JP5689773B2 - Photoelectric conversion element electrode, photoelectric conversion element, and silver paste used for manufacturing photoelectric conversion element electrode - Google Patents

Description

  The present invention relates to a photoelectric conversion element electrode, a photoelectric conversion element, and a silver paste used for manufacturing a photoelectric conversion element electrode.

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

  As such a dye-sensitized solar cell, a dye-sensitized solar cell described in Patent Document 1 below is known. The following Patent Document 1 has a working electrode and a counter electrode, and the working electrode covers the transparent conductive layer on the substrate, the metal wiring layer formed on the transparent conductive layer, and the surface of the metal wiring layer. A dye-sensitized solar cell having an insulating layer is disclosed. In Patent Document 1 below, a metal wiring layer is coated with a paste formed by blending a metal powder that becomes conductive particles and a binder such as glass fine particles so as to form a predetermined pattern, and is heated and fired. It is disclosed that it is obtained by doing.

JP 2010-140909 A

  However, although the dye-sensitized solar cell described in Patent Document 1 described above has excellent durability, it cannot be said that the photoelectric conversion characteristics are sufficiently high.

  This invention is made | formed in view of the said situation, manufacture of the electrode for photoelectric conversion elements which can provide the photoelectric conversion element which was excellent in the photoelectric conversion characteristic and durability, a photoelectric conversion element, and the electrode for photoelectric conversion elements It aims at providing the silver paste used for.

  The present inventor examined the reason why the photoelectric conversion characteristic of the dye-sensitized solar cell described in Patent Document 1 is not particularly high. As a result, the present inventors have produced the following when producing the dye-sensitized solar cell described in Patent Document 1, which means that the obtained dye-sensitized solar cell has sufficient photoelectric conversion characteristics. I thought it might be a cause that is not so high. That is, when the paste is heated, the glass fine particles are eventually melted and sink and reach the transparent conductive layer. As a result, the proportion of glass on the surface of the metal wiring layer that contacts the transparent conductive layer increases, and the proportion of silver particles decreases accordingly. For this reason, this inventor thought that the contact resistance between a transparent conductive layer and a metal wiring layer might increase. Therefore, as a result of further earnest research, the present inventor has found that the above-described problems can be solved by the following invention.

That is, the present invention includes a substrate, a conductive film provided on the substrate and containing tin, and a wiring portion provided on the conductive film and having a current collector wiring containing silver particles, and The wiring has a bonded body formed by bonding a silver-tin mixed portion made of a mixture of silver and tin and a glass frit portion made of glass frit, and in the bonded body, the silver-tin bonded portion and the glass frit Photoelectric conversion in which the portion is in contact with the conductive film, the glass frit portion has a recess formed between the glass frit portion and the conductive film, and the silver-tin mixture portion enters the recess This is an element electrode.

According to this electrode, the current collector wiring has a silver-tin mixed portion that contacts the conductive film. Here, the silver tin mixing part consists of a mixture of silver and tin. That is, the silver-tin mixed part has conductivity and contains tin common to the conductive film. Moreover, the silver tin mixing part contains silver common to the current collector wiring. For this reason, the silver tin mixing part can reduce the contact resistance of a current collection wiring and a electrically conductive film compared with a glass frit part. For this reason, according to the electrode for photoelectric conversion elements of the present invention, the contact resistance between the current collector wiring and the conductive film can be reduced. Moreover, the silver tin mixing part contains tin common to the conductive film and contains silver common to the current collector wiring. For this reason, a silver tin mixing part can ensure sufficient adhesiveness with respect to a conductive film and silver particle. In addition, according to this electrode, the current collector wiring has a bonded body formed by combining a glass frit portion that is in contact with the conductive film and a silver tin mixed portion that is in contact with the conductive film. A silver-tin mixed portion enters a recess formed between the frit portion and the conductive film. For this reason, in the combined body, the ratio of the area of the glass frit portion to the area of the contact surface between the current collector wiring and the conductive film is reduced by the amount of the silver-tin mixed portion entering the concave portion of the glass frit portion. . Here, since the silver-tin mixed portion is made of a mixture of silver and tin, as described above, the contact resistance between the current collector wiring and the conductive film can be reduced as compared with the glass frit portion. For this reason, according to the electrode for photoelectric conversion elements of the present invention, the contact resistance between the current collector wiring and the conductive film can be reduced. Further, since the glass frit portion is in contact with the conductive film, the adhesiveness of the current collector wiring to the conductive film can be more sufficiently ensured as compared with the case where the glass frit portion is not in contact with the conductive film. Therefore, according to the electrode for a photoelectric conversion element of the present invention, it is possible to reduce the contact resistance between the current collector wiring and the conductive film while ensuring sufficient adhesion of the current collector wiring to the conductive film. For this reason, according to the electrode for photoelectric conversion elements of the present invention, excellent photoelectric conversion characteristics and durability can be imparted to the photoelectric conversion element using the electrode for photoelectric conversion elements as an electrode.

  It is preferable that the current collection wiring further includes a gap formed at a position away from the conductive film.

  In this case, even when the current collecting wiring is thermally expanded or contracted, the stress applied to the current collecting wiring is sufficiently relaxed by the air gap, and the generation of cracks in the current collecting wiring is sufficiently suppressed.

  It is preferable that the wiring portion further includes a wiring protective layer that covers and protects the current collecting wiring.

  When the electrode having the wiring portion is used as an electrode of a photoelectric conversion element having an electrolyte, the wiring protective layer sufficiently suppresses corrosion of the current collecting wiring due to the electrolyte.

  In the said photoelectric conversion element electrode, it is preferable that the said current collection wiring further has the silver tin mixing part which consists of a mixture of silver and tin in the position away from the said electrically conductive film.

  In this case, the silver tin mixing part can fill the gap between the silver particles and the silver particles, and the volume resistance of the current collector wiring can be further reduced.

  The average particle diameter of the silver particles is preferably 0.3 to 10 μm.

  When the average particle diameter of the silver particles is within the above range, the volume resistance of the current collector wiring can be more sufficiently lowered than when the average particle diameter is outside the above range.

  Moreover, this invention is a photoelectric conversion element containing the electrode for photoelectric conversion elements mentioned above.

  Furthermore, the present invention is a silver paste containing silver particles, silver-tin mixed particles made of a mixture of silver and tin, a binder resin, and a solvent.

  When this silver paste is applied onto a conductive film provided on a substrate and baked, the silver-tin mixed particles first melt, and at least a part of the silver-tin mixed particles sinks, reaches the conductive film, and contacts the conductive film A silver-tin mixed part is formed. Thus, current collecting wiring is formed on the conductive film. Here, the silver tin mixing part consists of a mixture of silver and tin. That is, the silver-tin mixed part has conductivity and contains tin common to the conductive film. Moreover, the silver tin mixing part contains silver common to the current collector wiring. For this reason, the silver tin mixing part can reduce the contact resistance of a current collection wiring and a electrically conductive film compared with a glass frit part. For this reason, according to the silver paste of this invention, it becomes possible to form the current collection wiring which can reduce contact resistance with an electrically conductive film. Moreover, the silver tin mixing part contains tin common to the conductive film and contains silver common to the current collector wiring. For this reason, a silver tin mixing part can ensure sufficient adhesiveness with respect to a conductive film and silver particle. For this reason, according to the silver paste of this invention, it becomes possible to form the current collection wiring which can ensure sufficient adhesiveness with respect to a electrically conductive film and silver particle.

  The silver paste preferably further includes a glass frit that melts at a temperature higher than that of the silver-tin mixed particles.

  When this silver paste is applied onto a conductive film provided on a substrate and baked, the silver-tin mixed particles first melt before the glass frit, and at least a part of the silver-tin mixed particles sinks to reach the conductive film. Thus, a silver-tin mixed portion that contacts the conductive film is formed. When the temperature of the silver paste is further raised, the glass frit melts, the glass frit sinks, reaches the conductive film, and a glass frit portion that contacts the conductive film is formed. Thus, current collecting wiring is formed on the conductive film. At this time, since the glass frit part is formed after the silver-tin mixing part, it is possible to form a combined body in which the silver-tin mixing part enters a recess formed together with the conductive film in the glass frit part. For this reason, the ratio of the area of the glass frit part which occupies for the contact surface of a current collection wiring and a electrically conductive film can be reduced by the part of the silver tin mixed part which entered the recessed part of the glass frit part. Here, since the silver-tin mixed portion is made of a mixture of silver and tin, as described above, the contact resistance between the current collector wiring and the conductive film can be reduced as compared with the glass frit portion. For this reason, according to the silver paste of this invention, it becomes possible to form the current collection wiring which can reduce contact resistance with an electrically conductive film. In addition, since the glass frit part is in contact with the conductive film, a current collector wiring with sufficient adhesion to the conductive film is formed as compared with the case where the glass frit part is not in contact with the conductive film. Can do. Therefore, according to the silver paste of this invention, the current collection wiring which can reduce the contact resistance between electrically conductive films can be formed, ensuring sufficient adhesiveness with respect to an electrically conductive film.

  ADVANTAGE OF THE INVENTION According to this invention, the silver paste used for manufacture of the electrode for photoelectric conversion elements which can provide an excellent photoelectric conversion characteristic and durability to a photoelectric conversion element, the photoelectric conversion element, and the electrode for photoelectric conversion elements is provided. Is done.

It is sectional drawing which shows one Embodiment of the photoelectric conversion element which concerns on this invention. It is sectional drawing which shows the wiring part of FIG. It is sectional drawing which shows the coupling body of FIG.

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

  First, a preferred embodiment of a photoelectric conversion element according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a preferred embodiment of the photoelectric conversion element according to the present invention, and FIG. 2 is a 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 and a counter electrode 20 disposed so as to face the working electrode 10. An electrolyte 30 is disposed between the working electrode 10 and the counter electrode 20, and a sealing portion 40 that connects the working electrode 10 and the counter electrode 20 is provided around the electrolyte 30. Note that the dye-sensitized solar cell 100 includes not only an element that converts sunlight into electricity but also an element that converts light from an indoor light source (for example, a fluorescent lamp) into electricity.

  The working electrode 10 includes a conductive substrate 11, a porous oxide semiconductor layer 12 provided on the conductive substrate 11, and a wiring provided on the conductive substrate 11 so as to surround the porous oxide semiconductor layer 12. Part 13. The conductive substrate 11 includes a transparent substrate 14 and a transparent conductive film 15 provided on the counter electrode 20 side of the transparent substrate 14 and containing tin. A photosensitizing dye is supported on the porous oxide semiconductor layer 12 of the working electrode 10.

  The counter electrode 20 includes a counter electrode substrate 21 and a conductive catalyst layer 22 that is provided on the working electrode 10 side of the counter electrode substrate 21 and promotes a reduction reaction on the surface of the counter electrode 20.

  As shown in FIG. 2, 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 30.

  The current collector wiring 16 includes a sintered body containing silver particles 51. Then, the current collector wiring 16 is in contact with the transparent conductive portion 15 to join the glass frit portion 53 made of glass frit and the silver tin mixed portion 52 made of a mixture of silver and tin in contact with the transparent conductive film 15. A combined body 55 is formed.

  Here, the combined body 55 will be described with reference to FIG. FIG. 3 is a cross-sectional view showing the combined body 55 of FIG.

  As shown in FIG. 3, the bonded body 55 is in contact with the transparent conductive portion 15 and is in contact with the glass frit portion 53 made of glass frit, and the silver tin mixed portion made of a mixture of silver and tin is in contact with the transparent conductive film 15. 52.

  In the bonded body 55, the glass frit part 53 has a recess 54 formed together with the transparent conductive film 15. And the silver tin mixing part 52 has entered into the recess 54. Here, the recess 54 is open. For this reason, a part of the silver-tin mixing portion 52 entering the recess 54 is in contact with the silver particles 51.

  Further, as shown in FIG. 2, the current collector wiring 16 is in contact with the transparent conductive film 15, and is in contact with the glass frit part 53 that is not bonded to the silver-tin mixing part 52, and the transparent conductive film 15, and the glass frit part 53. And a silver-tin mixing portion 52 that is not bonded to the. The glass frit 53 is not formed with a recess, and the silver-tin mixing portion 52 is separated from the glass frit 53.

  As shown in FIG. 2, a gap A <b> 1 is formed between the current collector wiring 16 and the transparent conductive film 15. Further, the current collecting wiring 16 has a gap A2, a silver-tin mixing portion 62 made of a mixture of silver and tin, and a glass frit portion 63 made of glass frit at a position away from the transparent conductive film 15. Yes.

  According to this dye-sensitized solar cell 100, the current collector wiring 16 is formed by combining the glass frit part 53 that contacts the transparent conductive film 15 and the silver-tin mixed part 52 that contacts the transparent conductive film 15. In the combined body 55, the silver-tin mixed portion 52 enters the recess 54 formed together with the transparent conductive film 15 in the glass frit portion 53. For this reason, in the combined body 55, the area of the glass frit part 53 which occupies the contact surface of the current collection wiring 16 and the transparent conductive film 15 by the silver tin mixing part 52 accommodated in the recessed part 54 of the glass frit part 53. The percentage of is reduced. Here, the silver tin mixing part 52 consists of a mixture of silver and tin. That is, the silver tin mixing part 52 has conductivity, and contains tin common to the transparent conductive film 15. Moreover, the silver tin mixing part 52 contains the same silver as the current collector wiring 16. For this reason, the silver tin mixing part 52 can reduce the contact resistance of the current collection wiring 16 and the transparent conductive film 15 compared with the glass frit part 53.

  In the combined body 55 of the dye-sensitized solar cell 100, the silver-tin mixing portion 52 contains tin common to the transparent conductive film 15 and contains silver common to the current collector wiring 16. For this reason, the silver tin mixing part 52 can ensure sufficient adhesiveness with respect to the transparent conductive film 15 and the silver particles 51. Further, in the bonded body 55, the glass frit part 53 is in contact with the transparent conductive film 15. For this reason, compared with the case where the glass frit part 53 is not contacting the transparent conductive film 15, the adhesiveness of the current collection wiring 16 with respect to the transparent conductive film 15 can be ensured more fully.

  As described above, according to the dye-sensitized solar cell 100, the contact resistance between the current collector wiring 16 and the transparent conductive film 15 is reduced while sufficiently securing the adhesion of the current collector wiring 16 to the transparent conductive film 15. be able to. As a result, it is possible to have excellent photoelectric conversion characteristics and durability.

  In the dye-sensitized solar cell 100, the current collector wiring 16 has a gap A <b> 2 at a position away from the transparent conductive film 15. For this reason, even when the current collecting wiring 16 is thermally expanded or contracted, the stress applied to the current collecting wiring 16 is sufficiently relaxed by the gap A2, and the occurrence of cracks is sufficiently suppressed.

  Further, in the dye-sensitized solar cell 100, the current collecting wiring 16 has a silver-tin mixing portion 62 made of a mixture of silver and tin at a position away from the transparent conductive film 15. For this reason, the silver tin mixing part 62 can fill the gap between the silver particles 51 and the silver particles 51, and the volume resistance of the current collector wiring 16 can be further reduced.

  Further, in the dye-sensitized solar cell 100, the wiring portion 13 further includes a wiring protective layer 17 that covers and protects the current collecting wiring 16. For this reason, the wiring protective layer 17 sufficiently suppresses the corrosion of the current collecting wiring 16 by the electrolyte 30.

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

(Working electrode)
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 μm to 10000 μm, for example.

The transparent conductive film 15 may be made of a transparent material containing tin. Examples of the transparent material containing tin include tin-added indium oxide (ITO) and tin oxide (ITO). Examples thereof include conductive metal oxides such as SnO ₂ ) and fluorine-doped 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. When the transparent conductive film 15 is composed of a single layer, the transparent conductive film 15 is preferably composed of FTO because it has high heat resistance and chemical resistance. In addition, it is preferable to use a laminate composed of a plurality of layers as the transparent conductive film 15 because the characteristics of each layer can be reflected. The thickness of the transparent conductive film 15 may be in the range of 0.01 to 2 μm, for example.

  The porous oxide semiconductor layer 12 is composed of a porous oxide semiconductor, and the porous oxide semiconductor is composed of, for example, oxide semiconductor particles. The average particle size of these oxide semiconductor particles is preferably 1 to 1000 nm because the surface area of the oxide semiconductor covered with the dye increases and more electrons can be generated. The thickness of the porous oxide semiconductor layer 12 may be, for example, 0.5 to 50 μm.

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 ), and the like. These can be used alone or in combination of two or more.

  The current collector wiring 16 contains silver particles 51. The average particle diameter of the silver particles 51 is preferably 0.3 to 10 μm, and more preferably 0.5 to 2.0 μm. When the average particle diameter of the silver particles 51 is in the range of 0.3 to 10 μm, the volume resistance can be more sufficiently reduced as compared with the case where the average particle diameter is out of the range.

  The wiring protective layer 17 protects the current collecting wiring 16 from the electrolyte 30 and is made of, for example, a resin material or an inorganic material.

  Examples of the resin material include thermoplastic resins such as ionomers, ethylene-vinyl acetic anhydride copolymers, ethylene-methacrylic acid copolymers, ethylene-vinyl alcohol copolymers, ultraviolet curable resins, and vinyl alcohol polymers. Etc.

  Examples of the inorganic material include inorganic insulating materials such as a lead-free transparent low melting point glass frit.

(Photosensitizing dye)
Examples of the photosensitizing dye include a ruthenium complex having a ligand containing a bipyridine structure, a terpyridine structure, and the like, and organic dyes such as porphyrin, eosin, rhodamine, and merocyanine.

(Counter electrode)
As the counter electrode substrate 21, for example, a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, tungsten, or the like obtained by laminating a conductive oxide such as ITO or FTO on the transparent substrate 14 described above is used. be able to.

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

  The thickness of the counter electrode 20 should just be in the range of 0.005 mm-0.5 mm, for example.

(Electrolytes)
The electrolyte 30 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, 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 dye-sensitized solar cell 100 is an electrolytic solution that includes a volatile solute such as I ⁻ / I ₃ ⁻ as an oxidation-reduction pair and an organic solvent such as acetonitrile, methoxyacetonitrile, and methoxypropionitrile that easily volatilizes at high temperatures. This is particularly effective when used as an electrolyte. In this case, the change in the internal pressure of the cell space is particularly large due to the change in the ambient temperature around the dye-sensitized solar cell 100, and the interface between the sealing portion 40 and the counter electrode 20, and the sealing portion 40 and the working electrode 10. This is because the electrolyte 30 easily leaks from the interface. The electrolyte 30 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. Also in this case, the change in the internal pressure of the cell space increases due to the change in the ambient temperature around the dye-sensitized solar cell 100. As the ionic liquid, for example, a known iodine salt such as a pyridinium salt, an imidazolium salt, or a triazolium salt, and a room temperature molten salt that is in a molten state near room temperature is used. As such a room temperature molten salt, for example, 1-hexyl-3-methylimidazolium iodide is preferably used. An additive may be added to the electrolyte. Examples of the additive include LiI, 4-t-butylpyridine, N-methylbenzimidazole and the like. Further, as the electrolyte 30, a nanocomposite gel electrolyte which is a pseudo solid electrolyte formed by kneading nanoparticles such as SiO ₂ , TiO ₂ , and carbon nanotubes with the above electrolyte may be used, or polyvinylidene fluoride. Alternatively, an electrolyte gelled with an organic gelling agent such as a polyethylene oxide derivative or an amino acid derivative may be used.

(Sealing part)
The sealing portion 40 is made of, for example, a resin material. Examples of such resin materials include ionomers, ethylene-vinyl acetic anhydride copolymers, thermoplastic resins such as ethylene-methacrylic acid copolymers, ethylene-vinyl alcohol copolymers, ultraviolet curable resins, and vinyl alcohol. A polymer etc. are mentioned.

  Next, the manufacturing method of the dye-sensitized solar cell 100 is demonstrated.

[Preparation process]
First, the working electrode 10 and the counter electrode 20 are prepared.

(Working electrode)
The working electrode 10 can be obtained as follows.

  First, the transparent conductive film 15 is formed on the transparent substrate 14 to form a laminate. 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, a porous oxide semiconductor layer forming paste is printed on the transparent conductive film 15 obtained as described above. The paste for forming a porous oxide semiconductor layer 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.

  Next, the porous oxide semiconductor layer forming paste is fired to form the porous oxide semiconductor layer 12 on the transparent conductive film 15. The firing temperature varies depending on the oxide semiconductor particles, but is usually 350 to 600 ° C., and the firing time also varies depending on the oxide semiconductor particles, but is usually 1 to 5 hours.

  Next, the current collection wiring 16 is formed on the transparent conductive film 15 of the conductive substrate 11. At this time, the current collecting wiring 16 is formed so as to surround the porous oxide semiconductor layer 12.

  The current collector wiring 16 is, for example, silver containing silver particles, silver-tin mixed particles made of a mixture of silver and tin, glass frit that melts at a temperature higher than the silver-tin mixed particles, a binder resin, and a solvent. The paste can be obtained by coating the transparent conductive film 15 using a screen printing method or the like, and heating and baking the paste. Here, the silver-tin mixed particles can be produced, for example, by mixing and firing silver particles and tin particles.

  When this silver paste is applied onto the transparent conductive film 15 provided on the transparent substrate 14 and baked, the silver-tin mixed particles first melt before the glass frit, and at least a part of the silver-tin mixed particles sinks, The silver tin mixed part 52 which reaches the transparent conductive film 15 and contacts the transparent conductive film 15 is formed. When the temperature of the silver paste is further increased, the glass frit melts, the glass frit sinks, reaches the transparent conductive film 15, and a glass frit portion 53 that contacts the transparent conductive film 15 is formed. At this time, if the glass frit sinks and covers a part of the silver tin mixing portion 52, the glass frit portion 53 having the concave portion 54 is formed, and at the same time, the silver tin mixed portion 52 enters the concave portion 54, and the bonding A body 55 is formed. If the glass frit sinks and does not cover the silver-tin mixing portion 52, a glass frit portion 53 is formed.

  At this time, in order to obtain the silver tin mixed portion 52, the silver paste is heated at a temperature at which the silver tin mixed particles and the transparent conductive film 15 do not melt together. This is because when the silver paste is heated at a temperature at which the silver-tin mixed particles and the transparent conductive film 15 are melted together, an alloy of silver and tin is formed in the silver-tin mixed portion 52.

  The content of silver-tin mixed particles in the silver paste is preferably 0.3 to 3.0% by mass, and more preferably 0.5 to 2.5% by mass. When the content of the silver-tin mixed particles is within the above range, both low contact resistance and low volume resistance can be achieved as compared with the case where the content is out of the above range.

  The mass ratio of the glass frit to the silver-tin mixed particles is preferably 0.1 to 1.2, more preferably 0.2 to 1.0. When the mass ratio of the glass frit to the silver-tin mixed particles is within the above range, there is an advantage that adhesion with the transparent conductive film 15 is improved as compared with the case where the glass frit is out of the above range.

  Examples of the binder resin include dihydroterpineol. Examples of the solvent include ethyl cellulose.

  In order to form the gap A1 between the current collector wiring 16 and the transparent conductive film 15, the amount of solvent in the silver paste and the amount of glass frit may be adjusted.

  Further, in order to form the gap A2 at a position away from the transparent conductive film 15 in the current collecting wiring 16, a glass frit having a melting point lower than that of silver particles is used. In this case, since the glass frit is melted before the silver particles 51, the glass frit can be directed to the transparent conductive film 15 by the action of gravity. As a result, a gap A2 is formed in the current collecting wiring 16. The gap A2 is also formed by evaporation of the solvent or decomposition of the binder resin.

  Next, the current collector wiring 16 is covered with a wiring protective layer 17. At this time, the wiring protective layer 17 completely covers the current collecting wiring 16 and contacts the conductive substrate 11.

  Thus, the current collector wiring 16 and the wiring protective layer 17 are sequentially formed on the conductive substrate 11 to form the wiring portion 13.

  The working electrode 10 is obtained as described above.

[Dye support process]
Next, a photosensitizing dye is supported on 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 can also be adsorbed 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 it. Can be supported on the porous oxide semiconductor layer 12.

(Counter electrode)
On the other hand, the counter electrode 20 can be obtained as follows.

  That is, first, the counter electrode substrate 21 is prepared. Then, the catalyst layer 22 is formed on the counter electrode substrate 21. As a method for forming the catalyst layer 22, a sputtering method, a vapor deposition method, or the like is used. Of these, sputtering is preferred from the viewpoint of film uniformity.

[Sealing part fixing process]
Next, the sealing portion forming material is fixed to a portion of the working electrode 10 on the surface of the transparent conductive film 15 and surrounding the porous oxide semiconductor layer 12. For example, when the sealing portion 40 is made of an inorganic insulating material such as a lead-free transparent low melting point glass frit, for example, the sealing portion forming material is applied with a paste containing the inorganic insulating material on the annular portion. It can be obtained by firing. The sealing part forming material may be fixed not only to the annular part surrounding the porous oxide semiconductor layer 12 among the parts on the surface of the working electrode 10 but also to the annular part on the surface of the counter electrode 20. .

[Electrolyte layer placement process]
Next, the electrolyte 30 is disposed on the working electrode 10 and inside the sealing portion forming material. The electrolyte 30 can be obtained by being injected or printed on the working electrode 10 inside the sealing portion forming material.

  Here, when the electrolyte 30 is in a liquid state, the electrolyte 30 can be injected until it overflows beyond the sealing portion forming material and overflows to the outside of the sealing portion forming material. In this case, the electrolyte 30 can be sufficiently injected inside the sealing portion forming material. Further, when the sealing portion forming material and the sealing portion forming material are bonded to form the sealing portion 40, air is sufficiently removed from the cell space surrounded by the working electrode 10, the counter electrode 20, and the sealing portion 40. And the photoelectric conversion efficiency can be sufficiently improved.

[Polymerization process]
Next, the working electrode 10 and the counter electrode 20 are opposed to each other, and the sealing portion forming material fixed to the working electrode 10 and the counter electrode 20 are overlapped.

[Sealing part forming step]
Next, the sealing portion forming material is heated and melted while being pressurized. Thus, the sealing portion 40 is formed between the working electrode 10 and the counter electrode 20. At this time, the working electrode 10 and the counter electrode 20 can be bonded together by, for example, disposing the working electrode 10 and the counter electrode 20 in the decompression space and decompressing the decompression space.

  The pressure in the decompression space at that time is usually in the range of 50 Pa or more and less than 1013 hPa, preferably 50 to 800 Pa, and more preferably 300 to 800 Pa.

  Moreover, pressurization of the said sealing part formation material is normally performed at 1-50 Mpa, Preferably it is 2-30 Mpa, More preferably, it is performed at 3-20 Mpa.

  For example, when a thermoplastic resin is used as the resin constituting the sealing portion forming material, the temperature at which the sealing portion forming material is melted is equal to or higher than the melting point of the sealing portion forming material.

  However, the temperature at which the sealing portion forming material is melted is preferably (the melting point of the resin contained in the sealing portion forming material + 200 ° C.) or less. When the temperature exceeds (the melting point of the resin contained in the sealing portion forming material + 200 ° C.), the resin contained in the sealing portion forming material may be decomposed by heat.

  Thus, the dye-sensitized solar cell 100 is obtained, and the manufacture of the dye-sensitized solar cell 100 is completed.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the current collector wiring 16 has the glass frit portion 53 that contacts the transparent conductive film 15, but the current collector wiring 16 does not necessarily have the glass frit portion 53. In this case, in order to form the current collecting wiring 16, it is only necessary not to add glass frit to the silver paste for forming the current collecting wiring. The current collector wiring 16 has a silver-tin mixed portion 62 at a position away from the transparent conductive film 15, but the current collector wiring 16 has a silver-tin mixed portion 62 at a position away from the transparent conductive film 15. It does not have to be. In order to prevent the current collector wiring 16 from having the silver-tin mixed portion 62 at a position away from the transparent conductive film 15, for example, the silver-tin mixed portion 52 is printed on the transparent conductive film 15 in advance, and the current collector wiring 16 What is necessary is just not to put silver tin mixed particles in the silver paste for use. Or after apply | coating the silver paste containing silver tin mixed particle | grains on the transparent conductive film 15, what is necessary is just to bake by hold | maintaining a silver paste at 500 degreeC for 24 hours.

  Further, in the above embodiment, the current collector wiring 16 has the glass frit portion 63 at a position away from the transparent conductive film 15, but the current collector wiring 16 is at a position away from the transparent conductive film 15. 63 may not be included. In order to prevent the current collector wiring 16 from having the glass frit portion 63 at a position away from the transparent conductive film 15, for example, the melting point of the glass frit may be set to be equal to or lower than the melting point of the binder.

  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 20 cm × 20 cm × 4 mm FTO substrate formed by forming an FTO film on a glass substrate was prepared. Subsequently, a titanium oxide paste (manufactured by Solaronix, Tinanoxide T / sp) is applied on the FTO film of the FTO substrate by a doctor blade method at 24 locations so that the thickness becomes 17 μm, and then the FTO substrate. Was placed in a hot air circulation type oven and baked at 500 ° C. for 3 hours to form a porous oxide semiconductor layer on the FTO substrate.

  Next, silver particles having an average particle diameter of 0.8 μm, silver-tin mixed particles having an average particle diameter of 0.8 μm, ethyl cellulose, glass frit, and dihydroterpineol are 70% by mass and 2% by mass, respectively. A silver paste containing 3% by mass, 1% by mass, and 24% by mass was prepared. At this time, the silver-tin mixed particles were prepared by mixing and firing silver particles and tin particles. Then, after applying the silver paste so as to surround the porous oxide semiconductor layer, the silver paste is fired at 500 ° C. for 1 hour, and has a width of 0.4 mm, a thickness of 0.02 mm, and 20 mm × 5.5 mm. A grid-like current collector wiring having 24 square openings was formed.

  Next, a paste containing a low-melting glass frit (B20 manufactured by Central Glass Co., Ltd., melting point: 475 ° C.) is applied onto the current collector wiring, and the paste is heated at 500 ° C. for 3 hours and fired to form a fired body. did. In this way, a wiring part was formed on the FTO substrate to obtain a working electrode.

  On the other hand, a counter electrode substrate made of titanium of 19 cm × 17 cm × 0.04 mm was prepared. Then, a platinum catalyst layer having a thickness of 6 nm was formed on the counter electrode substrate by sputtering. In this way, a counter electrode was obtained.

  Next, 18.5 cm × 16.5 cm in the center of a sheet of 19.5 cm × 17.5 cm × 100 μm made of Nucrel (Mitsui DuPont Polychemical Co., Ltd., melting point: 98 ° C.) which is an ethylene-methacrylic acid copolymer. A square annular resin sheet having an opening of × 100 μm was prepared. And this resin sheet was arrange | positioned on the wiring part surrounding the porous oxide semiconductor layer of a working electrode. This resin sheet was heated and melted at 180 ° C. for 5 minutes to adhere to the wiring portion, and the sealing portion forming material was fixed on the wiring portion on the FTO substrate.

  Next, the working electrode on which the sealing portion forming material is fixed is immersed in a dehydrated ethanol solution in which 0.2 mM of N719 dye, which is a photosensitizing dye, is dissolved for 24 hours, and the photosensitizing dye is applied to the porous oxide semiconductor layer. Supported.

  On the other hand, a square annular resin sheet having an opening of 18.5 cm × 16.5 cm × 100 μm formed in the center of a 19.0 cm × 17.0 cm × 100 μm sheet made of nucler was prepared. And this resin sheet was arrange | positioned in the cyclic | annular site | part of a counter electrode. The resin sheet was heated and melted at 180 ° C. for 5 minutes to adhere to the annular portion, and the sealing portion forming material was fixed to the annular portion on the counter electrode.

  Next, the working electrode is arranged so that the surface of the FTO substrate on the porous oxide semiconductor layer side is horizontal, and inside the sealing portion forming material, a volatile solvent made of methoxypropionitrile is used as a main solvent, A volatile electrolyte containing 0.1M hexylmethylimidazolium iodide, 0.2M iodine, and 0.5M 4-tert-butylpyridine was injected.

  Next, the counter electrode on which the sealing portion forming material was fixed was made to face the working electrode, and the sealing portion forming material on the working electrode and the sealing portion forming material on the counter electrode were superposed under atmospheric pressure. Then, under a reduced pressure of 800 Pa, using a press machine, the sealing portion forming materials were heated and melted at 148 ° C. while being pressurized at 5 MPa through the counter electrode to obtain a sealing portion. Thus, a dye-sensitized solar cell was obtained.

  About the obtained dye-sensitized solar cell, when the cross section of current collection wiring was observed by SEM, the glass frit part which contacts an FTO film | membrane and the contact part which contacts an FTO film | membrane were combined with the current collection wiring. The resulting conjugate was confirmed. Here, the contact portion was subjected to element mapping analysis using an element mapping device (manufactured by ZEISS, ULTRA 55), and it was confirmed that the contact portion was a silver-tin mixture portion made of a mixture of silver and tin. In addition, the presence of an alloy of silver and tin was not confirmed in the silver-tin mixed part. The combined body includes a first combined body in which a silver-tin mixed portion is accommodated in an open concave portion formed in the glass frit portion, and a silver-tin mixed portion in a sealed concave portion formed in the glass frit portion. It was confirmed that there was a contained second combined body.

  Further, in the current collecting wiring, a glass frit part and a silver tin mixed part were confirmed at a position away from the FTO film.

  It was also confirmed that voids were formed between the current collector wiring and the transparent conductive film and in the current collector wiring.

  Further, when the average particle diameter of the silver particles was determined, the average particle diameter of the silver particles was 0.8 μm as shown in Table 1.

(Example 2)
As shown in Table 1, a dye-sensitized solar cell was obtained in the same manner as in Example 1 except that the average particle diameter of the silver particles was changed from 0.8 μm to 10 μm.

(Example 3)
As shown in Table 1, a dye-sensitized solar cell was produced in the same manner as in Example 1 except that the average particle diameter of the silver particles was changed from 0.8 μm to 2.0 μm.

Example 4
As shown in Table 1, a dye-sensitized solar cell was produced in the same manner as in Example 1 except that the average particle diameter of the silver particles was changed from 0.8 μm to 0.4 μm.

(Example 5)
As shown in Table 1, a dye-sensitized solar cell was produced in the same manner as in Example 1 except that the average particle diameter of the silver particles was changed from 0.8 μm to 3.5 μm.

  Example 6 A dye-sensitized solar cell was produced in the same manner as in Example 1 except that the bonded body did not have glass frit.

(Example 7)
When forming the current collector wiring on the FTO film, the firing time of the silver paste is set to 24 hours so that the current collector wiring does not have the silver tin mixed portion and the glass frit portion at a position away from the FTO film. A dye-sensitized solar cell was produced in the same manner as in Example 1 except that.

(Comparative Example 1)
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that silver-tin mixed particles and glass frit were not blended in the silver paste.

(Comparative Example 2)
A dye-sensitized solar cell was produced in the same manner as in Example 7 except that the silver-tin mixed particles were not blended in the silver paste.

[Evaluation of photoelectric conversion characteristics of dye-sensitized solar cells]
About the dye-sensitized solar cell obtained in Examples 1-7 and Comparative Examples 1-2, the photoelectric conversion efficiency ((eta) ₀ ) was measured. The results are shown in Table 1.

[Durability evaluation of dye-sensitized solar cells]
About the dye-sensitized solar cell obtained in Examples 1-7 and Comparative Examples 1-2, the photoelectric conversion efficiency ((eta)) after performing the temperature cycle test based on JISC8938 A-1 was also measured. And the following formula:
Retention rate of photoelectric conversion efficiency (%) = η / η ₀ × 100
Based on the above, the maintenance ratio of the photoelectric conversion efficiency was calculated. The results are shown in Table 1.

  From the results shown in Table 1, it was found that the dye-sensitized solar cells of Examples 1 to 7 had superior photoelectric conversion efficiency as compared with the dye-sensitized solar cell of Comparative Example 2.

  In addition, it was also found that the dye-sensitized solar cells of Examples 1 to 7 had a sufficiently high maintenance rate of photoelectric conversion efficiency as compared with the dye-sensitized solar cell of Comparative Example 1.

  Therefore, it was confirmed that the electrode for photoelectric conversion elements of the present invention can impart excellent photoelectric conversion characteristics and durability to the photoelectric conversion elements.

10 ... Working electrode (electrode for photoelectric conversion element)
13 ... Wiring part 14 ... Transparent substrate (substrate)
15 ... Transparent conductive film (conductive film)
DESCRIPTION OF SYMBOLS 16 ... Current collection wiring 17 ... Wiring protective layer 51 ... Silver particle 52, 52a ... Silver tin mixing part 53, 53a ... Glass frit part 54, 54a ... Recessed part 55 ... Combined body 62 ... Silver tin mixing part 63 ... Glass frit part 100 ... Dye-sensitized solar cells (photoelectric conversion elements)
A2 ... Gap

Claims (6)

A substrate,
A conductive film provided on the substrate and containing tin;
Provided on the conductive film, comprising a wiring portion having a current collector wiring containing silver particles,
The current collector wiring is
A combined body formed by combining a silver-tin mixed portion made of a mixture of silver and tin and a glass frit portion made of glass frit;
In the bonded body, the silver-tin mixed portion and the glass frit portion are in contact with the conductive film, and the glass frit portion has a recess formed between the glass frit portion and the conductive film, The silver-tin mixing part is in the recess,
Electrode for photoelectric conversion element. The photoelectric conversion element electrode according to claim 1, wherein the current collector wiring further includes a gap formed at a position away from the conductive film. The wiring part further has a wiring protective layer that covers and protects the collector wiring, the photoelectric conversion element electrode according to claim 1 or 2. The collector wiring is spaced apart from the conductive layer, silver and further having the silver-tin mixed unit consisting of a mixture of tin, a photoelectric conversion element electrode according to any one of claims 1-3. The electrode for photoelectric conversion elements as described in any one of Claims 1-4 whose average particle diameter of the said silver particle is 0.3-10 micrometers. The photoelectric conversion element containing the electrode for photoelectric conversion elements as described in any one of Claims 1-5 .

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