JP5778027B2 - Method for producing working electrode and working electrode - Google Patents

Description

  The present invention relates to a method for producing a working electrode and a working electrode.

  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, the working electrode generally has current collection wiring on a conductive substrate in order to efficiently extract the electricity obtained from the porous oxide semiconductor layer to the outside. Furthermore, at the working electrode, in order to prevent corrosion of the current collector wiring due to the electrolyte, the current collector 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. A method of manufacturing an electrode substrate by forming a coating layer that covers the surface of the current collecting electrode by firing at the firing temperature is known (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.

  This invention is made | formed in view of the said situation, and provides 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. For the purpose.

  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, first, the current collection wiring is formed by applying a metal paste containing metal particles, a binder resin, and a volatile solvent on a conductive substrate, and then baking it. In this firing step, since the metal particles are sintered while the volatile solvent is volatilized from the metal paste or the binder resin is decomposed, voids are formed in the formed current collector wiring. For this reason, when the present inventors cover the surface of the current collector wiring with a glass paste composition and form the coating layer by firing the glass paste composition as in Patent Document 1, the current collector wiring is formed on the current collector wiring. The air contained in the formed voids is heated to expand, and the expanded air penetrates the glass paste composition. As a result, in the obtained wiring protective layer, the path through which the electrolyte can enter the current collecting wiring I thought that would be generated. Therefore, the present inventors have covered the surface of the current collector wiring with a glass paste composition, and when the coating layer is formed by firing the glass paste composition, the air contained in the gaps in the current collector wiring is used as a wiring protective layer. It was thought that the above-mentioned problem could be solved if the current collector wiring could be formed so that it would be difficult to enter the cable. 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 includes a wiring portion forming step for forming a wiring portion on a conductive substrate, and the wiring portion forming step includes a current collecting wiring forming step for forming a current collecting wiring on the conductive substrate, and the current collecting step. A wiring protective layer forming step of forming a wiring protective layer by covering the electric wiring with a wiring protective layer forming material and heat-treating the wiring protective layer forming material, wherein the current collector wiring is the conductive substrate A first metal wiring portion provided on the first metal wiring portion including an inorganic binder and metal particles; and a second metal wiring portion provided on the first metal wiring portion and including metal particles. And the second metal wiring part has a gap, and the porosity of the second metal wiring part is smaller than the porosity of the first metal wiring part.

  According to the manufacturing method, the first metal wiring part and the second metal wiring part have a gap, and the porosity of the second metal wiring part is smaller than the porosity of the first metal wiring part. Therefore, when the wiring protective layer is formed by heat-treating the wiring protective layer forming material, even if the air contained in the gap of the first metal wiring portion expands, the second metal wiring portion expands the air. Air is sufficiently suppressed from penetrating the wiring protective layer. As a result, in the wiring protective layer, generation of a path through which the electrolyte can enter is sufficiently suppressed. Further, for example, when the sealing portion is bonded to the obtained working electrode by heating, even if the air contained in the gap of the first metal wiring portion expands, the expanded air is caused to be connected to the wiring by the second metal wiring portion. Penetration through the protective layer is sufficiently suppressed. For this reason, generation | occurrence | production of the path | route which an electrolyte can penetrate | invade in a wiring protective layer is fully 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, it is possible to produce a working electrode capable of imparting excellent durability to the dye-sensitized solar cell.

  The present invention also includes a conductive substrate and a wiring portion provided on the conductive substrate, the wiring portion covering the current collection wiring provided on the conductive substrate and the current collection wiring. A protection layer for protecting the wiring, and the current collector wiring is provided on the conductive substrate, and is provided on the first metal wiring portion including an inorganic binder and metal particles, and on the first metal wiring portion. And a second metal wiring part including metal particles, wherein the first metal wiring part and the second metal wiring part have a gap, and a porosity of the second metal wiring part is equal to that of the first metal wiring part. The working electrode is smaller than the porosity.

  According to this working electrode, the first metal wiring part and the second metal wiring part have gaps, and the porosity of the second metal wiring part is smaller than the porosity of the first metal wiring part. For this reason, for example, when the sealing portion forming material is bonded to the working electrode by heating, even if the air contained in the gap of the first metal wiring portion expands, the expanded air penetrates the wiring protective layer. Is sufficiently suppressed. For this reason, generation | occurrence | production of the path | route which an electrolyte can penetrate | invade in a wiring protective layer is fully 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 excellent durability to the dye-sensitized solar cell.

  In the said working electrode or its manufacturing method, it is preferable that the content rate of the said inorganic binder in a said 1st metal wiring part is 0.1-3 mass%.

  In this case, compared with the case where the content of the inorganic binder in the first metal wiring portion is less than 0.1% by mass, it becomes possible to exhibit better adhesion to the conductive substrate, and 3% by mass. Compared with the case where the value exceeds 1, the resistance of the first metal wiring part can be more sufficiently reduced.

  In the said working electrode or its manufacturing method, it is preferable that the content rate of the inorganic binder in the said 2nd metal wiring part is smaller than the content rate of the said inorganic binder in the said 1st metal wiring part.

  In this case, it is possible to easily realize the porosity of the second metal wiring portion to be smaller than the porosity of the first metal wiring portion.

  In the working electrode or the manufacturing method thereof, the content of the inorganic binder in the second metal wiring portion is smaller than the content of the inorganic binder in the first metal wiring portion, and the content in the first metal wiring portion is The difference between the content of the inorganic binder and the content of the inorganic binder in the second metal wiring part is preferably 0.1 to 3% by mass.

  In this case, the porosity generated in the first metal wiring portion is larger than the case where the difference between the content of the inorganic binder in the first metal wiring portion and the content of the inorganic binder in the second metal wiring portion is out of the above range. The porosity generated in the second metal wiring portion can be further reduced.

  In the said working electrode or its manufacturing method, it is preferable that the largest diameter of the space | gap in a said 2nd metal wiring part is 1-10 micrometers.

  In this case, when the wiring protective layer is formed by heat-treating the wiring protective layer forming material, even if the air contained in the gap of the first metal wiring portion expands, the expanded air penetrates the wiring protective layer. Is effectively suppressed.

In the present invention, the “void ratio” of the first metal wiring portion and the second metal wiring portion refers to the ratio of the void in the cross-sectional area of the wiring portion in the cross section of the wiring portion. The wiring section cross-sectional area is the area of the first metal wiring section that is surrounded by the outer layer of the first metal wiring section and the conductive substrate. Here, the outer layer of the first metal wiring portion is the second metal when the entire surface of the first metal wiring portion excluding the surface in contact with the conductive substrate is covered with the second metal wiring portion. When the first metal wiring part is covered with the second metal wiring part and the remaining part is covered with the wiring protective layer, meaning the wiring part. It means a second metal wiring part and a wiring protective layer. In addition, the wiring section cross-sectional area means that, for the second metal wiring section, the entire surface of the first metal wiring section excluding the surface in contact with the conductive substrate is covered with the second metal wiring section. The area of the surface surrounded by the outer layer of the second metal wiring part, the first metal wiring part and the conductive substrate, and a part of the surface excluding the surface in contact with the conductive substrate in the first metal wiring part is the first. In the case of being covered with two metal wiring parts and the remaining part being covered with a wiring protective layer, it is the area of the surface surrounded by the outer layer of the second metal wiring part and the first metal wiring part. The outer layer of the second metal wiring portion means a wiring protective layer. The porosity is a value calculated by dividing the occupied area of a void having a diameter of 1 μm or more in an image observed with an electron microscope by the cross-sectional area of each metal wiring portion. Here, the “diameter” is the following formula when the area of the void in the image observed with an electron microscope is S:
R = 2 × (S / π) ^1/2
The value of R calculated based on

  In the present invention, “inorganic binder content” refers to the ratio of the total mass of inorganic substances other than metals to the total mass of inorganic substances, calculated by a plasma mass spectrometer (ICP).

  Further, in the present invention, “the maximum diameter of the void in the second metal wiring portion” refers to the maximum diameter among the diameters of the voids observed in at least three wiring section cross sections when measuring the above-described porosity. And Here, the “diameter” refers to a diameter calculated in the same manner as the above-described gap diameter.

  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 are provided.

It is a fragmentary sectional view showing one embodiment of a working electrode of the present invention. It is a fragmentary sectional view which shows the working electrode of FIG. It is sectional drawing which shows an example of the current collection wiring of FIG. 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. 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. It is a fragmentary sectional view which shows the modification of the current collection wiring of FIG.

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

  FIG. 1 is a partial cross-sectional view showing an embodiment of a working electrode of 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 a partial cross-sectional view showing the current collector wiring 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.

  As shown in FIG. 2, the working electrode 10 includes a transparent conductive substrate 11, a porous oxide semiconductor layer 12 provided on the transparent conductive substrate 11, and a porous oxide on the transparent conductive substrate 11. And a wiring portion 13 provided around the semiconductor layer 12. The porous oxide semiconductor layer 12 carries a photosensitizing dye. The transparent 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 first metal wiring part 18 provided on the conductive substrate 11 and including the inorganic binder and the metal particles, and the second metal wiring part 19 provided on the first metal wiring part 18 and including the metal particles are included. . Here, the first metal wiring part 18 and the second metal wiring part 19 have a gap, and the porosity of the second metal wiring part 19 is smaller than the porosity of the first metal wiring part 18.

  Next, a method for manufacturing the dye-sensitized solar cell 100 will be described with reference to FIGS.

<Method for producing working electrode>
First, a method for manufacturing the working electrode 10 will be described.

  First, the transparent conductive substrate 11 formed by forming the transparent conductive film 15 on the 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 board glass, quartz glass, polyethylene terephthalate (PET), for example , Polyethylene naphthalate (PEN), polycarbonate (PC), polyethersulfone (PES) and the like. 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 the range of 50 to 10,000 μm, 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 transparent 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 baking the paste.

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 a solvent such as terpineol in addition to the oxide semiconductor particles.

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

  The firing temperature varies depending on the material of the oxide semiconductor particles, but is usually 100 to 600 ° C. The firing time also varies depending on the material of the oxide semiconductor particles, but is usually 1 to 5 hours.

(Wiring section forming process)
Next, the wiring part 13 is formed on the transparent conductive substrate 11.

  First, the current collector wiring 16 is formed on the transparent conductive film 15 of the transparent conductive substrate 11 (current collector wiring forming step). Subsequently, the current collector wiring 16 is covered with a wiring protective layer forming material, and the wiring protective layer forming material is heated to form the wiring protective layer 17 (wiring protective layer forming step).

  Here, as shown in FIG. 3, the current collector wiring 16 is provided on the transparent conductive film 15 of the transparent conductive substrate 11, and includes a first metal wiring portion 18 including an inorganic binder 51 and metal particles 50, And a second metal wiring part 19 including metal particles 60 provided on one metal wiring part 18. In the present embodiment, the second metal wiring portion 19 covers the entire surface of the first metal wiring portion 18 except the surface in contact with the transparent conductive substrate 11 and is bonded to the transparent conductive substrate 11. In the current collector wiring 16, the first metal wiring portion 18 and the second metal wiring portion 19 have gaps A 1 and A 2, respectively, and the porosity of the second metal wiring portion 19 is the porosity of the first metal wiring portion 18. It is formed so as to be smaller.

  Thus, the wiring part 13 is formed on the transparent conductive film 15 of the transparent conductive substrate 11.

  At this time, in the current collecting wiring 16, the first metal wiring portion 18 and the second metal wiring portion 19 have the gaps A1 and A2, respectively, and the porosity of the second metal wiring portion 19 is the gap of the first metal wiring portion 18. It is formed to be smaller than the rate. For this reason, when the current collector wiring 16 is covered with a wiring protective layer forming material and the wiring protective layer forming material is heated to form the wiring protective layer 17, it is included in the gap A 1 of the first metal wiring portion 18. Even if the air expands due to heating, the second metal wiring portion 19 sufficiently suppresses the air from penetrating the wiring protective layer 17. For this reason, in the wiring protective layer 17, the production | generation of the path | route which the electrolyte 30 can penetrate | invades is fully suppressed.

  The first metal wiring portion 18 includes the metal particles 50 and the inorganic binder 51 as described above.

  As a metal material which comprises the metal particle 50, silver and copper are mentioned, for example. These can be used alone or in combination of two or more.

  Examples of the inorganic binder 51 include glass frit such as low melting point glass and solder. These can be used alone or in combination of two or more.

  Although the content rate of the inorganic binder 51 in the 1st metal wiring part 18 is 1-5 mass% normally, it is preferable that it is 0.1-3 mass%.

  In this case, it becomes possible to show more excellent adhesion to the transparent conductive substrate 11 than when the content of the inorganic binder 51 in the first metal wiring portion 18 is less than 0.1 mass%. The resistance of the first metal wiring portion 18 can be more sufficiently reduced as compared with the case where it exceeds 3 mass%.

  The thickness of the 1st metal wiring part 18 should just be 2-60 micrometers, for example.

  The second metal wiring part 19 includes metal particles 60. As a metal material which comprises the metal particle 60, silver and copper are mentioned similarly to the 1st metal wiring part 18, for example.

  The second metal wiring part 19 may further include an inorganic binder 61 as shown in FIG. Examples of the inorganic binder 61 include glass frit such as low-melting glass and solder as in the case of the first metal wiring portion 18.

  The thickness of the 2nd metal wiring part 19 should just be 2-60 micrometers, for example.

  The content of the inorganic binder 61 in the second metal wiring part 19 is preferably smaller than the content of the inorganic binder 51 in the first metal wiring part 18.

  In this case, it is possible to easily realize the porosity of the second metal wiring part 19 to be smaller than the porosity of the first metal wiring part 18.

  Further, when the content of the inorganic binder 61 in the second metal wiring part 19 is smaller than the content of the inorganic binder 51 in the first metal wiring part 18, the content of the inorganic binder 51 in the first metal wiring part 18. The difference between the rate and the content of the inorganic binder 61 in the second metal wiring part 19 is preferably 0.1 to 3% by mass.

  In this case, compared with the case where the difference between the content of the inorganic binder 51 in the first metal wiring part 18 and the content of the inorganic binder 61 in the second metal wiring part 19 is out of the above range, the first metal wiring part. The porosity generated in the second metal wiring portion 19 can be made smaller than the porosity generated in 18.

  The maximum diameter of the gap A2 in the second metal wiring part 19 is normally 1 to 30 μm, preferably 1 to 10 μm, and more preferably 1 to 5 μm.

  In this case, when the wiring protective layer 17 is formed by heat-treating the wiring protective layer forming material, even if the air contained in the gap A1 of the first metal wiring portion 18 expands due to heating, the expanded air remains. Penetration through the wiring protective layer 17 is effectively suppressed.

  The current collector wiring 16 having the above-described configuration can be formed as follows, for example.

  First, as shown in FIG. 4, a first metal wiring part forming paste containing metal particles, an inorganic binder, and a solvent is applied to the transparent conductive film 15 of the transparent conductive substrate 11, and dried to dry the first metal wiring part 18. A first precursor layer 18A to be a precursor is formed. At this time, the average particle diameter of the metal particles is preferably 2000 nm or less, and more preferably 1000 nm or less. When the average particle diameter of the metal particles is in the range of 2000 nm or less, a denser first metal wiring portion 18 can be obtained as compared with the case where the average particle diameter exceeds 2000 nm or less.

  Next, as shown in FIG. 5, a second metal wiring part forming paste containing metal particles and a solvent is applied to the first precursor layer 18 </ b> A and dried to become a precursor of the second metal wiring part 19. A second precursor layer 19A is formed. 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 in the range of 1500 nm or less, the denser second metal wiring portion 19 can be obtained as compared with the case where the average particle diameter exceeds 1500 nm. The average particle diameter of the metal particles contained in the second metal wiring part forming paste may be the same as or different from the metal particles contained in the first metal wiring part forming paste.

  Finally, the first precursor layer 18A and the second precursor layer 19A are baked. At this time, the metal particles in the first precursor layer 18A and the second precursor layer 19A are sintered and the solvent is removed. Thus, the first metal wiring part 18 and the second metal wiring part 19 having a gap are formed (see FIG. 6).

  The first and second metal wiring part forming pastes may further include an organic binder such as polyethylene glycol, if necessary, in addition to the metal particles 50 and 60, the inorganic binders 51 and 61, and the solvent.

  In order to make the porosity of the second metal wiring part 19 smaller than the porosity of the first metal wiring part 18, for example, the content of volatile components such as an organic binder and a solvent in the paste for forming the second metal wiring part What is necessary is just to make it smaller than the content rate of the volatile component in the paste for 1st metal wiring part formation. In this way, the second metal wiring part 19 can be made denser than the first metal wiring part 18.

  As a method for applying the first and second metal wiring portion forming pastes, for example, a screen printing method, a doctor blade method, a bar coating method, or the like can be used.

  Although the drying temperature of the 1st and 2nd metal wiring part formation paste changes with compositions of the 1st and 2nd metal wiring part formation paste, it should just be 100-200 degreeC normally. Although drying time also changes with compositions of the 1st and 2nd metal wiring part formation paste, it may usually be 0.1 to 2 hours.

  The firing temperature of the first precursor layer 18A and the second precursor layer 19A may be 300 to 600 ° C., and the firing time may be 0.5 to 2 hours.

  In addition, as described above, after the first precursor layer 18A and the second precursor layer 19A are formed, the first metal interconnect portion 18 and the second metal interconnect portion 19 are collectively bundled with the first precursor layer 18A. The first metal wiring part 18 and the second metal wiring part 19 are simultaneously formed by firing the second precursor layer 19A and the first precursor layer 18A. After the first metal wiring part 18 is formed by baking, the second precursor layer 19A is formed on the first metal wiring part 18, and the second precursor layer 19A is fired to form the second metal wiring part 19. May be formed. At this time, the conditions for forming the first precursor layer 18A and the second precursor layer 19A are the same as the conditions for forming the first metal wiring part 18 and the second metal wiring part 19 at the same time. The conditions for firing the body layer 18A and the second precursor layer 19A are the same as the conditions for forming the first metal wiring part 18 and the second metal wiring part 19 at the same time.

  The wiring protective layer 17 may be made of a material that covers the current collecting wiring 16 and protects it from the electrolyte 40. As a material constituting the wiring protective layer 17, for example, an inorganic material such as low-melting glass, or a polyimide resin In addition, heat-resistant resins such as silicone resins and fluororesins can be used.

  When the wiring protective layer 17 is formed, the wiring protective layer forming material may include a resin such as polyethylene glycol and a solvent such as terpineol, if necessary, in addition to the above-described inorganic material or heat resistant resin.

  The thickness of the wiring protective layer 17 may be, for example, 1 to 10 μm.

  The wiring protective layer forming material is a paste containing the above-described inorganic material or heat-resistant resin.

  When the paste includes an inorganic material, the heat treatment is a treatment in which the paste 17A applied on the second metal wiring portion 19 of the current collector wiring 16 is dried and then baked, as shown in FIG. The firing temperature varies depending on the paste composition, but is usually 300 to 600 ° C. The firing time also varies depending on the paste composition, but is usually 0.5 to 2 hours.

  When the paste includes a heat resistant resin, the heat treatment is a treatment for 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 production of the working electrode 10 is completed (FIG. 2). If the paste contains a reactive heat-resistant resin, it may be further heated as necessary to complete the reaction. This condition varies depending on the composition of the paste, but may be performed, for example, at 200 to 400 ° C. for 0.5 to 4 hours.

<Photosensitizing dye supporting step>
Next, a photosensitizing dye is adsorbed 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, the dye is adsorbed on the porous oxide semiconductor layer 12, and then the excess dye is washed away with the solvent component of the solution. The photosensitizing dye may be adsorbed to the porous oxide semiconductor layer 12 by drying. However, the photosensitizing dye may be adsorbed to 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 photosensitizing dyes, for example, ruthenium complexes such as black dye, osmium complexes, iron complexes, copper complexes, platinum complexes, porphyrin metal complexes, phthalocyanine metal complexes, or other metal complex dyes, or cyanine, merocyanine, mercurochrome, xanthene series Organic dyes such as dyes, azo dyes, and coumarin dyes can be used.

<Sealing part adhesion process>
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 resins such as ionomer, ethylene-vinyl acetic anhydride copolymer, ethylene-methacrylic acid copolymer, ethylene-vinyl alcohol copolymer, ultraviolet curable resin, and vinyl alcohol polymer. Is mentioned.

  At this time, in the working electrode 10, the first metal wiring part 18 and the second metal wiring part 19 have gaps A 1 and A 2, respectively, and the porosity of the second metal wiring part 19 is the gap of the first metal wiring part 18. Smaller than the rate. For this reason, even when the air contained in the gap A1 of the first metal wiring portion 18 is expanded by the second metal wiring portion 19 when the sealing portion 30 is bonded to the working electrode 10 by heating and melting, for example, The expanded air is sufficiently suppressed from penetrating the wiring protective layer 17. As a result, in the obtained wiring protective layer 17, the generation of a path through which the electrolyte 40 can enter is sufficiently suppressed.

<Electrolyte placement process>
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 use an ionic liquid instead of the 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 and the like are preferably used. An additive may be added to the electrolyte. Examples of the additive include lithium iodide, 4-tertbutylpyridine, N-methylbenzimidazole 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 a printing method such as screen printing.

<Counterelectrode preparation process>
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 composed of, for example, a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, or tungsten, or a film formed of a conductive oxide such as ITO or FTO on the transparent substrate 14 described above. . 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 0.1 mm.

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

<Lamination process>
Next, 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.

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

  When the dye-sensitized solar cell 100 is manufactured as described above, even when the air contained in the gap of the first metal wiring portion 18 expands when the wiring protective layer 17 is formed, the second metal wiring portion 19 The expanded air is sufficiently suppressed from penetrating the wiring protective layer 17. For this reason, in the wiring protective layer 17, the production | generation of the path | route which the electrolyte 40 can penetrate | invades is fully suppressed. Further, when the sealing portion 30 is bonded to the working electrode 10, even if the air contained in the gap of the first metal wiring portion 18 expands, the expanded air causes the wiring protective layer 17 to be expanded by the second metal wiring portion 19. The penetration is sufficiently suppressed. For this reason, in the wiring protective layer 17, the production | generation of the path | route which the electrolyte 40 can penetrate | invades is fully suppressed. As a result, according to the obtained dye-sensitized solar cell 100, corrosion of the current collection wiring 16 by the electrolyte 40 is fully suppressed, and it becomes possible to have excellent durability.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, in the wiring portion 13, the second metal wiring portion 19 covers the entire surface of the first metal wiring portion 18 except for the surface in contact with the transparent conductive substrate 11 and the transparent conductive substrate 11. Although the second metal wiring portion 19 is bonded, a part of the surface of the first metal wiring portion 18 excluding the surface in contact with the transparent conductive substrate 11 as in the wiring portion 113 shown in FIG. It may be only covered and may not be bonded to the transparent conductive substrate 11. In the wiring portion 113, the remaining portion of the first metal wiring portion 18 that is not covered with the second metal wiring portion 19 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 metal wiring part 18 includes the inorganic binder 51, the inorganic binder in the wiring protective layer 17 and the inorganic binder 51 in the first metal wiring part 18 are bonded to each other. As a result, the adhesion between the wiring protective layer 17 and the first metal wiring portion 18 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 embodiment, although the transparent conductive substrate 11 is used as a conductive substrate which comprises the working electrode 10, a conductive substrate does not necessarily need to be transparent. For example, when the counter electrode 20 is a see-through electrode, the conductive substrate 21 can be configured by a non-transparent substrate. As the substrate that is not transparent, for example, a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, tungsten, or the like mentioned as the conductive substrate 21 of the counter electrode 20 can be used.

  Further, in the above embodiment, the working electrode 10 is bonded to the sealing portion 30 and the counter electrode 20 is bonded so as to close the opening of the sealing portion 30, but the sealing portion forming body is bonded to the working electrode 10. At the same time, the sealing portion 30 may be formed between the working electrode 10 and the counter electrode 20 by bonding the sealing portion forming body to the counter electrode 20 and bonding these sealing portion forming bodies together.

  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, a titanium oxide nanoparticle paste was applied onto the transparent conductive film by a doctor blade method so as to have a thickness of 10 μm, and then baked at 150 ° C. for 3 hours. Thus, a porous oxide semiconductor layer having a thickness of 6 μm was formed.

  Next, a silver paste containing silver particles having a particle size of 200 nm or less (trade name XA-9053, manufactured by Fujikura Kasei Co., Ltd.) has a glass frit content of 1 mass in the inorganic material in the first metal wiring after firing. A glass frit was blended so as to be%, and a first metal wiring portion forming paste was prepared. And this 1st metal wiring part formation paste was printed on the transparent conductive film with the screen printing method, and it was made to dry at 150 degreeC, and the 1st precursor layer was formed.

  Next, the silver paste (trade name XA-9053, manufactured by Fujikura Kasei Co., Ltd.) is printed on the first precursor layer by screen printing as a second metal wiring portion forming paste, and 150 ° C. And dried to form a second precursor layer.

  And the 1st precursor layer and the 2nd precursor layer were baked at 500 ° C for 1 hour, and the 1st metal wiring part and the 2nd metal wiring part were formed, respectively. At this time, the second metal wiring part covered only a part of the surface of the first metal wiring part excluding the surface in contact with the transparent conductive film. That is, the remaining part of the surface of the first metal wiring part excluding the surface in contact with the transparent conductive film was not covered with the second metal wiring part. The thicknesses of the first metal wiring part and the second metal wiring part were 10 μm and 10 μm, respectively. Here, the porosity included in the first metal wiring part and the second metal wiring part was measured. The results are shown in Table 1.

  Further, the content (% by mass) of the inorganic binder made of glass frit in the first metal wiring part and the second metal wiring part is as shown in Table 1.

  In addition, the maximum diameter of the void in the second metal wiring part was measured. The results are shown in Table 1.

  Next, a paste for forming a wiring protective layer containing glass frit, an organic binder made of ethyl cellulose, and a solvent made of terpineol was printed by a screen printing method so as to cover the first metal wiring portion and the second metal wiring portion. .

  Then, the wiring protective layer forming paste was baked at 500 ° C. for 1 hour to form a wiring protective layer having a thickness of 5 μm. Thus, a working electrode was obtained.

  Next, after the working electrode was immersed in the dye solution for 24 hours, the working electrode was taken out of the dye solution and dried to carry the photosensitizing dye on the porous oxide semiconductor layer. The dye solution was prepared by dissolving black dye (N749) in a mixed solvent obtained by mixing acetonitrile and tert-butanol at a volume ratio of 1: 1 so that the concentration was 0.0002 mol / L. .

  Next, an electrolyte containing iodine redox was applied and disposed on the porous oxide semiconductor layer.

  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 an ionomer resin (trade name: High Milan, manufactured by Mitsui DuPont Polychemical Co., Ltd.) having a size of 6 cm × 6 cm × 60 μm. Obtained by forming a square-shaped 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 working electrode, the sealing part formation body was adhere | attached on the working electrode by heat-melting.

  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 6 cm × 6 cm × 50 μm titanium foil by sputtering. Further, another sealing part forming body was prepared, and this sealing part forming body was adhered to the surface of the counter electrode facing the working electrode in the same manner as described above.

  And the sealing part formation body adhere | attached on the working electrode and the sealing part formation body adhere | attached on the counter electrode were made to oppose, and the sealing part formation bodies were piled up. 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.

(Examples 2 to 7)
The porosity of the first metal wiring part, the porosity of the second metal wiring part, the maximum diameter of the gap of the second metal wiring part, the content of the inorganic binder in the first metal wiring part, the inorganic in the second metal wiring part Example 1 except that the difference between the binder content, the inorganic binder content in the first metal wiring portion, and the inorganic binder content in the second metal wiring portion is as shown in Table 1. Thus, a dye-sensitized solar cell was obtained.

(Comparative Example 1)
The second metal wiring part is not formed, the thickness of the first metal wiring part is set to 20 μm, and the porosity of the first metal wiring part is changed as shown in Table 1 in the same manner as in Example 1. Thus, a dye-sensitized solar cell was produced.

(Comparative Example 2)
The porosity of the first metal wiring part, the content of the inorganic binder in the first metal wiring part, the difference between the content of the inorganic binder in the first metal wiring part and the content of the inorganic binder in the second metal wiring part Was changed as shown in Table 1, and a dye-sensitized solar cell was obtained in the same manner as in Example 1.

<Durability evaluation>
About the dye-sensitized solar cell of Examples 1-7 and Comparative Examples 1-2, durability evaluation was performed as follows.

The dye-sensitized solar cells of Examples 1 to 7 and Comparative Examples 1 and 2 are maintained in an environment of 85 ° C. and 85% RH according to JIS C8917, 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
The results are shown in Table 1 together with the photoelectric conversion efficiency (initial conversion efficiency) of the dye-sensitized solar cell immediately after production.

  From the result shown in Table 1, it turned out that the dye-sensitized solar cell of Examples 1-7 shows the maintenance rate of the photoelectric conversion efficiency which was more excellent compared with the dye-sensitized solar cell of Comparative Examples 1-2. .

  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 board | substrate 13,113 ... Wiring part 16 ... Current collection wiring 17 ... Wiring protective layer 18 ... 1st metal wiring part 19 ... 2nd metal wiring part 50, 60 ... Metal particle 51, 62 ... Inorganic Binder A1, A2 ... Gap

Claims (10)

Including a wiring part forming step of forming a wiring part on a conductive substrate;
The wiring part forming step includes
A current collector wiring forming step of forming a current collector wiring on the conductive substrate;
A wiring protective layer forming step of forming a wiring protective layer by covering the current collector wiring with a wiring protective layer forming material and heat-treating the wiring protective layer forming material;
The current collector wiring is
A first metal wiring portion provided on the conductive substrate and including an inorganic binder and metal particles;
A second metal wiring portion provided on the first metal wiring portion and including metal particles;
The first metal wiring part and the second metal wiring part have a gap,
A method for producing a working electrode, wherein the porosity of the second metal wiring portion is smaller than the porosity of the first metal wiring portion.   The manufacturing method of the working electrode of Claim 1 whose content rate of the said inorganic binder in a said 1st metal wiring part is 0.1-3 mass%.   The method for producing a working electrode according to claim 1 or 2, wherein the content of the inorganic binder in the second metal wiring portion is smaller than the content of the inorganic binder in the first metal wiring portion.   The working electrode according to claim 3, wherein a difference between the content of the inorganic binder in the first metal wiring portion and the content of the inorganic binder in the second metal wiring portion is 0.1 to 3% by mass. Manufacturing method.   The manufacturing method of the working electrode as described in any one of Claims 1-4 whose maximum diameter of the space | gap in a said 2nd metal wiring part is 1-10 micrometers. A conductive substrate;
A wiring portion provided on the conductive substrate,
The wiring part is
Current collection wiring provided on the conductive substrate;
A wiring protective layer that covers and protects the current collector wiring;
The current collector wiring is provided on the conductive substrate, and includes a first metal wiring portion including an inorganic binder and metal particles;
A second metal wiring portion provided on the first metal wiring portion and including metal particles, wherein the first metal wiring portion and the second metal wiring portion have a gap, A working electrode having a porosity smaller than that of the first metal wiring portion.   The working electrode according to claim 6, wherein the content of the inorganic binder in the first metal wiring portion is 0.1 to 3% by mass.   The working electrode according to claim 6 or 7, wherein a content ratio of the inorganic binder in the second metal wiring portion is smaller than a content ratio of the inorganic binder in the first metal wiring portion.   The effect | action of Claim 8 whose difference of the content rate of the said inorganic binder in the said 1st metal wiring part and the content rate of the said inorganic binder in the said 2nd metal wiring part is 0.1-3 mass%. very.   The working electrode according to any one of claims 6 to 9, wherein the maximum diameter of the gap in the second metal wiring portion is 1 to 10 µm.

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