JP2011042650A - Zwitterionic organic salt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zwitterionic organic salt. <P>SOLUTION: The zwitterionic organic salt is represented by general formula (I), wherein Q represents an atomic group which forms an aromatic cation of 5- or 6-membered ring together with a nitrogen atom, R<SB>1</SB>represents a hydrogen atom or a substituent, R<SB>2</SB>represents a substituent, n1 is an integer of 0-5, X<SB>1</SB>represents a counterion, n2 is an integer of 0-4, at least one of R<SB>1</SB>and R<SB>2</SB>represents a substituent represented by general formula (II) (wherein L<SB>1</SB>represents a bivalent bonding group bonding the aromatic cation and V<SB>1</SB>, V<SB>1</SB>and V<SB>2</SB>each represent -CO-, -SO-, -SO<SB>2</SB>- or -PO(OR<SB>4</SB>)-(wherein R<SB>4</SB>represents an alkyl group or the like), and R<SB>3</SB>represents an alkoxy, alkyl, alkenyl or perfluoroalkyl group). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel Twitter ion type organic salt that can be used in an electrolyte composition having excellent durability and charge transporting ability.

  Conventionally, a liquid electrolyte composition (electrolytic 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, resulting in lack of reliability.

  Nature, Vol. 353, pp. 737-740, 1991 (Non-patent Document 1), US Pat. No. 4,927,721 (Patent Document 1), etc., used a photoelectric conversion element using semiconductor fine particles sensitized with a dye and the same. Although the photoelectrochemical cell is disclosed, since the electrolyte is used for the charge transport layer in these, the electrolyte leaks or is depleted during long-term use or storage, and the photoelectric conversion efficiency is remarkably lowered. Or may not function as an element.

  Under such circumstances, WO93 / 20565 (Patent Document 2) has proposed a photoelectric conversion element using a solid electrolyte. In addition, Journal of Chemical Society of Japan, 7, 484 (1997) (Non-patent Document 2), JP-A-7-2881142 (Patent Document 3), Solid State Ionics, 89, 263 (1986) (Non-patent Document 3) and JP No. 9-27352 (Patent Document 4) proposed a photoelectric conversion element 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.

  In addition, a method using a pyridinium salt, an imidazolium salt, a triazolium salt or the like is disclosed in order to prevent leakage and depletion of the electrolyte composition and improve the durability of the photoelectric conversion element (WO 95/18456 (Patent) Document 5), JP-A-8-259543 (Patent Document 6), Electrochemistry, Vol. 65, 11, 923 (1997) (Non-Patent Document 4)). These salts are in a molten state at room temperature (around 25 ° C.) and are called room temperature molten salts. In this method, since a solvent such as water or an organic solvent is unnecessary or a small amount is sufficient, the durability of the photoelectrochemical cell is improved. However, all of the room temperature molten salts used in conventional photoelectric conversion elements are those in which the cation and the anion are not covalently linked, and the cation and the anion can move independently. It was disadvantageous from the viewpoint. Photoelectric conversion elements using such room temperature molten salts have poor photoelectric conversion efficiency.

US Patent 4927721 WO93 / 20565 pamphlet JP 7-2881142 A JP-A-9-27352 WO 95/18456 pamphlet JP-A-8-259543

Nature, 353, 737-740, 1991 The Chemical Society of Japan, 7, 484 (1997) Solid State Ionics, 89, 263 (1986) Electrochemistry, 65, 11, 923 (1997)

  An object of the present invention is to provide a novel Twitter ion type organic salt, and further, by using these compounds, an electrolyte composition excellent in durability and charge transporting ability, and this electrolyte composition. It is to provide a photoelectric conversion element and a photoelectrochemical cell exhibiting excellent durability and photoelectric conversion characteristics because they are used.

  As a result of diligent research in view of the above object, the present inventors have found that an electrolyte composition using a Twitter ion type organic salt in combination with an iodine salt is excellent in durability and charge transporting ability, and has arrived at the present invention. .

That is, the Twitter ion type organic salt of the present invention is represented by the following general formula (I).
In the general formula (I), Q represents an atomic group that forms a 5- or 6-membered aromatic cation with a nitrogen atom, and R ₁ represents a hydrogen atom, an alkyl group, an alkenyl group, or the following general formula (II). R ₂ represents an alkoxy group, a cyano group, an alkoxycarbonyl group, a carbonate group, an amide group, a carbamoyl group, a phosphonyl group, a heterocyclic group, an aryloxy group, an alkylthio group, an acyl group, a sulfonyl group, an acyloxy group. group, a sulfonyloxy group, an aryl group, an aryloxy group, an alkenyl group, an alkyl group, or a substituted group represented by the following general formula (II), n1 represents an integer of 0 to 5, X ₁ is a counterion N2 represents an integer of 0 to 4. When 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).
In general formula (II), L ₁ represents a divalent linking group composed of an alkylene group, an arylene group, an alkyleneoxy group, an aryleneoxy group, or a combination thereof, which links the aromatic cation and V _1, and V ₁ and V ₂ each independently represent —CO—, —SO—, —SO ₂ — or —PO (OR ₄ ) — (R ₄ represents an alkyl group or an aryl group), R ₃ represents an alkoxy group, an alkyl group, An alkenyl group or a perfluoroalkyl group is represented.

  Q preferably represents an imidazole ring or a pyridine ring together with a nitrogen atom.

It is preferable that at least one of V ₁ and V ₂ is —SO ₂ —.

In the present invention, a novel imidazolium organic salt represented by the following general formula (III) can be suitably used as a Twitter ion type organic salt.
In the general formula (III), R ₁₁ and R ₂₁ represent a hydrogen atom, an alkyl group, an alkenyl group, or a substituent represented by the following general formula (IV), R _{22 to} R ₂₄ are each independently a hydrogen atom, Alkoxy group, cyano group, alkoxycarbonyl group, carbonate group, amide group, carbamoyl group, phosphonyl group, heterocyclic group, aryloxy group, alkylthio group, acyl group, sulfonyl group, acyloxy group, sulfonyloxy group, aryl group, aryl It represents an oxy group, an alkenyl group, an alkyl group, or a substituent represented by the following general formula (IV), X ₁₁ represents a counter ion, and n 21 represents an integer of 0 to 4. R ₁₁ and R _{21 to} R ₂₄ may be the same or different, and at least one of R ₁₁ and R _{21 to} R ₂₄ is a substituent represented by the following general formula (IV).
In the general formula (IV), L ₁₁ is an alkylene group, an arylene group, an alkyleneoxy group, an aryleneoxy group, or a combination thereof that links the imidazolium cation in the general formula (III) and V ₁₁ 2 V ₁₁ and V ₂₁ represent —SO ₂ —, and R ₃₁ represents an alkoxy group, an alkyl group, an alkenyl group, or a perfluoroalkyl group.

  N21 is preferably 0.

R _{21 to} R ₂₄ are preferably each independently a hydrogen atom or a substituent represented by the general formula (IV).

  The electrolyte composition using the Twitter ion type organic salt of the present invention is excellent in durability and charge transporting ability, and the photoelectric conversion element using this electrolyte composition has excellent photoelectric conversion characteristics and characteristics over time. There is little deterioration. A photoelectrochemical cell comprising such a photoelectric conversion element is extremely effective as a solar cell.

It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element. It is a fragmentary sectional view which shows the structure of a photoelectric conversion element.

[1] Electrolyte Composition The electrolyte composition contains the Twitter ion type organic salt and iodine salt of the present invention, and may further contain iodine, a solvent, or the like. When the Twitter ion type organic salt is an iodine salt, the electrolyte composition does not need to contain another iodine salt. The electrolyte composition can be used for a chemical reaction, a reaction solvent such as metal plating, a CCD (charge coupled device) camera, various photoelectric conversion elements and batteries, and preferably used for a lithium secondary battery or a photoelectrochemical battery. More preferably, it is used for a photoelectrochemical cell using a semiconductor. Hereinafter, each component of the electrolyte composition will be described in detail.

(A) Twitter ion type organic salt The twitter ion type organic salt of the present invention is an organic compound having a part having a cationic charge and a part having an anion charge in one molecule, and both parts are linked by a covalent bond. It is. The Twitter ion type organic salt used in the electrolyte composition is preferably liquid at room temperature (around 25 ° C.).

The Twitter ion organic salt is preferably represented by the following general formula (I). Hereinafter, the Twitter ion type organic salt represented by the general formula (I) is referred to as “organic salt (I)” in the present application. The organic salt (I) is usually a low melting point salt, so-called molten salt. The melting point of the organic salt (I) is preferably 100 ° C. or less, more preferably 80 ° C. or less, and particularly preferably 60 ° C. or less. The organic salt (I) may be a molten salt that is liquid at room temperature (around 25 ° C.), that is, a so-called room temperature molten salt.

  In many cases, the mixture of the organic salt (I) and the iodine salt can be used as an electrolyte composition with almost no solvent, and there is no need to use a solvent. When this mixture is solid at room temperature (around 25 ° C.), it can be used as a liquid electrolyte composition by adding a solvent, an additive, or the like. Also, without adding anything, a method of dissolving by heating and permeating on the electrode, a method of permeating on 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 in a photoelectric conversion element by such as.

  In general formula (I), Q represents an atomic group that forms a 5- or 6-membered aromatic cation with a nitrogen atom. Q is preferably composed of one or more atoms 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 an oxazole ring, thiazole ring or imidazole 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. Of these, the 5- or 6-membered ring formed by Q together with the nitrogen atom is most preferably an imidazole ring.

In general formula (I), R ₁ represents a hydrogen atom or a substituent, and R ₂ represents a substituent. N1 indicating 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 connected 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 the general formula (II) is referred to as “substituent (II)”. The organic salt (I) preferably has 1 to 4 substituents (II), more preferably one. In particular, R ₁ is preferably a substituent (II).

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

In general formula (II), V ₁ and V ₂ each independently represent —CO—, —SO—, —SO ₂ — or —PO (OR ₄ ) —. Here, R ₄ represents an alkyl group or an aryl group. At least one of V ₁ and V ₂ is -SO ₂ - is preferably from both -SO ₂ - and more preferably is.

In the general formula (II), R ₃ represents a substituent, preferably an alkoxy group (methoxy group, ethoxy group, etc.), an alkyl group (preferably having 1 to 80 carbon atoms, such as a methyl group, an 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.) An alkenyl group (preferably having 2 to 80 carbon atoms, such as a vinyl group, an allyl group) or a perfluoroalkyl group, more preferably an alkyl group having 3 to 60 carbon atoms or 2 to 60 carbon atoms. And particularly preferably an alkyl group having 3 to 48 carbon atoms.

When R ₁ in the general formula (I) represents a substituent other than the above substituent (II), it is preferably an alkyl group (preferably having 1 to 80 carbon atoms, for example, a methyl group, an ethylpropyl group, a 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, such as vinyl group, allyl group, etc.), more preferably an alkyl group having 3 to 60 carbon atoms or an alkenyl group having 2 to 60 carbon atoms, especially An alkyl group having 3 to 48 carbon atoms is preferable. R ₁ may further have a substituent, and examples of the substituent include the same examples as the preferable substituent represented by R ₂ described later.

When R ₂ in the general formula (I) represents a substituent other than the above-described substituent (II), examples of preferred substituents include an alkoxy group (methoxy group, ethoxy group, — (OCH ₂ CH ₂ ) _n — OCH ₃ (n is an integer from 1 to 20), — (OCH ₂ CH ₂ ) _n —OCH ₂ CH ₃ (n is an integer from 1 to 20), etc., cyano group, alkoxycarbonyl group (ethoxycarbonyl group, methoxyethoxy) Carbonyl group etc.), carbonate 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.), aryloxy group (phenoxy 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 groups (phenyl, toluyl, etc.), aryloxy groups (phenoxy, etc.), alkenyl groups (vinyl, 1-propenyl, etc.), alkyl groups (methyl, ethyl, propyl, isopropyl, cyclo Propyl group, butyl group, 2-carboxyethyl group, benzyl group, etc.). Among them, an alkoxy group, a cyano group, a carbonate 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 n2 representing the number of X ₁ represents an integer of 0 to 4. n2 is selected so that the overall charge of the organic salt (I) is neutralized. That is, the counter ion X ₁ is necessary when the portion of the organic salt (I) other than X ₁ becomes a cation or an anion or has a net ionic charge depending on the nature of the substituent of the organic salt (I). It becomes. Also, when the organic salt (I) has a dissociable group that can have a negative charge, the charge of the entire organic salt (I) is neutralized by X ₁ . When X ₁ is a cation, examples thereof include inorganic or organic ammonium ions (tetraalkyl ammonium ions, pyridinium ions, etc.), alkali metal ions, and the like. When X ₁ is an anion, it may be an inorganic anion or an organic anion. Examples thereof include a halogen anion (fluoride ion, chloride ion, bromide ion, iodide ion, etc.), Substituted aryl sulfonate ions (p-toluene sulfonate ion, p-chlorobenzene sulfonate ion, etc.), aryl disulfonate ions (1,3-benzene disulfonate ion, 1,5-naphthalenedisulfonate ion, 2,6-naphthalene ion) 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 And ions. X ₁ may be a charge balanced counter ion such as an ionic polymer, or may be a metal complex ion (such as bisbenzene-1,2-dithiolatonickel (III)). In the present invention, it is preferred that n2 is 0 organic salt (I) does not have a X _1. That is, it is preferable that the organic salt (I) does not contain a counter ion that is not linked by a covalent bond.

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

In the present invention, a novel imidazolium organic salt represented by the following general formula (III) can be suitably used as the organic salt (I). Hereinafter, the imidazolium organic salt represented by the general formula (III) is referred to as “compound (III)”.

In the general formula (III), R ₁₁ and R _{21 to} R ₂₄ each independently represent a hydrogen atom or a substituent. R ₁₁ and R _{21 to} R ₂₄ may be the same or different. R ₁₁ and R _{21 to} R ₂₄ may be connected to each other to form a ring.

At least one of R ₁₁ and R _{21 to} R ₂₄ is a substituent represented by the following general formula (IV). Hereinafter, the substituent represented by the general formula (IV) is referred to as “substituent (IV)”. Compound (III) preferably has 1 to 4 substituents (IV), and more preferably 1 substituent. In particular, it is preferable that at least one of R ₁₁ and R ₂₁ is the substituent (IV).

In the general formula (IV), L ₁₁ represents a divalent linking group that links the imidazolium cation in the general formula (III) to V ₁₁ . Preferred embodiments and specific examples of L ₁₁ are the same as those of L _{1 in} the general formula (II). V ₁₁ and V ₂₁ both represent —SO ₂ —, R ₃₁ has the same meaning as R ₃ in the general formula (II), and the preferred embodiment is also the same.

When R ₁₁ and R ₂₁ in the general formula (III) represent a substituent other than the above substituent (IV), preferred embodiments thereof are the same as those for R _{1 in} the above general formula (I). Further, when R ₂₂ to R ₂₄ represents a substituent other than the substituent (IV), preferred embodiments thereof are the same as in the case of R ₂ in the general formula (I). X ₁₁ represents a counter ion, n21 indicating the number of X ₁₁ represents an integer of 0-4. X ₁₁ and n 21 have the same meanings as X ₁ and n 2 in the general formula (I), respectively, and preferred embodiments are also the same.

Compound (III) may form a multimer via any of R ₁₁ and R _{21 to} R ₂₄ . This multimer is preferably a dimer to tetramer, and more preferably a dimer.

  The content of the Twitter ion type organic salt in the electrolyte composition is preferably 10% by mass or more, and more preferably 20 to 95% by mass with respect to the entire electrolyte composition. Specific examples of the Twitter ion type organic salt are shown below, but the present invention is not limited thereto.

(B) Iodine salt The electrolyte composition contains a Twitter ion type organic salt and an iodine salt. When the above-mentioned Twitter ion type organic salt is not an iodine salt, it is necessary to add another iodine salt to the electrolyte composition. Examples of such iodine salts include pyridinium salts, imidazolium salts, triazolium salts described in WO 95/18456, JP-A-8-259543, Electrochemistry, 65, 11, 923 (1997), etc. Etc. can be used. The electrolyte composition may contain a salt other than the above-described Twitter ion type organic salt and iodine salt. The iodine salt content of the electrolyte composition is preferably 10% by mass or more, and more preferably 50 to 95% by mass with respect to the whole electrolyte composition.

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

Q _y1 in the general formula (Ya) represents an atomic group that forms a 5- or 6-membered aromatic cation with a nitrogen atom. Q _y1 is preferably composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom and a sulfur atom. The 5-membered ring formed by Q _y1 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. More preferably, it is particularly preferably an oxazole ring or an imidazole ring. The 6-membered ring formed by Q _y1 is preferably a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring or 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 _y11 in the general formulas (Ya), (Yb) and (Yc) are each independently a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, It may be branched or cyclic, for example, methyl group, ethyl group, propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-octyl group, decyl group , A dodecyl group, a tetradecyl group, a 2-hexyldecyl group, an octadecyl group, a cyclohexyl group, a cyclopentyl group, or the like, or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms, being linear May be branched, for example, vinyl group, allyl group, etc.). R _{y1 to} R _y11 are each independently 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 connected to each other to form a non-aromatic ring containing A _y1, and R _{y6 to} R _{y11 in} the general formula (Yc) Two or more of them may be connected to each other to form a ring.

Q _y1 and R _{y1 to} R _y11 may have a substituent. Examples of preferred substituents include halogen atoms (F, Cl, Br, I, etc.), cyano groups, alkoxy groups (methoxy groups, ethoxy groups, etc.), aryloxy groups (phenoxy groups, etc.), alkylthio groups (methylthio groups, ethylthio groups). Group), alkoxycarbonyl group (ethoxycarbonyl group etc.), carbonic acid 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) ), Carbamoyl group (N, N-dimethylcarbamoy) Group), 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.), complex Examples thereof include a ring group (pyridyl group, imidazolyl group, furanyl group, etc.), an alkenyl group (vinyl group, 1-propenyl group, etc.) and the like.

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

(C) Iodine The electrolyte composition preferably contains iodine. In particular, when this electrolyte composition is used for a photoelectric conversion element, the effect of adding iodine is great. The iodine added to the electrolyte composition may exist as I _{2 in the} composition, or may exist in an ionic state or a salt-formed state. When iodine is added to the electrolyte composition, the content of iodine is preferably 0.1 to 20% by mass, more preferably 0.5 to 5% by mass with respect to the entire electrolyte composition.

(D) Solvent The electrolyte composition 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 with respect to the entire electrolyte composition.

  The solvent used in the electrolyte composition is one that can exhibit excellent ionic conductivity because it has a low viscosity and high ion mobility, or has a high dielectric constant and can increase the effective carrier concentration, or both. Preferably there is. 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) Ethers), polyhydric alcohols (ethylene glycol, propylene glycol, polyethylene glycol) Coal, polypropylene glycol, glycerin, etc.), nitrile compounds (acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, benzonitrile, biscyanoethyl ether, etc.), esters (carboxylic esters, phosphates, phosphonates, etc.) , Aprotic polar solvents (dimethyl sulfoxide (DMSO), sulfolane, etc.), water and the like. These solvents may be used as a mixture of two or more.

(E) Others The electrolyte composition can be used after being gelled (solidified) by a technique such as addition of a polymer, addition of an oil gelling agent, polymerization including polyfunctional monomers, or a crosslinking reaction of the polymer.

  In the case of gelation by addition of polymer, polymers described in Polymer Electrolyte Reviews-1 and 2 (JR MacCallum and CA Vincent, ELSEVIER APPLIED SCIENCE) can be used, preferably polyacrylonitrile or polyvinylidene fluoride is used. To do.

  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. Chem Soc., Chem. Commun., 390 (1993), Angew. Chem. Int. Ed. Engl., 35, 1949 (1996), Chem. Lett., 885, (1996), J. Chem. Soc., The oil gelling agent described in Chem. Commun., 545, (1997) can be used, and a compound having an amide structure is preferably used.

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

  You may form a gel electrolyte composition by superposition | polymerization using the said 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-butylacrylamide, N, N -Dimethylacrylamide, N-methylmethacrylamide, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, acrylamidopropyltrimethylammonium chloride, methacrylamide, diacetone acrylamide, N-methylolacrylamide, N-methylolmethacrylamide, methyl acrylate, Ethyl acrylate, hydroxyethyl 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, ethyl carbitol 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, heptadecafluorodec 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, heptadecafluorodecyl methacrylate, n-octadecyl methacrylate, 2- Isobornyl methacrylate, 2-norbornylmethyl methacrylate, 5-norbornyl N-2-ylmethyl methacrylate, 3-methyl-2-norbornylmethyl methacrylate, dimethylaminoethyl methacrylate, etc.), vinyl esters (vinyl acetate, etc.), maleic acid or fumaric acid or esters derived therefrom (maleic acid) Dimethyl acid, dibutyl maleate, diethyl fumarate, etc.), sodium salt of p-styrenesulfonic acid, acrylonitrile, methacrylonitrile, dienes (butadiene, cyclopentadiene, isoprene, etc.), aromatic vinyl compounds (styrene, p-chloro) Styrene, t-butylstyrene, α-methylstyrene, sodium styrenesulfonate, etc.), N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, vinylsulfonic acid , Sodium vinyl sulfonate, Sodium Rusuruhon acid, sodium methacrylate sulfonate, vinylidene fluoride, vinylidene chloride, vinyl alkyl ethers (methyl vinyl ether), ethylene, propylene, 1-butene, isobutene, can be used N- phenylmaleimide and the like.

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

  The above-mentioned polyfunctional monomers and monofunctional monomers can be obtained from Takayuki Otsu and Masaaki Kinoshita "Experimental Methods for Polymer Synthesis" (Chemical Doujin) and Takayuki Otsu "Corporation Polymerization Reaction Theory 1 Radical Polymerization (I)" (Chemical Doujin) It can superpose | polymerize by radical polymerization which is the general polymer synthesis method as described in 1 above. The monomer can be radically polymerized by heating, light or electron beam, or electrochemically, and it is particularly preferable to radically polymerize by heating. In radical polymerization, a polymerization initiator may be used. Examples of preferable polymerization initiators include 2,2'-azobisisobutyronitrile and 2,2'-azobis (2,4-dimethylvaleronitrile). Azo initiators such as dimethyl-2,2'-azobis (2-methylpropionate), dimethyl-2,2'-azobisisobutyrate, lauryl peroxide, benzoyl peroxide, t-butylperoct And peroxide-based initiators such as ate. The addition amount of the polymerization initiator is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass with respect to the total amount of monomers.

  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 a polymer crosslinking reaction, it is preferable to use a polymer containing a crosslinkable reactive group and a crosslinking agent in combination. In this case, the reactive group is preferably a nitrogen-containing heterocyclic ring such as a pyridine ring, imidazole ring, thiazole ring, oxazole ring, triazole ring, morpholine ring, piperidine ring, piperazine ring, and the crosslinking agent preferably has a nitrogen atom. A compound (electrophile) having two or more functional groups capable of nuclear attack. For example, bifunctional or higher alkyl halides, halogenated aralkyls, sulfonic acid esters, acid anhydrides, acid chlorides, isocyanates and the like can be used.

The electrolyte composition, the metal iodide (LiI, NaI, KI, CsI , CaI 2 , etc.), a metal bromide (LiBr, NaBr, KBr, CsBr , CaBr 2 , etc.), quaternary ammonium bromine salt (tetraalkylammonium bromide, pyridinium Bromide, etc.), metal complexes (ferrocyanate-ferricyanate, ferrocene-ferricinium ion, etc.), sulfur compounds (sodium polysulfide, alkylthiol-alkyl disulfide, etc.), viologen dyes, hydroquinone-quinone, etc. It may be. These may be used as a mixture.

  Further, the electrolyte composition is a basic compound such as t-butylpyridine, 2-picoline, 2,6-lutidine and the like described in J. Am. Ceram. Soc., 80, (12), 3157-3171 (1997). It may contain. The concentration of the basic compound in the electrolyte composition is preferably 0.05 to 2M.

[2] Photoelectric conversion element The photoelectric conversion element has a conductive layer, a photosensitive layer, a charge transport layer and a counter electrode, and the charge transport layer contains the above-described electrolyte composition.

  As shown in FIG. 1, the photoelectric conversion element is preferably formed by laminating a conductive layer 10, an undercoat layer 60, a photosensitive layer 20, a charge transport layer 30, and a counter electrode conductive layer 40 in this order. It is composed of the sensed semiconductor fine particles 21 and the charge transport material 23 that has penetrated into the gaps between the semiconductor fine particles 21. Usually, the charge transport material 23 is composed of the same components as the electrolyte composition used for the charge transport layer 30. Further, a substrate 50 may be provided as a base for the conductive layer 10 and / or the counter electrode conductive layer 40 in order to impart strength to the photoelectric conversion element. In the present application, the layer composed of the conductive layer 10 and the optionally provided substrate 50 is referred to as “conductive support”, and the layer composed of the counter electrode conductive layer 40 and the optionally provided substrate 50 is referred to as “counter electrode”. Note that the conductive layer 10, the counter electrode conductive layer 40, and the substrate 50 in FIG. 1 may be the transparent conductive layer 10a, the transparent counter electrode conductive layer 40a, and the transparent substrate 50a, respectively.

  In the photoelectric conversion element shown in FIG. 1, when the semiconductor fine particles are n-type, the light incident on the photosensitive layer 20 including the semiconductor fine particles 21 sensitized by the dye 22 excites the dye 22 and the like, and the excited dye 22 High-energy electrons in the same are passed to the conduction band of the semiconductor fine particles 21, and further reach the conductive layer 10 by diffusion. At this time, the molecule such as the dye 22 is an oxidant. In the photoelectrochemical cell, electrons in the conductive layer 10 return to an oxidant such as the dye 22 through the counter electrode conductive layer 40 and the charge transport layer 30 while working in an external circuit, and the dye 22 is regenerated. The photosensitive layer 20 functions as a negative electrode (photoanode), and the counter electrode 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 electrode conductive layer 40, etc.) 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 maintain sufficient strength and sealability as the conductive layer, for example, a metal material (platinum, gold, silver, copper, zinc, titanium, aluminum, an alloy containing these, etc.) Can be used. In the case of (2), a substrate having a conductive layer containing a conductive agent on the photosensitive layer side can be used. Preferred conductive agents include metals (platinum, gold, silver, copper, zinc, titanium, aluminum, indium, alloys containing these), carbon, and conductive metal oxides (indium-tin composite oxides, fluorine in tin oxide) Or those doped with antimony). 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 range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less.

  When irradiating light from the conductive support side, the conductive support is preferably substantially transparent. The term “substantially transparent” means that the transmittance is 10% or more in a part or all of the light in the visible to near infrared region (400 to 1200 nm), preferably 50% or more, 80% or more is more preferable. In particular, it is preferable that the transmittance in a wavelength region where the photosensitive layer is sensitive is high.

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

  It is preferable to use a metal lead for the purpose of reducing 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 preferably installed on a transparent substrate by vapor deposition, sputtering or the like, and a transparent conductive layer made of conductive tin oxide, ITO film or the like is preferably provided thereon. The decrease in the amount of incident light due to the installation of the metal lead is preferably within 10%, more preferably 1 to 5%.

(B) Photosensitive layer The photosensitive layer preferably contains semiconductor fine particles sensitized with a dye. In the photosensitive layer, the semiconductor acts as a photoconductor, absorbs light, separates charges, and generates electrons and holes. In a dye-sensitized semiconductor, light absorption and generation of electrons and holes thereby occur mainly in the dye, and the semiconductor fine particles receive and transmit these electrons (or holes). The semiconductor is preferably an n-type semiconductor that gives an anode current when conductor electrons become carriers under photoexcitation.

(1) Semiconductors Semiconductors include simple semiconductors such as silicon and germanium, III-V group compound semiconductors, metal chalcogenides (oxides, sulfides, selenides, composites thereof, etc.), compounds having a perovskite structure (Strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) can be used.

Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxide, cadmium, zinc, lead, silver, antimony or bismuth. Sulfides, cadmium or lead selenides, cadmium tellurides and the like. 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, O is oxygen, and x, y and z are the number of combinations whose valence is neutral) Such composites can also be preferably used.

Semiconductor preferred embodiment _{is, Si, TiO 2, SnO 2} , Fe 2 O 3, WO 3, ZnO, Nb 2 O 5, CdS, ZnS, PbS, Bi 2 S 3, CdSe, CdTe, SrTiO 3, GaP, InP, GaAs, a CuInS _2, CuInSe _2, etc., more preferably _{TiO 2, ZnO, SnO 2,} Fe 2 O 3, WO 3, Nb 2 O 5, CdS, PbS, CdSe, SrTiO 3, InP, GaAs, CuInS ₂ or CuInSe ₂ , particularly preferably TiO ₂ or Nb ₂ O ₅ , and most preferably TiO ₂ . Preferably TiO ₂ containing anatase 70% among TiO _2, particularly preferably TiO ₂ 100% anatase. It is also effective to dope metals for the purpose of increasing the electronic conductivity in these semiconductors. As a metal to dope, a bivalent or trivalent metal is preferable. In order to prevent a reverse current from flowing from the semiconductor to the charge transport layer, it is also effective to dope the semiconductor with a monovalent metal.

  The semiconductor may be single crystal or polycrystal, but polycrystal is preferable from the viewpoint of manufacturing cost, securing raw materials, energy payback time, etc., and a porous film made of semiconductor fine particles is particularly preferable. Moreover, a part amorphous part 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 into a circle is preferably 5 to 200 nm, more preferably 8 to 100 nm. preferable. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 30 μm. Two or more kinds of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is preferably 25 nm or less, more preferably 10 nm or less. In order to improve the light capture rate by scattering incident light, it is also preferable to mix semiconductor particles having a large particle size, for example, about 100 to 300 nm.

Two or more different types of semiconductor fine particles 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 . More preferable combinations include ZnO and SnO ₂ , ZnO and WO ₃ , ZnO, SnO ₂ and WO _{3, and the} like. When two or more kinds of semiconductor fine particles are mixed and used, their particle sizes may be different. Particularly preferred is a combination in which the particle size of TiO ₂ , ZnO, Nb ₂ O ₅ or SrTiO ₃ is large and SnO ₂ , Fe ₂ O ₃ or WO ₃ is small. Preferably, the large particle size is 100 nm or more, and the small particle size is 15 nm or less.

  Semiconductor fine particles are prepared by Sakuo Sakuo's "Sol-gel Method Science" Agne Jofusha (1998), Technical Information Association "Sol-gel Method Thin Film Coating Technology" (1995), etc. The described sol-gel method and Tadao Sugimoto's "Synthesis and size control of monodisperse particles by the new synthetic gel-sol method", Materia, Vol. 35, No. 9, pp. 1012-1018 (1996) Etc.) is preferred. In addition, a method developed by Degussa for producing an oxide by high-temperature hydrolysis of a chloride in an oxyhydrogen salt can be preferably used.

  When the semiconductor fine particles are titanium oxide, the sol-gel method, gel-sol method, and high-temperature hydrolysis method in oxyhydrogen salt of chloride are all preferred, but Kiyoshi Manabu's “Titanium oxide properties and applied technology” The sulfuric acid method or the chlorine method described in Gihodo Publishing (1997) can also be used. Further, as a sol-gel method, the method described in Journal of American Ceramic Society of Barbe et al., Vol. 80, No. 12, pp. 3157-3171 (1997), or the chemistry of Burnside et al. , Vol. 10, No. 9, pages 2419-2425 are also preferred.

(2) Semiconductor fine particle layer In order to apply semiconductor fine particles on a conductive support, in addition to the method of applying a dispersion or colloidal solution of semiconductor fine particles on a conductive support, the sol-gel method described above is used. It can also be used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of conductive support, etc., a wet film forming method is relatively advantageous. Typical examples of the wet film forming method include a coating method, a printing method, an electrolytic deposition method, and an electrodeposition method. Also, a method of oxidizing metal, a method of depositing in a liquid phase from a metal solution by ligand exchange (LPD method), a method of vapor deposition by sputtering, a CVD method, or a metal that is thermally decomposed on a heated substrate An SPD method in which a metal oxide is formed by spraying an oxide precursor can also be used.

  In addition to the sol-gel method described above, a method for preparing a dispersion of semiconductor fine particles includes a method of grinding in a mortar, a method of dispersing while pulverizing using a mill, and fine particles in a solvent when synthesizing a semiconductor. The method of depositing and using as it is is mentioned.

  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, carboxymethyl cellulose, a surfactant, an acid, a chelating agent, or the like may be used as a dispersion aid as necessary. By changing the molecular weight of the polyethylene glycol, the viscosity of the dispersion can be adjusted, and a semiconductor layer that does not easily peel off can be formed and the porosity of the semiconductor layer can be controlled. Therefore, it is preferable to add polyethylene glycol.

  Application methods such as roller method and dip method as application system, air knife method and blade method as metering system, and application and metering are disclosed in Japanese Examined Patent Publication No. 58-4589. The wire bar method, the slide hopper method, the extrusion method, the curtain method and the like described in US Pat. Nos. 2681294, 2761419, 2761791 and the like are preferable. Moreover, a spin method and a spray method are also preferable as a general purpose machine. As the wet printing method, intaglio, rubber plate, screen printing and the like are preferred, including the three major printing methods of letterpress, offset and gravure. A film forming method may be selected from these according to the liquid viscosity and the wet thickness.

  The semiconductor fine particle layer is not limited to a single layer, and a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters, or a multi-layer coating of a coating layer containing different types of semiconductor fine particles (or different binders and additives) You can also Multi-layer coating is also effective when the film thickness is insufficient with a single coating.

In general, as the semiconductor fine particle layer thickness (same as the photosensitive layer thickness) increases, the amount of supported dye increases per unit projected area and thus the light capture rate increases. Loss due to coupling also increases. 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 more preferably 2 to 25 μm. The coating amount of 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 applied on the conductive support, the semiconductor fine particles are preferably brought into contact with each other electronically, and heat treatment is preferably performed in order to improve the coating strength and the adhesion to the support. A preferable heating temperature range is 40 ° C. or more and 700 ° C. or less, and more preferably 100 ° C. or more and 600 ° C. or less. The heating time is about 10 minutes to 10 hours. When using a support having a low melting point or softening point such as a polymer film, high temperature treatment is not preferable because it causes deterioration of the support. Moreover, it is preferable that it is as low temperature as possible (for example, 50 to 350 degreeC) also from a viewpoint of cost. The temperature can be lowered by heat treatment in the presence of small semiconductor particles of 5 nm or less, mineral acids, and metal oxide precursors, and by applying ultraviolet rays, infrared rays, microwaves, etc., electric fields, and ultrasonic waves. It can also be done. At the same time, for the purpose of removing unnecessary organic substances and the like, it is preferable to use a combination of irradiation, application, heating, decompression, oxygen plasma treatment, pure water cleaning, solvent cleaning, gas cleaning and the like in combination as appropriate.

  After the heat treatment, for example, chemical plating using titanium tetrachloride aqueous solution or titanium trichloride to increase the surface area of the semiconductor fine particles, increase the purity in the vicinity of the semiconductor fine particles, and increase the efficiency of electron injection from the dye into the semiconductor fine particles. You may perform the electrochemical plating process using aqueous solution. In order to prevent a reverse current from flowing from the semiconductor fine particles to the charge transport layer, it is also effective to adsorb an organic substance having a low electron conductivity other than the dye on the particle surface. 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 a large amount of dye can be adsorbed. The surface area of the semiconductor fine particle layer 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.

(3) Dye The sensitizing dye used in the photosensitive layer can be arbitrarily used as long as it is a compound that has absorption in the visible region and near infrared region and can sensitize semiconductors, but metal complex dyes, methine dyes, porphyrins Dyes and phthalocyanine dyes are preferred, and metal complex dyes are particularly preferred. In addition, two or more kinds of dyes can be used in combination or mixed in order to widen the wavelength range of photoelectric conversion as much as possible and increase the conversion efficiency. In this case, it is possible to select the dye to be used or mixed and the ratio thereof so as to match the wavelength range and intensity distribution of the target light source.

Such a dye preferably has an appropriate interlocking group capable of adsorbing to the surface of the semiconductor fine particles. Preferred linking groups include -COOH groups, -OH groups, -SO ₃ H groups, acidic groups such as -P (O) (OH) ₂ groups and -OP (O) (OH) ₂ groups, and oximes, Examples include chelating groups having π conductivity such as dioxime, hydroxyquinoline, salicylate and α-ketoenolate. Among them, -COOH group, -P (O) (OH) ₂ group and -OP (O) (OH) ₂ group are particularly preferable. These groups may form a salt with an alkali metal or the like, or may form an internal salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case where the methine chain forms a squarylium ring or a croconium ring, this part may be used as a linking group.

Hereinafter, preferred sensitizing dyes used in the photosensitive layer will be specifically described.
(a) Metal Complex Dye When the dye is a metal complex dye, a metal phthalocyanine dye, a metal porphyrin dye, or a ruthenium complex dye is preferable, and a ruthenium complex dye is particularly preferable. Examples of the ruthenium complex dye include, for example, U.S. Pat.Nos. 4,972,721, 4,684,537, 5,844,365, 5,350,644, 5,630,57, 5,525,440, JP-A-7-249790, JP-T-10-504512, WO 98 / And complex dyes described in JP 50393 and JP 2000-26487 A.

Furthermore, ruthenium complex dyes have the following general formula (V):
(A ₁ ) _p Ru (Ba) (Bb) (Bc) (V)
Is preferably represented by: In general formula (V), A ₁ represents a mono- or bidentate ligand, preferably Cl, SCN, H ₂ O, Br, I, CN, NCO, SeCN, β-diketone derivative, oxalic acid derivative and It is a ligand selected from the group consisting of dithiocarbamic acid derivatives. p is an integer of 0-3. Ba, Bb and Bc each independently represents an organic ligand represented by any one of the following formulas B-1 to B-10.

In formulas B-1 to B-10, R ₅ represents a hydrogen atom or a substituent. Examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, and 7 carbon atoms. A substituted or unsubstituted aralkyl group of -12, a substituted or unsubstituted aryl group of 6 to 12 carbon atoms, the aforementioned acidic groups (these acidic groups may form a salt) and a chelating group Can be mentioned. Here, the alkyl part of the alkyl group and the aralkyl group may be linear or branched, and the aryl part of the aryl group and the aralkyl group may be monocyclic or polycyclic (fused ring, ring assembly). Ba, Bb and Bc may be the same or different, and may be any one or two.

  Although the preferable specific example of a metal complex dye is shown below, it is not limited to these.

(b) Methine dyes Preferred methine dyes are polymethine dyes such as cyanine dyes, merocyanine dyes and squarylium dyes. Examples of polymethine dyes preferably used include JP-A-11-35836, JP-A-11-67285, JP-A-11-86916, JP-A-11-97725, JP-A-11-158395, and JP-A-11-163378. , JP-A-11-214730, JP-A-11-214731, JP-A-11-238905, JP-A-2000-26487, European Patents 892411, 918441 and 991092 Is mentioned. Specific examples of preferred methine dyes are shown below.

(4) Adsorption of dye to semiconductor fine particles Adsorption of dye to semiconductor fine particle film is performed by immersing a conductive support having a well-dried semiconductor fine particle layer in a dye solution, or by applying a dye solution to the semiconductor fine particle layer. A coating method can be used. In the former case, an immersion method, a dip method, a roller method, an air knife method or the like can be used. In the case of the immersion method, the adsorption of the dye may be performed at room temperature or may be performed by heating and refluxing as described in JP-A-7-249790. Examples of the latter application method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method. In addition, a dye can be applied in an image form by an inkjet method or the like, and the image itself can be used as a photoelectric conversion element. Preferred examples of the solvent for dissolving the dye include alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated carbonization. Hydrogen (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, butyl acetate, etc.), carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butanone, Cyclohexanone, etc.), carbonized water Examples thereof include hexane, petroleum ether, benzene, toluene and the like, and mixed solvents thereof.

The total amount of dye adsorbed is preferably 0.01 to 100 mmol per unit area (1 m ² ) of the porous semiconductor electrode substrate. The amount of the dye adsorbed on the semiconductor fine particles is preferably in the range of 0.01 to 1 mmol per 1 g of the semiconductor fine particles. By using such an amount of dye adsorbed, a sensitizing effect in a semiconductor can be sufficiently obtained. On the other hand, if the amount of the dye is too small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not attached to the semiconductor floats, which causes a reduction in the sensitizing effect. In order to increase the adsorption amount of the dye, it is preferable to perform a heat treatment before the adsorption. In order to avoid water adsorbing on the surface of the semiconductor fine particles after the heat treatment, it is preferable to quickly perform the dye adsorption operation at a temperature of the semiconductor electrode substrate of 60 to 150 ° C. without returning to normal temperature.

For the purpose of reducing interaction such as aggregation between the dyes, a colorless compound may be added to the dyes and co-adsorbed on the semiconductor fine particles. Compounds effective for this purpose are compounds having surface active properties and structures, and examples thereof include steroid compounds having a carboxyl group (for example, chenodeoxycholic acid) and sulfonates such as the following examples.

  The unadsorbed dye is preferably removed by washing immediately after adsorption. It is preferable to use a wet cleaning tank and perform cleaning 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 salt. Preferable amines include pyridine, 4-t-butylpyridine, polyvinylpyridine and the like, and preferable quaternary salts include tetrobutylammonium iodide, tetrahexylammonium iodide and the like. When these are liquids, they may be used as they are, or may be used after being dissolved in an organic solvent.

(C) Charge transport layer The charge transport layer contains the above electrolyte composition. There are two possible methods for forming the charge transport layer. One is a method in which a counter electrode is first bonded onto the photosensitive layer, and a liquid charge transport layer is sandwiched between the gaps. The other is a method in which a charge transport layer is provided directly on the photosensitive layer, and a counter electrode is subsequently provided.

  In the case of the former method, as a method for sandwiching the charge transport layer, a normal pressure process using 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 at a pressure lower than normal pressure can be used.

  In the case of the latter method, the wet charge transporting layer is provided with a counter electrode without being dried, and measures for preventing liquid leakage at the edge portion are taken. In the case of a gel electrolyte, there is a method in which it is applied in a wet manner and solidified by a method such as polymerization. In this case, the counter electrode can be applied after drying and fixing. As a method for applying the wet organic hole transporting material and the gel electrolyte in addition to the electrolytic solution, the same methods as those for the semiconductor fine particle layer and the dye can be used.

  In the case of a solid electrolyte or a solid hole transport material, a charge transport layer can be formed by a dry film forming process such as a vacuum deposition method or a CVD method, and then a counter electrode can be provided. The organic hole transport material can be introduced into the electrode by a technique such as a vacuum deposition method, a casting method, a coating method, 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 techniques such as casting, coating, spin coating, dipping, electrolytic deposition, and electroless plating.

  The moisture 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 support substrate, similarly to the above-described conductive support. As the conductive agent used for the counter electrode 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 above-mentioned conductive agent is applied or vapor-deposited thereon. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. The lower the surface resistance of the counter electrode conductive layer, the better. The range of the surface resistance is preferably 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 may be substantially transparent. . From the viewpoint of improving the power generation efficiency, it is preferable to make the conductive support transparent so that light is incident from the conductive support side. 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, or a metal thin film can be used.

  The counter electrode may be formed by directly applying, plating, or vapor-depositing (PVD, CVD) a conductive agent on the charge transport layer, or attaching the conductive layer side of the substrate having the conductive layer. 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, particularly when the counter electrode is transparent. In addition, the material and installation method of a preferable metal lead, the fall of the incident light amount by metal lead installation, etc. are the same as the case of an electroconductive support body.

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

  Moreover, you may provide functional layers, such as a protective layer and an antireflection layer, in the outer surface of one or both of the electroconductive support body which acts as an electrode, and a counter electrode, between an electroconductive layer and a board | substrate, or in the middle of a board | substrate. For forming these functional layers, a coating method, a vapor deposition method, a bonding 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 take various forms according to the purpose. If roughly divided into two, a structure that allows light to enter from both sides and a structure that allows only one side are possible. The internal structure of the photoelectric conversion element preferably applicable to FIGS.

  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. . In the structure shown in FIG. 3, a metal lead 11 is partially provided on a transparent substrate 50a, a transparent conductive layer 10a is provided thereon, and an undercoat layer 60, a photosensitive layer 20, a charge transport layer 30, and a counter electrode conductive layer 40 are arranged in this order. Further, a support substrate 50 is arranged, and light is incident from the conductive layer side. The structure shown in FIG. 4 has a conductive layer 10 on a support substrate 50, a photosensitive layer 20 provided through an undercoat layer 60, a charge transport layer 30 and a transparent counter electrode conductive layer 40a, and a metal in part The transparent substrate 50a provided with the leads 11 is disposed with the metal lead 11 side inward, and has a structure in which light enters from the counter electrode side. In the structure shown in FIG. 5, the primer layer 60, the photosensitive layer 20, and the charge transport layer 30 are provided between a pair of metal leads 11 provided on a transparent substrate 50 a and a transparent conductive layer 10 a (or 40 a). In this structure, light enters from both sides. In the structure shown in FIG. 6, a transparent conductive layer 10a, an undercoat layer 60, a photosensitive layer 20, a charge transport layer 30 and a counter electrode conductive layer 40 are provided on a transparent substrate 50a, and a support substrate 50 is disposed thereon. In this structure, light enters from the conductive layer side. The structure shown in FIG. 7 has a conductive layer 10 on a support substrate 50, a photosensitive layer 20 provided via an undercoat layer 60, a charge transport layer 30 and a transparent counter electrode conductive layer 40a, and a transparent substrate thereon. 50a is arranged, and light is incident from the counter electrode side. The structure shown in FIG. 8 has a transparent conductive layer 10a on a transparent substrate 50a, a photosensitive layer 20 is provided via an undercoat layer 60, a charge transport layer 30 and a transparent counter electrode conductive layer 40a are provided, and a transparent layer is provided thereon. The substrate 50a is disposed, and light is incident 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. It has a metal lead 11 and has a structure in which light is incident from the counter electrode side.

[3] Photoelectrochemical cell The photoelectrochemical cell is one in which the photoelectric conversion element is caused to work with an external load. Among the photoelectrochemical cells, those mainly intended for power generation 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 or volatilization of the contents. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one.

  Even when the photoelectric conversion element is applied to a solar cell, the structure inside the cell is basically the same as the structure of the photoelectric conversion element described above. In addition, a dye-sensitized solar cell using a photoelectric conversion element can basically have the same module structure as a conventional solar cell module. The solar cell module generally has a structure in which cells are formed on a support substrate such as metal or ceramic, and the cell is covered with a filling resin or protective glass, and light is taken in from the opposite side of the support substrate. It is also possible to use a transparent material such as tempered glass for the support substrate, configure a cell thereon, and take in light from the transparent support substrate side. Specifically, module structures called super straight type, substrate type, potting type, and substrate integrated module structures used in amorphous silicon solar cells, etc. are known. Dye-sensitized solar cells are also used for and where they are used. The module structure can be appropriately selected depending on the environment. Specifically, the structure and aspect described in JP-A-2000-268892 are preferable.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

1. Synthesis of Twitter ion-type organic salt A Twitter ion-type organic salt used in the electrolyte composition was synthesized as follows. The structure of each synthesized ionic organic salt was confirmed by NMR spectrum and MS spectrum.

(A) Synthesis of D-1
0.4 g of compound A-1 and 1.5 g of compound B-1 were dissolved in 10 ml of acetonitrile and reacted for 8 hours under heating reflux. This was concentrated under reduced pressure, methylene chloride was added to remove insoluble lithium chloride, and then purified by a silica gel column (developing solvent: methanol / methylene chloride) to obtain 1.1 g of compound D-1. When MS spectrum of the obtained compound D-1 was measured, it was M ⁺ (posi) = 335. The viscosity of Compound D-1 was 990 cP (25 ° C.).

(B) Synthesis of D-2
0.4 g of compound A-1 and 2.5 g of compound B-2 were dissolved in 10 ml of acetonitrile and reacted for 8 hours under heating and reflux. This was concentrated under reduced pressure, methylene chloride was added to remove insoluble lithium chloride, and then purified by a silica gel column (developing solvent: methanol / methylene chloride) to obtain 0.9 g of compound D-2. When MS spectrum of the obtained compound D-2 was measured, it was M ⁺ (posi) = 409. The viscosity of Compound D-2 was 1680 cP (25 ° C.).

(C) Synthesis of D-18
0.4 g of compound A-1 and 3.5 g of compound B-2 were dissolved in 20 ml of acetonitrile and reacted for 8 hours under reflux with heating. This was concentrated under reduced pressure, methylene chloride was added to remove insoluble lithium chloride, and a methanol solution of tetrabutylammonium was added and purified by a silica gel column (developing solvent: methanol / methylene chloride) to obtain 0.5 g of compound D. Got -18. The MS spectrum of Compound D-18 obtained was measured and found to be M ⁺ (posi) = 602. The viscosity of Compound D-18 was 3210 cP (25 ° C.).

2. Production of photoelectrochemical cell
(A) Preparation of titanium dioxide dispersion 15 g of titanium dioxide fine particles (Degussa P-25 manufactured by Nippon Aerosil Co., Ltd.), 45 g of water in a 200 ml stainless steel container with an inner volume of Teflon (registered trademark) coating Add 1 g of dispersant (Aldrich “Triton X-100”) and 30 g of zirconia beads (Nikkato, 0.5 mm in diameter), and disperse for 2 hours at 1500 rpm using a sand grinder mill (Eimex). Then, the zirconia beads were removed by filtration to obtain a titanium dioxide dispersion. The average particle diameter of the titanium dioxide fine particles in the obtained titanium dioxide dispersion was 2.5 μm. The particle size was measured using a master sizer manufactured by MALVERN.

(B) 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 to a size of 20mm x 20mm, surface The titanium dioxide dispersion was applied to the conductive surface side having a resistance of about 30Ω / □ using a glass rod. The coating amount of the semiconductor fine particles was 20 g / m ² . At that time, adhesive tape was stretched on a part of the conductive surface side (3 mm from the end) to form a spacer, and glass was lined up so that the adhesive tape came to 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 (a muffle furnace “FP-32 type” manufactured by Yamato Scientific Co., Ltd.) and baked at 450 ° C. for 30 minutes to obtain a TiO ₂ electrode. After this TiO ₂ electrode was taken out and cooled, it was immersed in an ethanol solution of dye R-1 (3 × 10 ⁻⁴ mol / l) for 3 hours and further immersed in 4-t-butylpyridine for 15 minutes. This was washed with acetonitrile and naturally dried to obtain a dye-sensitized TiO ₂ electrode substrate.

(C) Production of photoelectrochemical cell The above-described dye-sensitized TiO ₂ electrode substrate (20 mm × 20 mm) was superposed on platinum-deposited glass having the same size. Next, an electrolyte composition consisting of 10% by mass of the following electrolyte salt Y-1, 2% by mass of iodine and 88% by mass of biscyanoethyl ether (BCE) is soaked into the gap between the two glasses by utilizing capillary action. Then, it was introduced into a TiO ₂ electrode and sealed with an epoxy sealant to prepare a photoelectrochemical cell of Comparative Example 1 having the structure shown in FIG.

The photoelectrochemical cells of Examples 1 to 13 and Comparative Examples 2 to 8 were produced in the same manner as the photoelectrochemical cell of Comparative Example 1 except that the electrolyte composition was changed as shown in Table 1 below. . However, if the electrolyte composition has a high viscosity and it is difficult to make the electrolyte composition soak into the gap between the two glasses by utilizing capillary action, the electrolyte composition is heated to 50 ° C. and applied to the TiO ₂ electrode. Then, this was placed under reduced pressure to sufficiently infiltrate the electrolyte composition, and air in the TiO ₂ electrode was evacuated, and a platinum-deposited glass (counter electrode) was superposed. The structures of the electrolyte salts Y-1 to Y-4 used in each example and comparative example are shown below. “LiTFSI” in Table 1 represents lithium bis (trifluoromethanesulfonyl) imide.

3.Measurement of photoelectric conversion efficiency
Simulated sunlight that does not contain ultraviolet rays was generated by passing light from a 500 W xenon lamp (USHIO ELECTRIC CO., LTD.) Through the “AM1.5 filter” manufactured by Oriel and the “Kenko L-42” sharp cut filter. . The intensity of this light was 100 mW / cm ² . This simulated sunlight was irradiated to the photoelectrochemical cells of Examples 1 to 13 and Comparative Examples 1 to 8 at 45 ° C., and the generated electricity was measured with a current-voltage measuring device “Keutley SMU238 type”. Table 2 below shows the open-circuit voltage, short-circuit current density, shape factor, conversion efficiency, and rate of decrease in short-circuit current density after 72 hours of dark storage for each photoelectrochemical cell.

  As shown in Table 2, in the photoelectrochemical cell (Comparative Examples 1 to 3 and Examples 1 and 2) using the electrolyte composition containing 30% by mass or more of the organic solvent, the short-circuit current density after storage in the dark place However, the photoelectrochemical cells of Examples 1 and 2 using the electrolyte composition are more than the conventional photoelectrochemical cells of Comparative Examples 1 and 3 using the electrolyte composition containing only the imidazolium salt. Also showed excellent conversion efficiency and storage stability. Further, from Table 2, it can be seen that the solvent content of the electrolyte composition is preferably 10% by mass or less, and more preferably no solvent is used, in order to suppress a decrease in short circuit current density.

  In the conventional photoelectrochemical cells of Comparative Examples 4 and 5 using only the imidazolium salt, the short-circuit current density is low, which causes low photoelectric conversion efficiency. Further, the photoelectrochemical cell of Comparative Example 6 using only the organic salt (I), the photoelectrochemical cell of Comparative Example 7 using a combination of the conventional imidazolium salt and the organic salt (I), and the known LiTFSI The photoelectrochemical cell of Comparative Example 8 using the combination of the organic salt (I) showed almost no photoelectric conversion ability. In contrast, the photoelectrochemical cells of Examples 3 to 13 using the electrolyte composition containing the organic salt (I) and the iodine salt showed high short-circuit current density, and accordingly, excellent conversion efficiency was obtained. .

10 ... conductive layer
10a ・ ・ ・ Transparent conductive layer
11 ... Metal lead
20 ... Photosensitive layer
21 ... Semiconductor fine particles
22 ... Dye
23 ... Charge transport material
30 ... Charge transport layer
40 ... Counterelectrode conductive layer
40a ・ ・ ・ Transparent counter electrode conductive layer
50 ... Board
50a ・ ・ ・ Transparent substrate
60 ... Undercoat layer

Claims (6)

Twitter ion type organic salt represented by the following general formula (I).
In the general formula (I), Q represents an atomic group that forms a 5- or 6-membered aromatic cation with a nitrogen atom, and R ₁ represents a hydrogen atom, an alkyl group, an alkenyl group, or the following general formula (II). R ₂ represents an alkoxy group, a cyano group, an alkoxycarbonyl group, a carbonate group, an amide group, a carbamoyl group, a phosphonyl group, a heterocyclic group, an aryloxy group, an alkylthio group, an acyl group, a sulfonyl group, an acyloxy group. group, a sulfonyloxy group, an aryl group, an aryloxy group, an alkenyl group, an alkyl group, or a substituted group represented by the following general formula (II), n1 represents an integer of 0 to 5, X ₁ is a counterion N2 represents an integer of 0 to 4. When 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).
In general formula (II), L ₁ represents a divalent linking group composed of an alkylene group, an arylene group, an alkyleneoxy group, an aryleneoxy group, or a combination thereof, which links the aromatic cation and V _1, and V ₁ and V ₂ each independently represent —CO—, —SO—, —SO ₂ — or —PO (OR ₄ ) — (R ₄ represents an alkyl group or an aryl group), R ₃ represents an alkoxy group, an alkyl group, An alkenyl group or a perfluoroalkyl group is represented. The Twitter ion type organic salt according to claim 1, wherein the Q represents an imidazole ring or a pyridine ring together with a nitrogen atom. The Twitter ion type organic salt according to claim 1 or 2, wherein at least one of V ₁ and V ₂ is -SO _2- . An imidazolium organic salt represented by the following general formula (III).
In the general formula (III), R ₁₁ and R ₂₁ represent a hydrogen atom, an alkyl group, an alkenyl group, or a substituent represented by the following general formula (IV), R _{22 to} R ₂₄ are each independently a hydrogen atom, Alkoxy group, cyano group, alkoxycarbonyl group, carbonate group, amide group, carbamoyl group, phosphonyl group, heterocyclic group, aryloxy group, alkylthio group, acyl group, sulfonyl group, acyloxy group, sulfonyloxy group, aryl group, aryl It represents an oxy group, an alkenyl group, an alkyl group, or a substituent represented by the following general formula (IV), X ₁₁ represents a counter ion, and n 21 represents an integer of 0 to 4. R ₁₁ and R _{21 to} R ₂₄ may be the same or different, and at least one of R ₁₁ and R _{21 to} R ₂₄ is a substituent represented by the following general formula (IV).
In the general formula (IV), L ₁₁ is an alkylene group, an arylene group, an alkyleneoxy group, an aryleneoxy group, or a combination thereof, which links the imidazolium cation in the general formula (III) and V _11. V ₁₁ and V ₂₁ represent —SO ₂ —, and R ₃₁ represents an alkoxy group, an alkyl group, an alkenyl group, or a perfluoroalkyl group. The imidazolium organic salt according to claim 4, wherein the n21 is 0. 6. The imidazolium organic salt according to claim 4, wherein R _{21 to} R ₂₄ are each independently a hydrogen atom or a substituent represented by the general formula (IV). .