preferably used in a photoelectric conversion element without adding another iodine salt to the electrolyte composition. When the quaternary salt electrolyte (I) is not an iodine salt, another iodine salt may be added to the electrolyte composition. As such iodine salt,
WO 95/18456, JP-A-8-259543, Electrochemistry, Volume 65,
No. 11, page 923 (1997) and the like, pyridinium salts, imidazolium salts, triazolium salts and the like can be used. The electrolyte composition of the present invention may contain a salt other than the quaternary salt electrolyte (I) and iodine salt. The iodine salt content of the electrolyte composition of the present invention is preferably 10% by mass or more, and more preferably 50 to 95% by mass, based on the entire electrolyte composition.

Examples of preferable iodine salts include those represented by any of the following general formulas (Ya), (Yb) and (Yc).

[Chemical 9]

Q _y1 in the general formula (Ya) represents an atomic group forming a 5- or 6-membered aromatic cation together with a nitrogen atom. Q
_y1 is preferably composed of an atom selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom. The 5-membered ring formed by Q _y1 is preferably an oxazole ring, a thiazole ring, an imidazole ring, a pyrazole ring, an isoxazole ring, a thiadiazole ring, an oxadiazole ring or a triazole ring, and an oxazole ring, a thiazole ring or an imidazole ring. It is more preferable that it is, and it is particularly preferable that it is an oxazole ring or an imidazole ring. The 6-membered ring formed by Q _{y 1} is preferably a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring or a triazine ring, and particularly preferably a pyridine ring.

A _y1 in the general formula (Yb) represents a nitrogen atom or a phosphorus atom.

R _{y1 to} R in the general formulas (Ya), (Yb) and (Yc)
_y11 is independently a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, may be linear or branched, or may be cyclic, for example, a methyl group , Ethyl group, propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group,
t-octyl group, decyl group, dodecyl group, tetradecyl group, 2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, etc., or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms) ,
It may be linear or branched and represents, for example, a vinyl group or an allyl group. R _{y1 to} R _y11 each independently represent, more preferably, an alkyl group having 2 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and particularly preferably an alkyl group having 2 to 6 carbon atoms.

Two or more of R _{y2 to} R _{y5 in} the general formula (Yb) may be linked to each other to form a non-aromatic ring containing A _y1, and R _y6 to the general formula (Yc) to Two or more of R _y11 may be linked to each other to form a ring.

The above Q _y1 and R _{y1 to} R _y11 may have a substituent. Preferred examples of this substituent include a halogen atom (F, Cl, Br, I, etc.), a cyano group, an alkoxy group (methoxy group, ethoxy group, etc.), an aryloxy group (phenoxy group, etc.), an alkylthio group (methylthio group, Ethylthio group etc.), alkoxycarbonyl group (ethoxycarbonyl group etc.), carbonate ester group (ethoxycarbonyloxy group etc.), acyl group (acetyl group, propionyl group, benzoyl group etc.), sulfonyl group (methanesulfonyl group, benzenesulfonyl group) Etc.), acyloxy group (acetoxy group, benzoyloxy group, etc.), sulfonyloxy group (methanesulfonyloxy group, toluenesulfonyloxy group, etc.), phosphonyl group (diethylphosphonyl group, etc.), amide group (acetylamino group, benzoylamino group) Group), carbamoyl group (N, N-dimethylcarba) Moyl group, etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.), aryl group (phenyl group, toluyl group, etc.), hetero group Cyclic group (pyridyl group, imidazolyl group,
And a alkenyl group (vinyl group, 1-propenyl group, etc.) and the like.

The iodine salt represented by any of the general formulas (Ya), (Yb) and (Yc) may form a multimer via Q _y1 and any of R _{y1 to} R _y11 .

(C) Iodine The electrolyte composition of the present invention preferably contains iodine, and particularly when this electrolyte composition is used for a photoelectric conversion element, the addition of iodine has a great effect. The iodine added to the electrolyte composition may be present as I _{2 in the} composition, or may be present in an ionic state or a salt-forming state. When adding iodine to the electrolyte composition of the present invention, the content of iodine is 0.1 to 2 with respect to the entire electrolyte composition.
It is preferably 0% by mass, more preferably 0.5 to 5% by mass.

(D) Solvent The electrolyte composition of the present invention may contain a solvent. The solvent content of the electrolyte composition is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 10% by mass or less, based on the entire electrolyte composition.

The solvent used for the electrolyte composition exhibits excellent ion conductivity because it has a low viscosity and a high ion mobility, a high dielectric constant and a high effective carrier concentration, or both. It is preferable that it is possible. Examples of such solvents include carbonate compounds (ethylene carbonate, propylene carbonate, etc.), heterocyclic compounds (3-methyl-2-oxazolidinone, etc.), ether compounds (dioxane, diethyl ether, etc.), chain ethers (ethylene Glycol dialkyl ether, propylene glycol dialkyl ether,
Polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether, etc.), alcohols (methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, etc.), polyhydric alcohols ( Ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin, etc.), nitrile compounds (acetonitrile, glutadinitrile, methoxyacetonitrile, propionitrile, benzonitrile, biscyanoethyl ether, etc.), esters (carboxylic acid ester, phosphoric acid) Ester, phosphonate, etc.), aprotic polar solvent (diester Sulfoxide (DMSO), sulfolane, etc.), water and the like. You may use these solvents in mixture of 2 or more types.

(E) Others The electrolyte composition of the present invention is used by gelling (solidifying) by a method such as addition of a polymer, addition of an oil gelling agent, polymerization containing polyfunctional monomers, and crosslinking reaction of a polymer. You can

When gelation occurs by adding a polymer, Po
lymer Electrolyte Reviews-1 and 2 (JR MacCallu
(ELSEVIER APPLIED SCIENCE, co-edited by m and CA Vincent)
The polymers described in 1. can be used, preferably polyacrylonitrile or polyvinylidene fluoride.

In the case of gelation by adding an oil gelling agent, J. Chem. Soc. Japan, Ind. Chem. Soc., 46779.
(1943), J. Am. Chem. Soc., 111, 5542 (1989), J. Ch.
em.Soc., Chem. Commun., 390 (1993), Angew. Chem. I
nt. Ed. Engl., 35, 1949 (1996), Chem. Lett., 885,
(1996), J. Chem. Soc., Chem. Commun., 545, (1997).
The oil gelling agent described in, etc. can be used, and a compound having an amide structure is preferably used.

When the layer of gel electrolyte composition is formed by polymerization of polyfunctional monomers, a solution comprising polyfunctional monomers, a polymerization initiator, an electrolyte composition and a solvent is prepared,
It is preferable to form a sol layer on the photosensitive layer and the like by a method such as a casting method, a coating method, a dipping method, an impregnation method and the like, and then radically polymerize the sol layer for gelation. The polyfunctional monomers are preferably compounds having two or more ethylenically unsaturated groups, and preferred examples thereof include divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate,
Examples thereof include triethylene glycol diacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate and the like.

The gel electrolyte composition may be formed by polymerization using the above polyfunctional monomers and monofunctional monomers. Monofunctional monomers include acrylic acid or α-alkyl acrylic acid (acrylic acid, methacrylic acid, itaconic acid, etc.) or their esters or amides (N-isopropylacrylamide, Nn-butylacrylamide, Nt-
Butyl acrylamide, N, N-dimethyl acrylamide,
N-methylmethacrylamide, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, acrylamidopropyltrimethylammonium chloride, methacrylamide, diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, methyl acrylate, ethyl acrylate, hydroxy Ethyl acrylate, n-propyl acrylate, isopropyl acrylate, 2-hydroxypropyl acrylate,
2-methyl-2-nitropropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, t-pentyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-methoxyethoxyethyl acrylate, 2,2 , 2-trifluoroethyl acrylate, 2,2-dimethylbutyl acrylate,
3-methoxybutyl acrylate, ethylcarbitol acrylate, phenoxyethyl acrylate, n-pentyl acrylate, 3-pentyl acrylate, octafluoropentyl acrylate, n-hexyl acrylate,
Cyclohexyl acrylate, cyclopentyl acrylate, cetyl acrylate, benzyl acrylate, n-
Octyl acrylate, 2-ethylhexyl acrylate, 4-methyl-2-propylpentyl acrylate, heptadecafluorodecyl acrylate, n-octadecyl acrylate, methyl methacrylate, 2-methoxyethoxyethyl methacrylate, ethylene glycol ethyl carbonate methacrylate, 2,2,2 -Trifluoroethyl methacrylate, tetrafluoropropyl methacrylate, hexafluoropropyl methacrylate, hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, t-pentyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, benzyl methacrylate, heptadecafluorodecylmethac Rate, n- octadecyl methacrylate, 2-isobornyl methacrylate, 2-
Norbornyl methyl methacrylate, 5-norbornene-2
-Ylmethylmethacrylate, 3-methyl-2-norbornylmethylmethacrylate, dimethylaminoethylmethacrylate, etc.), vinyl esters (vinyl acetate, etc.), maleic acid or fumaric acid or esters derived therefrom (dimethyl maleate, Dibutyl maleate, diethyl fumarate, etc.), sodium salt of p-styrenesulfonic acid, acrylonitrile, methacrylonitrile, dienes (butadiene, cyclopentadiene, isoprene, etc.),
Aromatic vinyl compounds (styrene, p-chlorostyrene, t-
Butylstyrene, α-methylstyrene, sodium styrenesulfonate, etc.), N-vinylformamide, N-vinyl
-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, vinylsulfonic acid, sodium vinylsulfonate, sodium allylsulfonate, sodium methacrylsulfonate, vinylidene fluoride, vinylidene chloride, vinyl alkyl ethers (Methyl vinyl ether etc.), ethylene, propylene, 1-butene, isobutene, N-phenylmaleimide and the like can be used.

When a polyfunctional monomer and a monofunctional monomer are used together, the mass ratio of the polyfunctional monomer to the total amount of the monomers is preferably 0.5 to 70% by mass, and 1.0 to 50% by mass.
More preferably, it is mass%.

The above-mentioned polyfunctional monomers and monofunctional monomers are described in Takayuki Otsu and Masayoshi Kinoshita, "Experimental Method of Polymer Synthesis".
(Chemical coterie) and Takayuki Otsu "Lecture Polymerization reaction theory 1 radical polymerization (I)" (Chemical coterie) can be polymerized by radical polymerization which is a general polymer synthesis method. The above-mentioned monomer can be radically polymerized by heating, light or electron beam, or electrochemically, but it is particularly preferable to radically polymerize by heating. A polymerization initiator may be used in radical polymerization, and examples of preferred polymerization initiators include 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile). , Dimethyl-2,2'-azobis (2-methylpropionate), azo-2 initiator such as dimethyl-2,2'-azobisisobutyrate,
Examples thereof include peroxide initiators such as lauryl peroxide, benzoyl peroxide, and t-butyl peroctoate. The addition amount of the polymerization initiator is preferably 0.01 to 20 mass% with respect to the total amount of monomers, more preferably 0.1 to 10
It is% by mass.

The weight composition range of the monomer in the gel electrolyte composition is preferably 0.5 to 70% by mass, more preferably 1.0 to 50% by mass.

When the electrolyte composition is gelled by the cross-linking reaction of the polymer, it is preferable to use a polymer having a cross-linkable reactive group and a cross-linking agent together. in this case,
The reactive group is preferably a nitrogen-containing heterocycle such as a pyridine ring, an imidazole ring, a thiazole ring, an oxazole ring, a triazole ring, a morpholine ring, a piperidine ring, and a piperazine ring, and the crosslinking agent is preferably capable of nucleophilic attack by a nitrogen atom. It is a compound (electrophile) having two or more functional groups, and for example, a bifunctional or higher functional alkyl halide, halogenated aralkyl, sulfonic acid ester, acid anhydride, acid chloride, isocyanate or the like can be used.

The electrolyte composition of the present invention comprises a metal iodide (LiI, NaI, KI, CsI, CaI _2, etc.), a metal bromide (LiBr, N).
aBr, KBr, CsBr, CaBr _2, etc.), quaternary ammonium bromine salt (tetraalkyl ammonium bromide, pyridinium bromide, etc.), metal complex (ferrocyanate-ferricyanate, ferrocene-ferricinium ion, etc.), sulfur compound (Sodium polysulfide, alkylthiol-alkyldisulfide, etc.), viologen dye,
It may contain hydroquinone-quinone or the like. These may be mixed and used.

Further, the electrolyte composition of the present invention is J. Am. Cer
Am. Soc., 80, (12), 3157-3171 (1997), t-butylpyridine, and basic compounds such as 2-picoline and 2,6-lutidine may be contained. The concentration of the basic compound in the electrolyte composition is preferably 0.05 to 2M.

[2] Photoelectric Conversion Element The photoelectric conversion element of the present invention has a conductive support, a photosensitive layer, a charge transport layer and a counter electrode, and the charge transport layer is composed of the above-mentioned electrolyte composition of the present invention.

The photoelectric conversion element of the present invention is preferably the one shown in FIG.
As shown in FIG. 5, the conductive layer 10, the undercoat layer 60, the photosensitive layer 20, the charge transport layer 30, and the counter conductive layer 40 are laminated in this order.
Is composed of semiconductor fine particles 21 sensitized with a dye 22 and a charge transport material 23 that has penetrated into the spaces between the semiconductor fine particles 21. Usually, the charge transport material 23 comprises the same components as the electrolyte composition used for the charge transport layer 30. Further, in order to impart strength to the photoelectric conversion element, the conductive layer 10 and / or the counter conductive layer 40
The substrate 50 may be provided as a base of the substrate. In the present invention, the layer composed of the conductive layer 10 and the substrate 50 optionally provided is referred to as a “conductive support”, and the layer composed of the counter electrode conductive layer 40 and the substrate 50 optionally provided is referred to as a “counter electrode”. The conductive layer 10, the counter conductive layer 40, and the substrate 50 in FIG. 1 may be the transparent conductive layer 10a, the transparent counter conductive layer 40a, and the transparent substrate 50a, respectively.

In the photoelectric conversion device of the present invention shown in FIG. 1, when the semiconductor fine particles are n-type, the light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by the dye 22 excites the dye 22 and the like. The excited high-energy electrons in the dye 22 and the like are transferred to the conduction band of the semiconductor fine particles 21, and further reach the conductive layer 10 by diffusion. At this time, molecules such as the dye 22 are oxidants. In the photoelectrochemical cell, the electrons in the conductive layer 10 work in the external circuit while the counter conductive layer 40
And returns to an oxidant such as the dye 22 through the charge transport layer 30,
22 plays. The photosensitive layer 20 functions as a negative electrode (photoanode), and the counter conductive layer 40 functions as a positive electrode. At the boundary of each layer (for example, the boundary between the conductive layer 10 and the photosensitive layer 20, the boundary between the photosensitive layer 20 and the charge transport layer 30, the boundary between the charge transport layer 30 and the counter conductive layer 40, etc.), the constituent components of each layer They may be diffusively mixed with each other. Each layer will be described in detail below.

(A) Conductive Support The conductive support is composed of (1) a single layer of a conductive layer, or (2) two layers of a conductive layer and a substrate. In the case of (1), a material that can sufficiently maintain strength and hermeticity as a conductive layer, for example, a metal material (platinum, gold, silver, copper, zinc, titanium, aluminum,
Alloys including these) can be used. In the case of (2), it is possible to use a substrate having a conductive layer containing a conductive agent on the photosensitive layer side. Preferred conductive agents include metals (platinum, gold, silver, copper, zinc, titanium, aluminum, indium, alloys containing these, etc.), carbon, and conductive metal oxides (indium-tin composite oxide, tin oxide and fluorine. Or antimony-doped ones). The thickness of the conductive layer is preferably about 0.02 to 10 μm.

The lower the surface resistance of the conductive support, the better. The surface resistance is preferably 50 Ω / □ or less, more preferably 20 Ω / □ or less.

When light is irradiated from the side of the conductive support, the conductive support is preferably substantially transparent.
Substantially transparent means visible to near infrared region (400 to 120
(0 nm) light has a transmittance of 10% or more in a part or the whole area, preferably 50% or more, and 80% or more.
The above is more preferable. In particular, it is preferable that the photosensitive layer has a high transmittance in a wavelength range in which the photosensitive layer has sensitivity.

The transparent conductive support is preferably a transparent conductive layer made of a conductive metal oxide formed on the surface of a transparent substrate such as glass or plastic by coating or vapor deposition. Preferred as the transparent conductive layer is fluorine- or antimony-doped tin dioxide or indium-tin oxide (ITO). In addition to glass substrates such as soda glass and alkali-free glass that are not affected by alkali elution, which are advantageous in terms of cost and strength for transparent substrates,
A transparent polymer film can be used. Examples of transparent polymer film materials include triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PP).
S), polycarbonate (PC), polyarylate (PA
r), polysulfone (PSF), polyester sulfone (PES), polyimide (PI), polyetherimide (PE
I), cyclic polyolefin, brominated phenoxy resin and the like. In order to secure sufficient transparency, the amount of the conductive metal oxide applied is preferably 0.01 to 100 g per 1 m ² of the support.

It is preferable to use metal leads for the purpose of lowering the resistance of the transparent conductive support. The material of the metal lead is preferably a metal such as platinum, gold, nickel, titanium, aluminum, copper or silver. The metal lead is installed on the transparent substrate by vapor deposition, sputtering, etc., and conductive tin oxide, ITO is placed on it.
It is preferable to provide a transparent conductive layer made of a film or the like. The decrease in the amount of incident light due to the installation of the metal leads is preferably within 10%, more preferably 1 to 5%.

(B) Photosensitive Layer The photosensitive layer preferably contains fine semiconductor particles sensitized with a dye. In the photosensitive layer, the semiconductor acts as a photoreceptor, absorbs light and separates charges to generate electrons and holes. In a dye-sensitized semiconductor, light absorption and generation of electrons and holes due to light absorption mainly occur in the dye, and the semiconductor fine particles play a role of receiving and transmitting this electron (or hole). The semiconductor used in the present invention is preferably an n-type semiconductor in which a conductor electron serves as a carrier under photoexcitation and gives an anode current.

(1) Semiconductor As the semiconductor, silicon, a single semiconductor such as germanium, a III-V group compound semiconductor, a metal chalcogenide (oxide, sulfide, selenide, a compound thereof, etc.), a perovskite structure And the like (strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) and the like can be used.

Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium,
Hafnium, strontium, indium, cerium,
Examples thereof include yttrium, lanthanum, vanadium, niobium or tantalum oxide, cadmium, zinc, lead, silver, antimony or bismuth sulfide, cadmium or lead selenide, and cadmium telluride. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium, and cadmium, gallium-arsenic or copper-indium selenides, and copper-indium sulfides. Furthermore, M _x O _y S _z or M _1x M _2y O _z (M, M ₁ and M ₂ are metal elements respectively, O is oxygen, and x, y and z are the number of combinations having a neutral valence) Compounds such as can also be preferably used.

The semiconductor used in the present invention is preferably Si,
TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, ZnS, Pb
S, Bi ₂ S ₃ , CdSe, CdTe, SrTiO ₃ , GaP, InP, GaAs, CuIn
S ₂ , CuInSe _2, etc., more preferably TiO ₂ , ZnO, Sn
O ₂ , Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , CdS, PbS, CdSe, SrTiO ₃ , In
P, GaAs, CuInS ₂ or CuInSe ₂ , particularly preferably Ti
O ₂ or Nb ₂ O ₅ , most preferably TiO ₂ . TiO ₂
Preferably TiO ₂ containing anatase 70% among, particularly preferably TiO ₂ 100% anatase. It is also effective to dope a metal for the purpose of increasing electron conductivity in these semiconductors. The metal to be doped is preferably divalent or trivalent. It is also effective to dope the semiconductor with a monovalent metal for the purpose of preventing a reverse current from flowing from the semiconductor to the charge transport layer.

The semiconductor used in the present invention may be a single crystal or a polycrystal, but a polycrystal is preferable from the viewpoints of manufacturing cost, securing of raw materials, energy payback time and the like, and a porous film made of fine semiconductor particles is particularly preferable. In addition, a part of the amorphous portion may be included.

The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles obtained from the diameter when the projected area is converted to a circle is preferably 5 to 200 nm, and 8 to 100 nm is more preferred. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 30 μm. Two or more types of fine particles having different particle size distributions may be mixed, and in this case, the average size of the small particles is preferably 25 nm or less, more preferably 10 nm or less.
For the purpose of scattering incident light and improving the light capture rate, it is also preferable to mix semiconductor particles having a large particle size, for example, about 100 to 300 nm.

Two or more kinds of semiconductor fine particles of different kinds may be mixed and used. When two or more kinds of semiconductor fine particles are mixed and used, one of them is preferably TiO ₂ , ZnO, Nb ₂ O ₅ or SrTiO ₃ . The other is preferably SnO ₂ , Fe ₂ O ₃ or WO ₃ . Examples of more preferable combinations include combinations of ZnO and SnO ₂ , ZnO and WO ₃ , ZnO and SnO ₂ and WO _{3, and the} like. When two or more kinds of semiconductor fine particles are mixed and used, each particle size may be different. In particular, a combination in which TiO ₂ , ZnO, Nb ₂ O ₅ or SrTiO ₃ has a large particle size and SnO ₂ , Fe ₂ O ₃ or WO ₃ is small is preferable. Preferably, particles having a large particle size are 100 nm or more and particles having a small particle size are 15 nm or less.

As a method for producing semiconductor fine particles, Sakuhana Sakuo's "Sol-Gel Method Science" Agne Jofusha (1998), Technical Information Institute "Sol-Gel Method Thin Film Coating Technology" (1995 ), Etc., and Tadao Sugimoto, "Synthesis and Size Morphology Control of Monodisperse Particles by New Synthesis Gel-Sol Method," Materia, Vol. 35, No. 9, 1012-1018.
The gel-sol method described in page (1996) and the like is preferable. Also
A method developed by Degussa to produce an oxide by high-temperature hydrolysis of a chloride in an oxyhydrogen salt can also be preferably used.

When the semiconductor fine particles are titanium oxide, the sol-gel method, gel-sol method, and high-temperature hydrolysis method in chloride oxyhydrogen salt are all preferable. Applied Technology "Gihodo Publishing (1997)
It is also possible to use the sulfuric acid method or the chlorine method described in 1. In addition, Barbe et al., Journal of American Ceramic Society, Volume 80, No. 12, pp. 3157-3171 (19
1997) and the sol-gel method such as those described in Burnside et al., Chemistry of Materials, Volume 10, No. 9, pages 2419-2425.

(2) Semiconductor fine particle layer To coat the semiconductor fine particles on the conductive support, a method of coating a dispersion or colloidal solution of the semiconductor fine particles on the conductive support, the above-mentioned sol-gel method, etc. Can be used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of conductive support, and the like, a wet film forming method is relatively advantageous. As a wet film forming method,
The coating method, printing method, electrolytic deposition method and electrodeposition method are typical. Also, a method of oxidizing a metal, a method of depositing a metal solution in a liquid phase by ligand exchange or the like (LPD method), a method of depositing by a sputtering method, a CVD method, or a metal that is thermally decomposed on a heated substrate The SPD method of spraying an oxide precursor to form a metal oxide can also be used.

As a method of preparing a dispersion of semiconductor fine particles, in addition to the sol-gel method described above, a method of crushing with a mortar, a method of dispersing while crushing with a mill, a method of synthesizing a semiconductor in a solvent And a method of precipitating it as fine particles and using it as it is.

As the dispersion medium, water and various organic solvents (for example, methanol, ethanol, isopropyl alcohol, citronellol, terpineol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.) can be used. At the time of dispersion, a polymer such as polyethylene glycol, hydroxyethyl cellulose or carboxymethyl cellulose, a surfactant, an acid or a chelating agent may be used as a dispersion aid, if necessary. It is preferable to add polyethylene glycol because the viscosity of the dispersion can be adjusted by changing the molecular weight of polyethylene glycol, and a semiconductor layer that is hard to peel off can be formed and the porosity of the semiconductor layer can be controlled.

As a coating method, a roller method, a dip method or the like as an application system, an air knife method, a blade method or the like as a metering system, and as a method capable of making the application and the metering in the same part, Japanese Patent Publication No. 58-4.
Wirebar method disclosed in US Pat. No. 26812.
The slide hopper method, the extrusion method, the curtain method and the like described in No. 94, No. 2761419, No. 2761791 and the like can be preferably used. A spin method or a spray method is also preferable as a general-purpose machine. Wet printing methods include relief printing, offset and gravure three major printing methods, intaglio printing, rubber printing,
Screen printing and the like are preferable. The film forming method may be selected from these depending on the liquid viscosity and the wet thickness.

The layer of semiconductor fine particles is not limited to a single layer, and a dispersion of semiconductor fine particles having different particle diameters may be applied in multiple layers, or a coating layer containing different types of semiconductor fine particles (or different binders, additives, etc.) may be used. It is also possible to apply multiple layers. Multi-layer coating is effective even when the film thickness is insufficient after one coating.

Generally, as the thickness of the semiconductor fine particle layer (same as the thickness of the photosensitive layer) increases, the amount of supported dye per unit projected area increases, so that the light capture rate increases, but the diffusion distance of generated electrons increases. Therefore, the loss due to charge recombination becomes large. Therefore, the preferable thickness of the semiconductor fine particle layer is
0.1 to 100 μm. When used in a photoelectrochemical cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and 2 to 25 μm.
Is more preferable. The coating amount of the semiconductor fine particles per 1 m ² of the support is preferably 0.5 to 100 g, more preferably 3 to 50 g.

After the semiconductor fine particles are coated on the conductive support, it is preferable to perform a heat treatment in order to bring the semiconductor fine particles into electronic contact with each other and to improve the coating strength and the adhesion to the support. The heating temperature in the heat treatment is preferably 40 to 700 ° C, more preferably 100 to 600 ° C. The heating time is about 10 minutes to 10 hours. When a substrate having a low melting point or a low softening point such as a polymer film is used, treatment at a high temperature causes deterioration of the substrate, which is not preferable. In terms of cost, the temperature is as low as possible (eg 50
˜350 ° C.) is preferred. Temperature reduction can be achieved by heat treatment in the presence of small semiconductor particles of 5 nm or less, mineral acid, or metal oxide precursor.
It can also be performed by irradiation with infrared rays, microwaves, or the like, or by applying an electric field or ultrasonic waves. At the same time, in addition to the above irradiation and application, heating, decompression,
Oxygen plasma treatment, pure water cleaning, solvent cleaning, gas cleaning, etc. are preferably used in combination as appropriate.

After the heat treatment, for the purpose of increasing the surface area of the semiconductor fine particles, increasing the purity in the vicinity of the semiconductor fine particles, and increasing the efficiency of electron injection from the dye to the semiconductor fine particles, for example, chemical plating treatment using an aqueous solution of titanium tetrachloride or Electrochemical plating treatment using a titanium trichloride aqueous solution may be performed. Further, it is also effective to adsorb an organic substance having a low electron conductivity other than a dye on the particle surface for the purpose of preventing a reverse current from flowing from the semiconductor fine particles to the charge transport layer. The organic substance to be adsorbed is preferably one having a hydrophobic group.

The semiconductor fine particle layer preferably has a large surface area so that many dyes can be adsorbed.
The surface area of the semiconductor fine particle layer coated on the support is preferably 10 times or more the projected area,
It is more preferably 0 times or more. This upper limit is not particularly limited, but is usually about 1000 times.

(3) Dye The sensitizing dye used in the photosensitive layer can be arbitrarily selected as long as it has absorption in the visible region or near infrared region and can sensitize a semiconductor. Methine dyes, porphyrin dyes and phthalocyanine dyes are preferred. Further, two or more kinds of dyes can be used in combination in order to widen the wavelength range of photoelectric conversion as much as possible and to increase the conversion efficiency.
In this case, the dyes to be used in combination and the ratio thereof can be selected so as to match the wavelength range and intensity distribution of the target light source.

Such dyes are preferably semiconductor fine particles.
A suitable linking group (interloc
king group). The preferred linking group is -COOH
Group, -OH group, -SO₃H group, -P (O) (OH)₂Group and -OP (O) (OH)₂Basis
Acidic groups such as, as well as oximes, dioximes, hydro
Of xyquinoline, salicylate and α-ketoenolate
A chelating group having such π conductivity is mentioned. During ~
But -COOH group, -P (O) (OH) ₂Group and -OP (O) (OH)₂The group is particularly good
Good These groups form salts with alkali metals, etc.
Or an inner salt may be formed. See you
In the case of the Limethine dye, the methine chain has a squarylium ring or
Contain an acidic group, such as when forming a roconium ring
If this is the case, this part may be used as a bonding group. Below, in the photosensitive layer
The preferred sensitizing dye to be used will be specifically described.

(A) Metal Complex Dye The metal complex dye is preferably a metal phthalocyanine dye, a metal porphyrin dye or a ruthenium complex dye, and particularly preferably a ruthenium complex dye. Examples of ruthenium complex dyes include U.S. Pat.Nos. 4,927,721, 4,884,537 and 50.
No. 84365, No. 5350644, No. 5463057, No. 5525440, JP-A-7-249790, Tokuyohei 10-504512, WO 98/50393,
Examples thereof include those described in JP-A-2000-26487.

The ruthenium complex dye used in the present invention is preferably represented by the following general formula (III): (A ₁ ) _p Ru (Ba) (Bb) (Bc) ... (III). In the general formula (III), A ₁ is 1
Or a bidentate ligand, preferably Cl, SCN, H ₂ O, B
It is a ligand selected from the group consisting of r, I, CN, NCO, SeCN, β-diketone derivatives, oxalic acid derivatives and dithiocarbamic acid derivatives. p is an integer of 0 to 3. Ba, Bb
And Bc each independently represent an organic ligand represented by any of the following formulas B-1 to B-10.

[0080]

[Chemical 10]

In formulas B-1 to B-10, R ₃ represents a hydrogen atom or a substituent, and examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, and a carbon atom. Number of atoms 7
~ 12 substituted or unsubstituted aralkyl groups, 6 to 6 carbon atoms
There may be mentioned 12 substituted or unsubstituted aryl groups, the aforementioned acidic groups (these acidic groups may form a salt) and chelating groups. Here, the alkyl portion and the alkyl portion of the aralkyl group may be linear or branched, and the aryl portion and the aryl portion of the aralkyl group may be monocyclic or polycyclic (condensed ring, ring assembly, etc.). Ba, Bb and Bc may be the same or different, and may be any one or two.

Preferred specific examples of the metal complex dye are shown below, but the present invention is not limited thereto.

[0083]

[Chemical 11]

[0084]

[Chemical 12]

(B) Methine Dye The methine dye used in the present invention is preferably a polymethine dye such as a cyanine dye, a merocyanine dye and a squarylium dye. Specific examples of polymethine dyes include JP-A-11-35836, JP-A-11-67285, and JP-A-11-86916.
No. 11-97725, No. 11-158395, No. 11-158395
163378, JP11-214730, JP11-214731, JP11-238905, JP2000-26487, European patent 892411
No. 911841 and No. 991092. Specific examples of preferable methine dyes are shown below.

[0086]

[Chemical 13]

[0087]

[Chemical 14]

(4) Adsorption of Dye to Semiconductor Fine Particles A semiconductor is prepared by immersing a conductive support having a well-dried semiconductor fine particle layer in a solution of a dye or applying a solution of the dye to the semiconductor fine particle layer. A dye can be adsorbed on the fine particle film. In the former case, a dipping method, a dipping method, a roller method, an air knife method or the like can be used. In the dipping method, the dye may be adsorbed at room temperature or may be heated under reflux as described in JP-A-7-249790. Examples of the latter coating method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method and a spray method. Preferred examples of the solvent used for the dye solution (adsorption liquid) include alcohols (methanol, ethanol, t-butanol,
Benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile etc.), nitromethane, halogenated hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene etc.), ethers (diethyl ether, tetrahydrofuran etc.), Dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methylpyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, acetic acid Butyl etc.), carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate etc.), ketones (acetone, 2-butanone, cyclohexanone etc.), hydrocarbons (hexane,
Petroleum ether, benzene, toluene, etc.), a mixed solvent thereof, and the like.

The total amount of dye adsorbed is preferably 0.01 to 100 mmol per unit area (1 m ² ) of the semiconductor fine particle layer. 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 dye adsorbed, a sufficient sensitizing effect on the semiconductor can be obtained. If the amount of the dye is too small, the sensitizing effect will be insufficient, and if the amount of the dye is too large, the dye not attached to the semiconductor will float and the sensitizing effect will be reduced. In order to increase the amount of dye adsorbed, it is preferable to perform heat treatment before adsorbing the dye. After the heat treatment, in order to prevent water from adsorbing on the surface of the semiconductor fine particles, the temperature of the semiconductor fine particle layer should be kept at room temperature without returning to room temperature
It is preferable to rapidly perform the dye adsorption operation between 60 and 150 ° C.

In order to reduce interaction such as aggregation between dyes, a colorless compound having a surface active property may be added to the dye adsorbing solution and co-adsorbed on the semiconductor fine particles. Examples of such colorless compounds include steroid compounds having a carboxyl group (such as chenodeoxycholic acid) and the following sulfonates.

[Chemical 15]

The unadsorbed dye is preferably removed by washing immediately after adsorption. It is preferable that the cleaning is performed using a wet cleaning tank with a polar solvent such as acetonitrile or an organic solvent such as an alcohol solvent. After adsorbing the dye, the surface of the semiconductor fine particles may be treated with an amine or a quaternary ammonium salt. Preferable amines include pyridine, 4-t-butyl pyridine, polyvinyl pyridine and the like. Examples of preferable quaternary ammonium salts include tetrabutylammonium iodide and tetrahexylammonium iodide. These may be dissolved in an organic solvent and used, or may be used as they are in the case of a liquid.

(C) Charge Transport Layer The charge transport layer contains the above-mentioned electrolyte composition of the present invention. There are two possible methods for forming the charge transport layer. One is to attach the counter electrode on the photosensitive layer first,
In this method, a liquid electrolyte composition is sandwiched in the gap.
The other method is to apply the charge transport layer directly on the photosensitive layer, and the counter electrode will be applied thereafter.

In the case of the former method, as a method for sandwiching the charge transport layer, an atmospheric pressure process utilizing a capillary phenomenon due to dipping or the like, or a vacuum process in which the gas phase in the gap is replaced with a liquid phase by making the pressure lower than atmospheric pressure. Available.

In the case of the latter method, when using a liquid electrolyte composition, a counter electrode is applied in an undried state and a liquid leakage preventing measure is taken at the edge portion. When a gel electrolyte composition is used, it may be applied by a wet method and solidified by a method such as polymerization. In that case, a counter electrode may be applied after drying and fixing.

In the case of a solid electrolyte composition or a solid hole transport material, a charge transport layer may be formed by a dry film forming process such as a vacuum deposition method or a CVD method, and then a counter electrode may be provided.
Organic hole transport materials include vacuum deposition method, casting method, coating method,
It can be introduced into the electrode by a method such as a spin coating method, a dipping method, an electrolytic polymerization method, or a photoelectrolytic polymerization method. Also in the case of an inorganic solid compound, it can be introduced into the electrode by a method such as a casting method, a coating method, a spin coating method, a dipping method, an electrolytic deposition method and an electroless plating method.

The water content in the charge transport layer is preferably 10,000 ppm or less, more preferably 2,000 ppm or less, and particularly preferably 100 ppm or less.

(D) Counter Electrode The counter electrode may have a single-layer structure of a counter electrode conductive layer made of a conductive material, or may be composed of a counter electrode conductive layer and a supporting substrate, like the above-mentioned conductive support. As the conductive material used for the counter conductive layer, metals (platinum, gold, silver, copper, aluminum, magnesium, indium, etc.), carbon, and conductive metal oxides (indium-tin composite oxide, fluorine-doped tin oxide, etc.) Is mentioned. Among these, platinum, gold,
Silver, copper, aluminum and magnesium can be preferably used. The support substrate used for the counter electrode is preferably a glass substrate or a plastic substrate, and the conductive material is applied or vapor-deposited on the support substrate. Although the thickness of the counter conductive layer is not particularly limited, it is preferably 3 nm to 10 μm. The lower the surface resistance of the counter conductive layer, the better. The preferred surface resistance range is 50Ω / □ or less, more preferably 20Ω / □.
/ □ or less.

Since light may be irradiated from either or both of the conductive support and the counter electrode, in order for light to reach the photosensitive layer, at least one of the conductive support and the counter electrode is substantially transparent. I wish I had it. From the viewpoint of improving power generation efficiency, it is preferable to make the conductive support transparent and allow light to enter from the side of the conductive support. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic deposited with a metal or a conductive oxide,
Alternatively, a thin metal film can be used.

For the counter electrode, a conductive agent is applied directly on the charge transport layer,
It may be plated or vapor-deposited (PVD, CVD), or attached to the conductive layer side of a substrate having a conductive layer. Further, as in the case of the conductive support, it is preferable to use a metal lead for the purpose of reducing the resistance of the counter electrode, especially when the counter electrode is transparent. The preferable material and installation method of the metal lead, the decrease in the amount of incident light due to the installation of the metal lead, and the like are the same as in the case of the conductive support.

(E) Other Layers In order to prevent a short circuit between the counter electrode and the conductive support, a dense semiconductor thin film layer is previously coated as an undercoat layer between the conductive support and the photosensitive layer. It is preferable. The method of preventing a short circuit by this undercoat layer is particularly effective when an electron transport material or a hole transport material is used for the charge transport layer. The subbing layer is preferably TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO or Nb ₂
It consists of O ₅ , and more preferably TiO ₂ . The undercoat layer can be applied by, for example, a spray pyrolysis method described in Electrochim. Acta, 40, 643-652 (1995), a sputtering method, or the like. The thickness of the undercoat layer is preferably 5 to 1000 nm, more preferably 10 to 500 nm.

Further, a functional layer such as a protective layer or an antireflection layer may be provided on the outer surface of one or both of the conductive support which functions as an electrode and the counter electrode, or between the conductive layer and the substrate or between the substrates. Good. For forming these functional layers, a coating method, a vapor deposition method, a sticking method or the like can be used depending on the material.

(F) Specific Example of Internal Structure of Photoelectric Conversion Element As described above, the internal structure of the photoelectric conversion element can be variously formed according to the purpose. If roughly divided into two, it is possible to have a structure in which light can enter from both sides and a structure in which light can enter from only one side. 2 to 9 exemplify the internal structure of the photoelectric conversion element which is preferably applicable to the present invention.

In the structure shown in FIG. 2, the photosensitive layer 20 and the charge transport layer 30 are interposed between the transparent conductive layer 10a and the transparent counter electrode conductive layer 40a, and light is incident from both sides. Has become. In the structure shown in FIG. 3, the metal substrate 11 is partially provided on the transparent substrate 50a, the transparent conductive layer 10a is provided thereon, and the undercoat layer 60, the photosensitive layer 20, the charge transport layer 30, and the counter electrode conductive layer 40 are arranged in this order. And the support substrate 50 is further arranged,
The structure is such that light enters from the conductive layer side. The structure shown in FIG. 4 has a conductive layer 10 on a supporting substrate 50 and an undercoat layer 60.
The photosensitive layer 20 is provided via the above, the charge transport layer 30 and the transparent counter electrode conductive layer 40a are further provided, and the transparent substrate 50a partially provided with the metal lead 11 is arranged with the metal lead 11 side inside. The structure in which light is incident from the counter electrode side. In the structure shown in FIG. 5, a metal lead 11 is partially provided on a transparent substrate 50a, and a transparent conductive layer 10a (or 40a) is further provided between a set of an undercoat layer 60, a photosensitive layer 20, and a charge transport layer 30. Is a structure in which light is incident from both sides. The structure shown in FIG. 6 includes a transparent conductive layer 10a, an undercoat layer 60, and a transparent conductive layer 10a on a transparent substrate 50a.
The photosensitive layer 20, the charge transport layer 30, and the counter electrode conductive layer 40 are provided, and the support substrate 50 is disposed on the photosensitive layer 20, and the light is incident from the conductive layer side. The structure shown in FIG. 7 has a supporting substrate 50.
Having the conductive layer 10 on the top, the photosensitive layer 20 is provided via the undercoat layer 60, further the charge transport layer 30 and the transparent counter electrode conductive layer 40a are provided,
The transparent substrate 50a is arranged on this, and the structure is such that light enters from the counter electrode side. In the structure shown in FIG. 8, the transparent conductive layer 10a is provided on the transparent substrate 50a, the photosensitive layer 20 is provided via the undercoat layer 60, and the charge transport layer 30 and the transparent counter conductive layer 40 are further provided.
a is provided, and the transparent substrate 50a is arranged on this,
The structure is such that light enters from both sides. In the structure shown in FIG. 9, the conductive layer 10 is provided on the support substrate 50, the photosensitive layer 20 is provided via the undercoat layer 60, and the solid charge transport layer 30 is further provided.
A part of the counter electrode conductive layer 40 or the metal lead 11 is provided on this, and the structure is such that light enters from the counter electrode side.

[3] Photoelectrochemical Cell The photoelectrochemical cell of the present invention is such that the photoelectric conversion element of the present invention is caused to work by an external load. Among the photoelectrochemical cells, those that mainly aim to generate electricity by sunlight are called solar cells.

The side surface of the photoelectrochemical cell is preferably sealed with a polymer, an adhesive or the like in order to prevent deterioration of the constituents and volatilization of the contents. The external circuit itself, which is connected to the conductive support and the counter electrode via the lead, may be a known one.

When the photoelectric conversion element of the present invention is applied to a solar cell, the internal structure of the cell is basically the same as the structure of the photoelectric conversion element described above. Further, the dye-sensitized solar cell using the photoelectric conversion element of the present invention can basically have the same module structure as the conventional solar cell module. In the solar cell module, cells are generally formed on a supporting substrate such as metal or ceramic, and the structure is covered with a filling resin or protective glass to take in light from the opposite side of the supporting substrate. It is also possible to use a transparent material such as tempered glass for the supporting substrate and construct a cell on the transparent material to take in light from the transparent supporting substrate side. Specifically, a module structure called super straight type, substrate type, potting type,
A substrate-integrated module structure and the like used in amorphous silicon solar cells and the like are known, and the dye-sensitized solar cell of the present invention can also be appropriately selected in accordance with the purpose of use, place of use and environment. Specifically, JP 2000-2
It is preferable to adopt the structure and embodiment described in No. 68892.

[0107]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

1. Preparation of Titanium Dioxide Dispersion Inner Volume 20 Teflon® Coated Inside
In a 0 ml stainless steel container, 15 g of titanium dioxide fine particles (“Degussa P-25” manufactured by Nippon Aerosil Co., Ltd.), 45 g of water,
1 g of dispersant ("Triton X-100" manufactured by Aldrich),
And 30 g of zirconia beads (Nikkato, diameter 0.5
mm) and was subjected to a dispersion treatment for 2 hours at 1500 rpm using a sand grinder mill (manufactured by IMEX Co., Ltd.), and zirconia beads were removed by filtration to obtain a titanium dioxide dispersion liquid. The average particle diameter of the titanium dioxide fine particles in the obtained titanium dioxide dispersion was 2.5 μm. The particle size is MALVERN
It measured using the master sizer made by the company.

2. Preparation of Dye-Sensitized TiO ₂ Electrode Substrate Conductive glass having a tin oxide layer doped with fluorine (“TCO glass-U” manufactured by Asahi Glass Co., Ltd., cut into a size of 20 mm × 20 mm) The titanium dioxide dispersion was applied to the conductive surface side having a surface resistance of about 30 Ω / □ using a glass rod. The coating amount of semiconductor fine particles was 20 g / m ² . At that time, a part of the conductive surface (3 mm from the end) was covered with an adhesive tape to form a spacer, and the glass was lined up so that the adhesive tape was at both ends, and 8 sheets were applied at a time. After application, the adhesive tape was peeled off and air dried at room temperature for 1 day. Next, this glass was put into an electric furnace (Yamato Scientific Co., Ltd. muffle furnace “FP-32 type”) and baked at 450 ° C. for 30 minutes to obtain a TiO ₂ electrode. This TiO
₂ After taking out the electrode and cooling it, an ethanol solution of dye R-1
It was immersed in (3 × 10 ⁻⁴ mol / l) for 3 hours, and further immersed in 4-t-butylpyridine for 15 minutes. This was washed with acetonitrile and air-dried to obtain a dye-sensitized TiO ₂ electrode substrate.

3. Preparation of Photoelectrochemical Cell The above-mentioned dye-sensitized TiO ₂ electrode substrate (20 mm × 20 mm) was overlaid with platinum vapor-deposited glass of the same size. Next, 20% by mass of the following electrolyte salt Y-1, 2% by mass of iodine, and 78% by mass of biscyanoethyl ether (BCE) were used to soak the electrolyte composition into the gap between the two glasses using the capillary phenomenon. Then, it was introduced into a TiO ₂ electrode and sealed with an epoxy-based sealant to prepare a photoelectrochemical cell of Comparative Example 1 having the structure shown in FIG.

Photoelectrochemical cells of Examples 1 to 20 and Comparative Examples 2 to 5 were prepared in the same manner as in the photoelectrochemical cell of Comparative Example 1 except that the electrolyte composition was changed to that shown in Table 1 below. Each was produced. However, when the viscosity of the electrolyte composition is high and it is difficult to allow the electrolyte composition to soak into the gap between the two glasses by utilizing the capillary phenomenon, the electrolyte composition is used.
It was heated to 50 ° C. and applied to a TiO ₂ electrode, which was placed under a reduced pressure to sufficiently permeate the electrolyte composition, the air in the TiO ₂ electrode was removed, and platinum evaporated glass (counter electrode) was laminated.
The structures of the electrolyte salts Y-1 to Y-3 used in each example and comparative example are shown below.

[0112]

[Table 1]

[0113]

[Chemical 16]

4. Measurement of photoelectric conversion efficiency Light from a 500 W xenon lamp (manufactured by USHIO INC.)
Simulated sunlight not containing ultraviolet rays was generated by passing through "AM1.5 filter" manufactured by iel and sharp cut filter "Kenko L-42". The intensity of this light was 70 mW / cm ² . The simulated sunlight was applied to the photoelectrochemical cells of Examples 1 to 20 and Comparative Examples 1 to 5 at 50 ° C., and the generated electricity was measured by a current-voltage measuring device “Keithley SMU238 type”. Table 2 below shows the open-circuit voltage, short-circuit current density, form factor, conversion efficiency, and reduction rate of the short-circuit current density after storage in the dark for 72 hours for each photoelectrochemical cell.

[0115]

[Table 2]

As shown in Table 2, in the photoelectrochemical cells (Comparative Examples 1 to 3 and Examples 1 to 3) using the electrolyte composition containing 30% by mass or more of an organic solvent, after storage in a dark place, Although the decrease in the short-circuit current density is remarkable, the photoelectrochemical cells of Examples 1 to 3 using the electrolyte composition of the present invention are Comparative Examples 1 to 3 using the electrolyte composition containing only the conventional imidazolium salt. It showed better conversion efficiency and storage stability than the above photoelectrochemical cell. Further, from Table 2, the solvent content of the electrolyte composition is 10% by mass in order to suppress the decrease in the short circuit current density.
It can be seen that the following is preferable. In the photoelectrochemical cells of Comparative Examples 4 and 5 using only the conventional imidazolium salt, the short-circuit current density is low, which causes the low photoelectric conversion efficiency. On the other hand, the photoelectrochemical cells of Examples 4 to 20 using the electrolyte composition of the present invention containing the quaternary salt electrolyte (I) and the iodine salt show a high short circuit current density,
Along with that, excellent conversion efficiency was obtained.

[0117]

As described in detail above, the electrolyte composition of the present invention is excellent in durability and charge transporting ability, and the photoelectric conversion device using this electrolyte composition has excellent photoelectric conversion characteristics. Little deterioration in characteristics over time. A photoelectrochemical cell comprising such a photoelectric conversion element is extremely effective as a solar cell.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a structure of a preferable photoelectric conversion element of the present invention.

FIG. 2 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

FIG. 3 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

FIG. 4 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

FIG. 5 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

FIG. 6 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

FIG. 7 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

FIG. 8 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

FIG. 9 is a partial cross-sectional view showing the structure of a preferable photoelectric conversion element of the present invention.

[Explanation of symbols]

10 ... Conductive layer 10a ... Transparent conductive layer 11 ... Metal leads 20 ... Photosensitive layer 21 ... Semiconductor fine particles 22 ... Dye 23 ... Charge transport material 30 ... Charge transport layer 40 ... Counter electrode conductive layer 40a: Transparent counter electrode conductive layer 50 ... Substrate 50a ... Transparent substrate 60 ... Undercoat layer

Claims (13)

[Claims] 1. An electrolyte composition comprising a quaternary salt electrolyte represented by the following general formula (I). [Chemical 1] In general formula (I), Q represents an atomic group forming a 5- or 6-membered aromatic cation together with a nitrogen atom, R ₁ represents a hydrogen atom or a substituent, R ₂ represents a substituent, and n 1 represents Represents an integer of 0 to 5, X ₁ represents a counter ion, and n 2 represents an integer of 0 to 4. n1
Is 2 or more, a plurality of R ₂ may be the same or different, and at least one of R ₁ and R ₂ is a substituent represented by the following general formula (II). [Chemical 2] In the general formula (II), L represents a divalent linking group that links the aromatic cation and V, V is a carboxylic acid group, a sulfonic acid group,
It represents a proton dissociation product of a phosphonic acid group or a phosphoric acid group. 2. The electrolyte composition according to claim 1, which contains the quaternary salt electrolyte and an iodine salt. 3. The electrolyte composition according to claim 1 or 2, wherein the 5- or 6-membered ring formed by Q is an imidazole ring or a pyridine ring. 4. The electrolyte composition according to claim 3, wherein the 5- or 6-membered ring formed by Q is an imidazole ring. 5. The electrolyte composition according to any one of claims 1 to 4, wherein R ₁ is a substituent represented by the general formula (II). 6. The electrolyte composition according to claim 1, wherein V is a proton dissociation product of a carboxylic acid group or a sulfonic acid group. 7. The electrolyte composition according to claim 6, wherein V is a proton dissociation product of a sulfonic acid group. 8. The electrolyte composition according to any one of claims 1 to 7, wherein the n2 is 0. 9. The electrolyte composition according to any one of claims 1 to 8, wherein the solvent content is 10% by mass or less based on the whole electrolyte composition. 10. The electrolyte composition according to claim 1, wherein the electrolyte composition contains iodine. 11. The electrolyte composition according to claim 1, which is used for a photoelectrochemical cell. 12. A photoelectric conversion device having a conductive support, a photosensitive layer, a charge transport layer and a counter electrode, wherein the charge transport layer comprises the electrolyte composition according to any one of claims 1 to 11. Photoelectric conversion element. 13. A photoelectrochemical cell comprising the photoelectric conversion element according to claim 12.