JP2010080933A - Transparent conductive film for solar cell and composition for the transparent conductive film, and multi-junction solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive film that meets respective requirements such as excellent optical transparency, high electric conductivity, and a low refractive index for use for a multi-junction solar cell by manufacturing it by a wet coating method using a coating type material, and is also reducible in running cost by manufacturing it without using a vacuum film forming method. <P>SOLUTION: The transparent conductive film for solar cell is provided between photoelectric conversion layers of the multi-junction solar cell and formed in a state wherein a particulate layer is impregnated with a binder layer by impregnating a coating of particulates formed by applying a conductive particulate dispersion liquid by using a wet coating method with a binder dispersion liquid by the wet coating method and baking it, the transparent conductive film for solar cell being characterized in that a base material constituting the conductive film contains 5 to 95% by mass of conductive component and the conductive film is 5 to 200 nm thick. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multi-junction solar cell that improves conversion efficiency by stacking two or more types of photoelectric conversion layers, and a transparent conductive film for a solar cell that is provided between photoelectric conversion layers to improve cell output and a composition for the transparent conductive film And a multi-junction solar cell.

  Currently, clean energy research and development is underway from the standpoint of environmental protection. In particular, solar cells are attracting attention because of the infinite amount of sunlight, which is a resource, and no pollution. Conventionally, for solar power generation using a solar cell, a bulk solar cell in which a bulk crystal of single crystal silicon or polycrystalline silicon is manufactured and sliced to be used as a thick plate semiconductor has been used. However, the above silicon crystal used for bulk solar cells requires a lot of energy and time for crystal growth, and it is difficult to increase mass production efficiency because of the complicated manufacturing process required in the subsequent manufacturing process. It was difficult to provide solar cells.

  On the other hand, a thin film semiconductor solar cell using a semiconductor such as amorphous silicon having a thickness of several micrometers or less (hereinafter referred to as a thin film solar cell) is a photoelectric conversion layer on an inexpensive substrate such as glass or stainless steel. It is only necessary to form as many semiconductor layers as necessary. Therefore, this thin film solar cell is considered to become the mainstream of future solar cells because it is thin and light, low in manufacturing cost, and easy to increase in area.

  In thin-film solar cells in which the photoelectric conversion layer is formed of a silicon-based material, for example, the power generation efficiency is increased by taking a multi-junction structure formed in the order of transparent electrode, amorphous silicon, polycrystalline silicon, and back electrode. (For example, refer to Patent Documents 1 to 4 and Non-Patent Document 1). In the structures shown in Patent Documents 1 to 4 and Non-Patent Document 1, amorphous silicon and polycrystalline silicon constitute a photoelectric conversion layer.

  When the photoelectric conversion layer is made of a silicon-based material, the absorption coefficient of the photoelectric conversion layer is relatively small. The transmitted light does not contribute to power generation.

  Therefore, a transparent conductive film is provided as an intermediate film between the top cell and the bottom cell in one of the layers constituting the thin film solar cell (see, for example, Patent Documents 1 to 3 and Non-Patent Document 1).

  Originally, this transparent conductive film reflects part of the light that passes through the top cell and is incident on the bottom cell side in a wavelength-selective manner using the refractive index difference between the silicon layer and the transparent conductive film. The purpose is that. For example, in the case of a solar cell having a tandem structure of an amorphous silicon layer (top cell) and a microcrystalline silicon layer (bottom cell), the amorphous silicon layer has high conversion efficiency by providing a transparent conductive film at the interface between both photoelectric conversion layers. The transparent conductive film selectively reflects light in the short wavelength range shown. Since the reflected light in the short wavelength region is incident again on the amorphous silicon layer, it again contributes to power generation. This increases the effective photosensitivity as compared with the conventional structure even with the same top cell thickness. On the other hand, most of the light in the long wavelength region is transmitted through the transparent conductive film, and is incident on the microcrystalline silicon layer having high conversion efficiency with respect to the light in the long wavelength region.

JP 2006-31068 A JP 2006-310694 A International Publication No. 2005/011002 Pamphlet JP 2002-141524 A

Shozo Yanagida et al., “The Forefront of Thin-Film Solar Cell Development: Toward High Efficiency, Mass Production, and Popularization”, NTS Corporation, March 2005, p. 113 FIG. 1 (a)

  In the development so far in the thin film type solar cell, each layer has been formed by a vacuum film forming method such as a sputtering method. However, in general, a large amount of cost is required to maintain and operate a large-scale vacuum film forming apparatus. Therefore, the manufacturing method using the vacuum film forming method is replaced with the manufacturing method using the wet film forming method. Significant cost improvement is expected.

  In addition, the transparent conductive film must satisfy at least the requirements such as good light transmittance, high electrical conductivity, low refractive index, and sputtering resistance.

  Furthermore, one of the important features of a multi-junction solar cell is that the short-circuit current density is limited to the smallest short-circuit current density among the short-circuit current densities generated in each photoelectric conversion layer. It is known that the short circuit current increases in the whole cell by adjusting the light reflection characteristics inside the cell using a transparent conductive film and optimizing the short circuit current density generated in each photoelectric conversion layer.

  The object of the present invention is to produce good light transmission, high electrical conductivity, low refractive index, etc. required for use in multi-junction solar cells by producing by a wet coating method using a coating type material. An object of the present invention is to provide a transparent conductive film for a solar cell that can satisfy each requirement and can reduce the running cost by being manufactured without using a vacuum film forming method.

  Another object of the present invention is to easily adjust optical characteristics such as the refractive index of the transparent conductive film related to the difference in refractive index between the photoelectric conversion layer and the transparent conductive film, and to optimize the light reflection characteristics between the photoelectric conversion layers. The object is to provide a transparent conductive film for a solar cell that can be achieved.

  Another object of the present invention is to provide a transparent conductive film for a solar cell that is excellent in adhesiveness with a photoelectric conversion layer as a base and has little change with time.

  Still another object of the present invention is to provide a transparent conductive film composition for forming the transparent conductive film and a multi-junction solar cell using the transparent conductive film.

  As a result of intensive studies on the transparent conductive film provided between the photoelectric conversion layers of the multi-junction solar cell, the present inventors formed a coating film mainly composed of fine particles using a coating-type material. Each of the good light transmittance, high electrical conductivity, low refractive index, etc. required when used for multi-junction solar cells by wet coating method by impregnating and baking a dispersion containing binder It has been found that a transparent conductive film that satisfies the requirements can be produced, and that the running cost in the production of the transparent conductive film can be reduced as a technique that does not use the vacuum film formation method. In addition, the present inventors adjust the blending ratio etc. of the coating type material used in the wet coating method, such as the refractive index of the transparent conductive film related to the refractive index difference between the photoelectric conversion layer and the transparent conductive film. There is a merit that the optical characteristics can be easily adjusted, and by optimizing the light reflection characteristics between the photoelectric conversion layers, the performance improvement of the multi-junction solar cell that could not be achieved by the vacuum deposition method has been realized I found it possible.

  In addition, by adopting a two-layer structure of a conductive fine particle layer and a binder layer, compared with a single transparent conductive film, it has excellent adhesion to an amorphous silicon layer as a base, and the conductive fine particle layer is a binder layer. It was found that changes in the film over time were small by making the impregnation state.

  According to a first aspect of the present invention, in a transparent conductive film for a solar cell provided between photoelectric conversion layers of a multijunction solar cell, the conductive film includes a dispersion containing conductive fine particles (hereinafter referred to as a conductive fine particle dispersion). The fine particle layer is obtained by impregnating and baking a dispersion liquid containing a binder (hereinafter referred to as a binder dispersion liquid) on a fine particle coating film formed by applying a wet coating method using a wet coating method. Is impregnated with a binder layer, and in the base material constituting the conductive film, the conductive component is present in the range of 5 to 95% by mass, and the thickness of the conductive film is in the range of 5 to 200 nm. It is characterized by being.

  A second aspect of the present invention is an invention based on the first aspect, wherein the composition for a transparent conductive film further includes a binder that is cured by heating within a range of 100 to 400 ° C. or ultraviolet irradiation. And

  A third aspect of the present invention is an invention based on the second aspect, wherein the binder is an acrylic resin, acrylate resin, polycarbonate resin, polyester resin, alkyd resin, polyurethane resin, acrylic urethane resin, polystyrene resin, polyacetal. Containing any one or more of resin, polyamide resin, polyvinyl alcohol resin, polyvinyl acetate resin, cellulose resin, ethyl cellulose resin, epoxy resin, vinyl chloride resin, siloxane polymer or hydrolyzate of metal alkoxide (including sol-gel) It is characterized by.

  4th viewpoint of this invention is invention based on 1st viewpoint, Comprising: Furthermore, the composition for transparent conductive films was chosen from the group which consists of a silane coupling agent, an aluminum coupling agent, and a titanium coupling agent. It contains a seed or two or more kinds.

  A fifth aspect of the present invention is an invention based on the first aspect, wherein the conductive fine particles further comprise Zn, In, Sn, Sb, Si, Al, Ga, Co, Mg, Ca, Sr, Ba, It is the 1st fine particle comprised from the 1 type, 2 or more types of oxide selected from the group which consists of Ce, Ti, Y, and Zr, a hydroxide, or a composite compound, or these 2 or more types of mixtures. And

  A sixth aspect of the present invention is the invention based on the first aspect, wherein the conductive fine particles further comprise C, Si, Cu, Ni, Ag, Pd, Pt, Au, Ru, Rh, and Ir. It is the 2nd fine particle comprised from the nanoparticle which consists of a mixed alloy containing 1 type, or 2 or more types selected from more.

  A seventh aspect of the present invention is the invention based on the first aspect, characterized in that the conductive fine particles are a mixture of both the first fine particles and the second fine particles.

  The eighth aspect of the present invention is the invention based on the first aspect, and the wet coating method further includes a spray coating method, a dispenser coating method, a spin coating method, a knife coating method, a slit coating method, an inkjet coating method, It is a gravure printing method, a screen printing method, an offset printing method, or a die coating method.

  A ninth aspect of the present invention is an invention based on the first to eighth aspects, and further has a refractive index of 1.1 to 2.0.

  A tenth aspect of the present invention is a multi-junction solar cell, characterized in that a transparent conductive film for a solar cell based on the first to ninth aspects is provided between photoelectric conversion layers.

  An eleventh aspect of the present invention is a composition for a transparent conductive film for forming a transparent conductive film for a solar cell based on the first to ninth aspects.

  The present invention provides good light transmission, high electrical conductivity, low refractive index, etc. required for use in multi-junction solar cells by wet coating using a coating type material in the production of a transparent conductive film. It is possible to produce a transparent conductive film satisfying these requirements, and there is an advantage that the running cost in producing the transparent conductive film can be reduced as a technique not using the vacuum film formation method.

  Further, the present invention can easily adjust the optical characteristics such as the refractive index of the transparent conductive film related to the difference in refractive index between the photoelectric conversion layer and the transparent conductive film, and can optimize the light reflection characteristics between the photoelectric conversion layers. There is another advantage. Furthermore, since the transparent conductive film of the present invention is composed of two layers of a conductive fine particle layer and a binder layer, it has superior adhesion to the amorphous silicon layer as a base, compared to a single transparent conductive film. In addition, it has the advantage of little change over time.

It is the schematic of a multijunction solar cell. It is the figure which represented typically the cross section of the transparent conductive coating film before baking.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings.

  The transparent conductive film for solar cell of the present invention is provided between the photoelectric conversion layers of a multijunction solar cell. In the multi-junction solar cell, as shown in FIG. 1, a surface-side electrode layer 12 is formed on a transparent substrate 11, and an amorphous silicon layer 13 is formed on the electrode layer 12 as a first photoelectric conversion layer. . A transparent conductive film 14 is formed on the amorphous silicon layer 13, and a microcrystalline silicon layer 15 is formed on the transparent conductive film 14 as a second photoelectric conversion layer. The structure is sandwiched between the conversion layers 13 and 15. Further, a back electrode layer 16 is formed on the microcrystalline silicon layer 15.

  The transparent conductive film 14 of the present invention is formed by applying a conductive fine particle dispersion using a wet coating method to form a fine particle coating, and impregnating the binder dispersion on this coating using a wet coating method and firing. It is formed by doing. And in the base material which comprises a transparent conductive film, a conductive component exists in the range of 5-95 mass%, and the thickness of a conductive film exists in the range of 5-200 nm, It is characterized by the above-mentioned. Here, the conductive component is obtained by firing the conductive fine particles contained in the conductive fine particle dispersion and the form thereof is changed, and the base material remains after the binder contained in the binder dispersion is fired. The component is composed of the main component.

  When the transparent conductive film 14 is formed by a vacuum film formation method such as a sputtering method, the refractive index of the film is determined by the material of the target material, so that the refractive index suitable as an intermediate film provided between the photoelectric conversion layers of the solar cell is It is difficult to obtain and tends to have a high refractive index. On the other hand, in the case of a transparent conductive film formed using a wet coating method, it is generally formed by applying and baking a composition for transparent conductive film, which is a mixture of conductive fine particles and a binder and other components, A film formed using a wet coating method can have a desired low refractive index by adjusting the composition of the composition. From the above, it is possible to reduce the running cost by producing a transparent conductive film that has been produced by a vacuum film-forming method such as a conventional sputtering method by using a coating-type material. There is. Furthermore, by using a coating type material, there is another advantage that optical characteristics such as the refractive index of the transparent conductive film relating to the difference in refractive index between the photoelectric conversion layer and the transparent conductive film can be easily adjusted.

  For example, a single transparent conductive film formed by applying a composition prepared by containing conductive fine particles and a binder component together and then baking the transparent conductive film formed using a wet coating method Is mentioned. Even such a single transparent conductive film has a structure in which not only the conductive component but also the base material exists in the film, compared with a film manufactured by a technique using a vacuum film forming method such as a sputtering method. Thus, the refractive index of light can be lowered.

  On the other hand, the transparent conductive film 14 of the present invention first forms a coating film by applying a conductive fine particle dispersion containing no binder component on the amorphous silicon layer 13 which is a photoelectric conversion layer. A binder dispersion containing no conductive fine particles is applied to the film, and then fired at a predetermined temperature. That is, as shown in FIG. 1, the transparent conductive film 14 of the present invention has a binder layer 14b that does not contain conductive fine particles formed as an upper layer. The lower layer near the interface with the amorphous silicon layer 13 is composed of a conductive fine particle layer 14a in which part or all of the surface is covered with a binder layer 14b and part of the surface is impregnated by application of a binder dispersion. It is a thing. In the conductive fine particle layer 14a, a part of the particles is sintered by firing to ensure high conductivity.

  Since the transparent conductive film 14 of the present invention is configured as described above, it has only the advantage that a single transparent conductive film formed of a composition containing conductive fine particles and a binder component together has. Compared to this single transparent conductive film, the adhesive layer is excellent in adhesion to the underlying amorphous silicon layer, and part or all of the surface of the conductive fine particle layer 14a is covered with the binder layer 14b. Therefore, it also has the advantage of little change with time.

  The ratio of the conductive component in the base material is defined within the above range because sufficient conductivity cannot be obtained below the lower limit value, and when the upper limit value is exceeded, the adhesion with the photoelectric conversion layer contacting the upper layer and the lower layer is poor. This is because it cannot be obtained sufficiently. Moreover, it is because it will be difficult to adjust to a desired refractive index if it is out of the above range. A desirable ratio of the conductive component in the base material is 5 to 95% by mass, and more preferably 30 to 85% by mass.

  Here, the film thickness is within the above range because the film thickness is also one of the elements that can adjust the refractive index, and the difference in refractive index from the microcrystalline silicon layer can be increased. This is because it can. A preferable film thickness is 20 to 100 nm. The thickness of the transparent conductive film 14 here is a total thickness obtained by adding the thickness of the conductive fine particle layer 14a and the thickness of the binder layer 14b.

  The refractive index of the transparent conductive film 14 in the present invention is preferably adjusted to 1.1 to 2.0. Within the above range, the difference in refractive index from the microcrystalline silicon layer can be increased, only short wavelength light can be selectively and efficiently reflected, and long wavelength light can be transmitted well. can do. Among these, a particularly preferable refractive index is 1.3 to 1.8.

  The composition for transparent conductive film used for forming the transparent conductive film according to the present invention comprises two liquids, a conductive fine particle dispersion for forming the conductive fine particle layer 14a and a binder dispersion for forming the binder layer 14b.

  The conductive fine particle dispersion for forming the conductive fine particle layer 14a is a composition in which conductive fine particles and other necessary components are dispersed in a dispersion medium.

  The type of conductive fine particles used in the conductive fine particle dispersion is not particularly limited, but examples include Zn, In, Sn, Sb, Si, Al, Ga, Co, Mg, Ca, Sr, and Ba. Use first fine particles composed of one or more oxides, hydroxides or composite compounds selected from the group consisting of, Ce, Ti, Y and Zr, or a mixture of two or more thereof. Can do. Among these, it is preferable to use a tin oxide powder, a zinc oxide powder, or a compound doped with one or more metals. For example, ITO powder (Indium doped Tin Oxide), ZnO powder, ATO powder (Antimony doped Tin Oxide), AZO powder (Aluminum doped Zinc Oxide), IZO powder (Indium doped Zinc Oxide), TZO powder (Tantalum doped Zinc Oxide), etc. Is mentioned.

  The fine particles are composed of nanoparticles made of a mixed alloy containing one or more selected from the group consisting of C, Si, Cu, Ni, Ag, Pd, Pt, Au, Ru, Rh and Ir. The second fine particles may be used.

  Further, fine particles obtained by mixing both the first fine particles and the second fine particles in a desired ratio may be used.

  Moreover, it is preferable that the content rate of the electroconductive fine particle which occupies for the solid content contained in an electroconductive fine particle dispersion exists in the range of 50-90 mass%. The reason why the content ratio of the conductive fine particles is within the above range is that the conductivity of the conductive fine particle layer to be formed is lowered if the content is less than the lower limit, and the adhesion of the conductive fine particle layer to be formed is exceeded if the upper limit is exceeded. It is because it falls. Among these, it is especially preferable that it exists in the range of 70-90 mass%. The average particle diameter of the conductive fine particles is preferably in the range of 10 to 100 nm in order to maintain stability in the dispersion medium, and particularly preferably in the range of 20 to 60 nm.

  The type and ratio of the conductive fine particles to be used are appropriately selected according to various conditions such as the configuration of the target multi-junction solar cell and the refractive index difference between the photoelectric conversion layer and the transparent conductive film.

  The type of the dispersion medium used in the conductive fine particle dispersion is not particularly limited. Examples include water, alcohols such as methanol, ethanol, isopropanol, butanol, hexanol, acetone, methyl ethyl ketone, and methyl isobutyl ketone. , Ketones such as cyclohexanone, isophorone and 4-hydroxy-4-methyl-2-pentanone, hydrocarbons such as toluene, xylene, hexane and cyclohexane, amides such as N, N-dimethylformamide and N, N-dimethylacetamide , Sulfoxides such as dimethyl sulfoxide, glycols such as ethylene glycol, glycol ethers such as ethyl cellosolve, and the like. Further, two or more kinds of these dispersion media can be mixed and used.

  The content ratio of the dispersion medium is preferably in the range of 80 to 99% by mass in order to obtain good film formability.

  It is preferable to add a coupling agent to the conductive fine particle dispersion according to other components to be used. This is for improving the bonding property between the conductive fine particles and the binder and the adhesion between the conductive fine particle layer formed by the conductive fine particle dispersion and the photoelectric conversion layer. As a coupling agent, a silane coupling agent, an aluminum coupling agent, a titanium coupling agent, etc. are mentioned, You may use these 1 type or 2 or more types.

  Examples of silane coupling agents that can be used include vinyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

  Moreover, as an aluminum coupling agent which can be used, the aluminum coupling agent containing the acetoalkoxy group shown by following formula (1) is mentioned.

また、使用可能なチタンカップリング剤としては、イソプロピルトリイソステアロイルチタネート、イソプロピルトリデシルベンゼンスルホニルチタネート、イソプロピルトリス（ジオクチルパイロホスフェート）チタネート、テトライソプロピルビス（ジオクチルホスファイト）チタネート、テトラオクチルビス（ジトリデシルホスファイト）チタネート、テトラ（２，２−ジアリルオキシメチル−１−ブチル）ビス（ジ−トリデシル）ホスファイトチタネート、ビス（ジオクチルパイロホスフェート）オキシアセテートチタネート、トリス（ジオクチルパイロホスフェート）エチレンチタネートなどが挙げられる。

Examples of titanium coupling agents that can be used include isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, isopropyl tris (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecyl). Phosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (di-tridecyl) phosphite titanate, bis (dioctylpyrophosphate) oxyacetate titanate, tris (dioctylpyrophosphate) ethylene titanate It is done.

  When the titanium coupling agent is hydrolyzable (eg, tetraalkoxytitanium), it can also be used as a hydrolysis / condensation product. Among these, preferable organic titanium compounds are tetraalkoxy titaniums and titanium coupling agents represented by the following structural formulas (2) to (8).

カップリング剤の含有割合は、導電性微粒子分散液に占める固形分の割合として、０．２〜５質量％の範囲内が好ましい。下限値未満では、カップリング剤の十分な添加効果が得られず、上限値を越えると、微粒子同士の結合性をカップリング剤が阻害することによる導電性の低下を招くからである。このうち０．５〜２質量％の範囲内が特に好ましい。

The content of the coupling agent is preferably in the range of 0.2 to 5% by mass as the solid content in the conductive fine particle dispersion. If the amount is less than the lower limit, a sufficient effect of adding the coupling agent cannot be obtained. If the amount exceeds the upper limit, the coupling agent inhibits the bonding property between the fine particles, leading to a decrease in conductivity. Among these, the inside of the range of 0.5-2 mass% is especially preferable.

  In the conductive fine particle dispersion, the conductive fine particles and the dispersion medium are mixed in a desired ratio, and if necessary, the above-described coupling agent and other optional components are added and mixed. And prepared by uniformly dispersing the fine particles in the mixture.

  The binder dispersion forming the binder layer 14b is a composition in which a binder component and other necessary components are dispersed in a dispersion medium.

  Examples of the binder used in the binder dispersion include those that are cured by heating in the range of 100 to 400 ° C. or ultraviolet irradiation. If the heating temperature for curing is within the above range, the component derived from this binder remains in the transparent conductive film formed by baking the coating film, and can constitute the main component of the base material.

  Specific types include acrylic resin, acrylate resin, polycarbonate resin, polyester resin, alkyd resin, polyurethane resin, acrylic urethane resin, polystyrene resin, polyacetal resin, polyamide resin, polyvinyl alcohol resin, polyvinyl acetate resin, cellulose resin, Of ethyl cellulose resin, epoxy resin, vinyl chloride resin, siloxane polymer obtained by hydrolyzing alkoxysilane, and hydrolyzate of metal alkoxide (including sol-gel), a binder combining one or more kinds satisfying the above conditions Can be used.

  By using the above kind of binder, it is possible to form a transparent conductive film having a low haze ratio and volume resistivity at a low temperature, the resistivity of the transparent conductive film can be lowered, and a transparent conductive film to be formed. The refractive index of can be adjusted.

  The content of these binders is preferably in the range of 5 to 50% by mass as a proportion of the solid content in the binder dispersion. The reason why the binder content is within the above range is that the conductivity of the transparent conductive film to be formed is lowered if the content is less than the lower limit, and the adhesion of the transparent conductive film to be formed is lowered if the upper limit is exceeded. is there. Among these, the inside of the range of 10-30 mass% is especially preferable.

  For the preparation of the binder dispersion, it is preferable to use a dispersion medium of the same type as the dispersion medium used for the preparation of the dispersion used for forming the conductive fine particle layer. In order to form a uniform film, the content of the dispersion medium is preferably in the range of 50 to 99.99% by mass.

  Further, depending on the components used, optional additional components such as a surfactant and a pH adjuster can be further contained. Such additional components include surfactants (cationic, anionic, nonionic), pH adjusters (organic or inorganic acids such as formic acid, acetic acid, propionic acid, butyric acid, octylic acid, hydrochloric acid, nitric acid, perchlorine. Acid or amine).

  The content ratio when the surfactant is contained is preferably 0.5 to 2.0% by mass with respect to the conductive powder, and the content ratio when the pH adjuster is included is 0.5 to 2.0% with respect to the conductive powder. 2.0 mass% is preferable.

  Next, the manufacturing method of the multijunction solar cell of this invention is demonstrated.

First, as shown in FIG. 1, a transparent substrate 11 is prepared, and a surface electrode layer 12 is formed on the substrate. Usable transparent substrates 11 include glass substrates, acrylic resins, and polycarbonates. For the surface electrode layer 12 to be formed, a transparent and conductive material such as ITO, SnO ₂ , ZnO, or AZO is used. The method for forming the surface electrode layer 12 is not particularly limited, and may be formed by a conventionally known method. In addition, since the glass substrate 11 in which the transparent and electroconductive film | membrane was formed in the surface layer is marketed, you may use such a commercial item.

  Next, an amorphous silicon layer 13 is formed on the transparent substrate 11 on which the surface electrode layer 12 is formed. The method for forming the amorphous silicon layer 13 is not particularly limited, and may be formed by a conventionally known method such as a plasma CVD method.

  Next, as shown in FIG. 2, the conductive fine particle dispersion is applied onto the substrate provided with the amorphous silicon layer 13 by a wet coating method to form a conductive fine particle coating 24 a. The coating film 24a is dried at a temperature of 20 to 120 ° C., preferably 25 to 60 ° C. for 1 to 30 minutes, preferably 2 to 10 minutes.

  Next, the conductive fine particle coating film 24a is impregnated with the binder dispersion liquid by a wet coating method so that a part or all of the surface of the conductive fine particle coating film 24a is covered with the binder dispersion liquid coating film 24b. Apply to. Moreover, application | coating here is the mass ratio of 0.5-10 with respect to the gross mass of the electroconductive fine particles contained in the coating film of the electroconductive fine particles with which the mass of the binder component in the binder dispersion liquid to apply | coat is applied. It is preferable to apply so as to be (mass of binder component / mass of conductive fine particles in binder dispersion to be applied). If it is less than the lower limit, it is difficult to obtain sufficient adhesion, and if it exceeds the upper limit, the surface resistance tends to increase. Among these, the mass ratio is particularly preferably 0.5-3. The coating film 24b is dried at a temperature of 20 to 120 ° C., preferably 25 to 60 ° C. for 1 to 30 minutes, preferably 2 to 10 minutes. The conductive fine particle dispersion and the binder dispersion are applied so that the transparent conductive film formed after firing has a thickness of 5 to 200 nm, preferably 20 to 100 nm. Here, the reason for applying the conductive fine particle dispersion and the binder dispersion so that the thickness of the transparent conductive film after baking is 5 to 200 nm is that the formation of a uniform film becomes difficult if the lower limit is not reached, and the upper limit This is because if the value is exceeded, the amount of material used becomes more than necessary and the material is wasted. In this way, the transparent conductive coating film 24 composed of the conductive fine particle coating film 24a and the binder dispersion liquid coating film 24a is formed.

  The wet coating method is any one of spray coating method, dispenser coating method, spin coating method, knife coating method, slit coating method, inkjet coating method, gravure printing method, screen printing method, offset printing method or die coating method. Although it is particularly preferable, the present invention is not limited to this, and any method can be used.

  The spray coating method is a method in which the dispersion is atomized by compressed air and applied to the substrate, or the dispersion itself is pressurized and atomized to apply to the substrate. The dispenser coating method is, for example, a method in which the dispersion is injected into a syringe. The dispersion is discharged from the fine nozzle at the tip of the syringe and applied to the substrate by pushing the piston of the syringe. The spin coating method is a method in which a dispersion is dropped onto a rotating substrate, and the dropped dispersion is spread to the periphery of the substrate by its centrifugal force. The knife coating method leaves a predetermined gap from the tip of the knife. In this method, the substrate is provided so as to be movable in the horizontal direction, the dispersion is supplied onto the substrate upstream of the knife, and the substrate is moved horizontally toward the downstream side. The slit coating method is a method in which a dispersion is discharged from a narrow slit and applied onto a substrate, and the inkjet coating method is a method in which a dispersion is filled in an ink cartridge of a commercially available inkjet printer and ink jet printing is performed on the substrate. is there. The screen printing method is a method in which wrinkles are used as a pattern indicating material and a dispersion is transferred to a substrate through a plate image formed thereon. The offset printing method is a printing method utilizing the water repellency of ink, in which the dispersion attached to the plate is not directly attached to the substrate, but is transferred from the plate to a rubber sheet and then transferred from the rubber sheet to the substrate again. . The die coating method is a method in which a dispersion supplied in a die is distributed by a manifold and extruded onto a thin film from a slit to coat the surface of a traveling substrate. The die coating method includes a slot coat method, a slide coat method, and a curtain coat method.

  Next, the base material having the transparent conductive coating film 24 is heated to 130 to 400 ° C., preferably 150 to 350 ° C. in the air or an inert gas atmosphere such as nitrogen or argon, for 5 to 60 minutes, preferably 15 Hold for ~ 40 minutes and fire. As a result, the transparent conductive film 24 shown in FIG. 2 is baked and hardened, and the transparent conductive film 14 is formed on the amorphous silicon layer 13 as shown in FIG. The transparent conductive film 14 is formed in a state where the conductive fine particle layer 14a is impregnated with the binder layer 14b.

  The reason why the firing temperature is in the range of 130 to 400 ° C. is that when the temperature is less than 130 ° C., the surface resistance value of the transparent conductive film becomes too high. On the other hand, if the temperature exceeds 400 ° C., the production merit of the low temperature process cannot be utilized, that is, the manufacturing cost increases and the productivity decreases. In particular, amorphous silicon, microcrystalline silicon, or hybrid silicon solar cells using these are relatively weak against heat, and the conversion efficiency is reduced by the firing process.

  Furthermore, the reason why the firing time of the substrate having the coating film is within the above-mentioned range is that if the particle is less than the lower limit, sintering of the fine particles is insufficient, so that sufficient conductivity cannot be obtained, and the upper limit is exceeded. This is because the power generation performance is reduced due to excessive heating of the amorphous silicon layer.

  As described above, the transparent conductive film 14 of the present invention can be formed. Thus, using a coating-type material (a composition for transparent conductive film: conductive fine particle dispersion and binder dispersion), a coating film mainly composed of a component in which fine particles and a binder are combined is formed. We can fabricate transparent conductive films that meet the requirements for good light transmission, high electrical conductivity, low refractive index, etc. required for use in multi-junction solar cells by wet coating method by baking As a technique not using the vacuum film formation method, the running cost in the production of the transparent conductive film can be reduced.

  Moreover, the coating type material (composition for transparent conductive films) used in the wet coating method is a transparent conductive film related to the refractive index difference between the photoelectric conversion layer and the transparent conductive film by adjusting the blending ratio and the like. There is a merit that optical characteristics such as refractive index can be easily adjusted, and by optimizing the light reflection characteristics between the photoelectric conversion layers, multi-junction solar cells that could not be achieved by vacuum film formation Performance improvement is feasible.

  Next, a microcrystalline silicon layer 15 is formed on the transparent conductive film 14. The formation method of the microcrystalline silicon layer 15 is not particularly limited, and may be formed by a conventionally known method such as a plasma CVD method.

  Finally, the multi-junction solar cell 10 is obtained by forming the back surface side electrode layer 16 on the microcrystalline silicon layer 15. In this multi-junction thin-film solar cell 10, the transparent substrate 11 serves as a light receiving surface.

  Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
First, 10 cm square glass was prepared for the transparent substrate 11, and SnO ₂ was used as the surface side electrode layer 12. The film thickness of the surface side electrode layer 12 at this time was 800 nm, the sheet resistance was 10Ω / □, and the haze ratio was 15 to 20%.

  Next, an amorphous silicon layer 13 having a thickness of 300 nm was formed on the surface-side electrode layer 12 by plasma CVD.

  Next, a transparent conductive film composition comprising a conductive fine particle dispersion and a binder dispersion was prepared as follows.

  As shown in Table 1, 1.0 parts by mass of ITO powder having Sn / (Sn + In) = 0.1 and particle size of 0.03 μm as the conductive fine particles is shown in the above formula (3) as a coupling agent. The organic titanium coupling agent to be added was added in an amount of 0.01 parts by mass, and ethanol was added as a dispersion medium to make the whole 100 parts by mass.

  In addition, about the measuring method of the average particle diameter of the said electroconductive fine particles, it computed from the number average as follows. First, an electron micrograph of the target fine particles was taken. Regarding the electron microscope used for photographing, SEM or TEM was appropriately used depending on the size of the particle diameter and the type of powder. Next, from the obtained electron micrograph, the diameter of about 1000 particles was measured to obtain frequency distribution data. A numerical value with an accumulated frequency of 50% (D50) was taken as the average particle size.

  This mixture was operated for 2 hours with a dyno mill (horizontal bead mill) using zirconia beads having a diameter of 0.3 mm to disperse the fine particles in the mixture, thereby obtaining a conductive fine particle dispersion.

  Further, 1.0 part by mass of a siloxane polymer obtained by hydrolyzing ethyl silicate as a binder was prepared, and ethanol was added as a dispersion medium to make the whole 100 parts by mass to obtain a binder dispersion.

  Subsequently, the obtained conductive fine particle dispersion is applied on the amorphous silicon layer 13 by spin coating so that the film thickness of the fine particle layer becomes 80 nm, and then dried at a temperature of 50 ° C. for 5 minutes to be conductive. A coating of conductive fine particles was formed.

  Next, this conductive fine particle coating is impregnated with the obtained binder dispersion by spin coating so that the film thickness after firing becomes 90 nm, and dried at a temperature of 50 ° C. for 5 minutes to form a transparent conductive coating. A film was formed. About the film thickness of the fine particle layer after transparent conductive film formation, the cross section was measured with the photograph image | photographed by SEM. In the binder dispersion, the mass of the binder component in the binder dispersion is the mass ratio shown in the following Table 1 with respect to the total mass of fine particles contained in the coating film of the applied conductive fine particles (in the binder dispersion to be applied). The binder component mass / conductive fine particles + coupling agent mass).

  Furthermore, the transparent conductive film 14 was formed by baking the transparent conductive film at 200 ° C. for 30 minutes. Moreover, the film thickness of the transparent conductive film obtained by baking was measured with the photograph which image | photographed the cross section by SEM. The fine particle / binder ratio in the transparent conductive film obtained by firing was 1/1 in the fine particle / binder ratio. In addition, about the temperature at the time of baking, the temperature of 4 points | pieces of the corner | angular corner of a 10 cm square glass plate was measured, and it was set as the conditions which an average value enters into +/- 5 degreeC of preset temperature.

  Subsequently, a microcrystalline silicon layer 15 having a thickness of 1.7 μm is formed on the transparent conductive film 14 by using a plasma CVD method. Further, as the back electrode layer 16, a ZnO film is formed with a thickness of 80 nm and an Ag film is formed. Each film was formed by sputtering to a thickness of 300 nm.

The thus produced multi-junction thin film silicon solar cell was irradiated with AM1.5 light as incident light at a light illuminance of 100 mW / cm ² , and the short-circuit current density and conversion efficiency at that time were measured. In addition, about the value of a short circuit current density and conversion efficiency, the value of Example 1 is set to 1.0, and the values of the short circuit current density and conversion efficiency of the following Examples 2 to 50 and Comparative Examples 1 to 5 are It was expressed as a relative value to the value of Example 1. In addition, using a spectroscopic ellipsometer (manufactured by JA Woollam Japan; M-2000DI) and using the analysis software “WVASE32” attached to the same device, the film thickness observed in advance on the SEM cross section is input to obtain a multi-junction thin film. The refractive index at 600 nm wavelength of the transparent conductive film 14 of the silicon solar cell was measured. The results are shown in Table 4 below.

<Example 2>
As shown in Table 1, 0.5 parts by mass of ITO powder having an atomic ratio of Sb / (Sb + In) = 0.05 and a particle diameter of 0.02 μm as conductive fine particles is shown in the above formula (3) as a coupling agent. 0.01 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 0.2 parts by mass of a siloxane polymer as a binder are prepared. Furthermore, using a binder dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 20 nm. A coating film of conductive fine particles was formed, and a binder dispersion was impregnated on the coating film of conductive fine particles by spin coating so that the film thickness after firing was 20 nm. Outside, to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 5/2 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 3>
As shown in Table 1, 1.0 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.1 and a particle size of 0.02 μm as conductive fine particles, and the above as a coupling agent A conductive fine particle dispersion is prepared by adding 0.02 part by mass of a titanium coupling agent represented by the formula (2) and further adding ethanol as a dispersion medium to make the whole 100 parts by mass. Is applied by spin coating so that the film thickness of the fine particle layer becomes 70 nm to form a coating film of conductive fine particles, and the binder dispersion liquid is baked by spin coating method on the conductive fine particle coating film. A multi-junction thin film silicon solar cell was produced in the same manner as in Example 1 except that the film was impregnated so as to have a film thickness of 70 nm, and evaluated in the same manner as in Example 1. The ratio of fine particles to binder in the transparent conductive film at this time was 1/1 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 4>
As shown in Table 1, 1.5 parts by mass of ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.1 and a particle diameter of 0.03 μm as the conductive fine particles, and the coupling agent is shown in the above formula (1). 0.02 parts by mass of an aluminum coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 1.2 parts by mass of a siloxane polymer as a binder Furthermore, using a binder dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer becomes 120 nm. A coating film of conductive fine particles is formed, and a binder dispersion is impregnated on the coating film of conductive fine particles by spin coating so that the film thickness after baking becomes 120 nm. Except to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, it was evaluated in the same manner as in Example 1. At this time, the fine particle / binder ratio in the transparent conductive film was 15/12. The results are shown in Table 4 below.

<Example 5>
As shown in Table 1, 1.2 parts by mass of ZnO powder having a particle size of 0.03 μm as conductive fine particles, 0.03 parts by mass of vinyltriethoxysilane as a coupling agent, and ethanol as a dispersion medium are added. Then, using the conductive fine particle dispersion having 100 parts by mass as a whole, preparing 0.5 parts by mass of acrylic resin as a binder, and further adding ethanol as a dispersion medium, a binder dispersion having 100 parts by mass as a whole is prepared. The conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer becomes 80 nm to form a conductive fine particle coating, and the binder dispersion is applied on the conductive fine particle coating. A multi-junction thin-film silicon solar cell was fabricated in the same manner as in Example 1 except that the film thickness after firing was impregnated to be 80 nm by spin coating. It was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was such that the fine particle / binder ratio was 3/5. The results are shown in Table 4 below.

<Example 6>
As shown in Table 1, 0.8 parts by mass of AZO powder having an atomic ratio of Al / (Al + Zn) = 0.1 and a particle diameter of 0.03 μm as conductive fine particles is shown in the above formula (4) as a coupling agent. 0.01 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, 0.8 parts by mass of a cellulose resin as a binder are prepared. Furthermore, using a binder dispersion with 100 parts by mass as a whole by adding butyl carbitol acetate as a dispersion medium, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 60 nm. Then, a coating film of conductive fine particles is formed, and a binder dispersion is contained on the conductive fine particle coating film by spin coating so that the film thickness after firing is 80 nm. Except that is, to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 12/3 as a fine particle / binder ratio. The results are shown in Table 4 below.

<Example 7>
As shown in Table 1, 1.5 parts by mass of ITO powder with Sn / (Sn + In) = 0.05 and particle size of 0.02 μm as the conductive fine particles and γ-methacryloxypropyltrimethoxy as the coupling agent Add 0.01 parts by mass of silane, and further add ethanol as a dispersion medium to prepare a conductive fine particle dispersion with a total of 100 parts by mass, and prepare 0.9 parts by mass of an epoxy resin as a binder. As a coating film of conductive fine particles, a conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer becomes 100 nm using a binder dispersion with 100 parts by mass of toluene as a whole. Except that the binder dispersion is impregnated on the coating film of the conductive fine particles by spin coating so that the film thickness after baking becomes 100 nm. Produced a multi-junction thin film silicon solar cell in the same manner as in Example 1 and evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 15/9 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 8>
As shown in Table 1, 1.2 parts by mass of ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.05 and a particle diameter of 0.02 μm as the conductive fine particles is shown in the above formula (5) as a coupling agent. 0.02 parts by mass of a titanium-based coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion and 1.0 part by mass of a polyester resin as a binder Furthermore, using a binder dispersion liquid in which xylene is added as a dispersion medium to make the whole 100 parts by mass, the conductive fine particle dispersion liquid is applied by spin coating so that the film thickness of the fine particle layer becomes 80 nm. After forming a coating film of conductive fine particles and impregnating the coating film of conductive fine particles with a binder dispersion liquid by a spin coating method so that the film thickness after firing becomes 80 nm. It is to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of fine particles to binder in the transparent conductive film was 12/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 9>
As shown in Table 1, 2.0 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.05 and a particle size of 0.03 μm as conductive fine particles, and γ as a coupling agent -Addition of 0.05 parts by mass of glycidoxypropyltrimethoxysilane, and addition of ethanol as a dispersion medium to make a total of 100 parts by mass of conductive fine particle dispersion, and 1.1% of acrylic urethane resin as binder. Prepare a part by mass and use a binder dispersion with 100 parts by mass as a whole by adding isophorone as a dispersion medium, and apply the conductive fine particle dispersion to a film thickness of 140 nm by spin coating. Then, a coating film of conductive fine particles is formed, and the film thickness after baking the binder dispersion on the conductive fine particle coating film by spin coating method is 140 nm. A multi-junction thin-film silicon solar cell was produced in the same manner as in Example 1 except that it was impregnated, and evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was such that the fine particle / binder ratio was 20/11. The results are shown in Table 4 below.

<Example 10>
As shown in Table 1, 0.8 parts by mass of MgO powder having a particle size of 0.03 μm as conductive fine particles and 0.02 parts by mass of titanium-based coupling agent represented by the above formula (4) as a coupling agent are added. Then, using a composition for transparent conductive film with 100 parts by mass as a whole by adding ethanol as a dispersion medium, 1.0 part by mass of polystyrene resin as a binder is prepared, and cyclohexanone is further added as a dispersion medium. The conductive fine particle dispersion is coated by spin coating to form a coating film of conductive fine particles using a binder dispersion liquid containing 100 parts by mass of the conductive fine particle dispersion. In the same manner as in Example 1, except that the binder dispersion was impregnated with a spin coating method so that the film thickness after firing was 100 nm. To prepare a mold thin-film silicon solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 8/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 11>
As shown in Table 1, 2.0 parts by mass of TiO ₂ powder having a particle size of 0.02 μm as conductive fine particles, and 0.02 parts by mass of titanium-based coupling agent represented by the above formula (6) as a coupling agent. Add a conductive fine particle dispersion with 100 parts by weight as a whole by adding ethanol as a dispersion medium, prepare 1.5 parts by weight of a polyvinyl acetate resin as a binder, and add toluene as a dispersion medium. Then, using a binder dispersion with 100 parts by mass as a whole, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 120 nm to form a coating film of conductive fine particles. Multi-joint type in the same manner as in Example 1 except that a binder dispersion was impregnated onto the coating film of the conductive fine particles by spin coating so that the film thickness after firing was 120 nm. Thin film silicon solar cells were prepared and evaluated in the same manner as in Example 1. The ratio of fine particles to binder in the transparent conductive film at this time was 20/15 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 12>
As shown in Table 1, 1.0 part by mass of Ag powder having a particle size of 0.03 μm as conductive fine particles and 0.01 part by mass of a titanium coupling agent represented by the above formula (7) as a coupling agent are added. Furthermore, using conductive fine particle dispersion liquid with 100 parts by mass as a whole by adding ethanol as a dispersion medium, 1.0 part by mass of polyvinyl alcohol resin as a binder is prepared, and ethanol is further added as a dispersion medium. The conductive fine particle dispersion is coated by spin coating to form a coating film of conductive fine particles using a binder dispersion liquid containing 100 parts by mass of the conductive fine particle dispersion. In the same manner as in Example 1, except that a binder dispersion was impregnated on the coating film by spin coating so that the film thickness after firing was 80 nm. To produce a thin-film silicon solar cell was evaluated in the same manner as in Example 1. The ratio of fine particles to binder in the transparent conductive film at this time was 1/1 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 13>
As shown in Table 1, 0.8 parts by mass of Ag / Pd = 9/1, Ag—Pd alloy powder having a particle diameter of 0.02 μm as conductive fine particles, and titanium represented by the above formula (7) as a coupling agent 0.01 part by mass of a system coupling agent, and further using conductive fine particle dispersion liquid with 100 parts by mass as a whole by adding ethanol as a dispersion medium, preparing 0.8 part by mass of a siloxane polymer as a binder, Further, a conductive fine particle was prepared by applying a conductive fine particle dispersion to a film thickness of 50 nm by a spin coating method using a binder dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium. Except that the coating film of conductive fine particles was impregnated with the binder dispersion liquid by spin coating so that the film thickness after firing was 50 nm. 1 to produce a multi-junction thin-film silicon solar cell in the same manner, it was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 8/8 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 14>
As shown in Table 1, 1.0 part by mass of Au powder having a particle size of 0.02 μm as conductive fine particles and 0.01 part by mass of a titanium-based coupling agent represented by the above formula (8) as a coupling agent are added. Furthermore, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, preparing 1.2 parts by mass of polyamide resin as a binder, and further adding xylene as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. The multi-junction type thin film silicon was coated in the same manner as in Example 1 except that the coating film was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 110 nm. To produce a down solar cell was evaluated in the same manner as in Example 1. In addition, the ratio of the fine particles to the binder in the transparent conductive film at this time was 10/12. The results are shown in Table 4 below.

<Example 15>
As shown in Table 1, 1.2 parts by mass of Ru powder having a particle diameter of 0.03 μm as conductive fine particles and 0.03 parts by mass of titanium-based coupling agent represented by the above formula (8) as a coupling agent are added. Furthermore, using conductive fine particle dispersion liquid with 100 parts by mass as a whole by adding ethanol as a dispersion medium, 1.2 parts by mass of vinyl chloride resin is prepared as a binder, and xylene is further added as a dispersion medium. Using a binder dispersion with 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 90 nm to form a conductive fine particle coating film. In the same manner as in Example 1, except that a binder dispersion was impregnated on the coating film by spin coating so that the film thickness after firing was 100 nm. To produce a down solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was such that the fine particle / binder ratio was 12/12. The results are shown in Table 4 below.

<Example 16>
As shown in Table 1, 1.0 part by mass of Rh powder having a particle size of 0.03 μm as conductive fine particles, and 0.02 part by mass of titanium-based coupling agent represented by the above formula (8) as a coupling agent are added. Furthermore, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, preparing 0.8 parts by mass of acrylate resin as a binder, and further adding ethanol as a dispersion medium Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction thin film was prepared in the same manner as in Example 1 except that the coating film was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 80 nm. To prepare a con solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/8 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 17>
As shown in Table 1, 1.0 parts by mass of ITO powder having an atomic ratio of Sb / (Sb + In) = 0.1 and a particle diameter of 0.03 μm as conductive fine particles is shown in the above formula (3) as a coupling agent. 0.02 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion and 1.0 part by mass of a polycarbonate resin as a binder Furthermore, using a binder dispersion with 100 parts by weight as a whole by adding toluene as a dispersion medium, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer becomes 80 nm. A coating film of conductive fine particles was formed, and a binder dispersion was impregnated on the coating film of conductive fine particles by spin coating so that the film thickness after firing was 80 nm. Outside to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 18>
As shown in Table 2, 1.0 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.1 and a particle diameter of 0.02 μm as conductive fine particles, and the above as a coupling agent Add 0.01 parts by weight of the titanium coupling agent represented by formula (3), and further add conductive fine particle dispersion with 100 parts by weight as a whole by adding ethanol as a dispersion medium, and use an alkyd resin as a binder. Prepare 0.8 parts by mass and use a binder dispersion with 100 parts by mass as a whole by adding cyclohexanone as a dispersion medium, so that the conductive fine particle dispersion has a fine particle layer thickness of 80 nm by spin coating. To form a coating film of conductive fine particles, and the film thickness after baking the binder dispersion liquid by spin coating method on the coating film of conductive fine particles is 100 nm. Except impregnated on so that is fabricated multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/8 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 19>
As shown in Table 2, 1.0 parts by mass of ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.1 and a particle size of 0.03 μm as conductive fine particles is shown in the above formula (3) as a coupling agent. 0.02 parts by mass of a titanium-based coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 1.2 parts by mass of polyurethane fiber as a binder are prepared. Furthermore, using a binder dispersion liquid in which xylene is added as a dispersion medium to make the whole 100 parts by mass, the conductive fine particle dispersion liquid is applied by spin coating so that the film thickness of the fine particle layer becomes 80 nm. Except for forming a coating film of conductive fine particles and impregnating the conductive fine particle coating film with a binder dispersion by spin coating so that the film thickness after firing is 80 nm. To prepare a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. In addition, the ratio of the fine particles to the binder in the transparent conductive film at this time was 10/12. The results are shown in Table 4 below.

<Example 20>
As shown in Table 2, as the conductive fine particles, ITO powder having an atomic ratio of Sb / (Sb + In) = 0.05 and a particle diameter of 0.02 μm is 1.0 part by mass, and the coupling agent is shown in the above formula (2). 0.01 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 0.8 parts by mass of polyacetal resin as a binder are prepared. Further, a multi-junction thin-film silicon solar cell was produced in the same manner as in Example 1 except that a binder dispersion liquid with 100 parts by mass as a whole was added by adding hexane as a dispersion medium. evaluated. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/8 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 21>
As shown in Table 2, ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.05 and an ATO powder of 0.03 μm in terms of atomic ratio as conductive fine particles is shown in the above formula (2) as a coupling agent. 0.02 parts by mass of a titanium-based coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 1.0 part by mass of ethyl cellulose resin as a binder are prepared. Furthermore, using a binder dispersion liquid in which hexane is added as a dispersion medium to make the whole 100 parts by mass, the conductive fine particle dispersion liquid is applied by spin coating so that the film thickness of the fine particle layer becomes 80 nm. A coating film of conductive fine particles is formed, and a binder dispersion is impregnated on the conductive fine particle coating film by spin coating so that the film thickness after baking becomes 100 nm. Other than the can to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 22>
As shown in Table 2, 1.0 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.05 and a particle diameter of 0.02 μm as the conductive fine particles, the above as a coupling agent A conductive fine particle dispersion in which 0.01 parts by mass of the titanium coupling agent represented by the formula (2) is added and ethanol is added as a dispersion medium to make the whole 100 parts by mass is used, and Al methoxy is used as a binder. Prepare 1.0 parts by mass of the hydrolyzate, and further add methanol as a dispersion medium, and use a binder dispersion with 100 parts by mass as a whole. A film of conductive fine particles is formed by coating to a thickness of 70 nm, and the film thickness after baking the binder dispersion on the conductive fine particle coating film by spin coating is 70 n. Except that impregnated so that to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 23>
As shown in Table 2, 1.0 parts by mass of ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.1 and a particle diameter of 0.02 μm as the conductive fine particles is shown in the above formula (4) as a coupling agent. 0.02 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 7: 3 alkyd resin and polyamide resin as a binder. 1.0 parts by mass of the mixture prepared at the above ratio was prepared, and a binder dispersion liquid was added to which the total amount was 100 parts by mass by adding isophorone as a dispersion medium. Coating is carried out to a film thickness of 70 nm to form a coating film of conductive fine particles, and the binder dispersion liquid is baked on the coating film of conductive fine particles by a spin coating method. Thickness of non-impregnated so as to 90nm was produced a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 24>
As shown in Table 2, 1.0 part by mass of Si powder having a particle diameter of 0.02 μm as conductive fine particles, 0.01 part by mass of γ-methacryloxypropyltrimethoxysilane as a coupling agent were added, and a dispersion medium was further added. As a binder, 1.0 part by mass of siloxane polymer is prepared as a binder, and 100 parts by mass is added by adding ethanol as a dispersion medium. Using a binder dispersion, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film, on the conductive fine particle coating film, The multi-junction thin film silicon is the same as in Example 1 except that the binder dispersion is impregnated by spin coating so that the film thickness after firing is 80 nm. A solar cell was fabricated and evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 25>
As shown in Table 2, 1.0 parts by mass of Ga powder having a particle size of 0.03 μm as conductive fine particles and 0.01 parts by mass of titanium-based coupling agent represented by the above formula (2) as a coupling agent are added. Furthermore, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, preparing 1.0 part by mass of alkyd resin as a binder, and further adding cyclohexanone as a dispersion medium Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction thin film was formed on the coating film in the same manner as in Example 1 except that the binder dispersion was impregnated by spin coating so that the film thickness after firing was 100 nm. To prepare a silicon solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 26>
As shown in Table 2, 1.0 part by mass of Co powder having a particle size of 0.02 μm as conductive fine particles and 0.01 part by mass of a titanium coupling agent represented by the above formula (2) as a coupling agent are added. In addition, using conductive fine particle dispersion with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, 1.0 part by mass of ethyl cellulose resin as a binder is prepared, and hexane is further added as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction thin film was prepared in the same manner as in Example 1 except that the coating was impregnated with a binder dispersion so that the film thickness after firing was 80 nm by spin coating. To prepare a con solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 27>
As shown in Table 2, 1.0 part by mass of Ca powder having a particle diameter of 0.02 μm as conductive fine particles and 0.01 part by mass of a titanium coupling agent represented by the above formula (3) as a coupling agent are added. Further, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, 1.0 part by mass of polycarbonate resin as a binder is prepared, and toluene is further added as a dispersion medium. A multi-junction thin-film silicon solar cell was produced in the same manner as in Example 1 except that the binder dispersion liquid having 100 parts by mass was used, and evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 28>
As shown in Table 2, 1.0 part by mass of Sr powder having a particle size of 0.03 μm is added as conductive fine particles, and 0.01 part by mass of titanium-based coupling agent represented by the above formula (3) is added as a coupling agent. In addition, using conductive fine particle dispersion with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, 1.0 part by mass of polyacetal resin as a binder is prepared, and hexane is further added as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction type thin film was prepared in the same manner as in Example 1 except that the coating film was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 100 nm. To prepare a con solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 29>
As shown in Table 2, 1.0 part by mass of Ba (OH) ₂ powder having a particle diameter of 0.02 μm as the conductive fine particles, and a titanium coupling agent represented by the above formula (4) as the coupling agent was added in an amount of 0.0. Add 01 parts by mass, use conductive fine particle dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, prepare 1.0 part by mass of polyurethane resin as a binder, and add xylene as a dispersion medium By using a binder dispersion with 100 parts by mass as a whole, the conductive fine particle dispersion was applied by spin coating so that the film thickness of the fine particle layer was 80 nm to form a conductive fine particle coating film, A multi-junction thin film was formed in the same manner as in Example 1 except that the conductive fine particle coating was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 80 nm. To prepare a silicon solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 30>
As shown in Table 2, 1.0 part by mass of Ce powder having a particle size of 0.03 μm as conductive fine particles and 0.01 part by mass of titanium-based coupling agent represented by the above formula (4) as a coupling agent are added. In addition, using conductive fine particle dispersion with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, preparing 1.0 part by mass of polyamide resin as a binder and further adding xylene as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. The multi-junction thin film silicon is the same as in Example 1 except that the coating film is impregnated with a binder dispersion by spin coating so that the film thickness after firing becomes 100 nm. To prepare a solar cell were evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 31>
As shown in Table 2, 1.0 part by mass of Y powder having a particle size of 0.03 μm as conductive fine particles and 0.01 part by mass of titanium-based coupling agent represented by the above formula (5) as a coupling agent are added. Then, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, 1.0 part by mass of siloxane polymer as a binder is prepared, and ethanol is further added as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction type thin film silicon was applied in the same manner as in Example 1 except that the coating liquid was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 100 nm. To produce a down solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 32>
As shown in Table 2, 1.0 part by mass of Zr powder having a particle diameter of 0.02 μm as conductive fine particles and 0.01 part by mass of titanium-based coupling agent represented by the above formula (5) as a coupling agent are added. Furthermore, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, preparing 1.0 part by mass of alkyd resin as a binder, and further adding cyclohexanone as a dispersion medium Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction thin film was formed in the same manner as in Example 1 except that a binder dispersion was impregnated on the coating film by spin coating so that the film thickness after firing was 80 nm. To prepare a silicon solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 33>
As shown in Table 2, 1.0 part by mass of Sn (OH) ₂ powder having a particle diameter of 0.02 μm as conductive fine particles, and a titanium-based coupling agent represented by the above formula (6) as a coupling agent were added in an amount of 0.0. Add 01 parts by mass, use conductive fine particle dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, prepare 1.0 part by mass of ethyl cellulose resin as a binder, and add hexane as a dispersion medium Thus, a multi-junction thin film silicon solar cell was produced in the same manner as in Example 1 except that the binder dispersion liquid with 100 parts by mass as a whole was used, and evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 34>
As shown in Table 2, 1.0 parts by mass of a powder obtained by mixing MgO and ZnO ₂ having a particle diameter of 0.03 μm at a ratio of 5: 5 as the conductive fine particles is represented by the above formula (6) as a coupling agent. Add 0.01 parts by mass of a titanium coupling agent, and further add ethanol as a dispersion medium to prepare 100 parts by mass of a conductive fine particle dispersion, and prepare 1.0 part by mass of a polycarbonate resin as a binder. Furthermore, using a binder dispersion liquid in which 100 parts by mass as a whole is added by adding toluene as a dispersion medium, the conductive fine particle dispersion liquid is applied by spin coating so that the film thickness of the fine particle layer becomes 80 nm, Except for forming a coating film of fine particles and impregnating the conductive fine particle coating film with a binder dispersion by spin coating so that the film thickness after firing is 80 nm. A multi-junction thin film silicon solar cell was produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 35>
As shown in Table 3, 1.0 part by mass of C powder having a particle size of 0.03 μm as conductive fine particles and 0.01 part by mass of a titanium coupling agent represented by the above formula (7) as a coupling agent are added. In addition, using conductive fine particle dispersion with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, 1.0 part by mass of polyacetal resin as a binder is prepared, and hexane is further added as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction type thin film silicon was applied in the same manner as in Example 1 except that the coating liquid was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 100 nm. To produce a down solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 36>
As shown in Table 3, 1.0 part by mass of SiO ₂ powder having a particle size of 0.01 μm as the conductive fine particles, and 0.01 part by mass of the titanium-based coupling agent represented by the above formula (7) as the coupling agent. Then, using conductive fine particle dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, 1.0 part by mass of polyurethane resin as a binder is prepared, and xylene is further added as a dispersion medium. A multi-junction thin-film silicon solar cell was produced in the same manner as in Example 1 except that the binder dispersion liquid with 100 parts by mass was used and evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 37>
As shown in Table 3, 1.0 part by mass of Cu powder having a particle size of 0.03 μm as conductive fine particles and 0.01 part by mass of a titanium coupling agent represented by the above formula (8) as a coupling agent are added. In addition, using conductive fine particle dispersion with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, preparing 1.0 part by mass of polyamide resin as a binder and further adding xylene as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. The multi-junction type thin film silicon was applied in the same manner as in Example 1 except that the coating liquid was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 80 nm. To prepare a solar cell were evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 38>
As shown in Table 3, 1.0 part by mass of Ni powder having a particle size of 0.03 μm as conductive fine particles and 0.01 part by mass of titanium-based coupling agent represented by the above formula (8) as a coupling agent are added. Then, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, 1.0 part by mass of siloxane polymer as a binder is prepared, and ethanol is further added as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. The multi-junction type thin film silicon was coated in the same manner as in Example 1 except that the coating film was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 80 nm. To produce a down solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 39>
As shown in Table 3, 1.0 part by mass of Pt powder having a particle size of 0.02 μm as conductive fine particles and 0.01 part by mass of an aluminum coupling agent represented by the above formula (1) as a coupling agent are added. Furthermore, using conductive fine particle dispersion liquid with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, preparing 1.0 part by mass of alkyd resin as a binder, and further adding cyclohexanone as a dispersion medium Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction thin film was formed on the coating film in the same manner as in Example 1 except that the binder dispersion was impregnated by spin coating so that the film thickness after firing was 100 nm. To prepare a silicon solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 40>
As shown in Table 3, 1.0 part by mass of Ir powder having a particle size of 0.03 μm is added as conductive fine particles, and 0.01 part by mass of the aluminum coupling agent represented by the above formula (1) is added as a coupling agent. In addition, using conductive fine particle dispersion with 100 parts by mass as a dispersion medium by adding ethanol as a dispersion medium, 1.0 part by mass of ethyl cellulose resin as a binder is prepared, and hexane is further added as a dispersion medium. Using a binder dispersion liquid of 100 parts by mass, the conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm to form a conductive fine particle coating film. A multi-junction thin film was formed in the same manner as in Example 1 except that the coating liquid was impregnated with a binder dispersion by spin coating so that the film thickness after firing was 100 nm. To prepare a silicon solar cell was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 41>
As shown in Table 3, 0.8 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.1 and a particle diameter of 0.02 μm as a conductive fine particle, and the above as a coupling agent 0.01 parts by mass of a mixture of an aluminum coupling agent represented by the formula (1) and a titanium coupling agent represented by the above formula (3) in a ratio of 5: 5 was added, and ethanol was further used as a dispersion medium. The conductive fine particle dispersion with 100 parts by mass as a whole is added, 1.0 part by mass of polycarbonate resin is prepared as a binder, and the binder is dispersed with 100 parts by mass as a dispersion medium. The conductive fine particle dispersion is applied by spin coating so that the film thickness of the fine particle layer is 80 nm, and a conductive fine particle coating film is formed on the conductive fine particle coating film. A multi-junction thin-film silicon solar cell was prepared in the same manner as in Example 1 except that the binder dispersion was impregnated by spin coating so that the film thickness after firing was 80 nm, and evaluated in the same manner as in Example 1. did. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 8/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 42>
As shown in Table 3, 1.2 parts by mass of ITO powder having an atomic ratio of Sb / (Sb + In) = 0.1 and a particle diameter of 0.02 μm as the conductive fine particles is shown in the above formula (3) as a coupling agent. 0.02 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion and 1.0 part by mass of a siloxane polymer as a binder Furthermore, using a binder dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, the conductive fine particle dispersion is applied by spray coating so that the film thickness of the fine particle layer becomes 100 nm. A coating film of conductive fine particles is formed, and a binder dispersion is impregnated on the conductive fine particle coating film by a spray coating method so that the film thickness after baking is 120 nm. Except that was was produced a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of fine particles to binder in the transparent conductive film was 12/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 43>
As shown in Table 3, 1.2 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.1 and a particle size of 0.03 μm as the conductive fine particles, and the above as a coupling agent 0.02 parts by mass of a titanium coupling agent represented by the formula (3) is added, and further, a conductive fine particle dispersion having 100 parts by mass as a whole by adding ethanol as a dispersion medium is used, and a siloxane polymer is used as a binder. Prepare 1.2 parts by mass and use a binder dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, so that the film thickness of the fine particle layer becomes 100 nm by the dispenser coating method of the conductive fine particle dispersion. To form a coating film of conductive fine particles, and the film thickness after baking the binder dispersion on the coating film of conductive fine particles by the dispenser coating method is 1 Except that impregnated so that 0nm was produced a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was such that the fine particle / binder ratio was 12/12. The results are shown in Table 4 below.

<Example 44>
As shown in Table 3, 1.2 parts by mass of ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.1 and a particle diameter of 0.02 μm as the conductive fine particles, and the coupling agent shown in the above formula (3) 0.02 part by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 0.8 parts by mass of a siloxane polymer as a binder Furthermore, using a binder dispersion liquid with 100 parts by mass as a whole by adding ethanol as a dispersion medium, the conductive fine particle dispersion liquid is applied by a knife coating method so that the film thickness of the fine particle layer is 100 nm. A coating film of conductive fine particles is formed, and a binder dispersion is impregnated on the coating film of conductive fine particles by a knife coating method so that the film thickness after baking becomes 100 nm. Except to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, it was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 12/8. The results are shown in Table 4 below.

<Example 45>
As shown in Table 3, 1.2 parts by mass of ITO powder having an atomic ratio of Sb / (Sb + In) = 0.05 and a particle diameter of 0.02 μm as conductive fine particles is shown in the above formula (2) as a coupling agent. 0.02 parts by mass of a titanium-based coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 1.2 parts by mass of a siloxane polymer as a binder Furthermore, using a binder dispersion liquid with 100 parts by mass as a whole by adding ethanol as a dispersion medium, the conductive fine particle dispersion liquid is applied by a slit coating method so that the film thickness of the fine particle layer is 100 nm. A coating film of conductive fine particles is formed, and a binder dispersion liquid is contained on the conductive fine particle coating film by a slit coating method so that the film thickness after baking becomes 100 nm. Except that was to prepare a multi-junction thin-film silicon solar cell in the same manner as in Example 1, it was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was such that the fine particle / binder ratio was 12/12. The results are shown in Table 4 below.

<Example 46>
As shown in Table 3, 1.0 parts by mass of ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.05 and a particle diameter of 0.03 μm as conductive fine particles is shown in the above formula (2) as a coupling agent. 0.01 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion and 1.0 part by mass of a siloxane polymer as a binder Furthermore, using a binder dispersion liquid in which 100 parts by mass as a whole is added by adding ethanol as a dispersion medium, the conductive fine particle dispersion liquid is applied by an inkjet coating method so that the film thickness of the fine particle layer becomes 90 nm. A film of conductive fine particles is formed, and the film thickness after baking the binder dispersion on the conductive fine particle coating film by the inkjet coating method is 90 nm. Except that by Uni impregnated to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, it was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/10 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 47>
As shown in Table 3, 5.0 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.05 and a particle diameter of 0.02 μm as a conductive fine particle, and the above as a coupling agent 0.05 parts by mass of a titanium coupling agent represented by the formula (2) is added, and a conductive fine particle dispersion whose total is 100 parts by mass by adding ethylene glycol as a dispersion medium, and an acrylic resin as a binder. 5.0 parts by mass, and further using ethylene binder as a dispersion medium to form a binder dispersion liquid with a total mass of 100 parts by mass, the conductive fine particle dispersion has a fine particle layer thickness of 120 nm by gravure printing. The conductive fine particles are coated to form a coating film of conductive fine particles, and the film thickness after baking the binder dispersion on the conductive fine particle coating film by gravure printing method is 120 nm. Except impregnated on so that is fabricated multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 50/50 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 48>
As shown in Table 3, 5.0 parts by mass of an ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.1 and a particle diameter of 0.02 μm as conductive fine particles, and a coupling agent are shown in the above formula (4). 0.05 parts by mass of a titanium coupling agent to be added, and further using ethylene fine particle as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, and 5.0 parts by mass of ethyl cellulose resin as a binder Prepare a binder dispersion with 100 parts by mass as a whole by adding butyl carbitol acetate as a dispersion medium, and apply the conductive fine particle dispersion to a film thickness of 160 nm by screen printing. To form a coating film of conductive fine particles, and the film thickness after baking the binder dispersion on the conductive fine particle coating film by a screen printing method is 170 nm. Except impregnated in this way to produce a multi-junction thin-film silicon solar cell in the same manner as in Example 1, it was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 50/50 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 49>
As shown in Table 3, 5.0 parts by mass of PTO (P-doped SnO ₂ ) powder having an atomic ratio of P / (P + Sn) = 0.1 and a particle diameter of 0.02 μm was added as conductive fine particles, and a dispersion medium was further added. As a binder, 5.0 parts by mass of an alkyd resin is prepared as a binder, and 100 parts by mass of ethylene glycol is added as a dispersion medium. The conductive fine particle dispersion was coated by the offset printing method so that the film thickness of the fine particle layer was 140 nm to form a conductive fine particle coating film. In addition, a multi-junction thin film silicon solar cell was fabricated in the same manner as in Example 1 except that the binder dispersion was impregnated by an offset printing method so that the film thickness after firing was 150 nm. And it was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 50/50 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Example 50>
As shown in Table 3, 1.0 parts by mass of ATO powder having an atomic ratio of Sb / (Sb + Sn) = 0.1 and a particle diameter of 0.02 μm as conductive fine particles is shown in the above formula (3) as a coupling agent. 0.01 parts by mass of a titanium coupling agent to be added, and further using ethanol as a dispersion medium to add 100 parts by mass of a conductive fine particle dispersion, 0.8 parts by mass of a siloxane polymer as a binder are prepared. Furthermore, using a binder dispersion with 100 parts by mass as a whole by adding ethanol as a dispersion medium, the conductive fine particle dispersion is applied by a die coating method so that the film thickness of the fine particle layer becomes 70 nm. Except for forming a coating film of conductive fine particles and impregnating the conductive fine particle coating film with a binder dispersion by a die coating method so that the film thickness after firing is 70 nm. To prepare a multi-junction thin-film silicon solar cell in the same manner as in Example 1, was evaluated in the same manner as in Example 1. At this time, the ratio of the fine particles to the binder in the transparent conductive film was 10/8 in the fine particle / binder ratio. The results are shown in Table 4 below.

<Comparative Example 1>
Instead of applying the composition for transparent conductive film of Example 1 on the amorphous silicon layer 13, a gallium of about 1 × 10 ²¹ cm ^{−3 is formed under} the condition of a substrate temperature of 150 ° C. using a magnetron sputtering method. A multi-junction thin-film silicon solar cell was prepared in the same manner as in Example 1 except that the added ZnO was formed to have a thickness of 80 nm, and evaluated in the same manner as in Example 1. The results are shown in Table 5 below.

<Comparative example 2>
Instead of coating the composition for transparent conductive film of Example 1 on the amorphous silicon layer 13, the magnetron sputtering method is used in the same manner as in Comparative Example 1, and the substrate temperature is 150 ° C. and 1 × 10 ^21. After depositing ZnO to which gallium of about cm ⁻³ was added to a thickness of 250 nm, the substrate after the deposition was placed in a 0.5 mass% HCl aqueous solution maintained at a liquid temperature of 15 ° C. for 15 seconds. A multi-junction thin film silicon solar cell was produced in the same manner as in Example 1 except that it was immersed and etched, and was evaluated in the same manner as in Example 1. The results are shown in Table 5 below.

<Comparative Example 3>
Instead of ZnO to which gallium is added in Comparative Example 1, a magnetron sputtering method is used so that ZnO to which aluminum of about 1 × 10 ²¹ cm ⁻³ is added has a thickness of 50 nm under a substrate temperature of 150 ° C. A multi-junction thin film silicon solar cell was produced in the same manner as in Comparative Example 1 except that the film was formed in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 5 below.

<Comparative example 4>
In place of ZnO to which gallium is added in Comparative Example 2, magnetron sputtering is used, and ZnO to which aluminum of about 1 × 10 ²¹ cm ⁻³ is added has a thickness of 250 nm under a substrate temperature of 150 ° C. A multi-junction thin-film silicon solar cell was produced in the same manner as in Comparative Example 2 except that the film was formed in the same manner as in Example 1. The results are shown in Table 5 below.

<Comparative Example 5>
A multi-junction thin film silicon solar cell was fabricated in the same manner as in Comparative Example 3 except that ZnO to which aluminum of about 1 × 10 ²¹ cm ⁻³ was added was formed to a thickness of 30 nm. And evaluated in the same manner. The results are shown in Table 5 below.

  In the above embodiment, a silicon solar cell using silicon as a power generation layer was used. However, the present invention is not limited to a silicon solar cell if it is a multi-junction solar cell, and CIGS / CIGSS / CIS solar The present invention can also be applied to types such as batteries, CdTe, Cd solar cells, and organic thin film solar cells.

表４及び表５から明らかなように、実施例１〜５０では、屈折率が低く、また、短絡電流密度及び変換効率の結果が高く、スパッタ成膜によってＺｎＯ膜を形成した比較例１〜５の透明導電膜と比べて、優れたセル性能が得られていることが確認された。

As is clear from Tables 4 and 5, in Examples 1 to 50, the refractive index is low, the short circuit current density and the conversion efficiency are high, and Comparative Examples 1 to 5 in which a ZnO film is formed by sputtering film formation. It was confirmed that superior cell performance was obtained as compared with the transparent conductive film.

DESCRIPTION OF SYMBOLS 10 Multijunction type solar cell 11 Transparent substrate 12 Front surface side electrode layer 13 Amorphous silicon layer 14 Transparent conductive film 15 Microcrystalline silicon layer 16 Back surface side electrode layer

Claims (11)

In the transparent conductive film for solar cell provided between the photoelectric conversion layers of the multi-junction solar cell,
The conductive film is impregnated with a dispersion containing a binder using a wet coating method and baked on a coating of fine particles formed by applying a dispersion containing conductive fine particles using a wet coating method. Formed in a state where the fine particle layer is impregnated with the binder layer,
In the base material constituting the conductive film, a conductive component is present in the range of 5 to 95% by mass, and the thickness of the conductive film is in the range of 5 to 200 nm. Transparent conductive film.   The transparent conductive film for solar cells of Claim 1 in which the composition for transparent conductive films contains the binder hardened | cured by the heating in the range of 100-400 degreeC, or ultraviolet irradiation.   Binder is acrylic resin, acrylate resin, polycarbonate resin, polyester resin, alkyd resin, polyurethane resin, acrylic urethane resin, polystyrene resin, polyacetal resin, polyamide resin, polyvinyl alcohol resin, polyvinyl acetate resin, cellulose resin, ethyl cellulose resin, epoxy The transparent conductive film for solar cells according to claim 2, comprising at least one of a resin, a vinyl chloride resin, a siloxane polymer, or a hydrolyzate of metal alkoxide (including sol-gel).   The transparent conductive film for solar cells of Claim 1 in which the composition for transparent conductive films contains the 1 type (s) or 2 or more types chosen from the group which consists of a silane coupling agent, an aluminum coupling agent, and a titanium coupling agent.   The conductive fine particles are one or more selected from the group consisting of Zn, In, Sn, Sb, Si, Al, Ga, Co, Mg, Ca, Sr, Ba, Ce, Ti, Y and Zr. The transparent conductive film for a solar cell according to claim 1, wherein the transparent conductive film is a first fine particle composed of an oxide, a hydroxide, a composite compound, or a mixture of two or more thereof.   The conductive fine particles are composed of nanoparticles made of a mixed alloy containing one or more selected from the group consisting of C, Si, Cu, Ni, Ag, Pd, Pt, Au, Ru, Rh and Ir. The transparent conductive film for solar cells according to claim 1, wherein the second conductive particles are formed.   The transparent conductive film for solar cells according to claim 1, wherein the conductive fine particles are a mixture of both the first fine particles and the second fine particles.   The wet coating method is any of spray coating method, dispenser coating method, spin coating method, knife coating method, slit coating method, inkjet coating method, gravure printing method, screen printing method, offset printing method or die coating method. The transparent conductive film for solar cells according to claim 1.   The transparent conductive film for solar cells according to any one of claims 1 to 8, which has a refractive index of 1.1 to 2.0.   A multi-junction solar cell, wherein the transparent conductive film for solar cell according to claim 1 is provided between photoelectric conversion layers.   The composition for transparent conductive films for forming the transparent conductive film for solar cells of any one of Claims 1 thru | or 9.

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