JP2014071950A - Electrolyte for photoelectric conversion element and photoelectric conversion element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte for a photoelectric conversion element which can provide excellent durability to the photoelectric conversion element; and provide a photoelectric conversion element using the electrolyte.SOLUTION: A photoelectric conversion element electrolyte 40 used for a photoelectric conversion element 100 comprises: a redox pair 41 composed of a halide ion and a polyhalide ion; and a sulfur-containing compound 42. The sulfur-containing compound is composed of at least one compound selected from a group consisting of a compound having a -SX group, a compound having a -Sgroup and a compound having a -S-S- group where X represents a monovalent cation.

Description

  The present invention relates to an electrolyte for a photoelectric conversion element and a photoelectric conversion element using the same.

  A dye-sensitized solar cell is known as a photoelectric conversion element.

  A dye-sensitized solar cell generally includes a working electrode, a counter electrode, a sealing portion that connects the working electrode and the counter electrode, and an electrolyte that is filled in a cell space surrounded by the working electrode, the counter electrode, and the sealing portion. ing. As an example of the working electrode, there is a structure having a transparent conductive substrate, an oxide semiconductor layer provided on the transparent conductive substrate, and a metal wiring provided in the vicinity of the oxide semiconductor layer. Here, the metal wiring is generally covered with a wiring protective layer in order to prevent corrosion due to the electrolyte (see, for example, Patent Document 1 below).

JP 2011-91012 A

  However, the dye-sensitized solar cell described in Patent Document 1 has the following problems.

  That is, in the dye-sensitized solar cell described in Patent Document 1, the metal wiring may be corroded by the electrolyte. For this reason, the dye-sensitized solar cell has room for improvement in terms of durability.

  This invention is made | formed in view of the said situation, and it aims at providing the electrolyte for photoelectric conversion elements which can provide the outstanding durability with respect to a photoelectric conversion element, and a photoelectric conversion element using the same.

  The present inventors examined the cause of the above problem. First, in the dye-sensitized solar cell described in Patent Document 1, the metal wiring is covered with a wiring protective layer, and the wiring protective layer is densely formed. For this reason, it is considered that the metal wiring is hardly corroded by the electrolyte. However, the temperature, pressure, humidity and the like surrounding the dye-sensitized solar cell change every moment. For this reason, if an excessive stress is applied to the wiring protective layer and a defect such as a crack occurs, the electrolyte enters through the crack and comes into contact with the metal wiring, resulting in corrosion of the metal wiring and reduced durability. The present inventors thought that this would be the case. Therefore, as a result of further earnest research, the present inventors have found that the above-mentioned problems can be solved by including a specific sulfur-containing compound in addition to the redox couple in the electrolyte, and the present invention has been completed. It came to do.

That is, the present invention is an electrolyte for a photoelectric conversion element used for a photoelectric conversion element, comprising an oxidation-reduction pair comprising a halide ion and a polyhalide ion, and a sulfur-containing compound, wherein the sulfur-containing compound is -SX. compounds having a group, -S ^- compounds having a group, and is composed of at least one compound selected from the group consisting of compounds having a -S-S- group, X is a photoelectric conversion element that represents a monovalent cation Electrolyte.

This electrolyte for a photoelectric conversion element is useful when used as an electrolyte of a photoelectric conversion element having a metal wiring, a wiring protective layer that covers the metal wiring and protects from the electrolyte, and an electrolyte. That is, the temperature, pressure, humidity, etc. surrounding the photoelectric conversion element change from moment to moment. For this reason, an excessive stress is applied to the wiring protective layer, which may cause a defect such as a crack. Wherein the compound having an -SX group, -S ^- a compound having a group, a sulfur-containing compound comprising a compound having an -S-S- group, because it forms a SAM (Self-assembled monolayer) on the surface of the metal wire More easily adsorbed to metal wiring than polyhalide ions having high corrosiveness to metal wiring. For this reason, the contact between the oxidation-reduction pair and the metal wiring can be sufficiently suppressed. Therefore, according to the electrolyte for a photoelectric conversion element of the present invention, even if a defect such as a crack occurs in the wiring protective layer, corrosion of the metal wiring can be sufficiently suppressed, and as a result, the photoelectric conversion element is excellent. Durability can be imparted.

  In the above-described electrolyte for photoelectric conversion elements, it is preferable that the sulfur-containing compound further includes a functional group having a charge of the same polarity as the polyhalide ion in the molecule.

  In this case, a defect such as a crack is generated in the wiring protective layer, and after the sulfur-containing compound enters the defect and is adsorbed on the metal wiring, polyhalide ions are included in the sulfur-containing compound even if they approach the metal wiring. Since the functional group and the polyhalide ion have the same polarity, an electric repulsive force acts between them, and the polyhalide ion can be kept away from the metal wiring. For this reason, according to the said electrolyte for photoelectric conversion elements, corrosion of metal wiring can be suppressed more fully, As a result, the more outstanding durability can be provided with respect to a photoelectric conversion element.

  The present invention further includes a first electrode, a second electrode facing the first electrode, and an electrolyte provided between the first electrode and the second electrode, wherein the first electrode is a conductive substrate. And an oxide semiconductor layer provided on the conductive substrate, and a wiring portion provided on the conductive substrate, the wiring portion provided on the conductive substrate, and the metal wiring And a wiring protective layer that protects the electrolyte from the electrolyte, and the electrolyte is a photoelectric conversion element composed of the electrolyte for photoelectric conversion elements.

According to this photoelectric conversion element, defects such as cracks may occur in the wiring protective layer due to changes in the temperature, pressure, humidity and the like surrounding the photoelectric conversion element every moment. Wherein the compound having an -SX group, -S ^- compound having a group, and sulfur-containing compounds such as a compound having an -S-S- group forms a SAM (Self-assembled monolayer) on the surface of the metal wire Therefore, it is more easily adsorbed to the metal wiring than polyhalide ions having high corrosiveness to the metal wiring. For this reason, the contact between the oxidation-reduction pair and the metal wiring can be sufficiently suppressed. Therefore, according to the photoelectric conversion element of the present invention, even if a defect such as a crack occurs in the wiring protective layer, corrosion of the metal wiring is sufficiently suppressed, and as a result, it is possible to have excellent durability. Become.

  ADVANTAGE OF THE INVENTION According to this invention, the electrolyte for photoelectric conversion elements which can provide the outstanding durability with respect to a photoelectric conversion element, and a photoelectric conversion element using the same are provided.

It is sectional drawing which shows one Embodiment of the photoelectric conversion element of this invention. It is a fragmentary sectional view which shows the electrolyte of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of the photoelectric conversion element of the present invention, and FIG. 2 is a partial cross-sectional view showing the electrolyte of FIG.

  As shown in FIG. 1, the dye-sensitized solar cell 100 includes a working electrode 10, a counter electrode 20 that faces the working electrode 10, an annular sealing portion 30 that connects the working electrode 10 and the counter electrode 20, and a working electrode 10. And an electrolyte 40 disposed between the counter electrode 20 and the counter electrode 20.

  The counter electrode 20 includes a counter electrode substrate 21 and a catalyst layer 22 that is provided on the working electrode 10 side of the counter electrode substrate 21 and contributes to the reduction of the electrolyte.

  The working electrode 10 includes a transparent conductive substrate 15 formed of a transparent substrate 11 and a transparent conductive film 12 provided on the transparent substrate 11, and a transparent conductive film 12 of the transparent conductive substrate 15 inside the sealing portion 30. It has a porous oxide semiconductor layer 13 provided thereon and a wiring portion 16 provided on the transparent conductive film 12 of the transparent conductive substrate 15. The porous oxide semiconductor layer 13 carries a photosensitizing dye. The wiring portion 16 includes a metal wiring 17 provided on the transparent conductive film 12 of the transparent conductive substrate 15 and a wiring protection layer 18 that covers the metal wiring 17 and protects it from the electrolyte 40.

Here, as shown in FIG. 2, the electrolyte 40 includes a redox pair 41 composed of halide ions and polyhalide ions, a sulfur-containing compound 42, and an organic solvent 43. Here, a sulfur-containing compound 42 is a compound having an -SX group, -S ^- made up of at least one compound selected from the group consisting of compounds having compound having a group, and -S-S- group . Here, X represents a monovalent cation. In FIG. 2, for convenience of explanation, halide ions and polyhalide ions are collectively shown as a redox pair 41, but actually, halide ions and polyhalide ions are present in the electrolyte 40. In summary, they do not exist as the redox pair 41 but exist separately.

According to the dye-sensitized solar cell 100 described above, the temperature, pressure, humidity, and the like surrounding the dye-sensitized solar cell 100 change from moment to moment, so that defects such as cracks may occur in the wiring protective layer 18. . Wherein the compound having an -SX group, -S ^- sulfur-containing compound 42 comprised of at least one compound selected from the group consisting of compounds having the compound and -S-S- groups having a group, a metal wiring Since a SAM (Self-assembled monolayer) is formed on the surface of the metal wire, it is more easily adsorbed to the metal wiring 17 than polyhalide ions having high corrosiveness to the metal wiring 17. For this reason, the contact between the oxidation-reduction pair 41 and the metal wiring 17 can be sufficiently suppressed. Therefore, according to the dye-sensitized solar cell 100, even if a defect such as a crack occurs in the wiring protective layer 18, corrosion of the metal wiring 17 is sufficiently suppressed, and as a result, it has excellent durability. It becomes possible.

  Next, the working electrode 10, the counter electrode 20, the sealing part 30, the electrolyte 40, and the photosensitizing dye will be described in detail.

<Working electrode>
As described above, the working electrode 10 includes the transparent substrate 11, the transparent conductive film 12, the porous oxide semiconductor layer 13, and the wiring portion 16.

(Transparent substrate)
The material which comprises the transparent substrate 11 should just be a transparent material, for example, As such a transparent material, glass, such as borosilicate glass, soda lime glass, white plate glass, quartz glass, polyethylene terephthalate (PET), for example , Polyethylene naphthalate (PEN), polycarbonate (PC), polyethersulfone (PES) and the like. The thickness of the transparent substrate 11 is appropriately determined according to the size of the dye-sensitized solar cell 100 and is not particularly limited, but may be in the range of 50 to 10,000 μm, for example.

(Transparent conductive film)
Examples of the material constituting the transparent conductive film 12 include conductive metal oxides such as tin-added indium oxide (ITO), tin oxide (SnO ₂ ), fluorine-added tin oxide (FTO), and antimony-doped tin oxide (ATO). Can be mentioned. Especially, since the transparent conductive film 12 has high heat resistance and chemical resistance, it is preferable to be comprised by FTO. The thickness of the transparent conductive film 12 may be in the range of 0.01 to 2 μm, for example.

(Porous oxide semiconductor layer)
The porous oxide semiconductor layer 13 is composed of oxide semiconductor particles. The oxide semiconductor particles include, for example, titanium oxide (TiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₅ ), niobium oxide (Nb ₂ O ₅ ), strontium titanate (SrTiO ₅ ), tin oxide (SnO ₂ ). , Indium oxide (In ₃ O ₃ ), zirconium oxide (ZrO ₂ ), thallium oxide (Ta ₂ O ₅ ), lanthanum oxide (La ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), holmium oxide (Ho ₂ O) ₃ ), bismuth oxide (Bi ₂ O ₃ ), cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), or two or more thereof. The thickness of the porous oxide semiconductor layer 13 is usually 0.5 to 50 μm.

(Metal wiring)
The metal wiring 17 is made of a material having a lower resistance than the transparent conductive film 12. Examples of such materials include gold, silver, copper, aluminum, nickel, titanium, and carbon. These can be used alone or in combination of two or more. Among these, gold, silver or copper is preferably used as a material constituting the metal wiring 17. The thickness of the metal wiring 17 is usually 1 to 100 μm.

(Wiring protection layer)
The wiring protective layer 18 is made of an insulating material. Any insulating material may be used as long as it can protect the metal wiring 17 from the electrolyte 40. Examples of the insulating material include those obtained by firing a low melting point glass frit or a coating film of a paste-like composition containing the glass frit. Examples of the low melting glass frit include glass components such as lead borate glass, bismuth borosilicate salt glass, aluminophosphate glass, and zinc phosphate glass. The thickness of the wiring protective layer 18 is usually 1 to 100 μm. The wiring protective layer may be a single layer or a plurality of layers.

<Counter electrode>
The counter electrode 20 includes the counter electrode substrate 21 and the catalyst layer 22 as described above.

  The counter electrode substrate 21 is formed by, for example, forming a film made of a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, tungsten, stainless steel, or aluminum, or a film made of a conductive oxide such as ITO or FTO on the transparent substrate 11 described above. Composed. The thickness of the counter electrode substrate 21 is appropriately determined according to the size of the dye-sensitized solar cell 100, and is not particularly limited, but may be, for example, 0.01 to 10 mm.

  The catalyst layer 22 is composed of platinum, a carbon-based material, a conductive polymer, or the like.

<Sealing part>
Examples of the sealing portion 30 include various modified polyolefin resins including, for example, ionomers, ethylene-vinyl acetic anhydride copolymers, ethylene-methacrylic acid copolymers, ethylene-vinyl alcohol copolymers, ultraviolet curable resins, and vinyl. Examples thereof include resins such as alcohol polymers.

<Electrolyte>
The electrolyte 40 is usually composed of an electrolytic solution, and the electrolytic solution includes a redox couple 41, a sulfur-containing compound 42, and an organic solvent 43.

  As the organic solvent 43, for example, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, and the like can be used.

  The oxidation-reduction pair 41 is composed of halide ions and polyhalide ions. Examples of the redox pair 41 include a pair consisting of iodide ion and polyiodide ion, and a pair consisting of bromine ion and polybromide ion.

Sulfur-containing compounds 42 include compounds having an -SX group, -S ^- may be at least one compound selected from the group consisting of compounds having compound having a group, and -S-S- group. Here, X represents a monovalent cation.

式（１）中、Ｒ^１は特に制限されないが、Ｒ^１としては、例えば置換若しくは無置換の複素環基、置換若しくは無置換の炭素数１〜５のアルキル基、置換若しくは無置換のオリゴエチレングリコール基などが挙げられる。 The compound having a —SX group can be represented by the following formula (1).

In formula (1), R ¹ is not particularly limited. Examples of R ¹ include a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, and a substituted or unsubstituted oligoethylene. A glycol group etc. are mentioned.

m represents the number of —SX groups bonded to R ¹ . Although m is not particularly limited, usually about 1 to 3 can be used.

  X may be a monovalent cation. Examples of X include a hydrogen ion, a monovalent inorganic cation, and a monovalent organic cation. Examples of the monovalent inorganic cation include sodium ion and potassium ion. Examples of monovalent organic cations include ammonium ions and quaternized imidazolium ions.

  Examples of the compound represented by the above formula (1) include thiazole compounds such as 2-mercaptobenzothiazole, pyrimidine compounds such as 2-mercaptopyrimidine, 2-mercapto-1,3,4-thiadiazole, 2,5 -Thiadiazole compounds such as dimercapto-1,3,4-thiadiazole, trithiocyanuric acid (1,3,5-triazine-2,4,6-trithiol) and the like. These can be used alone or in combination of two or more.

-S ^- The compound having a group, by ionizing at least part of the -SX group in the compound represented by the above formula (1) X ⁺ can be mentioned those desorbed.

式（２）中、Ｒ^２およびＲ^３は特に制限されるものではなく、Ｒ^２およびＲ^３としては、Ｒ^１と同様の基を選ぶことができる。 Examples of the compound having a -S-S- group include a compound represented by the following formula (2).

In formula (2), R ² and R ³ are not particularly limited, and R ² and R ³ can be the same group as R ¹ .

  Examples of the compound represented by the formula (2) include dimers of thiadiazole compounds such as 2,5-dimercapto-1,3,4-thiadiazole.

  More preferably, the sulfur-containing compound 42 includes a functional group having a charge of the same polarity as that of the polyhalide ion in the molecule. That is, it is more preferable that the sulfur-containing compound 42 includes a functional group having a negative charge.

  In this case, a defect such as a crack occurs in the wiring protective layer 18, and the sulfur compound 42 enters the defect such as the crack and is adsorbed to the metal wiring 17, and then the polyhalide ions approach the metal wiring 17. Since the functional group contained in the sulfur-containing compound 42 and the polyhalide ion have the same polarity, an electrical repulsive force acts between them, and the polyhalide ion can be kept away from the metal wiring 17. For this reason, according to the electrolyte 40, corrosion of the metal wiring 17 can be suppressed more sufficiently, and as a result, more excellent durability can be imparted to the dye-sensitized solar cell 100.

  Examples of the functional group having a negative charge include a carboxyl group, a sulfo group, a sulfonyl group, and a phosphoryl group. The sulfur-containing compound 42 may contain one kind alone or two or more kinds in combination.

  These functional groups having a negative charge can be introduced as substituents such as a substituted heterocyclic group and a substituted alkyl group in the formula (1).

  The molecular size of the sulfur-containing compound 42 is not particularly limited, but is preferably equal to or smaller than the molecular size of the polyhalide ion contained in the redox couple 41.

  In this case, when a defect such as a crack occurs in the wiring protective layer 18, even if the defect such as the crack is large enough to allow polyhalide ions to enter, the sulfur-containing compound 42 does not have the crack or the like. It becomes easy to enter a defect and can be easily adsorbed to the metal wiring 17. For this reason, compared with the case where the molecular size of the sulfur containing compound 42 exceeds the molecular size of a polyhalide ion, the contact with the metal wiring 17 and a polyiodide ion can be suppressed more fully. For example, the molecular size in the longitudinal direction of triiodide ions is estimated to be about 6 cm.

  The concentration of the sulfur-containing compound 42 in the electrolyte 40 is not particularly limited, but is usually 1 to 500 mM.

The electrolyte 40 may use an ionic liquid instead of the organic solvent 43. The electrolyte 40 may use a mixture of an ionic liquid and the organic solvent 43 instead of the organic solvent 43. These solvents may also serve as a source for forming the redox couple 41. Examples of the ionic liquid include known iodide salts such as pyridinium salt, imidazolium salt, triazolium salt, ammonium salt, pyrrolidinium salt, bistrifluoromethylsulfonylimide salt, tetracyanoborate, etc. A room temperature molten salt in a state is used. Examples of such room temperature molten salts include 1-hexyl-3-methylimidazolium iodide, 1-propyl-3-methylimidazolium iodide, 1-ethyl-3-propylimidazolium iodide, and dimethylimidazolium iodide. Dide, ethylmethylimidazolium iodide, dimethylpropylimidazolium iodide, butylmethylimidazolium iodide, methylpropylimidazolium iodide, or the like is preferably used. An additive can be added to the electrolyte 40. As the _{additive, LiI, I 2, 4-} t- butylpyridine, guanidinium thiocyanate, 1-methylbenzimidazole, 1-butyl-benzimidazole and the like. The electrolyte 40 may be gelled with an organic gelling agent made of a polymer such as polyvinylidene fluoride, a polyethylene oxide derivative, or an amino acid derivative, or inorganic nanoparticles such as SiO ₂ , TiO ₂ , or a carbon nanotube. .

<Photosensitizing dye>
Examples of the photosensitizing dye include a ruthenium complex containing a bipyridine structure, a terpyridine structure or the like as a ligand, a metal-containing complex such as porphyrin or phthalocyanine, and an organic dye such as eosin, rhodamine or merocyanine. Among these, a ruthenium complex having a ligand containing a terpyridine structure is preferable. In this case, the photoelectric conversion characteristics of the dye-sensitized solar cell 100 can be further improved.

  Next, a method for producing the dye-sensitized solar cell 100 will be described. However, the following manufacturing method is an example, and the procedure is not limited thereto.

  First, a transparent conductive substrate 15 formed by forming a transparent conductive film 12 on one transparent substrate 11 is prepared.

  As a method for forming the transparent conductive film 12, a sputtering method, a vapor deposition method, a spray pyrolysis method, a CVD method, or the like is used.

  Next, a metal wiring 17 is formed on the transparent conductive film 12. The metal wiring 17 can be obtained by, for example, applying a paste containing a conductive material on the transparent conductive film 12, drying it, and baking it. In addition, the metal wiring 17 can be formed by plating, sputtering, welding, or the like, and can be formed without any particular limitation.

  Next, the porous oxide semiconductor layer 13 is formed in a region on the transparent conductive film 12 and surrounded by the metal wiring 17. The porous oxide semiconductor layer 13 is formed by applying a porous oxide semiconductor layer forming paste containing oxide semiconductor particles and then baking.

  The oxide semiconductor layer forming paste generally contains a resin such as polyethylene glycol and a solvent such as terpineol in addition to the oxide semiconductor particles described above.

  As a coating method of the oxide semiconductor layer forming paste, for example, a screen printing method, a doctor blade method, an ink jet printing method, a roll coating method, a spin coating method, a spray coating method, a bar coating method, or the like can be used.

  The firing temperature varies depending on the material of the oxide semiconductor particles and the base material, but when a glass substrate is used, it is usually 350 to 600 ° C., and the firing time also depends on the material of the oxide semiconductor particles, additives, solvent, etc. Although it varies, it is usually 0.5 to 5 hours.

  Next, the wiring protective layer 18 is formed on the metal wiring 17 as follows.

  The method for forming the wiring protective layer 18 is not particularly limited, but an example using an insulating paste will be described. First, an insulating paste containing an insulating material for forming the wiring protective layer 18 is prepared. Subsequently, this insulating paste is applied so as to cover the metal wiring 17 by a method such as screen printing or dispensing. Thereafter, the insulating material is heat-treated. In this way, the wiring part 16 is obtained by covering the metal wiring 17 with the wiring protective layer 18.

  Thus, the working electrode 10 is obtained.

  Next, the above-described photosensitizing dye is adsorbed on the surface of the porous oxide semiconductor layer 13 of the working electrode 10. For this purpose, the working electrode 10 is immersed in a solution containing a photosensitizing dye, the photosensitizing dye is adsorbed on the porous oxide semiconductor layer 13, and then the solvent component of the solution is used to add an excess. The photosensitizing dye may be adsorbed on the porous oxide semiconductor layer 13 by washing away the photosensitizing dye and drying it.

  Next, the electrolyte 40 is disposed on the porous oxide semiconductor layer 13. At this time, the electrolyte 40 can be obtained by dissolving the redox couple 41 and the sulfur-containing compound 42 in the organic solvent 43. The electrolyte 40 can be disposed, for example, by being applied on the working electrode 10.

  Next, the counter electrode 20 is prepared. The counter electrode 20 can be obtained by forming the catalyst layer 22 on the counter electrode substrate 21. As a method for forming the catalyst layer 22, a sputtering method, a screen printing method, a vapor deposition method, or the like is used.

  Next, the counter electrode 20 obtained as described above is overlaid so that the electrolyte 40 is disposed between the working electrode 10 and the counter electrode 20, and then the working electrode 10 and the counter electrode are interposed through the sealing portion forming body. 20 and pasted together. Thus, the sealing portion 30 is formed between the working electrode 10 and the counter electrode 20.

  The dye-sensitized solar cell 100 is obtained as described above.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the porous oxide semiconductor layer 13 is provided on the transparent conductive film 12 of the transparent conductive substrate 15 to receive light from this side, but the porous oxide semiconductor layer 13 is formed. An opaque material (for example, a metal substrate) may be used for the base material to be formed, a transparent material may be used for the base material for forming the counter electrode 20, and a structure for receiving light from the counter electrode side may be employed. I do not care.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Example 1
First, a working electrode was produced as follows. First, a glass substrate with an FTO film of 20 cm × 20 cm × 4 mm was prepared. Subsequently, a silver paste for forming a metal wiring was printed in a grid pattern on the surface on the FTO film side of the glass substrate with an FTO film by a screen printing method and dried at 130 ° C. At this time, a silver paste having a volume resistivity after firing of about 3 × 10 ⁻⁶ Ωcm was used. Specifically, the silver paste was mainly composed of silver particles, a glass frit serving as a binder material, a thickener, and a solvent. And the metal wiring was formed by sintering the coating film after drying at 500 degreeC.

  Next, a paste for forming a porous oxide semiconductor layer containing titanium oxide having an average particle diameter of about 20 nm by a screen printing method in a region surrounded by metal wiring on the surface of the FTO film of the glass substrate with an FTO film Was applied and dried. Thereafter, this coating film was baked at 500 ° C. for 1 hour to form a porous oxide semiconductor layer having a thickness of 12 μm on the glass substrate with the FTO film. Thus, a working electrode was produced.

  Next, an insulating paste containing a low-melting glass frit as a main component was prepared, and this insulating paste was applied so as to cover the metal wiring by a screen printing method. Next, this insulating paste was dried and then baked at 480 ° C. for 1 hour to form a wiring protective layer having a thickness of about 15 μm (metal wiring central portion). Thus, a structure having a wiring part was obtained.

  Next, the working electrode obtained as described above was immersed overnight in a dye solution obtained by dissolving N719 dye, which is a ruthenium bipyridine complex as a photosensitizing dye, in a mixed solvent of acetonitrile and t-butanol. A photosensitizing dye was supported on the working electrode.

  Next, an electrolyte obtained by dissolving iodine, 3-hexyl-1-methylimidazolium iodide salt, guanidine thiocyanate, N-methylbenzimidazole, 2-mercaptobenzothiazole in a solvent composed of 3-methoxypropionitrile. Prepared. At this time, the concentration of 2-mercaptobenzothiazole, which is a sulfur-containing compound, in the electrolyte was 4 mM. And this electrolyte was arrange | positioned so that a porous oxide semiconductor layer and a wiring part may be covered on the said working electrode arrange | positioned horizontally.

  Next, a counter electrode was prepared. The counter electrode had the same size as the working electrode, and was prepared by forming a catalyst layer made of platinum having a thickness of 8 nm on a titanium foil having a thickness of 40 μm by a sputtering method.

  And the produced working electrode and counter electrode were opposingly arranged through the sealing part formation body in the state which arrange | positioned electrolyte between both electrodes, and the cell was sealed by heat-sealing the sealing part formation body. The sealing operation was performed with the sample placed in a reduced pressure environment. Thus, a dye-sensitized solar cell was obtained.

(Example 2)
When preparing the electrolyte, a dye-sensitized solar cell was obtained in the same manner as in Example 1 except that 2-mercaptobenzothiazole was changed to 2-mercaptopyrimidine as a sulfur-containing compound to be dissolved in a solvent.

(Example 3)
When the electrolyte was prepared, the dye increase was performed in the same manner as in Example 1 except that 2-mercaptobenzothiazole was changed to 2-mercapto-1,3,4-thiadiazole as a sulfur-containing compound to be dissolved in the solvent. A solar cell was obtained.

Example 4
When the electrolyte was prepared, a dye-sensitized solar cell was obtained in the same manner as in Example 1 except that 2-mercaptobenzothiazole was changed to trithiocyanuric acid as a sulfur-containing compound to be dissolved in the solvent. .

(Example 5)
As in Example 1, except that 2-mercaptobenzothiazole was changed to a potassium salt of 2-mercapto-1,3,4-thiadiazole as a sulfur-containing compound to be dissolved in a solvent when the electrolyte was prepared. Thus, a dye-sensitized solar cell was obtained.

(Example 6)
When preparing an electrolyte, 2-mercaptobenzothiazole is changed to a dimer of 2-mercaptobenzothiazole (a product obtained by oxidizing and disulfating 2-mercaptobenzothiazole) as a sulfur-containing compound to be dissolved in a solvent. Except that, a dye-sensitized solar cell was obtained in the same manner as in Example 1.

(Example 7)
Dye-sensitized solar cell in the same manner as in Example 1 except that 2-mercaptobenzothiazole was changed to 5-carboxy-1-pentanethiol as a sulfur-containing compound to be dissolved in a solvent when preparing the electrolyte. Got.

(Comparative Example 1)
When preparing the electrolyte, a dye-sensitized solar cell was obtained in the same manner as in Example 1 except that 2-mercaptobenzothiazole, which is a sulfur-containing compound, was not dissolved in the solvent.

<Evaluation of photoelectric conversion characteristics>
For the dye-sensitized solar cells obtained in Examples 1 to 7 and Comparative Example 1, the photoelectric conversion efficiency (η ₀ ) was measured. Subsequently, the photoelectric conversion efficiency (η) after leaving the dye-sensitized solar cell for 300 hours in an environment of 60 ° C. was measured. And the following formula: Reduction rate of photoelectric conversion efficiency (%) = (η−η ₀ ) / η ₀ × 100
Based on the above, the reduction rate of the photoelectric conversion efficiency was calculated. The results are shown in Table 1.

  From the results shown in Table 1, it was found that the dye-sensitized solar cells of Examples 1 to 7 had a lower rate of decrease in photoelectric conversion efficiency than the dye-sensitized solar cell of Comparative Example 1.

As mentioned above, according to the electrolyte of this invention, it was confirmed that the outstanding durability can be provided with respect to a photoelectric conversion element.

10 ... Working electrode (first electrode)
13 ... Porous oxide semiconductor layer 15 ... Transparent conductive substrate (conductive substrate)
DESCRIPTION OF SYMBOLS 16 ... Wiring part 17 ... Metal wiring 18 ... Wiring protective layer 20 ... Counter electrode (2nd electrode)
DESCRIPTION OF SYMBOLS 40 ... Electrolyte 41 ... Redox couple 42 ... Sulfur containing compound 100 ... Dye-sensitized solar cell (photoelectric conversion element)

Claims (3)

An electrolyte for a photoelectric conversion element used for a photoelectric conversion element,
A redox couple consisting of halide and polyhalide ions;
A sulfur-containing compound,
Said sulfur-containing compound is a compound having an -SX group, -S ^- composed of at least one compound selected from the group consisting of compounds having compound having a group, and -S-S- group, X is a monovalent An electrolyte for a photoelectric conversion element that represents a positive ion.   The electrolyte for a photoelectric conversion element according to claim 1, wherein the sulfur-containing compound further includes a functional group having a charge of the same polarity as the polyhalide ion in the molecule. A first electrode;
A second electrode facing the first electrode;
An electrolyte provided between the first electrode and the second electrode,
The first electrode is
A conductive substrate;
An oxide semiconductor layer provided over a conductive substrate;
A wiring portion provided on the conductive substrate;
The wiring part is provided with a metal wiring provided on the conductive substrate;
A wiring protective layer that covers the metal wiring and protects it from the electrolyte;
The photoelectric conversion element comprised with the electrolyte for photoelectric conversion elements as described in any one of Claim 1 or 2 in which the said electrolyte is.

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