JP2016192502A - Dye-sensitized solar cell element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dye-sensitized solar cell element capable of obtaining higher photoelectric conversion efficiency than that of a conventional dye-sensitized solar cell element under a low illuminance environment.SOLUTION: A dye-sensitized solar cell element comprises a semiconductor electrode and a counter electrode that is disposed oppositely to the semiconductor electrode, and includes an electrolyte layer between the semiconductor electrode and the counter electrode. In the dye-sensitized solar cell element, the counter electrode contains a transition metal. The electrolyte layer contains a polyether compound having a repetition unit of a specific structure having an onium ion containing a cationic nitrogen atom. The polyether compound contains the repetition unit of the specific structure in 40 mol% or less in all the repetition units.SELECTED DRAWING: None

Description

  The present invention relates to a dye-sensitized solar cell element, and more particularly to a dye-sensitized solar cell element that can obtain high photoelectric conversion efficiency in a low illumination environment.

  In recent years, a dye-sensitized solar cell element in which a sensitizing dye that absorbs a visible light region is supported on a semiconductor layer has been studied. This dye-sensitized solar cell element has advantages such as being inexpensive and capable of being manufactured by a relatively simple process, and is expected to be put to practical use.

The dye-sensitized solar cell element is made of a metal oxide such as titanium oxide on a transparent substrate such as glass on which a transparent conductive film such as a mixture of tin oxide and indium oxide (hereinafter abbreviated as “ITO”) is formed. An anode electrode (semiconductor electrode) in which a porous film layer of a semiconductor is formed and a sensitizing dye such as a ruthenium dye is adsorbed on the surface of the metal oxide semiconductor particle, and a glass or the like on which a transparent conductive film such as ITO is formed A cathode electrode (counter electrode) having a catalyst layer formed on a substrate is disposed so that the porous membrane layer and the catalyst layer face each other, and an ionic electrolyte such as lithium iodide and a charge carrier such as iodine are dissolved therebetween. The electrolyte layer component is sealed.
When the semiconductor electrode is irradiated with visible light, the sensitizing dye molecule absorbs light and is excited, electrons flow from the sensitizing dye molecule through the metal oxide semiconductor to the semiconductor electrode, and an electric current is extracted outside.
On the other hand, the oxidized form of the sensitizing dye molecule that has lost the electrons receives electrons from the iodide ions of the electrolyte in the electrolyte solution, and is reduced and regenerated. The oxidized electrolyte ions are reduced by the catalyst layer on the surface of the counter electrode, and the cycle goes around. As the catalyst layer material of the counter electrode, a material having an appropriate band gap for transferring electrons to iodide ions is preferable, and various transition metals and nanocarbon materials are used. The iodide salt and iodine in the electrolyte solution form I ⁻ and I ₃ ⁻ in the electrolyte solution, and function as charge carriers between the two electrodes.
In addition, as a solvent for the electrolyte solution, a polar solvent such as methoxyacetonitrile or acetonitrile is generally used.

In recent years, a high-performance dye-sensitized solar cell element has been obtained by using an ionic liquid as an electrolyte. As the ionic liquid, a salt compound having an onium cation as an organic cation and an iodide ion or a triiodide ion as a counter anion, which is a liquid at room temperature, is used. When an ionic liquid is used as an electrolyte or electrolyte, the basic performance such as photoelectric conversion efficiency is good, but it is not sufficient, and because it is a liquid, there is a risk of leakage, so there is a prescription such as physical gelation. Necessary (Patent Document 1).
On the other hand, an electrolyte composition for a dye-sensitized solar cell element using a cationic polymer as an electrolyte has been studied (Patent Document 2, Patent Document 3, and Patent Document 4). However, these properties as a polymer electrolyte remain non-flowable or non-volatile, or even if an oligomer chain is introduced, the chain length is very short, so the performance as a low molecular ionic liquid remains. However, no significant improvement has been seen in the basic performance of the electromotive device such as the photoelectric conversion efficiency compared to the conventional electrolyte.

Patent 2004-319197 JP 2002-246066 A International Publication No. 2004/112184 JP 2001-256828 A

As described above, a practical dye-sensitized solar cell element that exhibits sufficient photoelectric conversion efficiency is provided, although improvement of each element constituting the dye-sensitized solar cell element has been studied so far. It is difficult to say that it is. In particular, in recent years, from the viewpoint of energy harvesting, there has been a demand for a self-supporting power source that does not require an external power source, and not only in high-light environments such as outdoors but also in low-light environments such as indoors. However, there is a need for a dye-sensitized solar cell element that exhibits sufficient photoelectric conversion efficiency.
Then, an object of this invention is to provide the dye-sensitized solar cell element from which a photoelectric conversion efficiency higher than the conventional dye-sensitized solar cell element is obtained in a low illumination intensity environment.

  As a result of diligent study, the inventors of the present invention have obtained a dye-sensitized solar cell element using a counter electrode containing a transition metal and an electrolyte layer containing a polyether compound containing a specific structural unit at a specific ratio. However, the present inventors have found that a dye-sensitized solar cell element that exhibits higher photoelectric conversion efficiency than a conventional dye-sensitized solar cell element can be obtained, and thus completed the present invention.

（式（１）中、Ａ^＋はカチオン性の窒素原子を含有するオニウムイオン構造を有する基であり、Ｘ⁻は対アニオンである。） Thus, according to the present invention, there is provided a dye-sensitized solar cell element including a semiconductor electrode and a counter electrode disposed to face the semiconductor electrode, and having an electrolyte layer between the semiconductor electrode and the counter electrode. The counter electrode contains a transition metal, and the electrolyte layer contains a polyether compound having a repeating unit represented by the following formula (1). In the polyether compound, A dye-sensitized solar cell element characterized by containing 40 mol% or less of a repeating unit represented by the following formula (1) in all repeating units is provided.

(In Formula (1), A ⁺ is a group having an onium ion structure containing a cationic nitrogen atom, and X ⁻ is a counter anion.)

  ADVANTAGE OF THE INVENTION According to this invention, the dye-sensitized solar cell element which can obtain a photoelectric conversion efficiency higher than the conventional dye-sensitized solar cell element in a low illumination intensity environment is provided.

（式（１）中、Ａ^＋はカチオン性の窒素原子を含有するオニウムイオン構造を有する基であり、Ｘ⁻は対アニオンである。）
以下、要素毎に、詳細に説明する。 The dye-sensitized solar cell element of the present invention includes a semiconductor electrode and a counter electrode disposed so as to face the semiconductor electrode, and has a electrolyte layer between the semiconductor electrode and the counter electrode. In the battery element, the counter electrode contains a transition metal, the electrolyte layer contains a polyether compound having a repeating unit represented by the following formula (1), The ether compound contains 40 mol% or less of a repeating unit represented by the following formula (1) in all repeating units.

(In Formula (1), A ⁺ is a group having an onium ion structure containing a cationic nitrogen atom, and X ⁻ is a counter anion.)
Hereinafter, each element will be described in detail.

1) Semiconductor electrode (anode electrode)
The semiconductor electrode used in the present invention preferably has a metal oxide semiconductor porous film carrying a dye on an electrode substrate. Since the electrode substrate needs to transmit external light to the metal oxide semiconductor porous film on which the dye is supported, a substrate in which a transparent conductive film is formed on the surface of the transparent substrate is usually used.

(Transparent substrate)
As the transparent substrate, those that transmit visible light (light having a wavelength of about 380 nm to 810 nm, the same applies hereinafter) can be used, and those having a total light transmittance of 80% or more are preferable. As the transparent substrate, transparent glass, a transparent plastic plate, a transparent plastic film, or the like can be suitably used. Further, a glass surface processed to scatter incident light, a translucent ground glass, a translucent plastic plate, a plastic film, or the like can be used.
The thickness of the transparent substrate is not particularly limited because it varies depending on the shape and use conditions of the solar cell. For example, when glass or plastic is used, the thickness is about 1 mm to 1 cm in consideration of durability during use. Yes, flexibility is required. On the other hand, when a plastic film or the like is used, the thickness is about 25 μm to 1 mm. Further, the transparent substrate may be subjected to surface treatment such as a hard coat for improving weather resistance, if necessary.

(Transparent conductive film)
As the transparent conductive film, one that transmits visible light and has conductivity can be used. Examples of the material for forming such a transparent conductive film include metal oxides and transparent conductive polymer materials. Preferable specific examples include tin oxide doped with fluorine (hereinafter sometimes abbreviated as “FTO”), tin oxide doped with antimony (hereinafter sometimes abbreviated as “ATO”), and indium oxide. , ITO, zinc oxide, PEDOT / PSS (Poly (3,4-ethylenedithiothiophene): poly (4-styrenesulfonic acid), and the like.

  Further, the transmissivity of the electrode substrate as a whole could be increased by forming a thin conductive material such as a mesh shape on a transparent substrate, such as a treatment method in which a conductive material is dispersedly supported. For example, an opaque conductive material can be used. Such materials include carbon materials and metals. Although it does not specifically limit as a carbon material, For example, a nano carbon material etc. are mentioned. Further, the metal is not particularly limited, and examples thereof include platinum, gold, silver, copper, aluminum, nickel, cobalt, chromium, iron, molybdenum, titanium, tantalum, niobium, and alloys thereof.

  Examples of a method for forming a transparent conductive film on the surface of a transparent substrate using a metal oxide include a sol-gel method, a vapor phase method such as sputtering or CVD, and coating of a dispersion paste. Moreover, when using an opaque electroconductive material, the method of fixing powder etc. with a transparent binder etc. is mentioned.

  The thickness of the transparent conductive film is not particularly limited because the conductivity varies depending on the material used. For example, in the case of commonly used glass with an FTO coating, the thickness of the FTO coating is 0.01 to 5 μm, preferably 0.1 to 1 μm. Further, the required conductivity varies depending on the area of the electrode substrate to be used, and the larger area electrode substrate is required to have lower resistance. Generally, it is 100Ω / □ or less, preferably 10Ω / □ or less, more preferably 5Ω / □ or less. Exceeding 100Ω / □ is not preferable because the internal resistance of the solar cell element increases.

(Metal oxide semiconductor porous film carrying dye)
A conventionally well-known thing can be used as a metal oxide semiconductor which comprises a metal oxide semiconductor porous film. That is, oxides of transition metals such as Ti, Nb, Zn, Sn, Zr, Y, La, and Ta; perovskite oxides such as SrTiO ₃ and CaTiO ₃ ; Among these, titanium oxide, zinc oxide, and tin oxide are preferable, titanium dioxide is more preferable, and anatase type titanium dioxide is particularly preferable.

  The metal oxide semiconductor porous film can be formed on the transparent conductive film of the electrode substrate by a known method. Examples of the method for forming the metal oxide semiconductor porous film include a sol-gel method, application of a dispersion paste of metal oxide semiconductor particles, electrodeposition and electrodeposition.

The metal oxide semiconductor porous film preferably has few metal oxide grain boundaries in order to lower the electric resistance value, and it is desirable to sinter the applied metal oxide semiconductor particles. Sintering conditions vary depending on the type and formation method of the metal oxide semiconductor to be used and the heat-resistant temperature of the electrode substrate, and can be appropriately selected.
In addition, in the case of using metal oxide semiconductor particles, it is desirable to increase the light absorption amount of the dye so that the particle diameter of the metal oxide semiconductor particles to be used is wide to facilitate light scattering.

The specific surface area of the metal oxide semiconductor porous film is preferably 10 to ²⁰⁰ m ² / g so that more pigment can be supported.
The thickness of the metal oxide semiconductor porous film is not particularly limited because the optimum value varies depending on the type of metal oxide semiconductor used and its property, but is preferably 0.1 to 50 μm, more preferably 5 to 30 μm.

(Dye)
The dye used (may be referred to as “sensitizing dye”) may be any dye that can be excited by sunlight and can inject electrons into the metal oxide semiconductor, and is usually used in dye-sensitized solar cells. Can be used. In order to improve the photoelectric conversion efficiency, it is preferable that the absorption spectrum overlaps with the sunlight spectrum in a wide wavelength region. From the viewpoint of durability, a dye having high light resistance is preferred.

The dye to be used is not particularly limited, but a ruthenium complex is preferable, a ruthenium polypyridine complex is more preferable, and a ruthenium complex represented by the formula: Ru (L) (L ′) (X) ₂ is more preferable. Here, L is 4,4′-dicarboxy-2,2′-bipyridine, a quaternary ammonium salt thereof, or a polypyridine ligand into which a carboxyl group is introduced, and L ′ is the same as L. Or 4,4′-substituted 2,2′-bipyridine. Examples of the substituent at the 4,4 ′ position of L ′ include a long-chain alkyl group (alkyl group having 6 to 20 carbon atoms), an alkyl-substituted vinylthienyl group, an alkyl or alkoxy-substituted styryl group, and a thienyl group derivative. X is SCN, Cl, or CN. More specifically, bis (4,4′-dicarboxy-2,2′-bipyridine) diisothiocyanate ruthenium complex and the like can be mentioned.

  In addition, as a dye, metal complex dyes other than ruthenium such as iron complex dyes and copper complex dyes; cyan dyes, porphyrin dyes, polyene dyes, coumarin dyes, cyanine dyes, squarylium dyes, styryl dyes, eosin Other dyes such as organic dyes such as system dyes can also be used. These pigment | dyes can be used individually by 1 type or in combination of 2 or more types.

  In addition, these dyes preferably have a bonding group with the metal oxide semiconductor in order to improve the efficiency of electron injection into the metal oxide semiconductor. The linking group is not particularly limited, and examples thereof include a carboxyl group and a sulfonyl group.

  A method for supporting the dye on the metal oxide semiconductor is not particularly limited. For example, a method of immersing a metal oxide semiconductor porous film formed on a transparent conductive film in a solution in which a dye is dissolved at room temperature and atmospheric pressure can be given. The immersion time is appropriately adjusted so that a monomolecular film of the dye is uniformly formed on the surface of the metal oxide semiconductor according to the type of the metal oxide semiconductor, the dye and the solvent, the dye concentration, and the like. In addition, in order to perform carrying | supporting effectively, immersion can also be performed under heating.

  The dye molecules are preferably not associated on the surface of the metal oxide semiconductor. If association occurs when the dye is supported alone, a co-adsorbent can be used as necessary. The coadsorbent to be used is not particularly limited because the optimum kind and concentration varies depending on the dye to be used, and examples thereof include organic carboxylic acids such as deoxycholic acid. When using a co-adsorbent, it is not particularly limited, but the co-adsorption is performed simultaneously with the loading of the dye by immersing the metal oxide semiconductor porous film after dissolving the co-adsorbent together with the dye in a solvent that dissolves the dye. The agent can be adsorbed.

Solvents used for dissolving the dye include alcohols such as ethanol and t-butyl alcohol; nitriles such as acetonitrile; ketones such as acetone; ethers such as diethyl ether; halogenated hydrocarbons such as chloroform; Examples thereof include aliphatic hydrocarbons such as n-hexane; aromatic hydrocarbons such as benzene; esters such as ethyl acetate; The concentration of the dye in the solution is desirably adjusted as appropriate depending on the type of the dye and the solvent used, and a concentration of 5 × 10 ⁻⁵ mol / L or more is preferable.

2. Counter electrode (cathode electrode)
The counter electrode used by this invention is arrange | positioned facing the said semiconductor electrode, and contains a transition metal. Usually, the counter electrode has a structure in which a support base, a conductive layer, and a catalyst layer are laminated in this order. A transition metal is a component which comprises a catalyst layer among them.

(Supporting substrate)
Although it does not specifically limit as a support base | substrate, For example, when transparency is calculated | required, glass and a transparent plastic resin board can be used. Further, a plastic resin plate can be used when light weight is required, and a plastic resin film or the like can be used when flexible.

  The thickness of the support substrate is not particularly limited because it varies depending on the shape and use conditions of the counter electrode. For example, when glass or plastic is used, it is about 1 mm to 1 cm in consideration of durability during actual use, and flexibility is required. On the other hand, when a plastic film or the like is used, the thickness is about 25 μm to 1 mm. Moreover, you may perform the process of a hard coat etc. which improve a weather resistance, and a film attachment process as needed.

(Conductive layer)
As a material constituting the conductive layer, a material having high electrical conductivity is preferably used in order to reduce the internal resistance of the solar cell element.
Examples of such materials include metals or alloys such as chromium, nickel, titanium, tantalum, niobium, stainless steel, and aluminum, which are alloys thereof, and conductive metals such as ITO, FTO, and ATO. Oxides; and the like.

  Examples of a method for forming a conductive film on the surface of a supporting substrate using a metal oxide include a sol-gel method, a sputtering method, a vapor phase method such as CVD, and a coating of a dispersion paste. Moreover, when using an opaque electroconductive material, the method of adhering powder etc. with a transparent binder etc. is mentioned.

The thickness of the conductive layer is appropriately selected according to the type of material used, the shape when used as an electrode, and usage conditions. When practical strength is maintained by using the support substrate, a thickness of about 100 nm may be used as long as the conductivity necessary for use as an electrode is ensured.
In addition, when a metal or alloy is used as the material of the conductive layer, for example, by setting the thickness to about 1 to 10 mm so that practical strength is maintained only by the conductive layer, the electrode is used without using a support. Can also be configured.
The conductivity required at this time varies depending on the area of the electrode to be used, and the larger area electrode is required to have lower resistance. The required conductivity is usually 100Ω / □ or less, preferably 5Ω / □ or less, more preferably 1Ω / □ or less. If it exceeds 100Ω / □, the internal resistance of the solar cell increases, which is not preferable.

<Catalyst layer>
In the present invention, a transition metal is used as the material constituting the catalyst layer. By using a transition metal as a constituent material of the catalyst layer, an oxidized form of a redox pair in the electrolyte layer described later can be efficiently reduced.

  The transition metal to be a catalyst that is a constituent material of the catalyst layer is not particularly limited, but platinum, palladium, ruthenium, rhodium, or an alloy thereof is preferable, from the viewpoint of excellent reduction performance and corrosion resistance, platinum, Or a platinum alloy is more preferable.

  The catalyst layer is usually formed on the conductive layer. As a method for forming a catalyst layer containing a transition metal on a conductive layer, a conventionally known method can be adopted. For example, a method of directly forming by sputtering, vapor deposition, or electrodeposition; a precursor such as chloroplatinic acid Can be used.

3. Electrolyte Layer The dye-sensitized solar cell element of the present invention has an electrolyte layer between the semiconductor electrode and the counter electrode. The electrolyte layer contains a polyether compound having a repeating unit represented by the following formula (1) (hereinafter sometimes referred to as “polyether compound”). In the repeating unit, 40 mol% or less of the repeating unit represented by the following formula (1) is contained.
Here, the semiconductor electrode and the counter electrode are arranged so that the metal oxide semiconductor porous film carrying the dye in the semiconductor electrode and the catalyst layer of the counter electrode face each other.

(Polyether compound)
In the present invention, the polyether compound constituting the electrolyte layer has a repeating unit represented by the following formula (1) (hereinafter sometimes referred to as “repeating unit (1)”), and in all the repeating units, A compound containing 40 mol% or less.

（式（１）中、Ａ^＋はカチオン性の窒素原子を含有するオニウムイオン構造を有する基であり、Ｘ⁻は対アニオンである。）

(In Formula (1), A ⁺ is a group having an onium ion structure containing a cationic nitrogen atom, and X ⁻ is a counter anion.)

In the formula (1), the onium ion structure containing a cationic nitrogen atom includes trimethylammonium, triethylammonium, n-butyldimethylammonium, n-octyldimethylammonium, n-stearyldimethylammonium, tributylammonium, trivinylammonium. , Triethanolammonium, 1-pyrrolidinium, imidazolium, N, N′-dimethylethanolammonium, tri (2-ethoxyethyl) ammonium, N, N′-dimethylanilinium and the like: N ⁺ R ¹ R ² R ³ (R ¹ , R ² and R ³ each independently have an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a hydroxyalkyl group having 1 to 20 carbon atoms, or a substituent. Represents a phenyl group which may be substituted.) Nmo ion structure; 1-methyl imidazolium, 1-ethyl imidazolium, pyridinium, 2,6-dimethyl pyridinium, quinolinium, etc. thiazolium, onium structure having a nitrogen-containing heterocycle; and the like. Especially, the onium ion structure which has a nitrogen-containing heterocyclic ring is preferable at the point which is excellent in photoelectric conversion efficiency, and the onium ion structure which has an imidazolium ring structure is more preferable.

In the formula (1), X ⁻ is a counter anion of the onium ion (cation) in the formula (1). The counter anion is not particularly limited, but specific examples thereof include halide ions such as Cl ⁻ , Br ⁻ , I ⁻ and I ₃ ⁻ , OH ⁻ , SCN ⁻ , BF ₄ ⁻ , PF ₆ ⁻ and ClO. _{^{4 -, (FSO 2) 2}} N -, (CF 3 SO 2) 2 N -, (CF 3 CF 2 SO 2) 2 N -, CH 3 SO 3 -, CF 3 SO 3 -, CF 3 COO -, PhCOO ^-, and the like. Among these, halide ions are preferable and iodide ions (I ⁻ ) are more preferable in terms of excellent photoelectric conversion efficiency.

  The polyether compound used in the present invention may have any repeating unit (1) and any repeating unit other than the repeating unit (1) as long as it has 40% by mole or less of the repeating unit (1) in all repeating units. You may have. As for the content rate of the repeating unit (1) in a polyether compound, 30 mol% or less is preferable in all the repeating units. On the other hand, the lower limit of the content ratio of the repeating unit (1) in the polyether compound is preferably 5 mol% or more and more preferably 10 mol% or more in all repeating units. When the ratio of the repeating unit (1) in the polyether compound is in the above range, the photoelectric conversion efficiency of the dye-sensitized solar cell element is excellent.

  Examples of the repeating unit other than the repeating unit (1) include nonionic oxirane monomer units (having neither a cationic group nor an anionic group in the main chain and side chain). The nonionic oxirane monomer unit can be divided into an oxirane monomer unit having a crosslinkable group and an oxirane monomer unit having no crosslinkable group.

  The crosslinkable group is not particularly limited as long as it is a group capable of forming a cross-linked structure between molecules by the action of a crosslinking agent or heat, for example, an ethylenic carbon-carbon unsaturated bond-containing group such as a vinyl group or an allyl group. Can be mentioned.

Examples of nonionic oxirane monomer units having a crosslinkable group include ethylenically unsaturated glycidyl ether units such as glycidyl methacrylate units, glycidyl acrylate units, vinyl glycidyl ether units, and allyl glycidyl ether units; butadiene monoepoxide units, Conjugated diene monoepoxide units such as chloroprene monoepoxide units; alkenyl epoxide units such as 1,2-epoxy-5-hexene units; and the like. Among these, from the viewpoint of facilitating the synthesis of the polyether compound, an ethylenically unsaturated glycidyl ether unit is preferable, and among them, a glycidyl methacrylate unit, a glycidyl acrylate unit, and an allyl glycidyl ether unit are particularly preferable.
By including a nonionic oxirane monomer unit having a crosslinkable group, the polyether compound forms a cross-linked structure, and has an effect of preventing volatilization of the solvent from the electrolyte layer or leakage due to breakage.
The content ratio of the nonionic oxirane monomer unit having a crosslinkable group is preferably 35 mol% or less, more preferably 20 mol% or less, based on all repeating units in the polyether compound.

  Nonionic oxirane monomer units having no crosslinkable groups include alkylene oxide monomer units such as ethylene oxide units, propylene oxide units and 1,2-butylene oxide units; aliphatic ring structures such as cyclohexene oxide units Oxirane monomer units containing; epihalohydrin monomer units such as epichlorohydrin units and epibromohydrin units; glycidyl ether monomer units containing ether chains such as methoxyethoxyethyl glycidyl ether units; Can be mentioned. The content of the nonionic oxirane monomer unit having no crosslinkable group is preferably 60 to 95 mol%, more preferably 70 to 90 mol%, based on all repeating units in the polyether compound. .

  When the polyether compound contains a nonionic oxirane monomer unit, the balance is composed of the repeating unit (1). In this case, the bonding mode of each repeating unit may be a block shape or a random shape, but is preferably a random shape.

Although the number average molecular weight (Mn) of the polyether compound used by this invention is not specifically limited, It is preferable that it is 1,000-1,000,000, and it is more preferable that it is 1,000-200,000. Moreover, the molecular weight distribution (Mw / Mn) calculated | required as ratio of the weight average molecular weight (Mw) with respect to the number average molecular weight of a polyether compound is not specifically limited, However, It is 1.0-4.0. Preferably, it is 1.0-3.0.
The number average molecular weight, weight average molecular weight, and molecular weight distribution of the polyether compound can be obtained by measuring the polyether compound by gel permeation chromatography and converting it to polystyrene.

  The method for synthesizing the polyether compound used in the present invention is not particularly limited as long as the objective polyether compound can be obtained. From the viewpoint of obtaining the desired polyether compound more easily, first, a polyether compound containing a halogen group is synthesized, and then an onium compound such as an imidazole compound is reacted to convert the halogen group (halogen atom) to onium. A method in which the halide ion of the onium halide group is further converted to an arbitrary anion by an anion exchange reaction after conversion to a halide group is preferable. This method is disclosed in JP 2012-133786 A and the like. The anion exchange reaction may be performed according to a conventional method. For example, an onium chloride group can be converted into an onium iodide group by bringing an iodide salt into contact with a polyether compound having an onium chloride group.

(Electrolyte layer)
The electrolyte layer in the present invention may be composed only of the polyether compound, but preferably contains a solvent from the viewpoint of ion mobility and ease of production of the dye-sensitized solar cell element.
The solvent is not particularly limited as long as it can dissolve the polyether compound used in the present invention and does not hinder ion conductivity, and a known electrolyte solvent can be used.
Solvents used include nitriles such as acetonitrile, methoxyacetonitrile, methoxypropionitrile, and benzonitrile; cyclic carbonates such as ethylene carbonate and propylene carbonate; chain carbonates such as dimethyl carbonate and diethyl carbonate; and γ-butyrolactone. Lactones; Amides such as N, N-dimethylformamide and N-methylpyrrolidone; Ethers such as ethylene glycol dialkyl ether and propylene glycol dialkyl ether; Alcohols such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether; Ethylene Polyhydric alcohols such as glycol and propylene glycol; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and methyl sulfolane; N, N′-dimethylimidazolide Emissions; N- methyl oxazolidinone; and the like. These can be used individually by 1 type or in mixture of 2 or more types.

  An appropriate concentration of the polyether compound in the electrolyte layer in the present invention can be defined by the onium ion concentration. Here, the onium ion concentration is the molar concentration of the repeating unit represented by the formula (1) in the electrolyte layer. The onium ion concentration is preferably 2.5 mol / L or less, more preferably 0.01 to 2.5 mol / L. When the onium ion concentration is in the above range, the photoelectric conversion efficiency of the dye-sensitized solar cell element is more excellent.

  The electrolyte layer in the present invention may contain an ionic liquid. As the ionic liquid, for example, the cation is 1-methyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-octyl-3-methylimidazolium, Imidazo such as 1-methyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-octyl-2,3-dimethylimidazolium A cation based on pyrium; a pyridinium cation such as 1-methyl-pyridinium, 1-butyl-pyridinium, 1-hexyl-pyridinium; a pyrazolium cation; an aliphatic amine cation; Hexafluoroborate, trifluoromethanesulfonate Fluorinated sulfonic acids; fluorinated carboxylic acids such as trifluoroacetic acid; thiocyanate; dicyanamide; tetracyanoborate; can be exemplified a is one and the like; sulfonyl imide such bisfluorosulfonylimide and bistrifluoromethanesulfonylimide. These can be used individually by 1 type or in combination of 2 or more types.

The electrolyte layer in the present invention may contain an additive capable of forming a redox pair and an additive capable of forming a redox pair with a counter anion in the polyether compound.
As the oxidation-reduction pair, those generally used in dye-sensitized solar cell elements can be used as long as the object of the present invention is not impaired. For example, iodine / iodide ion, bromine / bromide ion and the like can be mentioned. More specifically, iodine and metal iodides such as LiI, NaI and KI, iodide salts of iodine and quaternary imidazolium compounds, iodide salts of iodine and quaternary pyridinium compounds, iodine of tetraalkylammonium compounds and iodine. Iodide / iodide ion pairs such as iodide salts; bromide and metal bromides such as LiBr, NaBr and KBr, bromide salts of bromine and quaternary imidazolium compounds, bromide salts of bromine and quaternary pyridinium compounds, bromine and tetraalkylammonium compounds Bromine / bromide ions such as bromide salts of metal; metal complexes such as ferrocyanate-ferricyanate and ferrocene-ferricinium salt; disulfide compounds and mercapto compounds; hydroquinone; quinone; These can be used alone or in combination of two or more.
On the other hand, iodine, bromine, etc. are mentioned as an additive which can form a redox pair with the counter anion of a polyether compound.
However, in the dye-sensitized solar cell element of the present invention, sufficient photoelectric conversion is possible even without containing an additive capable of forming a redox pair or an additive capable of forming a redox pair with a counter anion in the polyether compound. It is a feature that efficiency can be obtained, and it is preferable not to add these additives to the electrolyte layer in the present invention. That is, it is not necessary to add corrosive iodine or the like to the electrode or the like, and the dye-sensitized solar cell element of the present invention is more excellent in durability and long-term reliability.

The electrolyte layer in the present invention may contain an inorganic salt and / or an organic salt from the viewpoint of improving the short-circuit current and improving the photoelectric conversion efficiency.
Examples of the inorganic salt and organic salt include alkali metal salts, alkaline earth metal salts, and the like. Specifically, lithium iodide, sodium iodide, potassium iodide, magnesium iodide, calcium iodide, Lithium fluoroacetate, sodium trifluoroacetate, lithium thiocyanate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bis (trifluoromethanesulfonyl) imide, guanidine thiocyanate, etc. And guanidine salts. These can be used alone or in combination of two or more.
The addition amount of the inorganic salt or organic salt is not particularly limited, and is appropriately selected unless the object of the present invention is impaired.

The electrolyte layer in the present invention may contain pyridines and benzimidazoles from the viewpoint of improving the open circuit voltage.
Specific examples of these compounds include alkylpyridines such as methylpyridine, ethylpyridine, propylpyridine, and butylpyridine; alkylimidazoles such as methylimidazole, ethylimidazole, and propylimidazole; methylbenzimidazole, ethylbenzimidazole, and butylbenzimidazole. And alkylbenzimidazoles such as propylbenzimidazole; and the like. These can be used alone or in combination of two or more.
The addition amount of these pyridines and benzimidazoles is not particularly limited, and is appropriately selected as long as the object of the present invention is not impaired.

The electrolyte layer in the present invention may contain fine particles. By containing fine particles, thixotropy is expressed, and after producing a dye-sensitized solar cell element, the electrolyte layer becomes solid, pasty or gel-like, and leakage due to evaporation or damage of the solvent from the electrolyte layer The effect which prevents etc. is produced.
The fine particles are not particularly limited, and known materials can be used. Examples thereof include inorganic oxides such as indium oxide, ITO and silica; carbon materials such as ketjen black, carbon black and nanocarbon materials; layered inorganic compounds such as kaolinite and montmorillonite.

  The electrolyte layer in the present invention can be blended with a crosslinking agent when the polyether compound used in the present invention has a crosslinkable group. The crosslinker can be selected to match the characteristics of the crosslinkable group. For example, sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur; sulfur monochloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, dibenzothiazyl disulfide, N, N′-dithio-bis ( Hexahydro-2H-azenopine-2), sulfur-containing compounds such as phosphorus-containing polysulfides and polymer polysulfides; organic peroxides such as dicumyl peroxide and ditertiarybutyl peroxide; p-quinonedioxime, p, p′- Quinone dioximes such as dibenzoylquinone dioxime; various ultraviolet crosslinking agents such as alkylphenone photopolymerization initiators such as 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one; etc. Is mentioned. These crosslinking agents can be used alone or in combination of two or more. What is necessary is just to select the mixture ratio of a crosslinking agent suitably.

  The electrolyte layer according to the present invention can be formed between the semiconductor electrode and the counter electrode by a known method. For example, an electrolyte solution in which a polyether compound is dissolved is dropped onto a metal oxide semiconductor porous film on which a dye in a semiconductor electrode is supported, and then the catalyst layer side of the counter electrode is opposed to the electrolyte solution. The method of sealing electrolyte solution by installing is mentioned.

  In the dye-sensitized solar cell element of the present invention configured as described above, the sensitizing dye is excited by absorbing light by irradiating the semiconductor electrode with visible light, and the metal oxide semiconductor is converted from the sensitizing dye. Via, electrons flow into the semiconductor electrode, and current is taken out to the outside. On the other hand, the oxidized form of the sensitizing dye that has lost the electrons is regenerated by receiving the electrons by the counter anion of the polyether compound constituting the electrolyte layer. The oxidized counter anion is reduced by the transition metal catalyst layer on the surface of the counter electrode, and the cycle goes around. At this time, the dye-sensitized solar cell element of the present invention has a counter electrode containing a transition metal and an electrolyte layer containing a polyether compound having a certain amount of a specific structure, so that it can be used in a low-light environment. Can exhibit higher photoelectric conversion efficiency than conventional dye-sensitized solar cell elements.

The dye-sensitized solar cell elements of the present invention are connected in series and / or in parallel to form a solar cell module.
The number of dye-sensitized solar cell elements is appropriately determined according to the application. Usually, a non-conductive partition is provided between the dye-sensitized solar cell elements, and the semiconductor electrode and the counter electrode of each element are connected by a conductive member to constitute a solar cell module.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited at all by the following examples.

Example 1
[Synthesis of Electrolyte (Polyether Compound 1)]
(Production Example A)
(Living anion copolymerization of propylene oxide and epichlorohydrin)
To a glass reactor equipped with a stirrer substituted with argon, 3.22 g of tetranormalbutylammonium bromide and 50 ml of toluene were added and cooled to 0 ° C. Subsequently, what melt | dissolved 1.370 g of triethylaluminum (1.2 equivalent with respect to tetranormal butyl ammonium bromide) in 10 ml of toluene was added, and it was made to react for 15 minutes. To the obtained catalyst composition, 8.0 g of propylene oxide and 2.0 g of epichlorohydrin were added, and a polymerization reaction was performed at 0 ° C. After the polymerization reaction started, the viscosity of the solution gradually increased. After the reaction for 12 hours, a small amount of isopropyl alcohol was poured into the polymerization reaction solution to stop the reaction. The resulting polymerization reaction solution was washed with a 0.1N aqueous hydrochloric acid solution to deash the catalyst residue, and further washed with ion-exchanged water, and then the organic layer was dried under reduced pressure at 50 ° C. for 12 hours. The yield of the colorless and transparent oily substance thus obtained was 9.9 g. Moreover, the number average molecular weight (Mn) by GPC of the obtained substance was 1,500, and molecular weight distribution was 1.35 (polystyrene conversion). Further, when the obtained oily substance was subjected to ¹ H-NMR measurement, it was found that the oily substance was a 24-mer consisting of 21 propylene oxide units and 3 epichlorohydrin units on average. It could be confirmed. From the above, the obtained oily substance was identified as an oligomer composed of propylene oxide units and epichlorohydrin units having a bromomethyl group at the polymerization initiation terminal and a hydroxyl group at the polymerization termination terminal.

(Production Example B)
(Quaternization of epichlorohydrin unit in copolymer with 1-methylimidazole)
5.0 g of the oligomer obtained in Production Example A and 8.0 g of 1-methylimidazole were added to a glass reactor equipped with a stirrer substituted with argon, and heated to 100 ° C. After reacting at 100 ° C. for 48 hours, the reaction was stopped by cooling to room temperature. The obtained reaction product was dried under reduced pressure at 50 ° C. for 120 hours to obtain 5.8 g of a yellowish brown viscous liquid substance. This viscous liquid substance was subjected to ¹ H-NMR measurement and elemental analysis. As a result, all the chloro groups in all epichlorohydrin units in the starting oligomer were converted into 1-methylimidazolium chloride groups, and all polymerizations were initiated. It was identified as a polyether compound in which the bromo group of the terminal bromomethyl group was substituted with a 1-methylimidazolium bromide group.

(Production Example C)
(Anion exchange of a polyether compound having a 1-methylimidazolium chloride group with potassium iodide)
5.0 g of the polyether compound obtained in Production Example B, 4.0 g of potassium iodide, 10 ml of methanol, and 10 ml of purified water were added to a glass reactor equipped with a stirrer. After reacting at room temperature for 30 minutes, it was dried under reduced pressure at 50 ° C. for 1 hour, and the obtained solid-liquid mixture was dissolved in ethanol and filtered to remove insoluble inorganic salts. The obtained filtrate was dried under reduced pressure at 50 ° C. for 12 hours to obtain 5.2 g of a yellowish brown viscous liquid substance. The obtained viscous liquid substance was subjected to ¹ H-NMR measurement and elemental analysis. As a result, the chloride ion of 1-methylimidazolium chloride group in the repeating unit of the polyether compound as a starting material and 1 of the polymerization initiation terminal were obtained. -It was identified to be an imidazolium structure-containing polyether compound having iodide ions as counter anions in which all bromide ions of the methylimidazolium bromide group were exchanged for iodide ions.
This compound is referred to as polyether compound 1.

(Preparation of electrolyte solution)
0.52 g of the polyether compound 1 was weighed and dissolved in 1 mL of γ-butyrolactone to prepare an electrolyte solution 1 having a polyether compound 1 concentration of 0.30 mol / L.

<Semiconductor electrode>
(Formation of titanium oxide semiconductor porous film)
As a transparent substrate with a transparent conductive film, a polyethylene naphthalate film with an ITO film (ITO-PEN, sheet resistance 15Ω / □, substrate thickness = 200 μm) was used, and a low-temperature deposited titanium oxide paste was applied to the surface of the film. Was fired at 150 ° C. to form a low-temperature deposited titanium oxide film (average film thickness 5.5 μm), thereby creating a porous titanium oxide semiconductor film.

(Dye support)
As the dye, bis (4-carboxy-4′-tetrabutylammoniumcarboxy-2,2′-bipyridine) diisothiocyanate ruthenium complex (manufactured by Tateyama Kasei Co., Ltd., N719dye) was used. A mixed solution of acetonitrile, ethanol, and t-butyl alcohol (volume ratio of 2: 1: 1) having a pigment concentration of 0.3 mmol / L is obtained from the transparent substrate with a porous titanium oxide semiconductor film heated to 40 ° C. under light shielding. It was immersed for 90 minutes with gentle shaking in it. Thereafter, excess dye was washed away with dehydrated acetonitrile and then air-dried to prepare a semiconductor electrode of a solar cell element.

<Counter electrode>
A counter electrode was formed by forming a platinum layer (catalyst layer) on the FTO surface of FTO-glass (sheet resistance 0.16Ω / □) by sputtering.

<Assembly of dye-sensitized solar cell element>
The semiconductor electrode produced as described above was placed horizontally with the dye-supported titanium oxide semiconductor porous membrane side up, and a Teflon sheet (film thickness 25 μm) was placed thereon as a spacer. Next, the electrolyte solution 1 produced as described above was gently dropped onto the titanium oxide semiconductor porous film carrying the dye. Then, the catalyst layer side of the counter electrode was placed so as to face the electrolyte solution, the electrolyte solution was sealed, and a solar cell element was produced.

(Test 1)
(Measurement of photoelectric conversion characteristics of dye-sensitized solar cell element)
For the dye-sensitized solar cell elements produced in Examples and Comparative Examples, a light irradiation area defining mask having a 10 mm square window with a 150 W xenon lamp light source and an AM1.5G filter at 25 ° C. Photoelectric conversion using a source meter (2400-type source meter, Keithley) while irradiating simulated light with a light intensity adjusted to 1000 lux using a solar simulator manufactured by Spectrometer. Efficiency was evaluated. About photoelectric conversion efficiency, it represents that a larger value is preferable as performance of a dye-sensitized solar cell element. The results are shown in Table 1.

(Example 2)
[Synthesis of Electrolyte (Polyether Compound 2)]
(Production Example D)
(Living anion copolymerization of propylene oxide and epichlorohydrin)
To a glass reactor equipped with a stirrer substituted with argon, 3.22 g of tetranormalbutylammonium bromide and 50 ml of toluene were added and cooled to 0 ° C. Subsequently, what melt | dissolved 1.370 g of triethylaluminum (1.2 equivalent with respect to tetranormal butyl ammonium bromide) in 10 ml of toluene was added, and it was made to react for 15 minutes. To the obtained catalyst composition, 6.0 g of propylene oxide and 4.0 g of epichlorohydrin were added, and a polymerization reaction was performed at 0 ° C. After the polymerization reaction started, the viscosity of the solution gradually increased. After the reaction for 12 hours, a small amount of isopropyl alcohol was poured into the polymerization reaction solution to stop the reaction. The resulting polymerization reaction solution was washed with a 0.1N aqueous hydrochloric acid solution to deash the catalyst residue, and further washed with ion-exchanged water, and then the organic layer was dried under reduced pressure at 50 ° C. for 12 hours. The yield of the colorless and transparent oily substance thus obtained was 9.9 g. Moreover, the number average molecular weight (Mn) by GPC of the obtained substance was 1,400, and molecular weight distribution was 1.36 (polystyrene conversion). Further, when ¹ H-NMR measurement was performed on the obtained oily substance, this oily substance was found to be a 21-mer consisting of 15 propylene oxide units and 6 epichlorohydrin units on average. It could be confirmed. From the above, the obtained oily substance was identified as an oligomer composed of propylene oxide units and epichlorohydrin units having a bromomethyl group at the polymerization initiation terminal and a hydroxyl group at the polymerization termination terminal.

(Production Example E)
(Quaternization of epichlorohydrin unit in copolymer with 1-methylimidazole)
5.0 g of the oligomer obtained in Production Example D and 9.0 g of 1-methylimidazole were added to a glass reactor equipped with a stirrer substituted with argon, and heated to 100 ° C. After reacting at 100 ° C. for 72 hours, the reaction was stopped by cooling to room temperature. The reaction solution was poured into ethyl acetate, and the resulting viscous solid was dried under reduced pressure at 50 ° C. for 120 hours. As a result, 6.6 g of a yellow powdery solid was obtained. This powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, all the chloro groups in all epichlorohydrin units in the starting oligomer were converted to 1-methylimidazolium chloride groups, and all polymerizations were initiated. It was identified as a polyether compound in which the bromo group of the terminal bromomethyl group was substituted with a 1-methylimidazolium bromide group.

(Production Example F)
(Anion exchange of a polyether compound having a 1-methylimidazolium chloride group with potassium iodide)
3.0 g of the polyether compound obtained in Production Example E, 4.3 g of potassium iodide, and 10 ml of purified water were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then dried under reduced pressure at 50 ° C. for 1 hour. The obtained solid was dissolved in ethanol and filtered to remove insoluble inorganic salts. The obtained filtrate was dried under reduced pressure at 50 ° C. for 12 hours to obtain 3.3 g of a tan powdery solid. The obtained powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, the chloride ion of 1-methylimidazolium chloride group in the repeating unit of the polyether compound as the starting material and 1 of the polymerization initiation terminal were obtained. -It was identified to be an imidazolium structure-containing polyether compound having iodide ions as counter anions in which all bromide ions of the methylimidazolium bromide group were exchanged for iodide ions.
This compound is referred to as polyether compound 2.

(Preparation of electrolyte solution)
0.30 g of the polyether compound 2 was weighed and dissolved in 1 mL of γ-butyrolactone to prepare an electrolyte solution 2 having a polyether compound 2 concentration of 0.30 mol / L.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 2 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

Example 3
(Preparation of electrolyte solution)
0.086 g of the polyether compound 2 was weighed and dissolved in 1 mL of γ-butyrolactone to prepare an electrolyte solution 3 in which the concentration of the polyether compound 2 was 0.04 mol / L.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 3 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

Example 4
(Preparation of electrolyte solution)
0.10 g of the polyether compound 2 was weighed and dissolved in 0.3 mL of γ-butyrolactone to prepare an electrolyte solution 4 having a polyether compound 2 concentration of 0.17 mol / L.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 4 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

(Comparative Example 1)
[Synthesis of Electrolyte (Polyether Compound 3)]
(Production Example G)
(Living anion copolymerization of propylene oxide and epichlorohydrin)
To a glass reactor equipped with a stirrer substituted with argon, 3.22 g of tetranormalbutylammonium bromide and 50 ml of toluene were added and cooled to 0 ° C. Subsequently, what melt | dissolved 1.370 g of triethylaluminum (1.2 equivalent with respect to tetranormal butyl ammonium bromide) in 10 ml of toluene was added, and it was made to react for 15 minutes. To the obtained catalyst composition, 4.0 g of propylene oxide and 6.0 g of epichlorohydrin were added, and a polymerization reaction was performed at 0 ° C. After the polymerization reaction started, the viscosity of the solution gradually increased. After the reaction for 12 hours, a small amount of isopropyl alcohol was poured into the polymerization reaction solution to stop the reaction. The resulting polymerization reaction solution was washed with a 0.1N aqueous hydrochloric acid solution to deash the catalyst residue, and further washed with ion-exchanged water, and then the organic layer was dried under reduced pressure at 50 ° C. for 12 hours. The yield of the colorless and transparent oily substance thus obtained was 9.9 g. Moreover, the number average molecular weight (Mn) by GPC of the obtained substance was 1,300, and molecular weight distribution was 1.34 (polystyrene conversion). Further, when the obtained oily substance was subjected to ¹ H-NMR measurement, it was found that this oily substance was a 17-mer consisting of 9 propylene oxide units and 8 epichlorohydrin units on average. It could be confirmed. From the above, the obtained oily substance was identified as an oligomer composed of propylene oxide units and epichlorohydrin units having a bromomethyl group at the polymerization initiation terminal and a hydroxyl group at the polymerization termination terminal.

(Production Example H)
(Quaternization of epichlorohydrin unit in copolymer with 1-methylimidazole)
5.0 g of the oligomer obtained in Production Example G and 14.0 g of 1-methylimidazole were added to a glass reactor equipped with a stirrer substituted with argon, and heated to 100 ° C. After reacting at 100 ° C. for 48 hours, the reaction was stopped by cooling to room temperature. The reaction solution was poured into ethyl acetate, and the resulting viscous solid was dried under reduced pressure at 50 ° C. for 72 hours to obtain 7.7 g of a tan powdery solid. This powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, all the chloro groups in all epichlorohydrin units in the starting oligomer were converted to 1-methylimidazolium chloride groups, and all polymerizations were initiated. It was identified as a polyether compound in which the bromo group of the terminal bromomethyl group was substituted with a 1-methylimidazolium bromide group.

(Production Example I)
(Anion exchange of a polyether compound having a 1-methylimidazolium chloride group with potassium iodide)
3.0 g of the polyether compound obtained in Production Example H, 6.5 g of potassium iodide, and 10 ml of purified water were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then dried under reduced pressure at 50 ° C. for 1 hour. The obtained solid was dissolved in ethanol and filtered to remove insoluble inorganic salts. The obtained filtrate was dried under reduced pressure at 50 ° C. for 12 hours to obtain 3.5 g of a tan powdery solid. The obtained powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, the chloride ion of 1-methylimidazolium chloride group in the repeating unit of the polyether compound as the starting material and 1 of the polymerization initiation terminal were obtained. -It was identified to be an imidazolium structure-containing polyether compound having iodide ions as counter anions in which all bromide ions of the methylimidazolium bromide group were exchanged for iodide ions.
This compound is referred to as a polyether compound 3.

(Preparation of electrolyte solution)
0.34 g of the polyether compound 3 was weighed and dissolved in 0.5 mL of γ-butyrolactone to prepare an electrolyte solution 5 having a polyether compound 3 concentration of 0.30 mol / L.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 5 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

(Comparative Example 2)
[Synthesis of Electrolyte (Polyether Compound 4)]
(Production Example J)
(Living anion copolymerization of propylene oxide and epichlorohydrin)
To a glass reactor equipped with a stirrer substituted with argon, 3.22 g of tetranormalbutylammonium bromide and 50 ml of toluene were added and cooled to 0 ° C. Subsequently, what melt | dissolved 1.370 g of triethylaluminum (1.2 equivalent with respect to tetranormal butyl ammonium bromide) in 10 ml of toluene was added, and it was made to react for 15 minutes. To the obtained catalyst composition, 2.0 g of propylene oxide and 8.0 g of epichlorohydrin were added, and a polymerization reaction was performed at 0 ° C. After the polymerization reaction started, the viscosity of the solution gradually increased. After the reaction for 12 hours, a small amount of isopropyl alcohol was poured into the polymerization reaction solution to stop the reaction. The resulting polymerization reaction solution was washed with a 0.1N aqueous hydrochloric acid solution to deash the catalyst residue, and further washed with ion-exchanged water, and then the organic layer was dried under reduced pressure at 50 ° C. for 12 hours. The yield of the colorless and transparent oily substance thus obtained was 9.9 g. Moreover, the number average molecular weight (Mn) by GPC of the obtained substance was 1,200, and molecular weight distribution was 1.28 (polystyrene conversion). Further, when ¹ H-NMR measurement was performed on the obtained oily substance, it was found that the oily substance was a 16-mer composed of 5 propylene oxide units and 11 epichlorohydrin units on average. It could be confirmed. From the above, the obtained oily substance was identified as an oligomer composed of propylene oxide units and epichlorohydrin units having a bromomethyl group at the polymerization initiation terminal and a hydroxyl group at the polymerization termination terminal.

(Production Example K)
(Quaternization of epichlorohydrin unit in copolymer with 1-methylimidazole)
5.0 g of the oligomer obtained in Production Example J and 10.0 g of 1-methylimidazole were added to a glass reactor equipped with a stirrer substituted with argon, and heated to 100 ° C. After reacting at 100 ° C. for 48 hours, the reaction was stopped by cooling to room temperature. The reaction solution was poured into ethyl acetate, and the resulting viscous solid was dried under reduced pressure at 50 ° C. for 72 hours. As a result, 8.0 g of a tan powdery solid was obtained. This powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, all the chloro groups in all epichlorohydrin units in the starting oligomer were converted to 1-methylimidazolium chloride groups, and all polymerizations were initiated. It was identified as a polyether compound in which the bromo group of the terminal bromomethyl group was substituted with a 1-methylimidazolium bromide group.

(Production Example L)
(Anion exchange of a polyether compound having a 1-methylimidazolium chloride group with potassium iodide)
3.0 g of the polyether compound obtained in Production Example K, 5.5 g of potassium iodide, and 10 ml of purified water were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then dried under reduced pressure at 50 ° C. for 1 hour. The obtained solid was dissolved in ethanol and filtered to remove insoluble inorganic salts. The obtained filtrate was dried under reduced pressure at 50 ° C. for 12 hours to obtain 3.2 g of a tan powdery solid. The obtained powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, the chloride ion of 1-methylimidazolium chloride group in the repeating unit of the polyether compound as the starting material and 1 of the polymerization initiation terminal were obtained. -It was identified to be an imidazolium structure-containing polyether compound having iodide ions as counter anions in which all bromide ions of the methylimidazolium bromide group were exchanged for iodide ions.
This compound is referred to as polyether compound 4.

(Preparation of electrolyte solution)
0.32 g of the polyether compound 4 was weighed and dissolved in 0.5 mL of γ-butyrolactone to prepare an electrolyte solution 6 having a polyether compound 4 concentration of 0.30 mol / L.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 6 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

(Comparative Example 3)
[Synthesis of Electrolyte (Polyether Compound 5)]
(Production Example M)
(Living anionic polymerization of epichlorohydrin)
To a glass reactor equipped with a stirrer substituted with argon, 3.22 g of tetranormalbutylammonium bromide and 50 ml of toluene were added and cooled to 0 ° C. Next, a solution obtained by dissolving 1.370 g of triethylaluminum (1.2 equivalent to tetranormalbutylammonium bromide) in 10 ml of toluene was added, and the whole volume was stirred at 0 ° C. for 15 minutes to obtain a catalyst composition. It was. To the resulting catalyst composition, 10 g of epichlorohydrin was added, and a polymerization reaction was performed at 0 ° C. for 2 hours. After the polymerization reaction started, the viscosity of the solution gradually increased. After completion of the reaction, a small amount of isopropyl alcohol was poured into the polymerization reaction solution to stop the reaction. The resulting polymerization reaction solution is washed with a 0.1N aqueous hydrochloric acid solution to decarburize the catalyst residue, and further washed with ion exchange water, and then the organic layer is dried under reduced pressure at 50 ° C. for 12 hours, 9.9 g of a colorless and transparent oily substance was obtained.
The number average molecular weight (Mn) by GPC of the obtained substance was 1,200, and the molecular weight distribution was 1.20 (polystyrene conversion). Furthermore, when ¹ H-NMR measurement was performed on the obtained polymer, it was confirmed that the oily substance was a 13-mer composed of 13 epichlorohydrin units on average. From the above, the obtained oily substance was identified as an oligomer composed of epichlorohydrin units having a bromomethyl group at the polymerization initiation terminal and a hydroxyl group at the polymerization termination terminal.

(Production Example N)
(Quaternization of epichlorohydrin oligomer with 1-methylimidazole)
5.0 g of the oligomer obtained in Production Example M and 13.3 g of 1-methylimidazole were added to a glass reactor equipped with a stirrer substituted with argon, and heated to 100 ° C. After reacting at 100 ° C. for 48 hours, the reaction was stopped by cooling to room temperature. The reaction solution was poured into ethyl acetate, and the resulting viscous solid was dried under reduced pressure at 50 ° C. for 72 hours. As a result, 9.0 g of a tan powdery solid was obtained. This powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, all the chloro groups in all epichlorohydrin units in the starting oligomer were converted to 1-methylimidazolium chloride groups, and all polymerizations were initiated. It was identified as a polyether compound in which the bromo group of the terminal bromomethyl group was substituted with a 1-methylimidazolium bromide group.

(Production Example O)
(Anion exchange of a polyether compound having a 1-methylimidazolium chloride group with potassium iodide)
3.0 g of the polyether compound obtained in Production Example N, 10.7 g of potassium iodide, and 30 ml of purified water were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then dried under reduced pressure at 50 ° C. for 1 hour. The obtained solid was dissolved in ethanol and filtered to remove insoluble inorganic salts. The obtained filtrate was dried under reduced pressure at 50 ° C. for 12 hours to obtain 3.4 g of a tan powdery solid. The obtained powdered solid was subjected to ¹ H-NMR measurement and elemental analysis. As a result, the chloride ion of 1-methylimidazolium chloride group in the repeating unit of the polyether compound as the starting material and 1 of the polymerization initiation terminal were obtained. -It was identified to be an imidazolium structure-containing polyether compound having iodide ions as counter anions in which all bromide ions of the methylimidazolium bromide group were exchanged for iodide ions.
This compound is designated as a polyether compound 5.

(Preparation of electrolyte solution)
0.36 g of the polyether compound 5 was weighed and dissolved in 0.5 mL of γ-butyrolactone to prepare an electrolyte solution 7 having a polyether compound 5 concentration of 0.30 mol / L.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 7 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

(Comparative Example 4)
[Synthesis of Electrolyte (Polyether Compound 6)]
(Production Example P)
(Living anion polymerization of propylene oxide)
To a glass reactor equipped with a stirrer whose inside was replaced with argon, 2.56 g (8 mmol) of tetranormalbutylammonium bromide and 50 ml of toluene were added and cooled to 0 ° C. Next, 1.37 g (12 mmol) of triethylaluminum (1.5 equivalent to tetranormalbutylammonium bromide) dissolved in 10 ml of toluene was added, and the whole volume was stirred at 0 ° C. for 15 minutes, whereby the catalyst composition I got a thing. 10 g of propylene oxide was added to the obtained catalyst composition, and a polymerization reaction was performed at 0 ° C. for 2 hours. After the polymerization reaction started, the viscosity of the solution gradually increased. After completion of the reaction, a small amount of isopropyl alcohol was poured into the polymerization reaction solution to stop the reaction. The resulting polymerization reaction solution is washed with a 0.1N aqueous hydrochloric acid solution to decarburize the catalyst residue, and further washed with ion exchange water, and then the organic layer is dried under reduced pressure at 50 ° C. for 12 hours, 9.9 g of a colorless and transparent oily substance was obtained.
The number average molecular weight (Mn) by GPC of the obtained substance was 1,250, and the molecular weight distribution was 1.15 (polystyrene conversion). Furthermore, ¹ H-NMR measurement and elemental analysis of the obtained polymer were measured. As a result, an oligomer (PO) n composed of propylene oxide units having a bromomethyl group at the polymerization initiation terminal and a hydroxyl group at the polymerization termination terminal. -Br, n = 25 was identified.

(Production Example Q)
(Quaternization of propylene oxide oligomer with 1-methylimidazole)
In a glass reactor equipped with a stirrer whose inside was replaced with argon, 5.0 g of propylene oxide oligomer (PO) n-Br obtained in Production Comparative Example P, 4.1 g of 1-methylimidazole (MeIm), and acetonitrile (ACN) 10 0.0 g was added and the whole was stirred at 80 ° C. for 24 hours. After completion of the reaction, the reaction solution was cooled to room temperature to stop the reaction. The obtained reaction mixture was washed with an equal weight mixed solution of toluene / ethanol / water, then the organic phase containing unreacted 1-methylimidazole and toluene was removed, and the aqueous phase was dried under reduced pressure at 50 ° C. for 12 hours. As a result, 5.4 g of a light yellow transparent oily oligomer was obtained.
The number average molecular weight (Mn) of the obtained substance by GPC was 1,300, and the molecular weight distribution was 1.18 (polystyrene conversion). Further, when ¹ H-NMR measurement and elemental analysis were performed, all the bromomethyl groups at the polymerization initiation end of the starting propylene oxide oligomer were substituted with 1-methylimidazole groups, and 1-methyl having a halide ion as a counter anion. Imidazolium structure-containing propylene oxide oligomer (PO) nMeIm-Br).

(Production Example R)
(Anion exchange of a polyether compound having a 1-methylimidazolium bromide group with potassium iodide)
3.0 g of the polyether compound obtained in Production Example Q, 6.5 g of potassium iodide, and 10 ml of purified water were added to a glass reactor equipped with a stirrer. The mixture was reacted at room temperature for 30 minutes, and then dried under reduced pressure at 50 ° C. for 1 hour. The obtained solid was dissolved in ethanol and filtered to remove insoluble inorganic salts. When the obtained filtrate was dried under reduced pressure at 50 ° C. for 12 hours, 3.1 g of a yellow transparent oily oligomer was obtained. The obtained yellow transparent oily oligomer was subjected to ¹ H-NMR measurement and elemental analysis. As a result, all the bromide ions of the 1-methylimidazolium bromide group at the polymerization initiation terminal of the polyether compound as a starting material were iodine. It was identified to be an imidazolium structure-containing polyether compound having iodide ions as counter anions exchanged for iodide ions.
This compound is referred to as a polyether compound 6.

(Preparation of electrolyte solution)
0.44 g of the polyether compound 4 was weighed and dissolved in 1.0 mL of γ-butyrolactone to prepare an electrolyte solution 8 having a polyether compound 6 concentration of 0.30 mol / L.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 8 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

(Comparative Example 5)
(Preparation of electrolyte solution)
As the electrolyte solution, 1-methyl-3-propylimidazolium iodide (referred to as “MPImI”) is used, and dissolved in γ-butyrolactone so that the concentration of MPImI is 0.30 mol / L. 9 was prepared.
A dye-sensitized solar electronic device was prepared in the same manner as in Example 1 except that the electrolyte solution 9 was used instead of the electrolyte solution 1, and the photoelectric conversion efficiency was evaluated. The results are shown in Table 1.

When the polyether compound specified in the present invention was used as the electrolyte solution and the repeating unit represented by the formula (1) was 40 mol% or less, the photoelectric conversion efficiency of the dye-sensitized solar cell element was excellent. (Examples 1-4).
On the other hand, when a polyether compound is used as the electrolyte solution, but the repeating unit represented by the formula (1) exceeds the upper limit of 40 mol% defined in the present invention (Comparative Examples 1, 2, and 3), When the polyether compound specified in the present invention is not used (Comparative Example 4) and when an ionic liquid is used (Comparative Example 5), the photoelectric conversion efficiency of the dye-sensitized solar cell element is insufficient. there were.

Claims (1)

A dye-sensitized solar cell element comprising a semiconductor electrode and a counter electrode disposed opposite to the semiconductor electrode, and having an electrolyte layer between the semiconductor electrode and the counter electrode,
The counter electrode contains a transition metal;
The electrolyte layer contains a polyether compound having a repeating unit represented by the following formula (1):
In the said polyether compound, 40 mol% or less of repeating units represented by following formula (1) are contained in all the repeating units, The dye-sensitized solar cell element characterized by the above-mentioned.

(In Formula (1), A ⁺ is a group having an onium ion structure containing a cationic nitrogen atom, and X ⁻ is a counter anion.)