JP4657664B2 - Method for manufacturing photoelectric conversion element - Google Patents

Description

  The present invention relates to a method for producing a photoelectric conversion element, and more specifically, a photoelectric conversion having excellent photoelectric conversion characteristics by devising a method for producing a current collector wiring provided on a working electrode and / or a counter electrode. The present invention relates to a method for manufacturing an element.

  It is known that a dye-sensitized solar cell, which is one of photoelectric conversion elements, is inexpensive and can provide high photoelectric conversion efficiency.

  The dye-sensitized solar cell is, for example, a transparent substrate made of a material such as glass having excellent light transmittance, a transparent conductive substrate formed of a transparent conductive film formed on one surface thereof, and porous Working electrode made of a porous oxide semiconductor layer, another base material made of an insulating material such as a glass substrate and a counter electrode made of a conductive film formed on one surface thereof, and iodine electrolysis sealed between them It is roughly composed of liquid.

In such a dye-sensitized solar cell, it is desired to increase the size of the element in order to obtain higher photoelectron quantum conversion efficiency.
However, the conventional dye-sensitized solar cell has a problem that it is difficult to avoid a decrease in photoelectron quantum conversion efficiency with an increase in the size of the element because the sheet resistance of the working electrode and the counter electrode constituting the dye-sensitized solar cell is high. It was.

  In order to increase the size of the dye-sensitized solar cell, the sheet resistance of the working electrode and the counter electrode must be reduced. As a countermeasure, for example, a dye-sensitized solar cell in which current collecting wiring is provided is proposed (for example, see Patent Document 1).

  As a method of providing the current collector wiring inside the solar cell, for example, after applying a conductive composition such as a silver paste to the surface of the working electrode or the counter electrode so as to have a predetermined shape using a screen printing method. A method of forming current collecting wiring by covering the surface of the conductive composition with an insulating film is used (for example, see Patent Document 2).

  This method can be provided at low cost with a current collector wiring on a large-area working electrode or counter electrode, so that it is one of the effective methods for realizing an increase in size of a dye-sensitized solar cell. It was thought. However, the working electrode and the counter electrode in which the current collector wiring is formed by screen printing with a conductive composition such as silver paste have a problem that the sheet resistance is higher than that in which the current collector wiring is formed by a method such as plating. It was.

  Thus, when the cause of the increase in sheet resistance of the working electrode and the counter electrode where the current collector wiring was formed by the screen printing method was investigated, the sheet resistance increased because of the conductive composition such as silver paste and the action. It was found that this was due to the high contact resistance with the electrode or counter electrode.

Here, FIG. 3 is a schematic cross-sectional view showing an example of a working electrode in which a current collection wiring is formed by screen printing using a conductive composition such as a conventional silver paste.
In this example, the surface of the transparent conductive film 102 provided on one surface of the transparent substrate 101 forming the working electrode 103 is composed of a conductive composition 106 in which a large number of silver particles 105 are dispersed in a vanider 104. A current collecting wiring 107 is formed.

  Since such a current collection wiring 107 is porous, the contact area between the current collection wiring 107 and the working electrode 103 is reduced, so that the contact resistance between them is increased.

Further, in order to improve the adhesion between the current collector wiring 107 and the working electrode 103, the binder 104 must exist at least partially between the silver particles 105 and the working electrode 103. If it does so, since between the silver particle 105 and the working electrode 103 is partially insulated, both contact resistance becomes high.
JP 2003-203681 A JP 2004-164970 A

  This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method of the photoelectric conversion element with low sheet resistance of a working electrode or a counter electrode.

In order to solve the above problems, the present invention includes a working electrode, a counter electrode, an electrolyte layer provided therebetween, and a current collector wiring disposed on the working electrode and / or the counter electrode. A process for producing a photoelectric conversion element comprising:
A conductive composition having an average particle size and a reducing agent having a function of reducing this with less silver oxide particles 0.5 [mu] m, provided by screen printing on the working electrode, a porous oxide on said working electrode printing step of providing the material of the object semiconductor layer, and said conductive composition disposed on the working electrode by a printing process and the material of the porous oxide semiconductor layer was fired at the same time, the current collector wire and the porous oxide There is provided a method for producing a photoelectric conversion element comprising at least a sintering step for simultaneously forming a physical semiconductor layer.

  In the manufacturing method of the photoelectric conversion element of the said structure, it is preferable that the viscosity of the said electroconductive composition is 50-300 poise.

  In the method for manufacturing a photoelectric conversion element having the above structure, the reducing agent is preferably a blocked reducing agent.

  In the method for manufacturing a photoelectric conversion element having the above structure, the reducing agent is preferably a latent reducing agent.

  In the method for manufacturing a photoelectric conversion element having the above configuration, the reducing agent is preferably a protective colloid.

  In the manufacturing method of the photoelectric conversion element having the above configuration, the latent reducing agent is preferably a glycol having 3 to 8 carbon atoms.

  In the method for producing a photoelectric conversion element having the above structure, the protective colloid is preferably a cellulose derivative.

In the method for producing a photoelectric conversion element according to the present invention, a conductive composition containing silver oxide fine particles and a reducing agent having a function of reducing the fine particles is provided on the working electrode and / or the counter electrode using a screen printing method. By having at least a printing step and a sintering step of firing a conductive composition disposed on the working electrode and / or the counter electrode by this printing step to form a current collector wiring, the specific resistance is low. A current collector wiring made of a conductive film can be easily formed.
In addition, since the current collector wiring is a non-porous conductive film formed only of metallic silver, the contact area with the transparent conductive film that forms the working electrode or the conductive film that forms the counter electrode is increased. Adhesion with the conductive film is improved, and the contact resistance between the current collector wiring and the transparent conductive film or the conductive film is reduced. As a result, since the sheet resistance of the working electrode or the counter electrode is lowered, the area of the dye-sensitized solar cell can be increased.
Furthermore, after applying the material forming the porous oxide semiconductor layer so as to cover the conductive composition applied on the working electrode, the conductive composition and the material forming the porous oxide semiconductor layer are simultaneously sintered. Since the current collector wiring and the porous oxide semiconductor layer can be simultaneously formed on the working electrode, the manufacturing process can be simplified, and as a result, the manufacturing cost can be reduced.

  Hereinafter, the manufacturing method of the photoelectric conversion element which implemented this invention is demonstrated with reference to drawings.

FIG. 1 is a schematic cross-sectional view showing an example of a dye-sensitized solar cell obtained by the method for producing a photoelectric conversion element according to the present invention.
In FIG. 1, 10 is a dye-sensitized solar cell, 11 is a transparent substrate, 12 is a transparent conductive film, 13 is a porous oxide semiconductor layer, 14 is a working electrode, 15 is an electrolyte layer, and 16 is another substrate. Material, 17 is a conductive film, 18 is a counter electrode, 19 is a laminate, 20 is a current collector wiring, and 21 is a coating layer.

  In this dye-sensitized solar cell 10, a porous oxide semiconductor layer 13 having a sensitizing dye supported on its surface is disposed opposite to a working electrode 14 provided on one surface 14a and the one surface 14a. The counter electrode 18, the one surface 14 a and the surface of the counter electrode 18 facing this surface (hereinafter referred to as “one surface”) 18 a, It is schematically configured from current collecting wiring 20 provided on the surface 14a.

  The working electrode 14 includes a transparent base material 11, and a transparent conductive film 12 and a porous oxide semiconductor layer 13 that are sequentially formed on the one surface 11a.

  The counter electrode 18 includes another base material 16 and a conductive film 17 formed on the one surface 16a.

In order to manufacture the dye-sensitized solar cell 10, first, the transparent conductive film 12 is formed so as to cover the entire area of the one surface 11 a of the transparent substrate 11.
In this step, examples of the method for forming the transparent conductive film 12 include sputtering, spray pyrolysis, and CVD.

  As the transparent base material 11, a substrate made of a light-transmitting material is used, and glass, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, etc., which are usually used as a transparent base material for solar cells. Anything can be used. The transparent base material 11 is appropriately selected from these in consideration of resistance to the electrolytic solution and the like, and a substrate that is as excellent in light transmittance as possible is preferable.

The transparent conductive film 12 is a thin film made of metal, carbon, conductive metal oxide, or the like formed on one surface 11a in order to impart conductivity to the transparent substrate 11.
In the case where a metal thin film or a carbon thin film is formed as the transparent conductive film 12, a structure that does not significantly impair the transparency of the transparent substrate 11 is adopted. Examples of the conductive metal oxide that forms the transparent conductive film 12 include tin-doped indium oxide (Indium Tin Oxide (ITO)), fluorine-doped tin oxide (Fluorine doped Tin Oxide (FTO)), and tin oxide [SnO ₂ ]. Etc. are used. Among these, ITO and FTO are preferable from the viewpoint of easy film formation and low manufacturing costs. Moreover, it is preferable that the transparent conductive film 12 is a single layer film made of only ITO or a laminated film in which a film made of FTO is laminated on a film made of ITO.

  Next, a paste-like conductive composition containing silver oxide fine particles and a reducing agent is applied in a predetermined shape on the transparent conductive film 12 by a screen printing method (printing step).

Examples of the silver oxide fine particles forming the conductive composition include silver (I) oxide, silver (II) oxide, silver acetate, and silver carbonate. These may be used in combination of two or more.
As such silver oxide fine particles, silver oxide having an average particle size of 0.5 μm or less obtained by reacting an aqueous solution of silver nitrate with an aqueous alkaline solution such as sodium hydroxide dropwise while stirring is preferable. In the present invention, the average particle diameter of the silver oxide fine particles is 0.5 μm, but in the range of 0.01 μm to 0.5 μm depending on the reduction reaction conditions such as the heating temperature and the reducing power of the reducing agent, The average particle diameter of the silver oxide fine particles can be appropriately selected.

  If the average particle diameter of the silver oxide fine particles is 0.5 μm or less, when the silver oxide fine particles are used in the conductive composition, the dispersibility in the reducing agent is improved and the speed of the reduction reaction is increased. . In order to further improve the dispersibility in the reducing agent and improve the reactivity with the reducing agent, the average particle size of the silver oxide fine particles is preferably 0.25 μm or less, more preferably 0.15 μm or less.

  Examples of the reducing agent that forms the conductive composition include a blocked reducing agent, a latent reducing agent, and a protective colloid.

  The blocked reducing agent is one in which the functional group of the reducing agent is blocked by some compound, and this compound is dissociated during heating to advance the reduction reaction by the functional group. For example, in the reducing agent ethylene glycol, the hydroxyl groups at both ends of the molecule become functional groups involved in the reduction reaction. The ethylene glycol derivative in which the hydroxyl group of ethylene glycol is blocked with some compound forms a blocking reducing agent.

  Examples of the blocking reducing agent that satisfies such conditions include ethylene glycol in which the hydroxyl group of ethylene glycol is esterified with carboxylic acid, particularly acetic acid, specifically ethylene glycol diacetate. Further, methyl acetate, ethyl acetate and the like obtained by esterifying a hydroxyl group of an alcohol such as methanol and ethanol with a carboxylic acid such as acetic acid can also be used as the blocking reducing agent. Other blocking reducing agents include triethylene glycol diacetate and tetraethylene glycol diacetate.

Such a blocking reducing agent hardly reacts with silver oxide fine particles at room temperature (0 to 40 ° C.), and when heated to about 150 ° C., it dissociates blocking groups such as blocked acetate groups and is reactive. It expresses functional groups such as hydroxyl groups rich in.
Therefore, when the conductive composition using the blocked reducing agent is heated to about 150 ° C., the reduction reaction of the silver oxide fine particles proceeds by the expressed functional groups to generate metal silver fine particles. Furthermore, the metal silver fine particles obtained by reducing the silver oxide fine particles are fused to each other to form a conductive film having a low specific resistance made of continuous metal silver. Further, the current collecting wiring made of this conductive film forms a non-porous thin film made of substantially only metallic silver. Therefore, since the contact area between the current collector wiring and the target object (in this embodiment, the transparent conductive film serving as the working electrode or the conductive film serving as the counter electrode) is increased, the adhesion between the current collector wiring and the target object is improved. In addition, the contact resistance between the two becomes low.

  The latent reducing agent is a reducing agent that has extremely low reactivity with silver oxide fine particles at room temperature (0 to 40 ° C.) and that exhibits reduction reactivity with silver oxide fine particles when heated to about 150 ° C. Blocked reducing agents are distinguished by the absence of blocking groups such as acetate groups.

The latent reducing agent reduces the above-mentioned silver oxide fine particles, and it is preferable that the by-product after the reduction reaction is a gas or a highly volatile liquid and does not remain in the generated conductive film. Specific examples of such a reducing agent include ethylene glycol, formalin, hydrin, ascorbic acid, various alcohols, and tertiary fatty acid silver salts.
The tertiary fatty acid silver salt is a silver salt of a tertiary fatty acid having a total carbon number of 5 to 30, for example, pivalic acid, neoheptanoic acid, neononanoic acid, neodecanoic acid, equacid (trade name: Idemitsu Petrochemical Co., Ltd.) Manufactured).
In the present invention, among the tertiary fatty acid silver salts, those having 10 or more carbon atoms are preferred. If the tertiary fatty acid silver salt has 10 or more carbon atoms, it decomposes at a lower temperature, so that the fusion of silver particles formed from silver oxide is further promoted. Examples of the tertiary fatty acid having 10 or more carbons include neodecanoic acid and equacid 13.
The amount of the latent reducing agent used is preferably about 0 to 20 moles per mole of silver oxide fine particles. In consideration of reaction efficiency and volatilization due to heating, it is preferable to add more than an equimolar amount, but even if it exceeds 20 mol at the maximum, the amount is wasted.

  In the conductive composition using this latent reducing agent, the reduction reaction with the silver oxide fine particles hardly proceeds at room temperature (0 to 40 ° C.), and when heated to about 150 ° C., the reduction reactivity is expressed, The reduction reaction of the silver oxide fine particles proceeds to produce metal silver fine particles. Furthermore, the metal silver fine particles obtained by reducing the silver oxide fine particles are fused to each other to form a conductive film having a low specific resistance made of continuous metal silver. Further, the current collecting wiring made of this conductive film forms a non-porous thin film made of substantially only metallic silver. Therefore, since the current collection wiring has a large contact area with the object (the transparent conductive film and / or the thin film as the counter electrode), the adhesion between the current collection wiring and the object is improved. Contact resistance is lowered.

The protective colloid is used to ensure the storage stability of the conductive composition. The protective colloid functions as a dispersion stabilizer (dispersion medium) for uniformly dispersing the silver oxide fine particles, and silver oxide at room temperature (0 to 40 ° C.). It has a function as a reducing agent that exhibits a reducing action when heated to 140 to 180 ° C. without reducing the fine particles.
Therefore, when the conductive composition using this protective colloid is heated to 140 to 180 ° C., the reduction reaction of the silver oxide fine particles proceeds due to the developed reducing action to produce metal silver fine particles. Furthermore, the metal silver fine particles obtained by reducing the silver oxide fine particles are fused to each other to form a conductive film having a low specific resistance made of continuous metal silver. Further, the current collecting wiring made of this conductive film forms a non-porous thin film made of substantially only metallic silver. Therefore, since the contact area between the current collector wiring and the target object (in this embodiment, the transparent conductive film serving as the working electrode or the conductive film serving as the counter electrode) is increased, the adhesion between the current collector wiring and the target object is improved. In addition, the contact resistance between the two becomes low.

As the protective colloid, a cellulose derivative is preferably used.
Cellulose derivatives include hydroxypropyl cellulose modified with cellulose (C ₆ H ₁₀ O ₅ ) _n , ethyl hydroxyethyl cellulose modified with cellulose, and a kind of ether in which hydrogen of hydroxyl group of cellulose is partially substituted by ethyl group. Some ethyl cellulose is used. Specific examples of such a cellulose derivative include hydroxypropyl cellulose manufactured by Nippon Soda Co., Ltd., ethyl hydroxyethyl cellulose manufactured by Akzo Nobel, and ethyl cellulose manufactured by Hercules.

These cellulose derivatives reduce the silver oxide fine particles, and by-products after the reduction reaction become a gas or a highly volatile liquid and do not remain in the generated conductive film.
In addition, the cellulose derivative functions as a dispersion stabilizer (dispersion medium), and the silver oxide fine particles are dispersed almost uniformly in the conductive composition, so that the conductivity of the generated conductive film does not vary. .

  It is desirable that the cellulose derivative be used in an amount larger than equimolar with respect to 1 mol of silver oxide fine particles.

  In such a conductive composition, the selection and use amount of the reducing type depends on the type of silver oxide fine particles and the film forming conditions of the conductive film, for example, the mesh roughness or printing of the printing plate in the screen printing method. Depending on the definition of the pattern, etc., it is adjusted as appropriate so that an optimal conductive film can be formed.

  Moreover, although the viscosity of this electroconductive composition changes with film-forming conditions of an electroconductive film, in the case of the screen printing method, it is desirable that it is about 50-300 poise.

  In addition, if necessary, a dispersion medium such as water, terpineol, tetrahydrofuran, ethanol, methanol, bitol acetate, butyl cellosolve acetate, or a dispersant such as acrylic resin, silicone oil, or cellulose derivative is added to the conductive composition. May be.

  Such a conductive composition can be prepared by using a blocking reducing agent, a latent reducing agent or a protective colloid as a reducing agent, even if it is left at room temperature (0 to 40 ° C.). After that, the period from when the silver oxide fine particles are reduced by the reducing agent until the metal silver fine particles are formed is as long as about 90 to 180 days, and the storage stability is excellent. Therefore, this electroconductive composition can be made into the one-pack type electroconductive composition which mixed silver oxide microparticles | fine-particles and the reducing agent from the time of manufacture. Therefore, it is easy to handle by eliminating the trouble of measuring and mixing the silver oxide fine particles and the reducing agent at the time of use. In addition, the reduction reaction of both proceeds sufficiently during heating, and a conductive film having a very low specific resistance is formed.

  This conductive composition is obtained by dispersing the silver oxide fine particles in a reducing agent. When preparing an electroconductive composition, you may add the said dispersion medium and a dispersing agent as needed.

  Next, the conductive composition applied in a predetermined shape on the transparent conductive film 12 is sintered to form the current collector wiring 20 made of metallic silver on the transparent conductive film 12 (sintering step).

  In this sintering step, the temperature at which the transparent substrate 11 coated with the conductive composition is heated is 140 to 180 ° C., and the heating time is 10 according to the reducing action of the reducing agent contained in the conductive composition. Minutes to 180 minutes.

  By doing so, the silver oxide fine particles are reduced by the reducing agent to become metal silver fine particles, and the metal silver fine particles are fused to each other to form a conductive film made of continuous metal silver.

The volume resistivity of the conductive film thus obtained shows a value ranging from 3 to 8 × 10 ⁻⁶ Ω · cm, which is about the same as the volume resistivity of metallic silver.
Moreover, in this conductive composition, since the average particle diameter of the silver oxide fine particles is 0.5 μm or less, the line width of the current collector wiring composed of the conductive film formed by applying this conductive composition to the object Can be made 10 μm or less. Moreover, since the current collection wiring itself has extremely high conductivity, it is not necessary to increase the thickness of the current collection wiring. For this reason, formation of current collection wiring becomes easy.

  Furthermore, since the heating temperature at the time of forming the conductive film is 140 to 180 ° C., the conductive composition can be applied even when the object is a plastic film having low heat resistance. Therefore, a highly conductive film can be formed on a plastic film having low heat resistance, and the plastic film is not thermally deteriorated.

  Next, an ultraviolet curable resin is applied so as to cover the current collector wiring 20, and then the ultraviolet light is irradiated to cure the ultraviolet curable resin, thereby forming the coating layer 21.

  The covering layer 21 is provided to insulate the current collecting wiring 20 and the electrolyte layer 15. As an insulating material for forming the covering layer 21, ultraviolet curable resins such as PTF6d manufactured by Kyoyo Chemical Co., Ltd., FA513 manufactured by Hitachi Chemical Co., Ltd., and FA731A are used.

Next, a porous oxide semiconductor layer 13 is provided so as to cover a region of the transparent conductive film 12 where the current collector wiring 20 is not provided, and the transparent substrate 11, the transparent conductive film 12, and the porous oxide semiconductor layer are provided. 13 is formed.
The formation of the porous oxide semiconductor layer 13 mainly includes a coating process and a drying / firing process.
The coating process is a process in which, for example, a paste of TiO ₂ colloid obtained by mixing TiO ₂ powder and a surfactant at a predetermined ratio is applied to the surface of the transparent conductive film 12 that has been made hydrophilic. At this time, as a coating method, a pressing unit (for example, a glass rod) is used to press the colloid on the transparent conductive film 12 so that the applied colloid has a uniform thickness. A method of moving the sky above the transparent conductive film 12 is exemplified.
The drying / firing process is, for example, a method in which the coated colloid is left to stand in an air atmosphere at room temperature for about 30 minutes and dried, and then fired at a temperature of 350 degrees for about 30 minutes using an electric furnace. Can be mentioned.

Next, the dye is supported on the porous oxide semiconductor layer 13 formed by the coating process and the drying / firing process.
As the dye solution for supporting the dye, for example, a solution prepared by adding an extremely small amount of N719 dye powder to a solvent in which acetonitrile and t-butanol were 1: 1 in volume ratio was prepared in advance.
The porous oxide semiconductor layer 13 that has been separately heated in an electric furnace at about 120 to 150 ° C. is immersed in a dye solvent placed in a petri dish-like container, and immersed in a dark place for a whole day and night (approximately 20 hours). did. Thereafter, the porous oxide semiconductor layer 13 taken out from the dye solution was washed with a mixed solution composed of acetonitrile and t-butanol.
Through the steps described above, a working electrode (also referred to as a window electrode) 14 in which a porous oxide semiconductor layer 13 made of a dye-supported TiO ₂ thin film was provided on the transparent conductive substrate 10 was obtained.

  On the other hand, a counter electrode 18 was produced by forming a conductive film 17 made of, for example, platinum on one surface 16a of another base material 16 (not necessarily transparent) 16 by vapor deposition or the like. The counter electrode 18 was provided with at least two holes (not shown) penetrating in the thickness direction. This hole is an inlet for injecting an electrolyte solution to be described later.

The working electrode 14 is disposed so that the porous oxide semiconductor layer 13 made of a dye-supported TiO ₂ thin film is located above, and the counter electrode 18 is disposed so that the porous oxide semiconductor layer 13 and the conductive film 17 face each other. A laminated body 19 was formed by being provided over the working electrode 14. Then, the side part of the laminated body 19, ie, the vicinity of the outer periphery where the working electrode 14 and the counter electrode 18 overlap, was sealed with a sealing member (not shown) made of, for example, an epoxy resin.

  After the sealing member (not shown) is dried and solidified, the inlet provided in the counter electrode 18 in the space of the laminate 19, that is, in the space surrounded by the working electrode 14, the counter electrode 18, and the sealing member (not shown). An electrolyte solution was injected from (not shown) to form a dye-sensitized solar cell 10.

  As a method for forming the porous oxide semiconductor layer 13 described above, for example, a dispersion in which commercially available oxide semiconductor fine particles are dispersed in a desired dispersion medium or a colloid solution that can be prepared by a sol-gel method is required. After adding a desired additive according to the above, it is applied by a known application method such as a screen printing method, an ink jet printing method, a roll coating method, a doctor blade method, a spin coating method, a spray coating method, and then sintered and porous. It is possible to apply a method for improving the quality, a method in which polymer microbeads are mixed and applied, and then the polymer microbeads are removed by heat treatment or chemical treatment to form voids to make them porous.

The semiconductor that forms the porous oxide semiconductor layer 13 is not particularly limited, and any semiconductor that can be used to form a porous semiconductor for solar cells can be used. As such a semiconductor, for example, titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), niobium oxide (Nb ₂ O ₅ ), or the like can be used. .

  As the sensitizing dyes described above, ruthenium complexes containing bipyridine structures, terpyridine structures, etc. as ligands, metal-containing complexes such as porphyrins and phthalocyanines, and organic dyes such as eosin, rhodamine and merocyanine can be applied. Among them, those exhibiting excitation behavior suitable for the application and the semiconductor used can be selected without particular limitation.

  As the electrolyte solution, an electrolyte solution in which an electrolyte component such as iodine, iodide ion or tertiary butyl pyridine is dissolved in an organic solvent such as ethylene carbonate or methoxyacetonitrile is used.

  When the electrolyte solution is gelled, polyvinylidene fluoride, a polyethylene oxide derivative, an amino acid hot conductor, or the like is used as a gelling agent.

The electrolyte solution may include an ionic liquid. In this case, the ionic liquid is not particularly limited, and examples thereof include room temperature meltable salts which are liquid at room temperature and have a quaternized nitrogen atom-containing compound as a cation or an anion.
Examples of the cation of the room temperature melting salt include quaternized imidazolium derivatives, quaternized pyridinium derivatives, quaternized ammonium derivatives and the like.
Examples of the anion of the room temperature melting salt include BF ₄ ⁻ , PF ₆ ⁻ , F (HF) _n ⁻ , bistrifluoromethylsulfonylimide [N (CF ₃ SO ₂ ) ₂ ⁻ ], and iodide ion.

  Specific examples of the ionic liquid include, but are not limited to, the type of substance and the particle size. However, the ionic liquid is excellent in miscibility with the electrolytic solution mainly composed of the ionic liquid and used to gel the electrolytic solution. It is done. Further, the oxide semiconductor particles are required to have excellent chemical stability against other coexisting components contained in the electrolyte without reducing the semiconductivity of the electrolyte. In particular, even when the electrolyte contains a redox pair such as iodine / iodide ions or bromine / bromide ions, the oxide semiconductor particles are preferably those that do not deteriorate due to an oxidation reaction.

Examples of such oxide semiconductor particles include TiO ₂ , SnO ₂ , WO ₃ , ZnO, Nb ₂ O ₅ , In ₂ O ₃ , ZrO ₂ , Ta ₂ O ₅ , La ₂ O ₃ , SrTiO ₃ , Y ₂ O. ₃ , Ho ₂ O ₃ , Bi ₂ O ₃ , CeO ₂ , Al ₂ O ₃ are preferably selected from one or a mixture of two or more, and titanium dioxide fine particles (nanoparticles) are particularly preferable. The average particle diameter of the titanium dioxide is preferably about 2 nm to 1000 nm.

  Moreover, the counter electrode 18 which consists of the other base material 16 and the electrically conductive film 17 formed in the one surface is formed.

  As the other base material 16, a metal plate, a synthetic resin plate, or the like is used because it is not necessary to have the same material as the transparent base material 11, or particularly need to have light transmittance.

  The conductive film 17 is a thin film made of metal, carbon, or the like formed on one surface 16a in order to impart conductivity to the other substrate 16. As the conductive film 17, for example, a carbon or platinum layer formed by vapor deposition or sputtering, or a film subjected to heat treatment after chloroplatinic acid coating is preferably used. There is no particular limitation.

  Here, although the dye-sensitized solar cell 10 in which the current collector wiring 20 is provided on the one surface 14a of the working electrode 14 is illustrated, the present invention is not limited to this. In the present invention, the current collecting wiring 20 and the covering layer 21 covering the current collecting wiring 20 may be provided on the surface of the counter electrode 18 facing the working electrode 14 (not shown).

  Moreover, here, although the method of apply | coating a conductive composition to the predetermined shape on the transparent conductive film 12, and sinter this conductive composition was illustrated, this invention is not limited to this. In this invention, after apply | coating the material which makes the porous oxide semiconductor layer 13 so that the conductive composition apply | coated on the transparent conductive film 12 may be covered, a conductive composition and a porous oxide semiconductor are applied. The current forming wiring 20 and the porous oxide semiconductor layer 13 may be simultaneously formed on the transparent conductive film 12 by simultaneously sintering the material forming the layer 13. In this way, since the porous oxide semiconductor layer 13 can be formed simultaneously with the reduction of the silver oxide fine particles contained in the conductive composition, the manufacturing process can be simplified, resulting in the manufacture. Cost can be reduced.

  As described above, in the method for producing a photoelectric conversion element according to the present invention, the silver oxide fine particles and the reducing agent are screen-printed on either the working electrode or the counter electrode, or on the working electrode and the counter electrode. After the conductive composition is applied, the conductive composition is heated to reduce the silver oxide fine particles, and the current collector wiring made of continuous metal silver is formed by fusing the metal silver fine particles to each other. Since it is formed, a current collector wiring made of a conductive film having a low specific resistance can be easily formed. Moreover, since the current collector wiring is a non-porous conductive film formed only of metallic silver, the contact area with the transparent conductive film forming the working electrode is increased, so that the adhesion with the transparent conductive film is improved. This improves the contact resistance between the current collector wiring and the transparent conductive film. As a result, the sheet resistance of the working electrode is reduced, so that the area of the dye-sensitized solar cell can be increased.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

(Example)
A borosilicate glass substrate having a thickness of 1.1 mm, a length of 140 mm, and a width of 140 mm was used as a transparent substrate, and an FTO film was provided on one surface of the transparent substrate to produce a conductive glass substrate.
Next, a highly conductive silver paste (model number: XA9053, manufactured by Fujikura Kasei Co., Ltd.) was applied in a grid pattern as a conductive composition on the transparent conductive film by screen printing. At this time, a highly conductive silver paste was applied so that the aperture ratio of the lattice was 85% and the thickness was about 8 μm.
Next, a titanium oxide paste (trade name: Ti-nanoxide / SP, manufactured by Solaronix) was applied by screen printing so as to cover a region of the transparent conductive film where the current collecting wiring was not provided.
Thereafter, the conductive glass substrate coated with the highly conductive silver paste and the titanium oxide paste was heated at 450 ° C. for 1 hour to form a current collecting wiring and a porous oxide semiconductor layer.
Next, an ultraviolet curable resin was applied so as to cover the current collector wiring, and then ultraviolet light was irradiated to cure the ultraviolet curable resin, thereby forming a coating layer.
Next, an N3 dye was supported on the porous oxide semiconductor layer to obtain a working electrode.
Further, a thin film made of platinum was formed on one surface of another base material made of titanium by a sputtering method to obtain a counter electrode.
Next, the working electrode and the counter electrode were bonded to each other through an adhesive (not shown) so that a space having a predetermined size was formed between them, thereby forming a laminate.
Next, an electrolyte solution was filled between the working electrode and the counter electrode through a through hole provided in the counter electrode, and an electrolyte layer made of this electrolyte solution was formed, thereby obtaining a dye-sensitized solar cell.

(Comparative example)
A dye-sensitized solar cell was obtained in the same manner as in Example except that sintered type silver paste (model number: GL-6000x14, manufactured by Fukuda Metal Co., Ltd.) was used as the conductive composition.

  Regarding the dye-sensitized solar cells obtained in Examples and Comparative Examples, the relationship between voltage and current density was examined by a measuring method according to JIS standard (JIS C8934-1995). The results are shown in FIG.

  2, η = 3.9% in the example, fill factor (FF, shape factor) = 61%, η = 3.2% in the comparative example, fill factor (FF, shape) Factor) = 51%. F. in Examples and Comparative Examples F. This difference is considered to be caused by a difference in internal resistance of the dye-sensitized solar cell, that is, a difference in sheet resistance of the working electrode.

  The method for producing a photoelectric conversion element according to the present invention can be used for other optically operated elements such as a liquid crystal element, an EL element, and various optical sensors in addition to a dye-sensitized solar cell. In addition, the dye-sensitized solar cell formed in the manufacturing method according to the present invention can be used for a solar power generation system that generates a large amount of power generation by connecting cells, in addition to using a single cell as a battery. it can.

It is a schematic sectional drawing which shows an example of the dye-sensitized solar cell obtained by the manufacturing method of the photoelectric conversion element which concerns on this invention. It is a graph which shows the result of having measured the relationship between a voltage and a current density about the dye-sensitized solar cell in an Example and a comparative example. It is a schematic sectional drawing which shows an example of the working electrode which formed the current collection wiring using the conventional conductive composition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dye-sensitized solar cell, 11 Transparent base material, 12 Transparent electrically conductive film, 13 Porous oxide semiconductor layer, 14 Working electrode, 15 Electrolyte layer, 16 Other base materials, 17 Conductive film, 18 Counter electrode, 19 Laminated body , 20 Current collecting wiring, 21 Coating layer.

Claims (7)

A method for producing a photoelectric conversion element comprising a working electrode, a counter electrode, an electrolyte layer provided therebetween, and a current collector wiring disposed on the working electrode and / or the counter electrode,
A conductive composition having an average particle size and a reducing agent having a function of reducing this with less silver oxide particles 0.5 [mu] m, provided by screen printing on the working electrode, a porous oxide on said working electrode A printing process for providing a material forming the physical semiconductor layer, and
Sintering step the printing step by firing the material forming the conductive composition disposed on the working electrode and the porous oxide semiconductor layer at the same time, to form the current collector wire and the porous oxide semiconductor layer at the same time,
A process for producing a photoelectric conversion element, comprising:   The method for manufacturing a photoelectric conversion element according to claim 1, wherein the conductive composition has a viscosity of 50 to 300 poise.   The method for producing a photoelectric conversion element according to claim 1, wherein the reducing agent is a blocked reducing agent.   The method for producing a photoelectric conversion element according to claim 1, wherein the reducing agent is a latent reducing agent.   The method for producing a photoelectric conversion element according to claim 1, wherein the reducing agent is a protective colloid.   The method for producing a photoelectric conversion element according to claim 4, wherein the latent reducing agent is a glycol having 3 to 8 carbon atoms.   The method for producing a photoelectric conversion element according to claim 5, wherein the protective colloid is a cellulose derivative.

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