JP6019688B2 - Electrolyte for photoelectric conversion element and photoelectric conversion element and dye-sensitized solar cell using the electrolyte - Google Patents

Description

  The present invention relates to an electrolyte for a photoelectric conversion element, a photoelectric conversion element using the electrolyte, and a dye-sensitized solar cell.

  In recent years, environmental problems such as global warming caused by an increase in carbon dioxide have become serious, and non-silicon solar cells have attracted attention as solar cells that can reduce environmental impact and reduce manufacturing costs. ing.

Among non-silicon-based solar cells, dye-sensitized solar cells developed by Grezel, etc. of Switzerland have high photoelectric conversion efficiency among solar cells using organic materials, and are less expensive to manufacture than silicon-based solar cells. It is also attracting attention as a new type of solar cell due to its advantages such as low price.
However, since dye-sensitized solar cells are electrochemical cells, organic electrolytes or ionic liquids are used as electrolytes. When organic electrolytes are used, they may volatilize or be depleted during long-term use. However, when using ionic liquids, volatilization and depletion during long-term use can be prevented, but there are durability problems such as structural deterioration due to liquid leakage. It was.
In view of this, studies have been made to change the electrolyte from liquid to gel or solid for the purpose of preventing volatilization and leakage of the electrolyte and ensuring long-term stability and durability of the solar cell.

For example, Patent Document 1 describes "(i) Layered clay mineral and / or organically modified layered clay mineral and (ii) an electrolyte for a photoelectric conversion element comprising an ionic liquid." 1]).
Patent Document 2 discloses that “(i) an electrolytic solution in which an electrolyte is dissolved in an organic solvent, (ii) a layered clay mineral and / or an organically modified layered clay mineral, and (iii) a gel comprising a polyvalent onium salt compound. Or a solid electrolyte. ”[Claim 1].
Further, Patent Document 3 discloses that “a photoelectric conversion element containing an ionic liquid (A) and a layered clay mineral (B), wherein the layered clay mineral (B) has an alkylsilyl group. Electrolyte for use ".

Special table 2007-531206 gazette JP 2008-71749 A JP2011-216461A

As a result of examining the photoelectric conversion element using the electrolyte for photoelectric conversion elements described in Patent Documents 1 to 3, the present inventor found that there is room for improvement in photoelectric conversion efficiency depending on the type of layered clay mineral used. It was clear.
Then, an object of this invention is to provide the electrolyte for photoelectric conversion elements which can achieve high photoelectric conversion efficiency, the photoelectric conversion element using the electrolyte, and a dye-sensitized solar cell.

As a result of intensive studies to solve the above problems, the present inventor has found that an electrolyte for a photoelectric conversion element using a layered clay mineral having an onium salt via a covalent bond can achieve high photoelectric conversion efficiency. The headline and the present invention were completed.
That is, the present invention provides the following (a) to (g).

(A) An electrolyte for a photoelectric conversion element comprising an organic salt compound (A) having a tertiary or quaternary cation and a layered clay mineral (B),
The electrolyte for photoelectric conversion elements, wherein the layered clay mineral (B) has an onium salt via a covalent bond.

  (B) The photoelectric conversion according to (a), wherein the onium salt is at least one selected from the group consisting of an imidazolium salt, a pyridinium salt, a pyrrolidinium salt, a piperidinium salt, an ammonium salt, a sulfonium salt, and a phosphonium salt. Electrolyte for device.

  (C) The electrolyte for a photoelectric conversion element according to (a) or (b), wherein the organic salt compound (A) has a cation represented by the following formula (1) or (2).

In Formula (1), R ¹ represents a hydrocarbon group that may contain a C 1-20 hetero atom, and has a substituent that may contain a C 1-20 hetero atom. May be. R ² and R ³ each independently represent a hydrogen atom or a hydrocarbon group that may contain a C 1-20 hetero atom. However, when the nitrogen atom contains a double bond, R ³ does not exist.
In the formula (2), Q represents a nitrogen atom, an oxygen atom, a phosphorus atom or a sulfur atom, and R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom or a hetero atom having 1 to 20 carbon atoms. Represents a hydrocarbon group which may contain However, when Q is an oxygen atom or a sulfur atom, R ⁷ does not exist, and when Q is a sulfur atom, R ⁴ and R ⁵ may be linked.

(D) The organic salt compound (A) contains the organic salt compound (a1) in excess of 50% by mass in terms of cation,
In the organic salt compound (a1), at least one of the substituents R ² and R ³ which R ¹ in the formula (1) may have contains a heteroatom having 5 to 20 carbon atoms. A compound representing a preferred hydrocarbon group, or a hydrocarbon in which at least one of R ⁴ , R ⁵ , R ⁶ and R ⁷ in formula (2) may contain a heteroatom having 5 to 20 carbon atoms The electrolyte for photoelectric conversion elements according to (c) above, which is a compound representing a group.

  (E) The electrolyte for photoelectric conversion elements according to any one of (a) to (d), wherein the organic salt compound (A) has a thiocyanate anion.

(F) a photoelectrode having a transparent conductive film and a metal oxide semiconductor porous film;
A counter electrode disposed to face the photoelectrode;
An electrolyte layer disposed between the photoelectrode and the counter electrode,
The photoelectric conversion element whose said electrolyte layer is the electrolyte for photoelectric conversion elements in any one of said (a)-(e).

  (G) A dye-sensitized solar cell obtained by supporting a photosensitizing dye on the photoelectrode according to (f).

  ADVANTAGE OF THE INVENTION According to this invention, the photoelectric conversion element electrolyte which can achieve high photoelectric conversion efficiency, the photoelectric conversion element using the electrolyte, and a dye-sensitized solar cell can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of the basic configuration of the photoelectric conversion element of the present invention. FIG. 2 is a drawing showing the basic configuration of the dye-sensitized solar cell of the present invention used in Examples and the like.

[Electrolyte for photoelectric conversion element]
The electrolyte for photoelectric conversion elements of the present invention (hereinafter also simply referred to as “the electrolyte of the present invention”) contains an organic salt compound (A) having a tertiary or quaternary cation and a layered clay mineral (B). An electrolyte for a photoelectric conversion element, wherein the layered clay mineral (B) has an onium salt via a covalent bond.
Next, each component of the electrolyte of the present invention will be described in detail.

[Organic salt compound (A)]
The organic salt compound (A) used in the electrolyte of the present invention is an organic salt compound having a tertiary or quaternary cation and an anion which is a counter ion thereof, and is either solid or liquid (so-called ionic liquid) at room temperature. It may be.
Here, the tertiary cation refers to a cation in which a positively charged periodic table group 16 element (for example, an oxygen atom, a sulfur atom, etc.) does not have a hydrogen atom, and the quaternary cation is A cation in which a Group 15 element (for example, a nitrogen atom or a phosphorus atom) having a positive charge does not have a hydrogen atom.

  Specific examples of the cation possessed by the organic salt compound (A) include cations represented by the following formula (1) or (2).

In Formula (1), R ¹ represents a hydrocarbon group that may contain a C 1-20 hetero atom, and has a substituent that may contain a C 1-20 hetero atom. May be. R ² and R ³ each independently represent a hydrogen atom or a hydrocarbon group that may contain a C 1-20 hetero atom. However, when the nitrogen atom contains a double bond, R ³ does not exist.
In the formula (2), Q represents a nitrogen atom, an oxygen atom, a phosphorus atom or a sulfur atom, and R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom or a hetero atom having 1 to 20 carbon atoms. Represents a hydrocarbon group which may contain However, when Q is an oxygen atom or a sulfur atom, R ⁷ does not exist, and when Q is a sulfur atom, R ⁴ and R ⁵ may be linked.

Here, as a hydrocarbon group which may contain a C1-C20 heteroatom represented by R ¹ in the above formula (1), a ring structure together with a nitrogen atom (ammonium ion) in the above formula (1). It is preferable that
Next, the substituent which may have a hetero atom having 1 to 20 carbon atoms which R ¹ in the above formula (1) may have is an alkyl group having 1 to 20 carbon atoms (for example, methyl Group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, ethylhexyl group, nonyl group, decyl group, dodecyl group, undecyl group, hexadecyl group, octadecyl group, cyclopropylmethyl group, tripropyl group Fluoroethyl group, etc.), alkenyl group having 2-20 carbon atoms (for example, vinyl group, allyl group, etc.), aryl group having 6-20 carbon atoms (for example, phenyl group, tolyl group, naphthyl group, etc.), carbon number 7 -20 aralkyl groups (for example, benzyl group, phenylethyl group, phenylpropyl group, etc.), C1-C20 alkoxy groups (for example, methoxy group, ethoxy group) N-propoxy group, iso-propoxy group, n-butoxy group, tert-butoxy group, sec-butoxy group, n-pentoxy group, n-hexoxy group, 1,2-dimethylbutoxy group, heptoxy group, octoxy group, Noninokishi group, decyloxy group, a phenoxy group, methylphenoxy group, ethylphenoxy group, etc.), alkyl alkoxy group having 2 to 20 carbon atoms (e.g., methylene methoxy group (-CH ₂ OCH _3), ethylene methoxy (-CH ₂ CH ₂ OCH ₃ ), n-propylene-iso-propoxy group (—CH ₂ CH ₂ CH ₂ OCH (CH ₃ ) ₂ ), methylene-t-butoxy group (—CH ₂ —O—C (CH ₃ ) ₃ , butylene Methoxy group, pentylene methoxy group, hexylene methoxy group, heptylene methoxy group, octylene methoxy group, nonylene methoxy Group, decylene methoxy group, methylene ethoxy group, ethylene ethoxy group, propylene ethoxy group, butylene ethoxy group, pentylene ethoxy group, hexylene ethoxy group, ethylene ethoxy methoxy group, cyclopropyl methoxy group, cyclohexyl methoxy group, methyl phenoxy group Methoxyphenoxy group, ethoxyphenoxy group, phenoxyphenoxy group, etc.) R ¹ in the above formula (1) may have two or more of these substituents.

Moreover, as a hydrocarbon group which may contain the C1-C20 heteroatom represented by R < ² > and R < ³ > in the said Formula (1), specifically, a C1-C20 alkyl group ( For example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, ethylhexyl, nonyl, decyl, dodecyl, undecyl, hexadecyl, octadecyl, cyclopropylmethyl Group, trifluoroethyl group, etc.), C2-C20 alkenyl group (e.g., vinyl group, allyl group, etc.), C6-C20 aryl group (e.g., phenyl group, tolyl group, naphthyl group, etc.), Aralkyl group having 7 to 20 carbon atoms (for example, benzyl group, phenylethyl group, phenylpropyl group, etc.), alkoxy group having 1 to 20 carbon atoms (for example, methoxy group, Ethoxy group, n-propoxy group, iso-propoxy group, n-butoxy group, tert-butoxy group, sec-butoxy group, n-pentoxy group, n-hexoxy group, 1,2-dimethylbutoxy group, heptoxy group, octoxy Group, noninoxy group, decyloxy group, phenoxy group, methylphenoxy group, ethylphenoxy group, etc.), an alkylalkoxy group having 2 to 20 carbon atoms (for example, methylenemethoxy group (—CH ₂ OCH ₃ ), ethylenemethoxy group (—CH ₂ CH ₂ OCH ₃ ), n-propylene-iso-propoxy group (—CH ₂ CH ₂ CH ₂ OCH (CH ₃ ) ₂ ), methylene-t-butoxy group (—CH ₂ —O—C (CH ₃ ) ₃ , Butylene methoxy group, pentylene methoxy group, hexylene methoxy group, heptylene methoxy group, octylene methoxy group, nonyl Methoxy group, decylene methoxy group, methylene ethoxy group, ethylene ethoxy group, propylene ethoxy group, butylene ethoxy group, pentylene ethoxy group, hexylene ethoxy group, ethylene ethoxy methoxy group, cyclopropyl methoxy group, cyclohexyl methoxy group, methyl phenoxy Group, methoxyphenoxy group, ethoxyphenoxy group, phenoxyphenoxy group and the like).

Further, in the above formula (2), the R ^4, R ^5, R ⁶ and R ⁷ represent hydrocarbon group which may contain a hetero atom having 1 to 20 carbon atoms, specifically, for example, the What was illustrated as a hydrocarbon group which may contain the C1-C20 hetero atom which R < ² > and R < ³ > in Formula (1) may contain is mentioned.

Examples of the cation represented by the above formula (1) include imidazolium ion, pyridinium ion, pyrrolidinium ion, piperidinium ion, and the like.
Specifically, a cation represented by any of the following formulas (3) to (6) is preferably exemplified.
Among these, a cation represented by the following formulas (3) and (5) is preferable because the photoelectric conversion efficiency of the photoelectric conversion element of the present invention tends to be better.

In formulas (3) to (6), each R independently represents a hydrocarbon group that may contain a heteroatom having 1 to 20 carbon atoms.
More specifically, the following cations are mentioned.

Examples of the cation represented by the above formula (2) include organic cations such as ammonium ion, sulfonium ion, phosphonium ion, and oxonium ion.
Specifically, the following cations are preferably exemplified.
Among these, aliphatic quaternary ammonium ions and sulfonium ions (particularly thiophenium ions) are preferable because the photoelectric conversion efficiency of the photoelectric conversion element of the present invention tends to be higher.

On the other hand, specific examples of the anion possessed by the organic salt compound (A) include I ⁻ , Br ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , NO ₃ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ and CH _3. COO ⁻ , CF ₃ COO ⁻ , CF ₃ SO ₃ ⁻ , (CN) ₄ B ⁻ , SCN ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CN) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , (CN) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , F (HF) _n ⁻ , CF ₃ CF ₂ CF ₂ CF ₂ SO ₃ ⁻ , (CF ₃ CF ₂ SO ₂ ) ₂ N ⁻ , CF ₃ CF ₂ CF ₂ COO ⁻ , phosphonate anion (for example, methylphosphonate) and the like are preferably exemplified.

Of these, bromine ions (Br ⁻ ) and iodine ions (I ⁻ ) are preferred, and iodine ions (I ⁻ ) are preferred because the photoelectric conversion efficiency of the photoelectric conversion element of the present invention tends to be higher. Is more preferable.
In addition, a thiocyanate anion (SCN ⁻ ) (including an isothiocyanate anion which is a linked isomer, the same applies hereinafter) is preferable because the heat resistance of the photoelectric conversion element of the present invention is improved. Considering that this is an effect exhibited when using a metal complex coordinated with a thiocyanate anion (for example, a ruthenium complex dye described later) as shown in the examples described later, the metal complex is heated by heating. Even if the coordination of the thiocyanate anion is off, the thiocyanate anion of the organic salt compound (A) can be re-coordinated, and functions as a dye, that is, a function of absorbing light and emitting electrons. It is thought that it was possible to maintain.

As said organic salt compound (A), the organic salt compound etc. which consist of a combination of the cation and anion which were illustrated above are mentioned, for example.
Among them, an organic salt compound having an imidazolium ion as a cation and an iodine ion as an anion is preferable because the photoelectric conversion efficiency of the photoelectric conversion element of the present invention is higher, and the heat resistance of the photoelectric conversion element of the present invention is preferred. Therefore, an organic salt compound having a thiocyanate anion is preferable, and an organic salt compound having an imidazolium ion and an iodine ion and an organic salt compound having a thiocyanate anion are more preferably used in combination.

  The method for synthesizing the organic salt compound (A) is not particularly limited, and various organic salt compounds composed of combinations of cations and anions exemplified above can be synthesized by a conventionally known method.

  Examples of the organic salt compound (A) include 1-methyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium iodide, 1-methyl-3-pentylimidazolium iodide, 1-methyl- 3-hexylimidazolium iodide, 1-((2-methoxyethoxy) ethyl) -3-((2-methoxyethoxy) ethyl) imidazolium iodide, 1-methyl-1-butylpyrrolidinium thiocyanate, 1- In addition to synthetic products such as methyl-1-ethylpyrrolidinium thiocyanate, commercially available products can be used. Specifically, for example, 1-methyl-3-propylimidazolium iodide (manufactured by Tokyo Chemical Industry Co., Ltd.), 1-methyl-3-butylimidazolium iodide (manufactured by Tokyo Chemical Industry Co., Ltd.), 1-methyl-1-methyl Pyrrolidinium iodide (manufactured by Aldrich), tetrapropylammonium iodide (manufactured by Tokyo Chemical Industry), tetrabutylammonium iodide (manufactured by Tokyo Chemical Industry), 1-ethyl-3-methylimidazolium tetracyanoborate (Merck) 1-ethyl-3-methylimidazolium thiocyanate (Merck), 1-methyl-3-butylimidazolium thiocyanate (BASF), tetrapropylammonium thiocyanate (Merck), 1-ethyl-3 -Methylimidazolium bis (trifluoromethylsulfonyl) imide (manufactured by Solvent Innovation), 1-ethyl-3-methylimidazolium methylphosphonate (manufactured by Kanto Chemical Co.), triethylhexylphosphonium bis (trifluoromethylsulfo) Le) amide (Aldrich), tri-hexyl tetradecyl phosphonium bis (trifluoromethylsulfonyl) amide (Aldrich) and the like can be used.

Since some organic salt compounds exhibit tautomerism, the organic salt compound (A) in the present invention includes the tautomer.
Specifically, for example, “1-methyl-3-pentylimidazolium iodide” includes “1-pentyl-3-methylimidazolium iodide” which is a tautomer thereof, and includes “1-methyl- “3-hexylimidazolium iodide” includes “1-hexyl-3-methylimidazolium iodide” which is a tautomer thereof.

In the present invention, the organic salt compound (A) contains an organic salt compound (a1) described later in excess of 50% by mass in terms of cation because the moisture resistance of the photoelectric conversion element of the present invention is improved. Is preferred.
In addition, cation conversion means the mass of only the cation except the anion in the said organic salt compound (A).

<Organic salt compound (a1)>
In the organic salt compound (a1), at least one of the “substituent which R ¹ may have”, “R ² ” and “R ³ ” in the above formula (1) has 5 to 5 carbon atoms. A compound representing a hydrocarbon group which may contain 20 heteroatoms, or at least four of “R ⁴ ”, “R ⁵ ”, “R ⁶ ” and “R ⁷ ” in the above formula (2) One is a compound which represents a hydrocarbon group which may contain a hetero atom having 5 to 20 carbon atoms.
Here, the reason why the moisture resistance of the photoelectric conversion element becomes good is that the cation of the organic salt compound (a1) occupying more than 50% by mass of the organic salt compound (A) in terms of cation is 5 to 20 carbon atoms. By having a chain hydrocarbon group, it is considered that the organic salt compound (A) itself is hydrophobized to prevent intrusion of water vapor existing in the atmosphere.

In the present invention, because both the moisture resistance and the photoelectric conversion efficiency of the photoelectric conversion element of the present invention are better, 90% by mass or less of the organic salt compound (A) in terms of cation is the organic salt compound (a1). ), More preferably more than 50% by mass and 85% by mass or less, and further preferably more than 50% by mass and 80% by mass or less.
In addition, when using the said organic salt compound (a1) and the said other organic salt compound (A) together, although each may be solid as a single-piece | unit, the said organic salt compound (A) which mixes and contains them ) Is preferably a liquid (so-called ionic liquid).

  The content of the organic salt compound (A) is preferably 50 to 95% by mass and more preferably 65 to 95% by mass with respect to the total mass of the electrolyte of the present invention. When the content is within this range, the photoelectric conversion efficiency of the photoelectric conversion element of the present invention becomes better.

[Layered clay mineral (B)]
The layered clay mineral (B) used in the electrolyte of the present invention is not particularly limited as long as it is a layered clay mineral having an onium salt via a covalent bond. For example, it has a layered clay mineral (b1) described later and an onium salt. A compound obtained by reacting an alkoxysilane, a carboxylic acid compound having an onium salt, and an onium salt-containing compound (b2) selected from the group consisting of a phosphoric acid compound having an onium salt can be used.

<Layered clay mineral b1>
The layered clay mineral (b1) used for the preparation of the layered clay mineral (B) is not particularly limited, but is preferably a phyllosilicate in which a silicate tetrahedron is bound in a two-dimensional sheet, and specific examples thereof include: Smectite clay minerals such as montmorillonite, bentonite, saponite, beidellite, nontronite, hectorite, and stevensite; vermiculite clay minerals such as vermiculite; mica clay minerals such as muskite, flocovite, mica, etc. These may be used alone or in combination of two or more.
The layered clay mineral (b1) may be a natural product or a synthetic product.

Of these, smectite clay minerals and swelling mica that swell in water and have cation exchange ability are preferred.
Here, the cation exchange amount of the layered clay mineral is preferably 10 to 300 meq / 100 g.

  As such a layered clay mineral (b1), a commercially available product can be used. For example, natural montmorillonite (trade name: Kunipia F, average particle size: 0.1 to 1 μm, manufactured by Kunimine Industries), synthetic smectite (product) Name: Smecton SA, average particle size: 20 nm, manufactured by Kunimine Kogyo Co., Ltd., synthetic swelling mica (trade name: Somasif ME-100, average particle size: 1-3 μm, manufactured by Coop Chemical Co.), synthetic smectite (product name: Lucentite SWN, average particle size: 0.02 μm, manufactured by Corp Chemical Co.) and synthetic smectite (trade name: Lucentite SWF, average particle size: 0.02 μm, manufactured by Corp Chemical Co.) are preferably used.

In the present invention, an organically layered clay mineral can be used as the layered clay mineral (b1).
Organized layered clay mineral can be obtained by performing cation exchange between common layers, for example, by adding organic onium ions to the aqueous slurry of layered clay mineral described above, and stirring and reacting, It is possible to obtain an organized layered clay mineral in which organic onium ions are introduced by ion interaction between layers of the layered clay mineral.
Here, the organic onium ion is a compound containing an element having a lone pair such as oxygen, sulfur, nitrogen, etc., and a proton or other cationic reagent is coordinated to these lone pairs. Is an ion generated from the organic onium compound generated.
In addition, the conditions for organicizing with organic onium ions are not particularly limited, but it is preferable to react the organic onium ions in an amount of 0.3 to 2.0 times the cation exchange capacity of the layered clay mineral, The reaction is more preferably performed in an amount of 0.5 to 1.5 times, and the reaction is preferably performed at a temperature of 10 to 95 ° C.

Examples of organic onium ions include ammonium ions, phosphonium ions, oxonium ions, sulfonium ions, and the like.
Of these, ammonium ions are the most common, and specifically include aliphatic ammonium ions, pyridinium ions, quinolinium ions, imidazolium ions, pyrrolidinium ions, piperidinium ions, betaines, lecithin, and cationic dyes. (Pigment) etc. are mentioned.
Further, an aliphatic ammonium ion represented by the following formula (I) or (II) is preferable, and specifically, for example, hydroxypolyoxyethylene trialkylammonium, hydroxypolyoxypropylene trialkylammonium, di (hydroxypolyoxyethylene) Dialkylammonium, di (hydroxypolyoxypropylene) dialkylammonium, dimethyldioctylammonium, dimethyldidodecylammonium, methylethyldioctylammonium, methylethyldioctylammonium, methyltrioctylammonium, methyltridodecylammonium, benzylmethyldioctylammonium, benzylmethyldi Dodecyl ammonium, benzyl ethyl dioctyl ammonium, benzyl ethyl dioctyl ammonium Um, benzyl trioctyl ammonium, benzyltrimethylammonium dodecyl ammonium and the like.

In the formula (I), R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, R ² and R ³ are each independently a polyoxyethylene group (— (CH ₂ CH ₂ O) _n —H), polyoxy Represents a propylene group (— (CH ₂ CH (CH ₃ ) O) _n —H, — (CH ₂ CH ₂ CH ₂ O) _n —H) or a hydrocarbon group having 1 to 10 carbon atoms, and R ⁴ represents polyoxy Ethylene group (— (CH ₂ CH ₂ O) _n —H) or polyoxypropylene group (— (CH ₂ CH (CH ₃ ) O) _n —H, — (CH ₂ CH ₂ CH ₂ O) _n —H) Represents. Moreover, n = 1-50 is represented.

In formula (II), R ¹ represents a methyl group or a benzyl group, R ² represents a hydrocarbon group having 1 to 3 carbon atoms or a hydrocarbon group having 6 to 15 carbon atoms, and R ³ and R ⁴ are each independently Represents a hydrocarbon group having 6 to 15 carbon atoms.

  As such an organized layered clay mineral, commercially available products can be used, and specifically, for example, Esbene NX, Esbene WX, Organite, Organite D manufactured by Hojun Co., Ltd. Tight SEN, Lucentite SPN, Lucentite SAN, Lucentite STN, Somasif MAE, Somasif MEE, Somasif MPE, Somasif MTE, etc. can be used.

<Onium salt-containing compound (b2)>
The onium salt-containing compound (b2) used for the preparation of the layered clay mineral (B) is selected from the group consisting of an alkoxysilane having an onium salt, a carboxylic acid compound having an onium salt, and a phosphate compound having an onium salt. It is a compound.
Here, examples of the alkoxysilane, the carboxylic acid compound, and the phosphoric acid compound include compounds represented by the following formulas (7) to (9), respectively.

In the above formula (7), respectively R ⁹ and R ¹⁰ independently represent an alkyl group having 1 to 6 carbon atoms, R ¹⁰ represents an alkylene group having 1 to 6 carbon atoms, m represents an integer of 1 to 3 . When m is 2 or 3, the plurality of R ⁹ may be the same or different, and when m is 1, the plurality of R ¹⁰ may be the same or different.
In the above formulas (7) to (9), n represents an integer of 1 to 24, Y ⁺ represents an onium ion (cation), and Z ⁻ represents a counter ion (anion).

Here, in the above formula (7), as the alkyl group having 1 to 6 carbon atoms represented by R ⁹ and R ¹⁰ , specifically, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl Group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, hexyl Group, and the like. Among them, a methyl group and an ethyl group are preferable.

In addition, in the above formulas (7) to (9), examples of the cation (Y ⁺ ) include imidazolium ions, pyridinium ions, pyrrolidinium ions, piperidini described as the cations possessed by the organic salt compound (A). In particular, imidazolium ion, pyrrolidinium ion, piperidinium ion, ammonium are preferable because the photoelectric conversion efficiency of the photoelectric conversion device of the present invention is improved. More preferred are ions, sulfonium ions, and phosphonium ions.

Similarly, in the above formulas (7) to (9), examples of the anion (Z ⁻ ) include those described as the anion possessed by the organic salt compound (A), and the anion (Z ⁻ ) The organic salt compound (A) can be easily exchanged for an anion, and is not necessarily limited. However, for the reason that the photoelectric conversion efficiency of the photoelectric conversion element of the present invention becomes better, bromine ion (Br ⁻ ). , Iodine ion (I ⁻ ) is preferable, and iodine ion (I ⁻ ) is preferable.

  Specific examples of the compound represented by the formula (7) include, for example, trimethyl [3- (trimethoxysilyl) propyl] ammonium iodide, trimethyl [3- (triethoxysilyl) propyl] ammonium iodide, 3- [3- (trimethoxysilyl) propyl] -1-methylimidazolium iodide, 3- [3- (triethoxysilyl) propyl] -1-methylimidazolium iodide, 1- [3- (trimethoxy Silyl) propyl] pyridinium iodide, 1- [3- (triethoxysilyl) propyl] pyridinium iodide, 1- [3- (trimethoxysilyl) propyl] -1-methylpyrrolidinium iodide, 1- [3 -(Triethoxysilyl) propyl] -1-methylpyrrolidinium iodai 1- [3- (trimethoxysilyl) propyl] -1-methylpiperidinium iodide, 1- [3- (triethoxysilyl) propyl] -1-methylpiperidinium iodide, dimethyl [3- ( Trimethoxysilyl) propyl] sulfonium iodide, dimethyl [3- (triethoxysilyl) propyl] sulfonium iodide, trimethyl [3- (trimethoxysilyl) propyl] phosphonium iodide, trimethyl [3- (triethoxysilyl) propyl ] Phosphonium iodide etc. are mentioned, These may be used individually by 1 type and may use 2 or more types together.

  The compound represented by the formula (7) includes, for example, 3-trimethoxysilylpropyl chloride and an imidazole compound (for example, methylimidazole), a pyridine compound, a pyrrolidine compound, a piperidine compound, an amine compound, a sulfide compound, and a phosphine. It can be synthesized by reacting with a compound such as a compound (quaternization reaction).

Specifically as a compound represented by the said Formula (8), the compound etc. which are represented by a following formula are mentioned, for example.

Specifically as a compound represented by the said Formula (9), the compound etc. which are represented by a following formula are mentioned, for example.

In the present invention, the reaction between the layered clay mineral (b1) and the onium salt-containing compound (b2) is not particularly limited. For example, these are carried out in an organic solvent such as methanol at a temperature of about 0 to 250 ° C. By stirring, the hydroxyl group of the layered clay mineral (b1) reacts with the hydrolyzable group, carboxy group or phosphate group of the onium salt-containing compound (b2), and an onium base is introduced through a covalent bond. A layered clay mineral (B) can be prepared.
Here, the hydroxyl group possessed by the layered clay mineral (b1) refers to a hydroxyl group usually possessed by a crystal layer (mainly an end face) of a known layered clay mineral such as montmorillonite or smectite. It is not necessary that all the hydroxyl groups of the clay mineral (b1) are substituted with an onium base.

By containing such a layered clay mineral (B), a photoelectric conversion element having high photoelectric conversion efficiency can be formed.
Although this is not clear in detail, in the layered clay mineral (B), in addition to the ionic interaction, a covalent bond (reaction between the layered clay mineral (b1) and the onium salt-containing compound (b2)). It is considered that the introduced onium salt is arranged along the layered sheet, and for example, the formation of a path of iodine ions (I ⁻ ) is further increased.

In this invention, it is preferable that content of the said layered clay mineral (B) is 1-250 mass parts in conversion of an inorganic substance with respect to 100 mass parts of said organic salt compounds (A), and is 2-150 mass parts. More preferably.
Here, the inorganic substance conversion means the mass excluding the cation between layers in the layered clay mineral (B), that is, the above-described organic onium ion.

[Other ingredients]
From the viewpoint of further improving the photoelectric conversion efficiency of the photoelectric conversion element of the present invention, the electrolyte of the present invention can be added with a redox pair (redox pair).
As the redox couple, any one generally used or usable in a dye-sensitized solar cell can be used as long as the object of the present invention is not impaired.
For example, iodine / iodide ions, bromine / bromide ions, and the like can be used. Specifically, metal iodides of iodine and LiI, NaI, KI, etc., iodide salts of iodine and quaternary imidazolium compounds, iodide salts of iodine and quaternary pyridinium compounds, iodine and tetraalkylammonium compounds Iodine / iodide ion pairs such as iodide salts with; bromide and metal bromides with LiBr, NaBr, KBr, etc., bromide salts with bromine and quaternary imidazolium compounds, bromide salts with bromine and quaternary pyridinium compounds, Bromine / bromide ions such as bromide salts of bromine and tetraalkylammonium compounds; metal complexes such as ferrocyanate-ferricyanate, ferrocene-ferricinium salts, cobalt complexes; sulfur compounds of disulfide compounds and mercapto compounds; hydroquinones -Quinone; viologen dye; etc., and these can be used alone At best, it may be used in combination of two or more thereof.
Of these, iodine / iodide ions and bromine / bromide ions are preferred.

Moreover, the electrolyte of this invention can add inorganic salt and / or organic salt from a viewpoint of improving the short circuit current of the photoelectric conversion element of this invention.
Examples of inorganic salts and organic salts include alkali metal, alkaline earth metal salts, and the like. Specifically, lithium iodide, sodium iodide, potassium iodide, magnesium iodide, calcium iodide, Lithium trifluoroacetate, sodium trifluoroacetate, lithium thiocyanate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bis (trifluoromethanesulfonyl) imide, guanidine thiocyanate The guanidine salt etc. are mentioned, These may be used individually by 1 type and may use 2 or more types together.
The amount of the inorganic salt or organic salt added is not particularly limited, and can be the same as before as long as the object of the present invention is not impaired.

Moreover, pyridines and benzimidazoles can be added to the electrolyte of this invention from a viewpoint of improving the open circuit voltage of the photoelectric conversion element of this invention.
Specifically, alkyl pyridines such as methyl pyridine, ethyl pyridine, propyl pyridine and butyl pyridine; alkyl imidazoles such as methyl imidazole, ethyl imidazole and propyl imidazole; methyl benzimidazole, ethyl benzimidazole, butyl benzimidazole and propyl benz Examples thereof include alkylbenzimidazoles such as imidazole, and the like. These may be used alone or in combination of two or more.
The addition amount of pyridines and benzimidazoles is not particularly limited and can be the same as before as long as the object of the present invention is not impaired.

An organic solvent may be added to the electrolyte of the present invention. Specific examples thereof include carbonates such as ethylene carbonate and propylene carbonate; ethers such as ethylene glycol dialkyl ether and propylene glycol dialkyl ether; ethylene glycol monoalkyl. Alcohols such as ether and propylene glycol monoalkyl ether; Polyhydric alcohols such as ethylene glycol and propylene glycol; Nitriles such as acetonitrile, propionitrile, methoxypropionitrile, cyanoethyl ether, glutaronitrile and valeronitrile; γ -Lactones such as butyrolactone; Amides such as dimethylformamide and N-methylpyrrolidone; Aprotic polar solvents such as dimethylsulfoxide and sulfolane; It is, may be used those either alone, or in combination of two or more.
The content of the organic solvent is not particularly limited, and can be conventional as long as the object of the present invention is not impaired.

〔Production method〕
The method for producing the electrolyte of the present invention is not particularly limited. For example, the organic salt compound (A) and the layered clay mineral (B), and a redox couple or an organic solvent that may be optionally contained are mixed, and a ball mill is mixed. , Sand mill, pigment disperser, pulverizer, ultrasonic disperser, homogenizer, planetary mixer, Hobart mixer, roll, kneader, etc., thoroughly mixed at room temperature or under heating (eg 40-150 ° C.) It can be produced by dispersing (kneading).
Here, for the mixing, an organic solvent (for example, toluene or the like) may be used in combination as necessary, and the organic solvent may be distilled off after mixing.

[Photoelectric conversion element, dye-sensitized solar cell]
Next, the photoelectric conversion element and the dye-sensitized solar cell of the present invention will be described in detail with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of the basic configuration of the photoelectric conversion element of the present invention.

  The photoelectric conversion element of the present invention includes a photoelectrode having a transparent conductive film and a metal oxide semiconductor porous film, a counter electrode disposed to face the photoelectrode, and the photoelectrode and the counter electrode. And an electrolyte layer disposed thereon.

[Photoelectrode]
For example, as shown in FIG. 1, the photoelectrode includes a transparent substrate 1, a transparent conductive film 2, and an oxide semiconductor porous film 3.
Here, the transparent substrate 1 preferably has good light transmittance. Specific examples thereof include a glass substrate, polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyphenylene sulfide, and cyclic olefin polymer. And resin substrates (films) such as polyethersulfone, polysulfone, polyetherimide, polyarylate, triacetylcellulose, and polymethylmethacrylate.

As the transparent conductive film 2, specifically, for example, conductive metal oxides such as tin oxide doped with antimony or fluorine, zinc oxide doped with aluminum or gallium, indium oxide doped with tin, etc. Is mentioned.
Moreover, it is preferable that the thickness of the transparent conductive film 2 is about 0.01 to 1.0 μm.
Furthermore, the method for providing the transparent conductive film 2 is not particularly limited, and examples thereof include a coating method, a sputtering method, a vacuum deposition method, a spray pyrolysis method, a chemical vapor deposition method (CVD), and a sol-gel method.

Next, the oxide semiconductor porous film 3 is obtained by applying a dispersion of oxide semiconductor fine particles on the transparent conductive film 2.
Specific examples of the oxide semiconductor fine particles include titanium oxide, tin oxide, zinc oxide, tungsten oxide, zirconium oxide, hafnium oxide, strontium oxide, vanadium oxide, niobium oxide, and the like. You may use independently and may use 2 or more types together.

The dispersion is obtained by mixing the oxide semiconductor fine particles and the dispersion medium with a dispersing machine such as a sand mill, a bead mill, a ball mill, a three roll mill, a colloid mill, an ultrasonic homogenizer, a Henschel mixer, or a jet mill.
The dispersion is preferably obtained by mixing with a disperser and then subjected to ultrasonic treatment using an ultrasonic homogenizer or the like immediately before use (coating). By performing ultrasonic treatment immediately before use, the photoelectric conversion efficiency of the photoelectric conversion element of the present invention becomes better. This is because the oxide semiconductor porous film formed using a dispersion subjected to ultrasonic treatment immediately before use is easily filled with the electrolyte of the present invention containing the organic salt compound (A), This is thought to be due to an increase in dye adsorption capacity.
Furthermore, in order to prevent re-aggregation of the oxide semiconductor fine particles in the dispersion, acetylacetone, hydrochloric acid, nitric acid, a surfactant, a chelating agent, or the like may be added to the dispersion. Therefore, a polymer such as polyethylene oxide and polyvinyl alcohol, a cellulose-based thickener, or the like may be added.

  Examples of the dispersion include titanium oxide pastes SP100 and SP200 (both manufactured by Showa Denko KK), titanium oxide fine particles Ti-Nanoxide T (manufactured by Solaronics), Ti-Nanoxide D (manufactured by Solaronics), and Ti-Nanoxide T. / SP (manufactured by Solaronics), Ti-Nanoxide D / SP (manufactured by Solaronics), titania coating paste PECC01 (manufactured by Pexel Technologies), titania particle paste PST-18NR, PST-400C It is also possible to use commercially available products such as those manufactured by the same company.

As a method for applying the dispersion on the transparent conductive film, for example, a known wet film forming method can be used.
Specific examples of the wet film forming method include a screen printing method, an ink jet printing method, a roll coating method, a doctor blade method, a spin coating method, and a spray coating method.

In addition, after applying the dispersion onto the transparent conductive film, for the purpose of improving electronic contact between the fine particles, improving adhesion with the transparent conductive film, and improving film strength, heat treatment, chemical treatment, plasma, It is preferable to perform ozone treatment or the like.
As temperature of heat processing, it is preferable that it is 40 to 700 degreeC, and it is preferable that it is 40 to 650 degreeC. The time for the heat treatment is not particularly limited, but is usually about 10 seconds to 24 hours.
Specific examples of the chemical treatment include chemical plating treatment using a titanium tetrachloride aqueous solution, chemical adsorption treatment using a carboxylic acid derivative, and electrochemical plating treatment using a titanium trichloride aqueous solution.

[Counter electrode]
As shown in FIG. 1, the counter electrode is an electrode 5 disposed to face the photoelectrode 4. For example, a metal substrate, a glass substrate having a conductive film on the surface, a resin substrate, or the like can be used. .
As the metal substrate, metals such as platinum, gold, silver, copper, aluminum, indium, and titanium can be used. As the resin substrate, in addition to the substrate (film) exemplified as the transparent substrate 1 constituting the photoelectrode 4, a general resin substrate which is opaque or inferior in transparency can also be used.
As the conductive film provided on the surface, platinum, gold, silver, copper, aluminum, indium, titanium, magnesium, molybdenum and other metals; carbon; tin oxide doped with tin oxide, antimony and fluorine, zinc oxide, aluminum And conductive metal oxides such as zinc oxide doped with gallium and indium oxide doped with tin. The thickness and formation method of the conductive film can be the same as those of the transparent conductive film 2 constituting the photoelectrode 4.

In the present invention, the counter electrode 5 may be an electrode in which a conductive polymer film is formed on a substrate or a conductive polymer film electrode.
Specific examples of the conductive polymer include polythiophene, polypyrrole, polyaniline, and the like.
As a method for forming a conductive polymer film on a substrate, a conductive polymer film is formed on a substrate from a polymer dispersion using a dipping method, a spin coating method, or the like that is usually known as a wet film formation method. be able to.
Examples of conductive polymer dispersions include polyaniline dispersions disclosed in JP-A No. 2006-169291, polythiophene derivative aqueous dispersions (Vitron P, manufactured by Bayer) which are commercially available products, Mitsubishi Rayon Co., Ltd. (Aquasave, polyaniline). Derivative aqueous solution) and the like can be used.
When the substrate is the conductive substrate, a conductive polymer film can be formed on the substrate by an electrolytic polymerization method in addition to the above method. Conductive polymer film electrode is a casting that is usually known as a wet film-forming method from a self-supporting film or a conductive polymer dispersion obtained by peeling off a conductive polymer film formed on an electrode by electrolytic polymerization. It is also possible to use a self-supporting film formed using a method or a spin coating method. The conductive polymer dispersion referred to here is a conductive polymer dispersion in which conductive polymer fine particles are dispersed in a solvent and a conductive polymer is dissolved in a solvent. A functional polymer dispersion.

(Electrolyte layer)
As shown in FIG. 1, the electrolyte layer is an electrolyte layer 6 provided between the photoelectrode 4 and the counter electrode 5, and the above-described electrolyte of the present invention is used in the photoelectric conversion element of the present invention.

  Since the photoelectric conversion element of the present invention uses the above-described electrolyte of the present invention, high photoelectric conversion efficiency can be achieved.

The dye-sensitized solar cell of the present invention is one type of photoelectric conversion element in which a photosensitizing dye is supported on the photoelectrode that constitutes the above-described photoelectric conversion element of the present invention.
Here, the photosensitizing dye is not particularly limited as long as it is a dye having absorption in the visible light region and / or the infrared light region, and a metal complex, an organic dye, or the like can be used.

  Specific examples of the metal complex include a ruthenium complex dye (see the following formula) coordinated with a ligand such as a bipyridine structure or a terpyridine structure, an iron complex dye, an osmium complex dye, a platinum complex dye, or an iridium complex dye. Further, metal phthalocyanine, metal porphyrin, and the like can be used.

  On the other hand, as the organic dye, specifically, for example, porphyrin dye, phthalocyanine dye, cyanine dye, merocyanine dye, xanthene dye, coumarin dye, indole dye, fluorene dye, triphenylamine System dyes can be used.

  The method for supporting the photosensitizing dye is not particularly limited. For example, the dye is dissolved in water, an alcohol solvent, a nitrile solvent, and the oxide semiconductor porous film 3 is immersed in the dye solution or the dye solution. Is supported on the oxide semiconductor porous film 3 by coating.

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

[Examples 1-6, Comparative Examples 1-3]
<Preparation of electrolyte>
In the mixing container, the components shown in Table 1 below were stirred and mixed at the composition ratio (parts by mass) shown in Table 1 to prepare an electrolyte.
Specifically, the layered clay mineral shown in Table 1 is added to the mixed solution of the organic salt compounds shown in Table 1 with stirring at the composition ratio shown in Table 1, and the layered clay mineral is swollen and dispersed in advance. A gelled substance (organic salt compound / clay complex) was obtained.
Next, iodine shown in Table 1 and N-methylbenzimidazole were added to the obtained composite at a composition ratio shown in Table 1 and mixed.

<Cation conversion (a1 / A)>
For each Example and Comparative Example, the cation mass of the organic salt compound 1 (corresponding to the organic salt compound (a1)) relative to the total cation mass of the organic salt compounds 1 to 3 (corresponding to the organic salt compound (A)) used. Was determined as “cation conversion (a1 / A)” ([mass%]). The cation mass of each organic salt compound was calculated from the ratio of the molecular weight of the imidazolium cation to the molecular weight of the organic salt compound.

<Preparation of dye-sensitized solar cell>
A titanium oxide paste Ti-Nanoxide D (manufactured by Solaronix) is applied onto transparent conductive glass (FTO glass, surface resistance 15Ω / □, manufactured by Nippon Sheet Glass Co., Ltd.), dried at room temperature, and then heated to 450 ° C. Was sintered for 30 minutes to produce a photoelectrode in which a porous titanium oxide film was formed on transparent conductive glass.
The produced photoelectrode was converted into a ruthenium complex dye (cis- (diisothiocyanate) -N, N′-bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium (II) complex) (Ruthenium). It was immersed in a butyl alcohol / acetonitrile solution (volume ratio: 1/1, concentration 3 × 10 ⁻⁴ mol / L) of 535-bisTBA (manufactured by Solaronix) for 4 hours.
Then, it wash | cleaned with acetonitrile, and what carried the sensitizing dye on the titanium oxide electrode of the photoelectrode by drying under nitrogen stream in the dark place was used as a photoelectrode.
The electrolyte prepared above is applied on the photoelectrode carrying the photosensitizing dye, and this is and a transparent conductive glass substrate (indium oxide doped with tin on the conductive surface, sheet resistance: 8Ω / □, manufactured by Nippon Sheet Glass Co., Ltd.) A platinum counter electrode having a surface formed with a platinum thin film having a thickness of about 100 nm by sputtering was bonded together. At the time of bonding, a dye-sensitized solar cell (photosensitizing dye: photosensitizing dye :) is prepared by interposing a heat-sealing film between the photoelectrode and the platinum counter electrode and heat-sealing at 150 ° C. Ruthenium complex dye) was obtained.

<Evaluation>
About the obtained dye-sensitized solar cell, the photoelectric conversion efficiency and its maintenance factor were measured and evaluated by the method shown below, respectively. The results are shown in Table 1 below.

<Photoelectric conversion efficiency>
As shown in FIG. 2, a solar simulator is used as a light source, and AM1.5 simulated sunlight is irradiated from the photoelectrode side with a light intensity of 100 mW / cm ² , and a current-voltage measuring device (Digital Source Meter 2400 manufactured by Keithley Instruments Co., Ltd.). ) To obtain the conversion efficiency [%].

<Moisture resistance (maintenance rate)>
The dye-sensitized solar cell whose photoelectric conversion efficiency was measured was allowed to stand for 1000 hours under the conditions of 40 ° C. and 85% RH. Thereafter, the photoelectric conversion efficiency was measured by the same method as described above, and the maintenance rate (photoelectricity after humidification) Conversion efficiency / photoelectric conversion efficiency before humidification × 100) [%] was calculated.
As a result, if the maintenance rate of photoelectric conversion efficiency is 80% or more, it can be evaluated that the moisture resistance is excellent.

<Moisture and heat resistance (maintenance rate)>
The dye-sensitized solar cell whose photoelectric conversion efficiency was measured was allowed to stand for 1000 hours under the conditions of 85 ° C. and 85% RH. Thereafter, the photoelectric conversion efficiency was measured by the same method as described above, and the retention rate (photoelectricity after humidification) Conversion efficiency / photoelectric conversion efficiency before humidification × 100) [%] was calculated.
As a result, if the maintenance ratio of photoelectric conversion efficiency is 80 [%] or more, it can be evaluated that the heat and moisture resistance is excellent.

The following components were used as the components in Table 1 and the like.
Organic salt compound 1 (MOctImI): 1-methyl-3-octylimidazolium iodide (specific gravity: 1.335 g / cm ³ , manufactured by Merck & Co., Inc.)
Organic salt compound 2 (MPImI): 1-methyl-3-propylimidazolium iodide (specific gravity: 1.536 g / cm ³ , manufactured by Tokyo Chemical Industry Co., Ltd.)
Organic salt compound 3 (EMImSCN): 1-ethyl-3-methylimidazolium thiocyanate (specific gravity: 1.115 g / cm ³ , manufactured by Merck)

Layered clay mineral 1: First, 3-trimethoxy obtained by the Finkelstein reaction (TW Baughman, JC Sworen, KB Wagener, Tetrahedron, 2004, 60, 10943.) using 3-trimethoxysilylpropyl chloride as a starting material. 3- [3- (trimethoxysilyl) propyl] -1-methylimidazolium iodide was synthesized by reacting silylpropyl iodide with 1-methylimidazole in toluene.
Subsequently, the synthesized 3- [3- (trimethoxysilyl) propyl] -1-methylimidazolium iodide and synthetic smectite (trade name: Lucentite SWN, average particle size: 0.02-0.05 μm, Corp Chemical The layered clay mineral 1 was prepared by stirring at 60 ° C. in toluene.

Layered clay mineral 2: Synthetic smectite [trade name: Lucentite SPN [Organized layered clay mineral obtained by organizing Lucentite SWN (average particle size: 0.02 to 0.05 μm, manufactured by Corp Chemical)], Cope Chemical Company]
Layered clay mineral 3: Silane-treated organic bentonite treated with quaternary ammonium and alkyltrialkoxysilane (manufactured by Hojun Co.)

Polyvalent onium salt compound: A diimidazolium salt synthesized by reacting N-methylimidazolium and 1,6-diiodohexane in toluene at 80 ° C. for 16 hours according to the following reaction formula was used.

As is clear from the results shown in Table 1, it was found that all of Examples 1 to 6 have high photoelectric conversion efficiency.
In particular, Examples 1-4 in which a specific amount of the organic salt compound (a1) is blended have good moisture resistance, and Examples 1-3, in which an organic salt compound having a thiocyanate anion is blended, also have good heat and heat resistance. I found out that
On the other hand, Comparative Examples 1 to 3 using layered clay minerals having no onium base are blended in the same amount of organic salt compounds 1 to 3, and compared with Example 3 in which the same amount of layered clay mineral is blended. The photoelectric conversion efficiency was found to be slightly inferior. In addition, it was found that Comparative Example 3 using a layered clay mineral having an alkylsilyl group had good moisture resistance and heat and heat resistance although the photoelectric conversion efficiency was slightly inferior.

1: transparent substrate 2: transparent conductive film 3: oxide semiconductor porous film 4: photoelectrode 5: counter electrode 6: electrolyte layer 11: transparent substrate 12: transparent conductive film (ITO, FTO)
13: Metal oxide 14: Electrolyte 15: Platinum thin film 16: Transparent conductive film (ITO, FTO)
17: Substrate 18: Counter electrode

Claims (6)

An electrolyte for a photoelectric conversion element comprising an organic salt compound (A) having a tertiary or quaternary cation and a layered clay mineral (B),
The layered clay mineral (B) is, have a onium salt through a covalent bond,
The electrolyte for a photoelectric conversion element , wherein the onium salt is at least one selected from the group consisting of an imidazolium salt, a pyridinium salt, a pyrrolidinium salt, a piperidinium salt, an ammonium salt, a sulfonium salt, and a phosphonium salt . The electrolyte for photoelectric conversion elements according to claim 1, wherein the organic salt compound (A) has a cation represented by the following formula (1) or (2).
(In the formula (1), R ¹ represents a hydrocarbon group which may contain a hetero atom having 1 to 20 carbon atoms, having a substituent group which may contain a hetero atom having 1 to 20 carbon atoms R ² and R ³ each independently represents a hydrogen atom or a hydrocarbon group that may contain a heteroatom having 1 to 20 carbon atoms, provided that when the nitrogen atom contains a double bond, R ³ does not exist.
In the formula (2), Q represents a nitrogen atom, an oxygen atom, a phosphorus atom or a sulfur atom, and R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom or a hetero atom having 1 to 20 carbon atoms. Represents a hydrocarbon group which may contain However, when Q is an oxygen atom or a sulfur atom, R ⁷ does not exist, and when Q is a sulfur atom, R ⁴ and R ⁵ may be linked. ) The organic salt compound (A) contains the organic salt compound (a1) in excess of 50% by mass in terms of cation,
In the organic salt compound (a1), at least one of substituents R ² and R ³ which R ¹ in the formula (1) may have contains a heteroatom having 5 to 20 carbon atoms. Or a compound representing a hydrocarbon group, or a hydrocarbon in which at least one of R ⁴ , R ⁵ , R ⁶ and R ⁷ in formula (2) contains a heteroatom having 5 to 20 carbon atoms The electrolyte for photoelectric conversion elements according to claim 2 , which is a compound representing a group. The organic salt compound (A) has a thiocyanate anion, a photoelectric conversion element for electrolyte according to any one of claims 1-3. A photoelectrode having a transparent conductive film and a metal oxide semiconductor porous film;
A counter electrode disposed to face the photoelectrode;
An electrolyte layer disposed between the photoelectrode and the counter electrode,
The photoelectric conversion element whose said electrolyte layer is the electrolyte for photoelectric conversion elements in any one of Claims 1-4 . A dye-sensitized solar cell obtained by supporting a photosensitizing dye on the photoelectrode according to claim 5 .