JP2013211103A - Method of manufacturing working electrode, working electrode, method of manufacturing dy-sensitized solar cell, and dy-sensitized solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a working electrode which can impart excellent durability to a dye-sensitized solar cell, and to provide a working electrode, a method of manufacturing a dye-sensitized solar cell, and a dye-sensitized solar cell.SOLUTION: The method of manufacturing a working electrode 10 includes a current collecting wiring formation step for forming a metal layer 19 by coating a conductive substrate 11 with a metal paste containing metal particles and then heating, and forming current collecting wiring 16 by infiltrating a filler 18 into the metal layer 19, and a step for forming a wiring protection layer for forming a wiring protection layer 17 by covering the surface of the current collecting wiring 16 with a material for forming a wiring protection layer and then heating the material for forming a wiring protection layer.

Description

  The present invention relates to a method for producing a working electrode, a working electrode, a method for producing a dye-sensitized solar cell, and a dye-sensitized solar cell.

  As a photoelectric conversion element, a dye-sensitized solar cell has attracted attention because it is inexpensive and high photoelectric conversion efficiency can be obtained, and various developments have been made on the dye-sensitized solar cell.

  A dye-sensitized solar cell generally includes a working electrode having a porous metal oxide semiconductor layer on a conductive substrate, a counter electrode, a sealing portion connecting the working electrode and the counter electrode, a working electrode, a counter electrode, and a sealing. And an electrolyte disposed in a cell space surrounded by the portion.

  Here, as a working electrode, a structure having a current collecting wiring on a conductive substrate has been proposed in order to efficiently extract the electricity obtained from the porous oxide semiconductor layer to the outside. Furthermore, in order to prevent corrosion of the current collecting wiring due to the electrolyte, the current collecting wiring is generally covered with a wiring protective layer.

  As a method for producing such a working electrode, for example, after applying a glass paste composition containing glass frit or the like to the surface of a collecting electrode provided on a transparent conductive substrate, the glass paste composition is specified. There is known a method of manufacturing an electrode substrate by forming a coating layer that covers the surface of a collecting electrode by heating at a heating temperature (see Patent Document 1 below). In the following Patent Document 1, it is proposed that the electrode substrate manufactured as described above prevents the generation of cracks in the coating layer and ensures sufficient resistance to electrolyte.

JP 2011-91012 A

  However, the manufacturing method of the electrode substrate described in Patent Document 1 has the following problems.

  That is, with respect to the electrode substrate obtained by the electrode substrate manufacturing method described in Patent Document 1, the current collector wiring is corroded by the electrolyte when the electrode substrate is used as a working electrode of a dye-sensitized solar cell. In some cases, the electrode substrate has room for improvement in terms of durability.

  The present invention has been made in view of the above circumstances, and a method for producing a working electrode capable of producing a working electrode capable of imparting excellent durability to a dye-sensitized solar cell, a working electrode, and a dye sensitizing method. An object is to provide a method for producing a solar cell and a dye-sensitized solar cell.

  As a result of intensive studies to solve the above problems, the present inventors have thought that the current collector wiring may be corroded due to the following reasons. That is, the current collector wiring is formed by applying a metal paste containing metal particles on a conductive substrate and then heating. However, voids are generated in the gaps when the metal particles are fused together, and current collector wiring having voids communicating from the inside to the surface may be formed. In this case, as in Patent Document 1, when the surface of the current collector wiring is covered with a glass paste composition and the glass paste composition is heated to form a coating layer, the current collector wiring is communicated from the inside to the surface. The air contained in the voids is heated and expanded, and the expanded air penetrates to the surface of the glass paste composition. As a result, the present inventors considered that a path through which the electrolyte can enter the current collector wiring may be generated in the obtained wiring protective layer. Therefore, the present inventors have thought that the above-described problems can be solved if the porosity inside the current collector wiring is reduced as much as possible. As a result of further intensive studies, the present inventors have found that the above problems can be solved by the following invention, and have completed the present invention.

  That is, the present invention provides a current collector wiring in which a metal layer containing metal particles is applied on a conductive substrate and heated to form a metal layer, and a filler is infiltrated into the metal layer to form a current collector wiring. And a wiring protective layer forming step of covering the surface of the current collector wiring with a wiring protective layer forming material and heating the wiring protective layer forming material to form a wiring protective layer. It is a manufacturing method of an electrode.

  According to the above manufacturing method, by allowing the filler to penetrate into the inside of the metal layer, the void formed in communication from the inside of the metal layer to the surface by the heating of the metal paste is filled with the filler. Can be made as small as possible. For this reason, when the current collector wiring is covered with a wiring protective layer forming material and the wiring protective layer forming material is heated to form the wiring protective layer, the air contained in the voids remaining inside the current collecting wiring expands. However, since the amount of the expanded air is extremely small, it is possible to prevent air from entering the wiring protective layer as much as possible. Therefore, voids are hardly generated in the wiring protective layer and the current collecting wiring, and the generation of a path through which the electrolyte can penetrate from the wiring protective layer to the current collecting wiring is sufficiently suppressed. As a result, corrosion of the current collector wiring due to the electrolyte can be prevented, and deterioration of the working electrode can be suppressed. For example, when the sealing part is bonded to the surface of the obtained working electrode by heating, even if the air contained in the gap remaining inside the current collector wiring expands, the amount of the expanding air is small, so that the wiring protection It can suppress as much as possible that the stress by expansion | swelling of air is added to a layer. For this reason, the crack which generate | occur | produces inside a wiring protective layer hardly arises. Therefore, generation of a path through which the electrolyte can enter from the wiring protective layer to the current collecting wiring is sufficiently suppressed. As a result, when the obtained working electrode is applied as a working electrode of a dye-sensitized solar cell having an electrolyte, corrosion of the current collector wiring by the electrolyte is sufficiently suppressed. Therefore, according to the method for producing a working electrode of the present invention, a working electrode capable of imparting excellent durability to the dye-sensitized solar cell can be produced.

  In addition, the present invention includes a conductive substrate, a current collector wiring provided on the conductive substrate and including metal particles and a filler, and a wiring protective layer that covers and protects the current collector wiring. Is the working electrode.

  According to this working electrode, since the voids in the current collector wiring are filled with the filler, the current collector wiring has a structure with a small porosity. For this reason, when the sealing portion forming material is adhered to the surface of the working electrode by heating, for example, even if the air contained in the gap remaining in the current collector wiring expands, the amount of the expanding air is small Therefore, it can suppress as much as possible that the stress by expansion | swelling of air is added to a wiring protective layer. For this reason, cracks hardly occur inside the wiring protective layer. Therefore, generation of a path through which the electrolyte can enter from the wiring protective layer to the current collecting wiring is sufficiently suppressed. As a result, when the obtained working electrode is applied as a working electrode of a dye-sensitized solar cell having an electrolyte, corrosion of the current collector wiring by the electrolyte is sufficiently suppressed. Therefore, according to the working electrode of the present invention, it is possible to impart more excellent durability to the dye-sensitized solar cell.

  In the method for producing the working electrode, the metal paste preferably contains inorganic binder particles.

  In this case, the inorganic binder is melted by heating the metal paste. At this time, the inorganic binder moves from the inside of the metal paste toward the surface of the conductive substrate and adheres to the surface of the conductive substrate. As a result, the adhesive force between the current collector wiring and the conductive substrate can be improved. Therefore, since the current collection wiring is difficult to peel from the conductive substrate, the durability of the current collection wiring can be improved. On the other hand, a relatively large void is formed at the site where the inorganic binder has moved. Since this void is filled with a filler, the void inside the metal layer is present even when the metal paste has inorganic binder particles. The rate can be made as small as possible.

  In the said working electrode, it is preferable that current collection wiring contains an inorganic binder.

  Thereby, the working electrode which the adhesive force of current collection wiring and an electroconductive board | substrate improved more can be formed. Therefore, since the current collection wiring is difficult to peel from the conductive substrate, the durability of the current collection wiring can be improved.

  In the working electrode or the manufacturing method thereof, the filler preferably contains a metal material.

  Thereby, since the electrical conductivity of the current collector wiring is increased, the electricity obtained from the porous oxide semiconductor layer can be easily and efficiently extracted to the outside.

  The dye-sensitized solar cell according to the present invention is preferably obtained by the method for producing a working electrode.

  By producing a dye-sensitized solar cell by the above method for producing a working electrode, a dye-sensitized solar cell having almost no cracks inside the wiring protective layer can be realized. Therefore, generation of a path through which the electrolyte can enter from the wiring protective layer to the current collecting wiring is sufficiently suppressed. As a result, when the obtained working electrode is applied as a working electrode of a dye-sensitized solar cell having an electrolyte, corrosion of the current collector wiring by the electrolyte is sufficiently suppressed. Therefore, according to the dye-sensitized solar cell obtained by the manufacturing method of the working electrode, it is possible to realize a dye-sensitized solar cell having durability superior to that of the conventional one.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and working electrode of a working electrode which can manufacture the working electrode which can provide the outstanding durability with respect to a dye-sensitized solar cell, the manufacturing method and dye-sensitizing of a dye-sensitized solar cell A solar cell is provided.

It is sectional drawing which shows 1st Embodiment in the dye-sensitized solar cell which concerns on this invention. FIG. 2 is an enlarged partial cross-sectional view showing a wiring portion in FIG. 1. It is a figure which shows 1 process of the manufacturing method of the working electrode of FIG. It is a figure which shows 1 process of the manufacturing method of the working electrode of FIG. 1, Comprising: (a) is sectional drawing, (b) is an expanded partial sectional view corresponding to sectional drawing of (a). It is a figure which shows 1 process of the manufacturing method of the working electrode of FIG. 1, Comprising: (a) is sectional drawing, (b) is an expanded partial sectional view corresponding to sectional drawing of (a). It is a figure which shows 1 process of the manufacturing method of the working electrode of FIG. It is sectional drawing which shows 1st Embodiment of the working electrode which concerns on this invention. It is an expanded partial sectional view of the wiring part in 2nd Embodiment of the working electrode which concerns on this invention. It is an expanded partial sectional view of the wiring part in the modification of 2nd Embodiment of the working electrode which concerns on this invention.

<First Embodiment>
Hereinafter, a first embodiment of a method for producing a working electrode, a working electrode, a method for producing a dye-sensitized solar cell, and a dye-sensitized solar cell according to the present invention will be described in detail with reference to FIGS. Note that the present invention is not limited to such an embodiment. In addition, the drawings used in the following description may show the main part in an enlarged manner for the sake of convenience in order to make the characteristics of the present invention easier to understand. Not necessarily.

  FIG. 1 is a cross-sectional view showing a first embodiment of a working electrode according to the present invention, and shows a state in which the working electrode of the present invention is used as a working electrode of a dye-sensitized solar cell. FIG. 2 is an enlarged partial cross-sectional view showing the wiring portion 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 in a cell space formed by the counter electrode 20 and the sealing portion 30.

  The counter electrode 20 includes a conductive substrate 21 and a catalyst layer 22 provided on the working electrode 10 side of the conductive substrate 21 to promote a catalytic reaction.

  The working electrode 10 includes a conductive substrate 11, a porous oxide semiconductor layer 12 supporting a photosensitizing dye provided on the conductive substrate 11, and a porous oxide semiconductor layer on the conductive substrate 11. 12 and a wiring portion 13 provided around 12. The conductive substrate 11 includes a transparent substrate 14 and a transparent conductive film 15 provided on the transparent substrate 14. The wiring portion 13 includes a current collecting wiring 16 provided on the transparent conductive film 15 and a wiring protective layer 17 that covers the current collecting wiring 16 and protects it from the electrolyte 40. The current collecting wiring 16 has a conductive property. It is provided on the substrate 11 and includes a filler 18 and a metal layer 19. In addition, as shown in FIG. 2, the current collecting wiring 16 includes an inorganic binder 50 that is provided below the current collecting wiring 16. At this time, a small number of air gaps A are generated inside the current collecting wiring 16. The space A includes a space that does not communicate with the surface and forms a closed space.

  Next, the manufacturing method of the said dye-sensitized solar cell 100 is demonstrated based on FIGS.

  First, a method for manufacturing the working electrode 10 will be described.

  First, as shown in FIG. 3, a conductive substrate 11 formed by forming a transparent conductive film 15 on a transparent substrate 14 is prepared.

  The material which comprises the transparent substrate 14 should just be a transparent material, for example, As such a transparent material, glass, such as borosilicate glass, soda lime glass, white plate glass, high strain point glass, quartz glass, for example, Examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyether sulfone (PES), and transparent polyimide. The thickness of the transparent substrate 14 is appropriately determined according to the size of the dye-sensitized solar cell 100 and is not particularly limited, but may be in a range of 0.05 to 10 mm, for example.

Examples of the material constituting the transparent conductive film 15 include conductive metal oxides such as tin-added indium oxide (ITO), tin oxide (SnO ₂ ), and fluorine-added tin oxide (FTO). The transparent conductive film 15 may be a single layer or a laminate of a plurality of layers made of different conductive metal oxides. The thickness of the transparent conductive film 15 may be in the range of 0.01 to 2 μm, for example.

  As a method for forming the transparent conductive film 15, a sputtering method, a vapor deposition method, a spray pyrolysis (SPD) method, a CVD method, or the like is used.

  Next, the porous oxide semiconductor layer 12 is formed on the conductive substrate 11. The porous oxide semiconductor layer 12 is formed by printing a porous oxide semiconductor layer forming paste containing oxide semiconductor particles and then heating.

Examples of the oxide semiconductor particles include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₅ ), niobium oxide (Nb ₂ O ₅ ), strontium titanate (SrTiO ₅ ), and 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 of these. The thickness of the porous oxide semiconductor layer 12 may be, for example, 0.5 to 50 μm.

  The porous oxide semiconductor layer forming paste contains a resin such as polyethylene glycol and cellulose derivative, and a solvent such as terpineol, in addition to the oxide semiconductor particles.

  As a printing method of the paste for forming a porous oxide semiconductor layer, for example, a screen printing method, a metal mask method, a doctor blade method, a bar coating method, or the like can be used.

  The heating temperature varies depending on the material of the oxide semiconductor particles, but is usually 100 to 600 ° C. Although the heating time varies depending on the material of the oxide semiconductor particles, it is usually 0.5 to 5 hours.

  Next, the wiring part 13 is formed on the conductive substrate 11. Here, the forming process of the wiring portion 13 includes a current collecting wiring forming process and a wiring protective layer forming process.

  First, the current collector wiring forming process will be described. Here, as shown in FIG. 3, a metal paste containing metal particles and inorganic binder particles is applied onto the transparent conductive film 15 of the conductive substrate 11, and then dried to form a metal layer precursor 19 </ b> A.

  Examples of the metal material constituting the metal particles include silver, copper, gold, aluminum, nickel, and titanium. These can be used alone or in combination of two or more.

  Examples of the material constituting the inorganic binder particles include glass frit such as low melting point glass and solder. The low melting point glass is preferably one that softens at a temperature lower than the firing temperature of the paste forming the metal wiring, and preferably has a softening point of 550 ° C. or less, for example. These can be used alone or in combination of two or more.

  In addition to the above-described metal particles and inorganic binder particles, the metal paste may further contain a solvent such as a volatile solvent and, if necessary, organic binder particles such as polyethylene glycol.

  As a method for applying the metal paste, for example, a screen printing method, a metal mask method, an ink jet method, a doctor blade method, a bar coating method, a dispensing method, or the like can be used.

  Although the drying temperature of a metal paste changes with compositions, it should just be 100-200 degreeC normally. Although drying time also changes with compositions, it should just be 0.1 to 2 hours normally.

  At this time, the average particle diameter of the metal particles is preferably 1500 nm or less, and more preferably 900 nm or less. When the average particle diameter of the metal particles is within the above range, it is possible to obtain a current collector wiring 16 that is denser and has a smaller average gap diameter than when the average particle diameter is outside the above range.

  In addition, the thickness of the current collection wiring 16 should just be 2-60 micrometers, for example at this time.

  In order to make the porosity of the current collector wiring 16 smaller, for example, the content of the disappearing component at the time of firing such as organic binder particles in the metal paste may be reduced. By doing in this way, the current collection wiring 16 can be made denser.

  Next, the metal layer precursor 19A is heated. At this time, the metal particles in the metal layer precursor 19A are sintered. Thus, the metal layer 19 is formed as shown in FIG. At this time, as shown in FIGS. 4A and 4B, a gap A is generated inside the metal layer 19. Here, the void A includes both a void communicating from the inside of the metal layer 19 to the surface and a void not communicating from the inside of the metal layer 19 to the surface and forming a closed space. In addition, the gap communicating from the inside of the metal layer 19 to the surface is not communicated to the surface in the cross section of FIG. 4B, but the gap is communicated when viewed three-dimensionally. In FIG. 2, voids communicating to the surface of the metal layer 19 are included.

  The heating temperature of the metal layer precursor 19A may be 300 to 600 ° C., and the heating time may be 0.1 to 2 hours.

  Next, as shown in FIG. 5A, the filler 18 is infiltrated into the metal layer 19. For this reason, as shown in FIGS. 5A and 5B, the gap A generated in the metal layer 19 by the heat treatment of the metal layer precursor 19 </ b> A is filled with the filler 18. As a result, the current collecting wiring 16 including the filler 18 inside is formed.

  Here, the material constituting the filler 18 is not particularly limited as long as it is a material that can fill the gap A. For example, a metal material is included from the viewpoint of electrical conductivity, and a resin material is included from the viewpoint of fillability. It is preferable.

  When a metal material is used as the material of the filler 18, the electrical conductivity of the current collecting wiring is increased, so that the electricity obtained from the porous oxide semiconductor layer 12 can be easily and efficiently drawn to the outside.

  When a metal material is used as the material of the filler 18, it is not particularly limited as long as it can exhibit the above functions. For example, a conductive plating material such as silver or copper is particularly suitable. Note that the metal material may be changed into an oxide or the like after heating.

  When a resin material is used as the material of the filler 18, it is not particularly limited as long as it can exhibit the above functions. For example, materials such as a polyimide resin, a polybenzoxazole resin, and a fluororesin are particularly suitable. Note that the resin material may be carbonized when the wiring protective layer forming material 17A described later is heated to form the wiring protective layer 17.

  In addition, said metal material and resin material can be used individually or in combination of 2 or more types. Moreover, the material of the filler 18 is not limited to a metal material and a resin material as long as it can express the said function, For example, materials, such as an ionic liquid, are mentioned.

  The content of the inorganic binder 50 in the current collector wiring 16 is preferably 0.1 to 5% by mass, and more preferably 0.1 to 3% by mass.

  In this case, compared with the case where the content of the inorganic binder 50 in the current collector wiring 16 is less than 0.1% by mass, it is possible to exhibit better adhesion to the conductive substrate 11 and 3 masses. The resistance of the current collecting wiring 16 can be more sufficiently reduced than in the case where the percentage exceeds 50%.

  Subsequently, the wiring protective layer forming step will be described. Here, as shown in FIG. 6, a wiring protective layer forming material 17 </ b> A is provided so as to cover the current collecting wiring 16.

  The wiring protective layer 17 may be made of a material that covers the current collector wiring 16 and protects from the electrolyte 40. As the wiring protective layer forming material 17A that forms the wiring protective layer 17, for example, an inorganic material such as low-melting glass is used. A paste containing a material, a heat-resistant resin such as a polyimide resin, a silicone resin, or a fluororesin can be used. A technique such as attaching a hot melt adhesive can also be applied. As the hot melt adhesive, for example, a polyolefin-based hot melt adhesive can be used.

  In the case of forming the wiring protective layer 17, the wiring protective layer forming material 17A is made of a resin such as polyethylene glycol or a solvent such as terpineol, if necessary, in addition to the inorganic material described above or a resin material such as a heat resistant resin. May be included.

  The thickness of the wiring protective layer 17 may be, for example, 1 to 30 μm.

  Then, as shown in FIG. 7, the wiring protective layer 17 is formed by heating the wiring protective layer forming material 17A.

  When the paste includes an inorganic material, the heat treatment is performed by drying and then heating and baking the paste applied on the current collector wiring 16. Although heating temperature changes with paste compositions, it is 300-600 degreeC normally. Although the heating time varies depending on the paste composition, it is usually 0.5 to 2 hours.

  When the paste includes a heat resistant resin, the heat treatment is performed by drying the paste by heating. The drying temperature varies depending on the paste composition, but is usually 100 to 200 ° C. The drying time also varies depending on the paste composition, but is usually 0.5 to 2 hours. As described above, the wiring part 13 is formed on the transparent conductive film 15 of the conductive substrate 11 as shown in FIG. If the paste contains a reactive heat-resistant resin, it may be further heated as necessary to complete the reaction. Although this condition varies depending on the composition of the paste, for example, the conditions are 200 to 400 ° C. and 0.5 to 4 hours.

  The wiring protective layer 17 may have a multilayer structure of an inorganic material or a multilayer structure of an inorganic material and a resin material. When making an inorganic material into a multilayer, you may use the inorganic material from which melting temperature differs.

  Thus, the working electrode 10 is formed.

  Next, a photosensitizing dye is supported on the surface of the porous oxide semiconductor layer 12 of the working electrode 10. For this purpose, the working electrode 10 is immersed in a solution containing a photosensitizing dye, and after the dye is supported on the porous oxide semiconductor layer 12, excess dye is washed away with the solvent component of the solution, The photosensitizing dye may be supported on the porous oxide semiconductor layer 12 by drying. However, the photosensitizing dye may be supported on the porous oxide semiconductor layer 12 by applying a solution containing the photosensitizing dye to the porous oxide semiconductor layer 12 and then drying the solution.

  As the photosensitizing dye, for example, a ruthenium complex, a osmium complex, an iron complex, a copper complex, a platinum complex, a porphyrin metal complex, a phthalocyanine metal complex, or a metal complex dye having a bipyridine or terpyridine ligand, or cyanine Organic dyes such as merocyanine, mercurochrome, xanthene dyes, azo dyes, and coumarin dyes can be used.

  Next, the sealing part 30 is prepared. The sealing part 30 can be obtained by preparing a sealing resin and forming a rectangular opening in the sealing resin film.

  Then, the sealing portion 30 is adhered on the working electrode 10. At this time, the porous oxide semiconductor layer 12 is arranged inside the opening of the sealing portion 30. Adhesion of the sealing portion 30 to the working electrode 10 can be performed by heating and melting the sealing portion 30. Examples of the sealing resin film include various modified polyolefin resins including, for example, ionomer resins, ethylene-vinyl acetic anhydride copolymers, ethylene-methacrylic acid copolymers, ethylene-vinyl alcohol copolymers, ultraviolet curable resins, And resin, such as a vinyl alcohol polymer, is mentioned.

  Next, the electrolyte 40 is disposed on the porous oxide semiconductor layer 12.

The electrolyte 40 is usually composed of an electrolytic solution, and this electrolytic solution contains an oxidation-reduction pair such as I ⁻ / I ₃ ^— and an organic solvent. As the organic solvent, acetonitrile, methoxyacetonitrile, 3-methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, and the like can be used. Examples of the redox pair include I ⁻ / I ₃ ⁻ and bromine / bromide ion pairs. The electrolyte 40 may be an ionic liquid instead of an organic solvent. Moreover, the electrolyte which consists of a mixture of an ionic liquid and an organic solvent may be sufficient. As the ionic liquid, for example, 1,2-dimethyl-3-propylimidazolium iodide, 1-hexyl-3-methylimidazolium iodide, 1-propyl-3-methylimidazolium iodide and the like are preferably used. An additive may be added to the electrolyte 40. Examples of the additive include lithium iodide, 4-tertbutylpyridine, N-methylbenzimidazole, guanidine thiocyanate and the like. Further, as the electrolyte 40, a nano-composite gel electrolyte, which is a pseudo-solid electrolyte formed by kneading nanoparticles such as SiO ₂ , TiO ₂ , carbon nanotubes, etc. into the electrolyte, may be used, and polyvinylidene fluoride may be used. Alternatively, an electrolyte gelled with an organic gelling agent such as a polyethylene oxide derivative or an amino acid derivative may be used.

  The electrolyte 40 can be disposed by, for example, a printing method such as screen printing or a coating method using a dispenser.

  Next, the counter electrode 20 is prepared.

  As described above, the counter electrode 20 includes the conductive substrate 21 and the conductive catalyst layer 22 that is provided on the working electrode 10 side of the conductive substrate 21 and promotes the reduction reaction on the surface of the counter electrode 20. is there.

  The conductive substrate 21 is, for example, 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 14 described above. Consists of. The thickness of the conductive 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, 0.005 to 10 mm.

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

  Finally, the counter electrode 20 is bonded so as to close the opening of the sealing portion 30. Lamination of the counter electrode 20 to the sealing portion 30 may be performed under atmospheric pressure or under reduced pressure, but is preferably performed under reduced pressure.

  As described above, a dye-sensitized solar cell 100 is obtained as shown in FIG.

  When produced as described above, it is possible to realize the dye-sensitized solar cell 100 in which the voids generated in the current collecting wiring 16 are extremely small.

  Hereinafter, the operation and effect of the first embodiment according to the present invention will be described. Conventionally, the current collector wiring 16 is formed as the metal layer 19 by applying a metal paste containing metal particles and inorganic binder particles on the conductive substrate 11 and then heating. However, since the inorganic binder 50 is melted and moves toward the surface of the conductive substrate 11 by this heat treatment, a relatively large gap A is formed in the portion where the inorganic binder 50 has moved. For this reason, the comparatively big space | gap A will be formed in the inside of the current collection wiring 16 formed after heat processing. Therefore, when the surface of the current collecting wiring 16 is covered with the wiring protective layer forming material 17A and the wiring protective layer forming material 17A is heated to form the wiring protective layer 17, the gap A formed in the current collecting wiring 16 is formed. The contained air is heated to expand, the expanded air penetrates the wiring protective layer forming material 17A, and a path through which the electrolyte 40 can enter the current collecting wiring 16 is generated in the wiring protective layer 17 obtained. Is done. As a result, the current collector wiring 16 is corroded by the electrolyte 40 that enters, and the durability of the working electrode 10 is deteriorated.

  According to the first embodiment of the present invention, the above problem can be solved. That is, the filler 18 is infiltrated into the metal layer 19 so that the porosity in the current collector wiring 16 can be minimized. Thereby, since the space | gap A which arises inside the metal layer 19 by the heat processing of a metal paste is filled, the porosity inside the current collection wiring 16 can be made as small as possible. Therefore, when the current collector wiring 16 is covered with the wiring protective layer forming material 17A and the wiring protective layer forming material 17A is heated to form the wiring protective layer 17, it is included in the gap A remaining in the current collecting wiring 16 inside. Even when the generated air expands, the amount of the expanded air is extremely small, so that the intrusion of air into the wiring protective layer 17 can be prevented as much as possible. Therefore, voids are hardly generated in the wiring protective layer 17 and the current collecting wiring 16, and the generation of a path through which the electrolyte 40 can penetrate from the wiring protective layer 17 to the current collecting wiring 16 is sufficiently suppressed. As a result, corrosion of the current collector wiring 16 by the electrolyte 40 can be prevented, and deterioration of durability in the working electrode 10 can be suppressed.

  Further, when the sealing portion 30 is adhered to the surface of the obtained working electrode 10 by heating, for example, even if the air contained in the gap A remaining in the current collector wiring 16 expands, the amount of air that expands remains. Since there are few, it can suppress as much as possible that the stress by the expansion | swelling of air is added to the wiring protective layer 17. FIG. For this reason, cracks hardly occur inside the wiring protective layer 17. Therefore, generation of a path through which the electrolyte 40 can enter from the wiring protective layer 17 to the current collecting wiring 16 is sufficiently suppressed. As a result, when the obtained working electrode 10 is applied as the working electrode 10 of the dye-sensitized solar cell 100 having the electrolyte 40, corrosion of the current collector wiring 16 by the electrolyte 40 is sufficiently suppressed. Therefore, according to the method for manufacturing the working electrode 10 according to the first embodiment of the present invention, the working electrode 10 capable of imparting excellent durability to the dye-sensitized solar cell 100 can be manufactured. .

Second Embodiment
Next, a second embodiment of the working electrode of the present invention will be described in detail based on FIG. FIG. 8 is a cross-sectional view of the wiring portion 113 used in the second embodiment of the working electrode 10 according to the present invention. That is, the current collecting wiring 16 has a structure including a first current collecting wiring 41 provided on the conductive substrate 11 and a second current collecting wiring 42 provided on the first current collecting wiring 41. May be. Further, the gaps A1 and A2 generated inside the first current collecting wiring 41 and the second current collecting wiring 42 are filled with the filler 18 respectively. At this time, the porosity of the second current collector wiring 42 is formed to be smaller than the porosity of the first current collector wiring 41.

  Since the gaps A1 and A2 generated inside the first current collecting wiring 41 and the second current collecting wiring 42 are filled with the filler 18, respectively, the wiring protective layer 17 and the first current collecting wiring 17 are formed in the same manner as in the first embodiment. Generation of a path through which the void is very unlikely to be generated inside the current collecting wiring 41 and the second current collecting wiring 42 and the electrolyte 40 can penetrate from the wiring protective layer 17 to the first current collecting wiring 41 and the second current collecting wiring 42. Is sufficiently suppressed. Furthermore, in this embodiment, since the porosity of the 2nd current collection wiring 42 is formed so that it may become smaller than the porosity of the 1st current collection wiring 41, the 1st current collection wiring 41 and the 2nd current collection wiring 41 are formed. When the wiring 42 is covered with the wiring protective layer forming material 17A and the wiring protective layer 17 is formed by heating the wiring protective layer forming material 17A, the air contained in the gap A1 of the first current collecting wiring 41 is heated. Even if it expands, the second current collector wiring 42 sufficiently suppresses the air from penetrating the wiring protective layer 17. For this reason, the air in the gap A1 hardly penetrates into the wiring protective layer 17, so that voids are less likely to occur inside the wiring protective layer 17. As a result, in the wiring protective layer 17, the effect of suppressing the generation of a path through which the electrolyte 40 can enter is further improved. Therefore, when the obtained working electrode 10 is applied as a working electrode of the dye-sensitized solar cell 100 having the electrolyte 40, corrosion of the current collector wiring 16 by the electrolyte 40 is sufficiently suppressed. Therefore, according to the method for producing the working electrode 10 of the present invention, the working electrode 10 capable of imparting excellent durability to the dye-sensitized solar cell 100 can be produced.

  Here, the material used for the 1st current collection wiring 41 and the 2nd current collection wiring 42 uses the metal material containing silver, copper, etc. as metal particles like the material used for the above-mentioned current collection wiring 16, for example. Yes. The first current collecting wiring 41 uses a metal material containing glass frit such as low melting point glass or solder as the inorganic binder 50. The second current collector wiring 42 may contain an inorganic binder 60. At this time, the content of the inorganic binder 60 is preferably smaller than that of the first current collector wiring 41, and the difference is more preferably 0.1 to 3% by mass. In this case, compared with the case where the difference between the content of the inorganic binder 50 in the first current collector wiring 41 and the content of the inorganic binder 60 in the second current collector wiring 42 is out of the above range, the first current collector wiring. The porosity of the second current collector wiring 42 can be easily made lower than the porosity of 41. Therefore, when the first current collection wiring 41 and the second current collection wiring 42 are covered with the wiring protective layer forming material 17A and the wiring protective layer forming material 17A is heated to form the wiring protective layer 17, the first current collecting wiring 41 and the second current collecting wiring 42 are covered. Even if the air contained in the gap A <b> 1 of the electric wiring 41 expands due to heating, the second current collecting wiring 42 sufficiently suppresses the air from penetrating the wiring protective layer 17. For this reason, the air in the gap A <b> 2 hardly penetrates into the wiring protection layer 17, so that voids are less likely to be generated inside the wiring protection layer 17. As a result, in the wiring protective layer 17, the effect of suppressing the generation of a path through which the electrolyte 40 can enter is further improved.

  Furthermore, the maximum diameter of the gap A2 in the second current collector wiring 42 is preferably smaller than the maximum diameter of the gap A1 in the first current collector wiring 41. In this case, the first current collecting wiring 41 and the second current collecting wiring 42 are covered with the wiring protective layer forming material 17A, and the wiring protective layer forming material 17A is heated to form the wiring protective layer 17. Even if the air contained in the gap A <b> 1 of the current collection wiring 41 expands due to heating, the second current collection wiring 42 sufficiently suppresses the air from penetrating the wiring protection layer 17.

  The average particle diameter of the metal particles in the first current collector wiring 41 may be the same as that in the current collector wiring 16, preferably 2000 nm or less, and more preferably 1000 nm or less. The average particle diameter of the metal particles in the second current collector wiring 42 is preferably 1500 nm or less, and more preferably 900 nm or less. When the average particle diameter of the metal particles is within the above range, it is possible to obtain denser first current collector wiring 41 and second current collector wiring 42 than when the average particle diameter is outside the above range. In addition, the average particle diameter of the metal particles contained in the second metal paste may be the same as or different from the metal particles contained in the first metal paste.

  Moreover, the thickness of the 1st current collection wiring 41 should just be the same as the case of the said current collection wiring 16, for example, what is necessary is just 2-60 micrometers. Moreover, the thickness of the 2nd current collection wiring 42 should just be 2-60 micrometers, for example.

  Next, a second embodiment of the working electrode manufacturing method according to the present invention will be described. Here, description is omitted about the common part with the manufacturing method of 1st Embodiment, and only the part from which a manufacturing method differs is demonstrated. First, after forming the first metal layer precursor 41A by the same method as the current collector wiring 16, a second metal paste containing metal particles and an inorganic binder 60 is applied on the first metal layer precursor 41A. The second metal layer precursor 42A is formed by drying. Next, the first metal layer precursor 41A and the second metal layer precursor 42A are heated together. At this time, the metal particles in the first metal layer precursor 41A and the second metal layer precursor 42A are sintered. Thus, the first metal layer 41B and the second metal layer 42B in which the gaps A1 and A2 are generated are formed at the same time. Finally, the filler 18 is infiltrated into the first metal layer 41B and the second metal layer 42B. At this time, the gaps A1 and A2 generated in the first metal layer 41B and the second metal layer 42B are filled with the filler 18, respectively, and the first current collecting wiring 41 and the second current collecting wiring 42 are simultaneously formed. Thereby, since the heat treatment step and the filling step of the filler 18 can be performed in one step, it is possible to simplify the formation method and reduce the cost.

  In addition, 2nd Embodiment in the manufacturing method of the working electrode which concerns on this invention is not limited to the said formation method, It may replace with the said formation method and may perform the following formation method. That is, the first metal layer precursor 41A is heat-treated, the filler 18 is applied after the formation of the first metal layer 41B, the first current collection wiring 41 is formed, and then the same procedure as the first current collection wiring 41 is performed. The heat treatment process and the filling process of the filler 18 such as forming the second current collector wiring 42 may be performed twice. The formation conditions at this time are the same as the conditions for forming the first current collecting wiring 41 and the second current collecting wiring 42 simultaneously. As a result, the filler 18 can easily permeate into the respective current collector wirings, so that it is possible to further reduce the porosity and the void diameter in the first current collector wiring 41 and the second current collector wiring 42. .

  Moreover, 2nd Embodiment in the working electrode of this invention is not limited to the said form, You may take a form as shown in FIG. 9 as a modification. Here, FIG. 9 is a cross-sectional view of a wiring portion 213 used as a modification of the second embodiment in the working electrode 10 according to the present invention. That is, in the wiring part 213, the second current collecting wiring 42 may cover only a part of the surface of the first current collecting wiring 41 except the surface in contact with the conductive substrate 11. It is good also as a form which is not adhere | attached on. In this case, in the wiring portion 213, the remaining portion of the first current collecting wire 41 that is not covered with the second current collecting wire 42 and the wiring protective layer 17 are bonded to each other. Here, it is preferable that the wiring protective layer 17 includes an inorganic binder. In this case, since the first current collecting wiring 41 includes the inorganic binder 50, the inorganic binder in the wiring protective layer 17 and the inorganic binder 50 in the first current collecting wiring 41 are coupled to each other. As a result, the adhesion between the wiring protective layer 17 and the first current collecting wiring 41 can be improved. Here, as the inorganic binder, glass frit is particularly preferable because it has corrosion resistance to the electrolyte 40 and can sufficiently suppress leakage of volatile substances contained in the electrolyte 40.

  Moreover, in the said 1st Embodiment and 2nd Embodiment, although the transparent conductive substrate is used as the conductive substrate 11 which comprises the working electrode 10, the conductive substrate 11 does not necessarily need to be transparent. For example, when the counter electrode 20 is a see-through electrode, the conductive substrate 11 can be configured by a non-transparent substrate. As the substrate that is not transparent, for example, the same substrate as the conductive substrate 21 of the counter electrode 20 can be used.

Moreover, in the said 1st Embodiment and 2nd Embodiment, although the inorganic binder is contained in the current collection wiring 16, the current collection wiring 16 does not necessarily need to contain an inorganic binder. In this case, it is possible to make it relatively difficult to generate a relatively large gap.

  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 transparent conductive substrate was prepared by forming a transparent conductive film made of FTO having a thickness of 1 μm on a transparent substrate made of glass having a thickness of 1 mm.

Next, glass frit is blended with silver paste (trade name XA-9053, manufactured by Fujikura Kasei Co., Ltd.) so that the content of glass frit in the inorganic material in the current collector wiring after heat treatment is 1% by mass. Then, a metal paste was prepared so that the volume resistivity after the heat treatment was about 3.0 × 10 ⁻⁶ Ωm. And this metal paste was printed on the transparent conductive film by the screen printing method, and the silver circuit part was formed in the grid | lattice form. Then, it dried at 130 degreeC and the metal layer precursor was formed.

  Next, this metal layer precursor was heated at 500 ° C. for 1 hour to form a metal layer. At this time, when the cross section of the metal layer and the like were observed, many voids could be confirmed in the gaps between the fused portions of the silver particles. At this time, there were two types of voids that communicated from the inside of the metal layer to the surface and two types of voids that closed inside the metal layer to form a closed space.

  Next, in the metal layer formed by the above method, portions other than the silver circuit portion were masked, and copper plating by electrolytic plating was applied as a filler on the silver circuit portion to form a current collecting wiring. At this time, when the cross section of the current collector wiring was observed, it was confirmed that the gap communicating with the surface of the current collector wiring was filled with copper plating. At this time, the thickness of the current collector wiring was 10 μm.

  Next, a material for forming a wiring protective layer mainly composed of a low melting point glass frit was applied a plurality of times by screen printing so as to cover the current collecting wiring. And the said wiring protective layer forming material was heated at 500 degreeC for 1 hour, and the 10-micrometer-thick wiring protective layer was formed. Thus, a current collector wiring covered with the wiring protective layer was obtained.

  Thereafter, the working electrode was immersed in an iodine electrolyte under heating at 85 ° C. Here, the number of samples in which corrosion occurred in the current collector wiring among 10 samples was confirmed. The results are shown in Table 1.

(Examples 2 and 3)
In Example 2, silver plating by electrolytic plating was used as a filler instead of copper plating by electrolytic plating used in Example 1, and in Example 3, polyimide varnish was applied on the silver circuit portion, and 350 after impregnation. A current collecting wiring was formed in the same manner as in Example 1 except that the heat curing was performed at 0 ° C. Thereafter, as in Example 1, the number of samples in which corrosion occurred was confirmed. The results are shown in Table 1, respectively.

(Comparative Example 1)
A current collector wiring covered with a wiring protective layer was formed in the same manner as in Example 1 except that the metal layer was not filled with a filler. The results are shown in Table 1, respectively.

Example 4
After forming current collection wiring on the conditions equivalent to Example 1, the paste of the titanium oxide nanoparticle was apply | coated by the screen printing method on the transparent conductive film, and it heated at 500 degreeC for 1 hour after drying. In this way, a 10 μm thick porous oxide semiconductor layer was formed.

  Next, a wiring protective layer was formed under the same conditions as in Example 1, and immersed in an acetonitrile / t-butanol solution of ruthenium bipyridine complex (N719 dye) for more than one day and night, then taken out from the dye solution and dried. The photosensitizing dye was supported on the porous oxide semiconductor layer.

  Next, an electrolyte containing iodine redox was applied and disposed on the working electrode in a circulation purification type Globe Books filled with an inert gas.

  Next, the sealing part formation body for forming a sealing part was prepared. The sealing part forming body prepared a single sealing resin film made of 6 cm × 6 cm × 60 μm ionomer resin (trade name: Binnel, manufactured by DuPont), and the sealing resin film has a rectangular shape. Obtained by forming an opening. At this time, the opening was made to have a size of 5 cm × 5 cm × 60 μm. As a result, a sealing part forming body having a width of 5 mm was obtained.

  And after mounting this sealing part formation body on a wiring protection layer, it was made to adhere to a wiring protection layer by heat-melting a sealing part formation body.

  Next, a counter electrode was prepared. The counter electrode was prepared by forming a catalyst layer made of platinum having a thickness of 10 nm on a conductive substrate made of titanium foil of 6 cm × 6 cm × 50 μm by sputtering. Another sealing part forming body was prepared, and this sealing part forming body was bonded to the end of the surface of the counter electrode facing the working electrode in the same manner as described above.

  Next, the sealing part forming body bonded to the working electrode and the sealing part forming body bonded to the counter electrode were opposed to each other, and the sealing part forming bodies were overlapped with each other. And the sealing part formation body was heat-melted, pressing the sealing part formation body in this state. Thus, a sealing portion was formed between the working electrode and the counter electrode, and a dye-sensitized solar cell was obtained.

  Next, the dye-sensitized solar cell produced through the above steps was inserted into a water-proof package and sealed.

(Examples 5 and 6)
In Example 5, silver plating by electrolytic plating was used as a filler instead of copper plating by electrolytic plating used in Example 4, and in Example 6, polyimide varnish was applied on the silver circuit portion and impregnated. A dye-sensitized solar cell was produced in the same manner as in Example 4 except that it was subsequently heat-cured at 350 ° C.

(Comparative Example 2)
A dye-sensitized solar cell was produced in the same manner as in Example 4 except that the metal layer was not filled with a filler.

  Then, as durability evaluation, the maintenance rate of the photoelectric conversion efficiency after 1000 hours in a cell was evaluated as follows.

The dye-sensitized solar cells of Examples 4 to 6 and Comparative Example 2 are held in an environment at 85 ° C., and the maintenance ratio of photoelectric conversion efficiency after 1000 hours is expressed by the following formula: maintenance ratio (%) of photoelectric conversion efficiency. = Photoelectric conversion efficiency after 1000 hours / Photoelectric conversion efficiency immediately after production × 100
Calculated according to
Table 2 shows the result of the maintenance ratio of the photoelectric conversion efficiency calculated by the above method.

  From the results shown in Table 1, it was found that the current collecting wirings of Examples 1 to 3 showed better corrosion prevention properties than the current collecting wiring of Comparative Example 1.

  From the results shown in Table 2, it was found that the dye-sensitized solar cells of Examples 4 to 6 showed a higher maintenance rate of photoelectric conversion efficiency than the dye-sensitized solar cell of Comparative Example 2.

  As mentioned above, according to the manufacturing method of the working electrode of this invention, it was confirmed that the working electrode which can provide the outstanding durability with respect to a dye-sensitized solar cell can be manufactured.

DESCRIPTION OF SYMBOLS 10 ... Working electrode 11 ... Conductive substrate 12 ... Porous oxide semiconductor layer 13,113,213 ... Wiring part 14 ... Transparent substrate 15 ... Transparent conductive film 16 ... Current collection wiring 17 ... Wiring protection layer 17A ... Wiring protection layer formation Materials 18 ... Filler 19 ... Metal layer 19A ... Metal layer precursor 20 ... Counter electrode 21 ... Conductive substrate 22 ... Catalyst layer 30 ... Sealing part 40 ... Electrolyte 41 ... First current collector wire 42 ... Second current collector wire 50, 60 ... Inorganic binder 100 ... Dye-sensitized solar cell A, A1, A2 ... Air gap

Claims (8)

  A current collector wiring forming step of forming a metal layer by applying a metal paste containing metal particles on a conductive substrate and heating, and infiltrating a filler into the metal layer to form a current collector wiring; and And a wiring protective layer forming step of covering the surface of the current collector wiring with a wiring protective layer forming material and heating the wiring protective layer forming material to form a wiring protective layer. Method.   The method for producing a working electrode according to claim 1, wherein the metal paste contains inorganic binder particles.   The method for manufacturing a working electrode according to claim 1, wherein the filler includes a metal material.   The manufacturing method of the dye-sensitized solar cell using the manufacturing method of the working electrode in any one of Claims 1-3. A conductive substrate;
A current collector wiring provided on the conductive substrate and including metal particles and a filler;
A wiring protective layer that covers and protects the current collector wiring;
A working electrode comprising:   The working electrode according to claim 5, wherein the current collector wiring contains an inorganic binder.   The working electrode according to claim 5, wherein the filler includes a metal material.   A dye-sensitized solar cell comprising the working electrode according to claim 5.

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