JP4789480B2 - Method for producing dye-sensitized photoelectric conversion element and paint for dye-sensitized photoelectric conversion element - Google Patents

Description

  The present invention relates to a method for producing a dye-sensitized photoelectric conversion element and a paint for a dye-sensitized photoelectric conversion element.

  A dye-sensitized photoelectric conversion element and a photoelectrochemical cell are composed of a photoelectrode composed of a semiconductor fine particle-containing layer adsorbing a dye formed on a conductive support, a charge transfer layer, and a counter electrode. In particular, Nature (Vol. 353, 737-740, 1991) and US Pat. No. 4,927,721 disclose a photoelectric conversion element and a solar cell using semiconductor fine particles sensitized with a dye, and a material for producing the same. And manufacturing techniques are disclosed.

  The photoelectric conversion element and solar cell described above include a photoelectrode composed of a porous semiconductor film spectrally sensitized with a light absorbing dye, and a charge transfer layer containing a redox species of halogens such as iodine and bromine. And a counter electrode on which a catalyst for facilitating electron transfer to the redox electrolyte is fixed on a conductive substrate, if necessary. In particular, the porous semiconductor film is composed of titanium oxide, the sensitizing dye is composed of a ruthenium metal complex, the electrolyte is composed of an electrolytic solution obtained by dissolving iodine redox in an organic solvent, and the counter electrode is composed of platinum metal. It is known that high photoelectric conversion efficiency can be obtained when it is made of a material fixed to tin oxide transparent conductive glass.

  Since this type of photoelectric conversion element and solar cell can be prepared by applying a porous semiconductor film to a substrate by applying a paste-like substance containing semiconductor fine particles to a substrate and firing it appropriately, conventional silicon single crystals, polycrystalline solar cells, Compared with compound semiconductor solar cells such as amorphous silicon solar cells, GaAs, and CIS, the production cost is expected to be reduced to a fraction.

  However, paying attention to the photoelectric conversion element of this example and the counter electrode in the solar cell, platinum metal acting as a catalyst is produced on a conductive substrate by a vacuum process such as sputtering (Patent Document 1). ). According to the process such as the sputtering method, it is difficult to reduce the cost by simplifying the manufacturing equipment, which is one of the major characteristics of the photoelectric conversion element and the solar cell in such an example.

  Moreover, although the photoelectric conversion element and photovoltaic cell of such an example are commercialized also in the form connected in large numbers on the same board | substrate, it is necessary to pattern-process the platinum metal of a counter electrode in such a case. . The platinum metal film produced by processes such as sputtering is very strong in corrosion resistance, so it is difficult to apply the usual photolithographic etching method, so it is necessary to use a multi-stage process such as a lift-off process, making the production process complicated. There are also problems such as

JP 2001-35551 A

  An object of the present invention is to easily obtain a high-performance dye-sensitized photoelectric conversion element, particularly by simplifying the manufacturing process of the counter electrode.

In order to achieve the above object, the present invention comprises a step of forming a colloidal solution containing metal platinum fine particles,
Forming a catalyst layer containing platinum by applying the colloidal solution onto a predetermined conductive substrate, and forming a counter electrode having the conductive substrate and the catalyst layer;
A step of forming a photoelectrode having a semiconductor layer adsorbing a predetermined dye and generating an electromotive force by being excited by light absorption;
Forming a charge transfer layer between the counter electrode and the photoelectrode;
The present invention relates to a method for producing a dye-sensitized photoelectric conversion element.

The inventors of the present invention have intensively studied to achieve the above object. As a result, when forming a catalyst layer containing platinum metal that acts as a catalyst on the counter electrode of the dye-sensitized photoelectric conversion element, it is necessary to use a coating method instead of the conventional sputtering method. I found it.
Such a coating method can be realized only by preparing and using an inexpensive and simple apparatus such as a printing apparatus. Furthermore, since the obtained platinum metal film can be processed by a normal photolithography etching method, pattern processing or the like can be easily performed. Therefore, a large number of the counter electrodes, and thus the dye-sensitized photoelectric conversion elements, can be simultaneously formed on the same substrate through a simple process, and the dye-sensitized photoelectric conversion element or a solar battery cell using the same Photochemical battery cells such as can be easily and inexpensively commercialized.

  In the present invention, the colloidal solution can be formed in a state in which the metal platinum fine particles are directly dispersed. However, a composite is formed by supporting the colloidal solution on predetermined conductive fine particles, and this composite is dispersed. It can also be. Even in this case, the catalyst layer formed by applying the colloidal solution exhibits the same effect, and the counter electrode, and thus the dye-sensitized photoelectric conversion element or the photochemical battery cell including the same can be simplified. It can be commercialized at low cost.

  The composite can be directly supported on the conductive fine particles, but can also be produced by carrying out a reduction treatment after supporting a predetermined platinum complex on the conductive particles.

Japanese Patent Application Laid-Open No. 2002-93475 discloses a dye-sensitized solar cell (dye-sensitized photoelectric conversion element) in which an electrode layer is provided by pattern coating (coating method) of platinum paste. It can be seen that a dye-carrying semiconductor layer is formed on the electrode layer, and the electrode layer constitutes a photoelectrode instead of a counter electrode. Therefore, in the said gazette, the photoelectrode is formed by the apply | coating method and it differs from the photoelectric conversion element of this invention which formed the counter electrode by the apply | coating method. The publication relates to a photoelectric conversion element configured to introduce light from the counter electrode side,
Compared with the photoelectric conversion element according to the present invention in which light is introduced from the photoelectrode side, the photoelectric conversion efficiency is remarkably lowered.

Further, in the above publication, the platinum paste is formed from a platinum salt such as H ₂ PtCl _6, and the platinum paste prepared from a halide such as chlorine or element is applied using a normal printing machine or the like. This will corrode the metal parts of the printing press. Therefore, the technique described in the publication is not suitable for practical use. On the other hand, in the present invention, a colloidal solution containing no platinum halide such as chlorine or bromine is prepared, and the catalyst layer of the counter electrode is formed from the colloidal solution by a coating method. Such corrosion problems do not occur. Therefore, it can be seen that the technique of the present invention is a very practical method compared to the technique of the above publication.
JP 2002-93475 A

  In addition, "applying on a conductive substrate" includes forming on a conductive layer when the conductive substrate includes a conductive layer. In the case where the conductive substrate includes a conductive layer, the substrate itself constituting the conductive layer substrate does not necessarily have conductivity.

  As described above, according to the present invention, the catalyst layer of the counter electrode of the solar battery cell can be formed on a predetermined substrate by applying paint, so that vacuum equipment such as sputtering becomes unnecessary. Further, when the paint is made into a paste, it can be printed at a desired position on the substrate, and a processing process by photolithography etching can be applied. Accordingly, the dye-sensitized photoelectric conversion element or a photochemical battery cell such as a solar battery cell using the same can be easily and inexpensively commercialized.

  Hereinafter, details of the present invention and other features and advantages will be described based on the best mode for carrying out the invention.

(Photoelectric conversion element)
FIG. 1 is a configuration diagram schematically showing an example of the photoelectric conversion element of the present invention. In the actual manufacturing process, as shown in FIG. 2, a configuration is adopted in which a plurality of photoelectric conversion elements are arranged vertically and horizontally on a conductive substrate constituting a counter electrode. Of the plurality of photoelectric conversion elements shown, attention is focused on only one photoelectric conversion element. 2A is a plan view of the state in which a plurality of photoelectric conversion elements are arranged as viewed from above, and FIG. 2B is a side view of the state in which the plurality of photoelectric conversion elements are arranged. It is a side view at the time of seeing from. For ease of illustration, FIG. 2 shows a state in which no photoelectrode is formed.

  The photoelectric conversion element 100 illustrated in FIG. 1 is provided such that the photoelectrode 101 and the counter electrode 109 face each other. The distance between the photoelectrode 101 and the counter electrode 109 is several μm to several mm. The photoelectrode 101 includes a transparent conductive substrate 102 in which a transparent conductive layer 105 is formed on a transparent substrate 104 and an oxide semiconductor electrode 103 provided on the transparent conductive substrate 102. An electrolyte 108 as a charge transfer layer is enclosed between the photoelectrode 101 and the counter electrode 109 together with the partition wall 120.

  As shown in an enlarged view in FIG. 3, the oxide semiconductor electrode 103 has a configuration in which a sensitizing dye 107 is adsorbed and supported on the surface of the oxide semiconductor fine particles 106. On the other hand, the counter electrode 109 has a configuration in which a conductive layer 111 and a catalyst layer 112 are sequentially formed on a substrate 110 as shown in an enlarged view in FIG.

  In addition, when the electrolyte 108 is in a solid, semi-solid, or pseudo-solid state and there is no possibility of leakage, the partition wall 120 may be omitted. However, as described in detail below, as the electrolyte 108, an iodine redox electrolytic solution or the like may be used. In order to seal such an electrolytic solution, the partition wall 120 is an essential element.

  In the present invention, at least a portion of the catalyst layer 112 constituting the counter electrode 109 that is in contact with the electrolyte 108 is made of platinum. However, practically, due to the manufacturing method described in detail below, the catalyst layer 112 itself may be made of platinum or distributed throughout the thickness direction of the catalyst layer 112. Preferred (when present as particulate).

  Platinum is preferably present in the catalyst layer 112 in the form of fine particles. In this case, the total surface area of the catalyst layer 112 with respect to the apparent area is increased, and the area in contact with the electrolyte 108 is substantially increased, so that the charge transfer resistance from the electrolyte 108 to the catalyst layer 112 can be reduced. Become. As a result, the electron transfer property from the electrolyte 108 to the conductive layer 111 can be improved.

  When platinum is present as fine particles, the size is preferably 50 nm or less. As a result, it is possible to more effectively realize the above-described reduction in charge transfer resistance and the accompanying improvement in electron transfer performance. The lower limit of the size is not particularly limited, but is about 2 nm due to the current micronization technology.

  Platinum itself can exist as fine particles, but can also be supported on conductive fine particles. Also in these cases, the size of the platinum particles of the composite element is preferably 50 nm or less, and the size required for the entire composite particle is preferably 200 nm or less.

  Further, the total surface area of the catalyst layer 112, that is, the total surface area of the counter electrode 109 in contact with the electrolyte 108 is 1 with respect to the apparent area of the catalyst layer 112, that is, the apparent area of the counter electrode 109 in contact with the electrolyte 108. -1000 times is preferable. As a result, the above-described charge transfer resistance can be sufficiently reduced, and the electron acceptability can be sufficiently improved. Such a relatively large total surface area can be realized by making platinum fine particles and making it porous as necessary, as described above. It is also effective to laminate composite particles carrying platinum fine particles on conductive fine particles.

  In the photoelectric conversion element 100 shown in FIG. 1, the photoelectrode 101 can be an anode electrode and the counter electrode 109 can be a cathode electrode. When light having a predetermined wavelength and intensity enters the photoelectrode 101, the sensitizing dye 107 absorbs the light and emits electrons. The electrons are absorbed by the oxide semiconductor particles 106 and emitted into the electrolyte 108. The electrons move in the electrolyte 108 toward the counter electrode 109, and electrons are exchanged at the counter electrode 109. As a result, a predetermined current is generated in the photoelectric conversion element 100, resulting in power generation.

  As the transparent substrate 104, for example, a glass substrate such as white plate glass, blue plate glass, or quartz glass, or a transparent substrate such as plastic can be used. Plastics are polyester, cellulose acetate, polypropylene, polyethylene, polyamide, polyimide, polyethersulfone, polysulfone, polyvinyl acetal, polyetherketone, polyvinyl chloride, polyvinylidene chloride, polymethyl acrylate, polymethyl methacrylate, polycarbonate, polyurethane, Examples include stretched or unstretched transparent plastic films and plates such as polyethylene terephthalate and polyethylene naphthalate.

The transparent conductive layer 105 can be composed of a transparent conductive oxide such as tin oxide (SnO ₂ ), fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), or the like. The thickness of the transparent conductive layer 105 is preferably about 0.05 to 10 μm. Preferably 100 [Omega / cm ² or less as the surface resistivity, and further preferably not 20 [Omega / cm ² or less. Although there is no restriction | limiting in particular in this lower limit, Usually, it is about 0.1 ohm / cm < ² >. The light transmittance of the transparent conductive layer 105 is preferably 50% or more, and particularly preferably 70% or more. The upper limit is not particularly limited, but is usually about 90%. Further, it is possible to increase the light transmittance by providing an antireflection layer on the light incident side.

  The oxide semiconductor electrode 103 preferably includes the oxide semiconductor fine particles 106 as described above. The oxide semiconductor electrode 103 is required to have an oxide semiconductor substrate for supporting the sensitizing dye 107. By forming the oxide semiconductor substrate from the oxide semiconductor fine particles 106, the oxide semiconductor substrate 103 is substantially The surface area can be increased, and the amount of the sensitizing dye 107 that can be carried can be increased. As a result, the power generation amount as a whole of the photoelectric conversion element 100 can be increased.

  Note that the ratio of the total surface area to the apparent area of the oxide semiconductor fine particles 106 is preferably 100 times or more, and more preferably 100 to 2000 times. As a result, the amount of the sensitizing dye 107 that can be adsorbed and supported can be increased. Therefore, the oxide semiconductor fine particles 106 are preferably not only fine particles but also porous. However, the oxide semiconductor fine particle 106 is not an essential requirement of the present invention, and may be a non-particulate oxide semiconductor substrate.

  As the oxide semiconductor fine particles 106, a single metal oxide, a compound having a perovskite structure, or the like can be used. The single metal oxide is preferably an oxide of titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum. Preferred examples of the compound having a perovskite structure include strontium titanate, calcium titanate, sodium titanate, barium titanate, and potassium niobate.

More preferable examples of the oxide semiconductor used in the present invention include TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , SrTiO ₃ , and BaTiO ₃ . More preferred are TiO ₂ , ZnO, SnO ₂ , Nb ₂ O ₅ , SrTiO ₃ , BaTiO ₃ , and most preferred is TiO ₂ . For the purpose of increasing the conductivity of these semiconductors, those doped with elements such as Cr, Nb, Ta, Sb, W, As, and N can be used.

Further, in order to prevent electrons from flowing from the oxide semiconductor electrode 106 to the electrolyte 108, a metal oxide or a metal carbonate is formed on the surface of the oxide semiconductor electrode 106, specifically on the surface of the oxide semiconductor fine particle 106. Can also be formed. Particularly, when the oxide semiconductor fine particles 106 composed of TiO _{2 is, ZnO, Y 2 O 3,} Al 2 O 3, SrO, MgO, Nb 2 O 5, TaO, ZrO 2, CeO, SrCO 3, MgCO 3 Can be suitably used.

The sensitizing dye 107 is preferably composed of a metal complex dye and / or an organic dye having light absorptivity in a wavelength range of 300 nm to 1200 nm, which is a wavelength range of natural light, from a practical viewpoint. The sensitizing dye 107 preferably has an appropriate bonding group to the surface of the oxide semiconductor fine particles 106. An example of the dye is a ruthenium complex dye. For example, complex dyes described in U.S. Pat. Nos. 4,927,721, 4,684,537, 5,084,365, 5,350,644, 5,463,057, and 5,525,440 are preferably used.

  The electrolyte 108 is preferably an electron conductive material including redox. The form of the electron conductive material may be liquid at normal temperature, may be a gel material, or may be solid, and is not particularly limited. In the case of using a solvent, acetonitrile, propionitrile, 3-methoxypropionitrile, methoxyacetonitrile, propylene carbonate, ethylene carbonate and the like are preferably used. Examples of the molten salt include lithium iodide and at least one other lithium salt and 1,3-dimethylpropylimidazolium.

  Moreover, a gelling agent can be added to these organic solvents and molten salts to form a semi-solid electron conductive material. As an example of the gelling agent, examples of the polymer used in the matrix of the gel electrolyte include polyacrylonitrile and polyvinylidene fluoride.

As the redox couple, a combination of an oxidized form of iodine and a reduced form is preferably used. I ₂ and various iodides (for example, metal iodides such as LiI, NaI, KI, CsI, CaI ₂ and MgI ₂ ), iodine salts of quaternary imidazolium compounds, quaternary pyridinium Iodine salts of compounds, iodine salts of tetraalkylammonium compounds, etc.) can be used. Among them, LiI, NaI, KI, CsI, CaI ₂ , MgI ₂ metal iodide, quaternary imidazolium compound iodine salt, quaternary pyridinium compound iodine salt or tetraalkyl ammonium compound iodine salt and I ₂ A combination is preferable, and a combination of a plurality of iodides and I ₂ is more preferable. More preferably, an iodine salt of LiI, I ₂ and a quaternary imidazolium compound can be suitably used.

  The concentration of the redox couple is preferably 0.1 mol / liter or more, particularly preferably 0.3 mol / liter or more. Although there is no particular limitation, the upper limit is usually about 3 mol / liter because of its solubility in a solvent.

  However, in the photoelectric conversion element 100 shown in FIG. 1, since the partition 120 is provided, moisture permeation from the outside can be reduced as much as possible. The partition 120 can be comprised from organic substances, such as a polymer and an adhesive agent, and inorganic substances, such as glass frit and metal foil.

  The substrate 110 of the counter electrode 109 is made of a metal plate such as Ni, Fe, Pt, Al, In, Sn, Cu, Zn, Ag, Au, Mo, Ti, Zr, SUS, or tin oxide, fluorine-doped tin oxide, Tin oxide on a conductive oxide substrate such as tin-doped indium oxide or a metal plate such as Ni, Fe, Pt, Al, In, Sn, Cu, Z, Ag, Au, Mo, Ti, Zr, SUS On a conductive oxide substrate such as tin oxide, fluorine-doped tin oxide, tin-doped indium oxide, etc. A material in which a metal film such as Ni, Fe, Pt, Al, In, Sn, Cu, Zn, Ag, Au, Mo, Ti, Zr, or SUS is formed can be used. Further, a glass substrate, a transparent plastic film, a plate, and the like similar to the transparent substrate 104 can be used.

  Of these, considering the cost, it is preferable to use the above-mentioned plastic film and metal plate formed with a conductive oxide film. However, when a plastic film is used, the corrosion resistance is slightly reduced. On the other hand, although it is disadvantageous in terms of cost, the one in which the conductive oxide film is formed on the glass substrate exhibits high corrosion resistance.

  In addition, as described above, when the substrate 110 is formed of the above-described metal plate or conductive oxide substrate, or when the substrate 110 exhibits conductivity by including a conductive oxide film or a metal film, the conductive layer 111 is particularly There is no need to provide it.

  In the case where the conductive layer 111 is provided as shown in FIG. 4, the conductive layer 111 is preferably composed of tin oxide, fluorine-doped tin oxide, tin-doped indium oxide, or the like. In this case, even when the electrolyte 108 contains an iodine redox electrolytic solution, the electrolyte 108 exhibits high corrosion resistance.

  The catalyst layer 112 of the counter electrode 109 can be composed of the above-described platinum fine particles, and other components such as silicon, aluminum, zirconium, cerium, titanium, etc., if necessary, for the purpose of further improving film adhesion strength, conductivity and the like. Containing fine particles of oxide or composite oxide such as yttrium, zinc, magnesium, indium, tin, antimony, gallium, ruthenium, and conductive oxide fine particles such as tin oxide, fluorine-doped tin oxide, and tin-doped indium oxide preferable.

(Manufacturing method of photoelectric conversion element)
Next, the manufacturing method of the photoelectric conversion element of this invention is demonstrated, making it relate with the photoelectric conversion element 100 shown in FIGS.

  First, a method for manufacturing the photoelectrode 101 will be described. A transparent substrate 104 is prepared, a transparent conductive layer 105 is formed thereon, and a transparent conductive substrate 102 is manufactured. The transparent conductive layer 105 can be formed using a known film formation technique such as a sputtering method, a CVD method, or a coating method. A transparent substrate 104 on which a commercially available transparent conductive layer 105 is formed can also be used directly as the transparent conductive substrate 102.

  Next, an oxide semiconductor fine particle paste containing a predetermined binder is prepared, applied on the transparent conductive substrate 102, and baked to remove the binder, thereby removing the oxide semiconductor fine particles on the transparent conductive substrate 102. 106 is formed.

  The coating is performed using any of ordinary thin film coating techniques such as screen printing, spin coating, roll coating, spraying, bar coating, dip, meniscus coating, gravure printing, dispensing, and inkjet. Is possible. Among these, the screen printing method is a particularly preferable coating method because a film can be formed at a desired position on the printing substrate.

  Next, the sensitizing dye 107 is dissolved in a predetermined solvent to prepare a sensitizing dye solution, and the oxide semiconductor fine particles 106 are immersed in the solution together with the substrate, whereby the sensitizing dye 107 is converted into the oxide semiconductor fine particles 106. Adsorbed and supported on the top. As the solvent, alcohols such as methanol, ethanol, 2 propanol, 1 butanol, t-butanol, nitriles such as acetonitrile, methoxyacetonitrile, propionitrile, 3 methoxypropionitrile, or a mixed solvent thereof may be used. Can do.

  Through the operation as described above, the oxide semiconductor fine particles 106 to which the sensitizing dye 107 is adsorbed, that is, the photoelectrode 101 including the oxide semiconductor electrode 103 can be obtained.

  Next, a method for manufacturing the counter electrode 109 will be described. First, the substrate 110 is prepared, and if necessary, the conductive layer 111 is formed by a known method such as a coating method. Next, the catalyst layer 112 is formed on the substrate 110 or the conductive layer 111 by a coating method according to the present invention. Hereinafter, a method for forming the catalyst layer 112 will be described.

  First, a colloidal solution in which metal platinum fine particles are dispersed in a predetermined solvent is prepared. At this time, a predetermined colloid agent is used as necessary.

  Examples of the solvent include water, alcohols such as methanol, ethanol, 2-propanol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, methyl cellosolve (β-oxyethyl methyl ether), ethyl cellosolve (β- Cellosolves such as oxyethyl ether) and butyl cellosolve (butyl-β-oxyethyl ether), aromatic hydrocarbons such as benzene, toluene and xylene, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether Acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol mono Esters such as chill ether acetate can be preferably used.

  The size of the metal platinum fine particles in the colloidal solution is preferably 50 nm or less. Thereby, the size of the platinum fine particles contained in the catalyst layer 112 can be set within a preferable range of 50 nm or less as described above.

  The colloidal solution can also be prepared in such a state that the metal platinum fine particles are supported on predetermined conductive particles to form a complex and the complex is dispersed. In this case, the solvent constituting the colloidal solution can be composed of those exemplified above. Further, since the conductive particles together with the metal platinum fine particles will later constitute the catalyst layer 112, the above-described tin oxide, fluorine-doped tin oxide, tin-doped indium oxide, etc., related to the catalyst layer 112, etc. It can be composed of conductive oxide fine particles.

  In addition, when producing a colloidal solution from the composite_body | complex mentioned above, it is preferable that the magnitude | size of the said composite is 200 nm or less. As a result, the total size of the catalyst layer 112 including the conductive particles and the platinum fine particles supported thereon can be reduced to 200 nm or less, and the above-described effects can be obtained.

  The composite can also be formed by directly supporting the metal platinum fine particles on the conductive particles, but after using a predetermined platinum complex and supporting the platinum complex on the conductive particles. It can also be obtained by performing a reduction treatment. The reduction treatment can be obtained by using a predetermined reducing agent or using a method of irradiating ultraviolet rays after immersion in alcohol. Examples of the platinum metal complex include platinum acetylacetonate, platinum EDTA complex, and platinum bipyridyl complex.

  The dispersibility of the platinum fine particles or the composite in the solution can be improved by adding a dispersant to the colloidal solution and / or using a method such as ultrasonic dispersion. As the dispersant, organic carboxylic acids, organic amines, and the like can be used. Examples of the organic carboxylic acid that can be used include acetic acid, oxalic acid, succinic acid, malonic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, citric acid, tartaric acid, and metal salts thereof. Examples of organic amines that can be used include alkanolamines such as dimethylaminoethanol, diethanolamine, propanolamine, and butanolamine.

  For the purpose of controlling dispersibility, for example, polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polypropylene glycol, polyacrylic acid, and the like can be used as a dispersion aid.

  Furthermore, a binder may be added to the solution as necessary to form a paste.

  As described above, the coating is performed by a normal thin film coating method such as a screen printing method, a spin coating method, a roll coating method, a spray method, a bar coating method, a dip method, a meniscus coating method, a gravure printing method, a dispensing method, and an inkjet method. Any technique can be used. Among these, the screen printing method is a particularly preferable coating method because a film can be formed at a desired position on the printing substrate.

  In addition, a baking process can be given with respect to the obtained coating film after the said application | coating. The solvent contained in the colloidal solution is volatilized and removed naturally after coating, but when the paste is used, the binder remains even after coating and drying. Therefore, in order to use the coating film as a catalyst layer, it is necessary to bake the paste in the coating film and remove the resin component.

  Moreover, according to the kind of the said paste, it can also remove the resin part of the whole coating film obtained by irradiating with an ultraviolet-ray or a plasma instead of the said baking processing.

  In addition, the solution and colloid solution mentioned above have the property as a coating material at the time of forming the catalyst layer 112 in the counter electrode 109 of the photoelectric conversion element 100 of this invention shown to FIGS.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely according to an Example, this invention is not limited to the content of an Example.

Example 1
<Production of photoelectrode>
Using titanium oxide fine particles (manufactured by Sumitomo Osaka Cement Co., Ltd., average particle size 20 nm) as semiconductor fine particles, a paste containing titanium oxide fine particles was prepared. Preparation ratio of 25% by weight of TiO ₂ ultrafine particles and 75% by weight of 1-p-menten-8-ol (α-terpineol (trade name): manufactured by Kanto Chemical Co., Inc.) and 5% by weight of polyvinyl butyral (Sekisui Chemical BM-1) And mixed. Mixing was performed with three rolls (manufactured by EXAKT).

Next, a glass substrate with a tin oxide transparent conductive film (manufactured by Nippon Sheet Glass Co., Ltd., surface resistance 10Ω / □) is cut into a size of 35 mm × 20 mm, and the above oxidation is performed on the conductive surface side using a silk screen printing method. Titanium paste was printed in a 10 mm × 10 mm square shape. This was put into an electric furnace (Maffle furnace FP-32 type manufactured by Yamato Scientific Co., Ltd.) and baked at 500 ° C. for 30 minutes. After firing, before the substrate temperature becomes 100 ° C. or lower (ethanol solution of (cis-di (thiocyanate) bis (2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium (II)) (both 3 × 10 ^-4 mol / liter) was adsorbed for 3 hours to adsorb the dye, and an oxide semiconductor electrode was formed on the glass substrate with a transparent conductive film to produce a photoelectrode.

<Preparation of counter electrode>
First, a solution obtained by dissolving 1.5 g of sodium borohydride in 9000 g of pure water and 8 g of chloroplatinic acid hexahydrate dissolved in pure water 800 were rapidly mixed to prepare a platinum colloid. The obtained colloidal dispersion was filtered by an ultrafiltration method and washed until the conductivity of the filtrate became 1 μS · cm to remove chlorine in the colloidal dispersion. Further, it was concentrated by an ultrafiltration method to obtain an aqueous sol (colloid solution) containing 4.5% by weight of platinum fine particles. The average particle size of the platinum fine particles was 10 nm.

  Subsequently, 1 g of 1-p-menten-8-ol (α-terpineol (trade name): manufactured by Kanto Chemical Co., Inc.) was obtained by dispersing the platinum colloid solution in isopropanol so that the concentration of platinum was 1% by weight. ) Was mixed at a charging ratio of 15 g of a vehicle dissolved in 10% by weight of polyvinyl butyral (Sekisui Chemical BM-1) to prepare a platinum-containing paste. Subsequently, after mixing by a mechanical homogenizer (manufactured by IKA), isopropanol was removed by a rotary evaporator (manufactured by Tokyo Rika Co., Ltd.). The kneading was performed with three rolls (manufactured by EXAKT).

  Thereafter, a glass substrate with a tin oxide transparent conductive film (manufactured by Nippon Sheet Glass Co., Ltd., surface resistance 10Ω / □) is cut into a size of 35 mm × 20 mm, a φ0.6 mm through hole is opened with a sandblaster device, and an electrolyte is injected. A hole was formed. The platinum colloid-containing paste was printed in a square shape of 10 mm × 10 mm on the conductive surface side of the substrate using a silk screen printing method. Then, the paste was put together with the glass substrate with the transparent conductive film into an electric furnace (Maffle furnace FP-32 type manufactured by Yamato Scientific Co., Ltd.) and baked at 500 ° C. for 1 hour to produce a counter electrode.

<Production of photoelectric conversion element>
A film adhesive (HM52 manufactured by Tamapoly Co., Ltd.) made of a thermoplastic / thermocompression-bonding resin is placed between the photoelectrode and counter electrode produced as described above, and placed in an electric furnace maintained at 120 ° C. for 2 minutes. A partition wall was formed by adhering the adhesive to the photoelectrode and the counter electrode.

  Next, an electrolytic solution (methoxypropyldinitrile as a supporting electrolyte, 1-2dimethyl-3-propylimidazolium iodine salt 0.65 mol / liter, lithium iodide 0.5 mol / liter, iodine 0.05 mol / liter , Tert-butylpyridine 0.5 mol / liter) was injected from the electrolyte injection hole formed in the counter electrode, and sealed with the photoelectrode, the counter electrode and the partition wall A photoelectric conversion element was obtained.

(Example 2)
In this example, the photoelectrode and the photoelectric conversion element were manufactured in the same manner as in Example 1. However, the counter electrode was produced as follows.

<Preparation of counter electrode>
Ethyl cellulose (manufactured by Kanto Chemical Co., Inc.) and 6.66 g of a dispersion liquid (manufactured by Sumitomo Osaka Cement Co., Ltd.) in which ultrafine particles of ITO (tin-doped indium oxide) are dispersed at a concentration of 30% by weight in isopropanol are used. 5.0 g of the vehicle in which the solution was dissolved and 7.5 g of 1-p-menten-8-ol (α-terpineol (trade name): manufactured by Kanto Chemical Co., Inc.) were mixed. After mixing by a mechanical homogenizer (manufactured by IKA), isopropanol and ethanol were removed by a rotary evaporator (manufactured by Tokyo Rika). Kneading was carried out with three rolls (manufactured by EXAKT) to prepare an ITO paste.

Next, a glass substrate with a tin oxide transparent conductive film (manufactured by Nippon Sheet Glass Co., Ltd., surface resistance 10Ω / □) is cut into a size of 35 mm × 20 mm, a φ0.6 mm through hole is opened with a sandblaster device, and an electrolyte is injected. A hole was formed. The ITO paste was printed in a 10 mm × 10 mm square shape on the conductive surface side of the substrate using a silk screen printing method. It was kept for 10 minutes in an electric furnace (Yamato Scientific Muffle Furnace FP-32) held at 150 ° C. and dried to form a film containing ITO fine particles on the glass substrate with a transparent conductive film.
Next, a platinum-containing paste prepared by the same method as in ITO film Example 1 was printed using a screen printing method. A counter electrode formed in an electric furnace (Yamato Scientific muffle furnace FP-32 type), fired at 500 ° C. for 1 hour, and formed on the glass substrate with the transparent conductive film from an ITO layer and a catalyst layer made of platinum. Was made.

(Comparative Example 1)
In this comparative example, the photoelectrode and the photoelectric conversion element were manufactured in the same manner as in Example 1. However, a substrate with a Pt film was used as the counter electrode in accordance with Patent Document 1 described above. This substrate was produced by forming 200 nm of Pt on a glass substrate with a tin oxide transparent conductive film (manufactured by Nippon Sheet Glass Co., Ltd., surface resistance 10Ω / □) using a plasma sputtering apparatus. This was cut into a size of 35 mm × 20 mm, a φ0.6 mm through hole was opened with a sandblaster device to form an electrolyte injection hole, and a counter electrode was produced.

(Comparative Example 2)
Also in this example, the photoelectrode and the photoelectric conversion element were manufactured in the same manner as in Example 1. However, the counter electrode was produced in the following manner according to Patent Document 2.
9.38 g of chloroplatinic acid hexahydrate (manufactured by Kanto Chemical Co., Inc.) dissolved in isopropanol at a concentration of 4% by weight was dissolved in 1-p-menten-8-ol (α-terpineol (product). Name): manufactured by Kanto Chemical Co.) was mixed with 15 g of a vehicle in which ethyl cellulose (manufactured by Kanto Chemical Co., Ltd.) was dissolved at a concentration of 10% by weight. After mixing with a mechanical homogenizer (manufactured by IKA), isopropanol was removed with a rotary evaporator (manufactured by Tokyo Rika). Kneading was performed with three rolls (manufactured by EXAKT) to prepare a chloroplatinic acid paste.

(Evaluation)
Next, the photoelectric conversion characteristics of the photoelectric conversion elements obtained in the above Examples and Comparative Examples, the pattern processability of the counter electrode, and the metal corrosion resistance of the colloid solution paste were examined.

<Photoelectric conversion characteristics>
Simulated sunlight was generated by a solar simulator (YSS80A manufactured by Yamashita Denso Co., Ltd.) having spectral emission characteristics of AM1.5 and JIS-Class A. The intensity of this light was 100 mW / cm ² . This element was continuously irradiated with simulated sunlight, and the conversion efficiency was determined by measuring the IV characteristics with a current-voltage measuring device (Caseley 240).

<Corrosion resistance>
5 g of the counter electrode preparation pastes of the above examples and comparative examples were put into a mixed solution of 40 g of isopropanol and 5 g of ion-exchanged water, and stirred with a mechanical homogenizer. This liquid was put into a 100 mL screw tube bottle, a 20 mm × 10 mm × t 1 mm SUS304 plate was put in, and held in a thermostat at 70 ° C. for 1 month, and the change of the SUS304 plate was observed.

<Pattern workability>
A catalyst layer pattern was formed on the transparent conductive glass using the counter electrode preparation pastes of the above Examples and Comparative Examples. A strip test pattern with a line width of 25 μm to 500 μm between the printed part and the non-printed part was printed on a 325 mesh stainless steel screen with a screen plate formed with a photosensitive emulsion, and the solvent was removed in a dryer maintained at 120 ° C. Dried. Pattern workability was judged from the width at which the stripe pattern of the catalyst layer pattern could be clearly observed.

  The above evaluation results are shown in Table 1. FIG. 5 shows a graph (IV characteristics) showing the relationship between the photoelectric short-circuit current density Jsc (mA / cm 2) and the optical open circuit voltage Vco (V) regarding the photoelectric conversion efficiency of the photoelectric conversion element.

  As is apparent from Table 1 and FIG. 5, it can be seen that the photoelectric conversion element obtained by the method of the present invention has high photoelectric conversion efficiency. Further, as is apparent from Table 1, it was found that the method of the present invention was excellent in the patterning property of the counter electrode, and the colloidal solution paste used had high metal corrosion resistance, that is, low metal corrosion resistance. . On the other hand, the counter electrode formed by the sputtering method as in Patent Document 1 is inferior in pattern workability, and the colloid solution paste composed of a platinum salt as used in Patent Document 2 has low metal corrosion resistance, It was found to be highly corrosive to metals.

  As described above, the present invention has been described in detail based on the embodiments of the present invention with specific examples. However, the present invention is not limited to the above contents, and all modifications and changes are made without departing from the scope of the present invention. It can be changed.

  For example, the above-described colloid solution may contain a resin component as long as the dispersibility of platinum colloid or the like is not inhibited. Examples of the resin component include thermosetting or acrylic resin, polyester resin, polyurethane resin, polyolefin resin, polystyrene resin, cellulose, polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, butyral resin, alkyd resin, and vinyl chloride resin. Thermoplastic organic polymer compounds, ultraviolet (UV) curable organic polymer compounds, electron beam (EB) curable organic polymer compounds, inorganic polymer compounds such as polysiloxane, etc. can be used alone or in combination. .

It is a block diagram which shows roughly an example of the photoelectric conversion element obtained according to the method of this invention. It is the figure which showed the structure by which the several photoelectric conversion element was arranged vertically and horizontally on the electroconductive board | substrate which comprises a counter electrode. It is a figure which expands and shows the photoelectrode part of the photoelectric conversion element shown in FIG. It is a figure which expands and shows the counter electrode part of the photoelectric conversion element shown in FIG. It is a graph which shows the conversion efficiency (IV characteristic) of the photoelectric conversion element obtained according to the method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Photoelectric conversion element 101 Photoelectrode 102 Transparent conductive substrate 103 Oxide semiconductor electrode 104 Transparent substrate 105 Transparent conductive layer 106 Oxide semiconductor fine particle 107 Sensitizing dye 108 Electrolyte 109 Counter electrode 110 Substrate 111 Conductive layer 112 Catalyst layer 120 Partition wall

Claims (9)

Forming a colloidal solution containing metal platinum particulates;
Forming a catalyst layer containing platinum by applying the colloidal solution onto a predetermined conductive substrate, and forming a counter electrode having the conductive substrate and the catalyst layer;
A step of forming a photoelectrode having a semiconductor layer adsorbing a predetermined dye and generating an electromotive force by being excited by light absorption;
Forming a charge transfer layer between the counter electrode and the photoelectrode.
In the method for producing a dye-sensitized photoelectric conversion element,
The metal platinum fine particles constitute a composite supported on conductive particles,
The method for producing a dye-sensitized photoelectric conversion element, wherein the colloidal solution contains the complex. 2. The method for producing a dye-sensitized photoelectric conversion element according to claim 1 , wherein the complex is produced through a reduction treatment after a platinum complex is supported on the conductive particles. 3.   The method for producing a dye-sensitized photoelectric conversion element according to claim 1, wherein the size of the metal platinum fine particles in the colloidal solution is 50 nm or less. The method for producing a dye-sensitized photoelectric conversion element according to claim 1 or 2 , wherein the size of the complex in the colloidal solution is 200 nm or less. The method for producing a dye-sensitized photoelectric conversion element according to any one of claims 1 to 4 , wherein a baking treatment is performed after the application of the colloid solution onto the conductive substrate. In the coating for a dye-sensitized photoelectric conversion element, comprising a colloid solution containing metal platinum fine particles, the metal platinum fine particles constitute a complex supported on conductive particles, and the colloid solution contains the complex. A paint for a dye-sensitized photoelectric conversion element, characterized in that The paint for a dye-sensitized photoelectric conversion element according to claim 6 , wherein the complex is prepared by carrying a reduction treatment after supporting the platinum complex on the conductive particles. The paint for a dye-sensitized photoelectric conversion element according to claim 6 , wherein the size of the metal platinum fine particles in the colloidal solution is 50 nm or less. The paint for a dye-sensitized photoelectric conversion element according to claim 6 or 8 , wherein the size of the complex in the colloidal solution is 200 nm or less.

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