JP2011204972A - Method of manufacturing solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a solar cell that improves conversion efficiency of the solar cell, by decreasing the contact resistance between a power generation layer and a back-side transparent electrode layer and decreasing the series resistance of the solar cell at power generation.SOLUTION: The present invention relates to the improvement in the method of manufacturing the solar cell in which the silicon-based power generation layer is formed on a top-side electrode layer of a transparent substrate having the top-side electrode layer formed on a surface and further the back-side transparent electrode layer is formed on the power generation layer, and the method of manufacturing the solar cell is such that processing liquid contacting processing wherein processing liquid is brought into contact with at least a surface of the power generation layer is carried out after the power generation layer is formed and before the back-side transparent electrode layer is formed.

Description

  The present invention relates to a method for manufacturing a thin-film silicon solar cell that can reduce contact resistance between a power generation layer and a back-side transparent electrode layer and improve conversion efficiency.

  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.

  For example, a thin film solar cell has been studied to increase power generation efficiency by adopting a structure in which a transparent electrode, amorphous silicon, polycrystalline silicon, and a back electrode are formed in this order (see, for example, Non-Patent Document 1). . In the structure shown in this non-patent document 1, amorphous silicon or polycrystalline silicon constitutes a power generation layer. In particular, when the solar cell is formed of a silicon-based material for the power generation layer, the absorption coefficient of the power generation layer by the above material is relatively small. The portion passes through the power generation layer, and the transmitted light does not contribute to power generation. Therefore, the power generation efficiency is improved by using the back electrode as a reflection film, or forming a reflection film on the back electrode, reflecting the light that has not been absorbed and transmitted through the power generation layer, and returning it to the power generation layer again. It is generally done.

  Conventionally, when such a thin film solar cell is manufactured, each layer is formed by a vacuum film forming method such as a sputtering method. However, in general, maintenance and operation of a large-scale vacuum film forming apparatus requires a great deal of cost, and therefore, development of a method for manufacturing at a lower cost is being promoted by replacing this with a wet film forming method as much as possible. (For example, refer to Patent Document 1). The method disclosed in Patent Document 1 discloses a method in which the transparent conductive film located on the substrate side, that is, the surface electrode 12 shown in FIG.

JP-A-10-12059 (paragraph [0028], paragraph [0029])

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)

  By the way, in the thin film solar cell, in order to improve the power generation efficiency, the electrical resistance of the layer constituting each electrode or the film itself is decreased, or the good contact property between the power generation layer and the electrodes or between the electrodes or Conductivity is required. The present inventors have studied a method of replacing the formation of the electrode located on the back side with a wet film forming method. Depending on the film forming conditions, the material used, and the like, the back side electrode layer 14 shown in FIG. It has been found that there is a large difference between the work function of the surface and the work function of the surface of the power generation layer 13 on which the back electrode layer 14 is formed, and this is an adverse effect of improving the conversion efficiency. For example, when the difference between the work function of the surface of the power generation layer 13 and the work function of the surface of the back side electrode layer 14 increases, the contact resistance between the power generation layer 13 and the back side electrode layer 14 during power generation increases. As a result, the series resistance of the solar cell was increased, and as a result, the conversion efficiency was hindered.

  An object of the present invention is to provide a solar cell manufacturing method capable of improving the conversion efficiency of a solar cell by reducing the contact resistance between the power generation layer and the transparent electrode layer on the back side and reducing the series resistance in the solar cell during power generation. Is to provide.

  As shown in FIG. 1, the first aspect of the present invention is to form a silicon-based power generation layer 13 on the surface-side electrode layer 12 of the transparent substrate 11 having the surface-side electrode layer 12 formed on the surface. In the method for manufacturing a solar cell in which the back surface side transparent electrode layer 14 is formed on the power generation layer 13 by a wet coating method, at least the power generation layer 13 after the power generation layer 13 and before the back surface side transparent electrode layer 14 is formed. A treatment liquid contact treatment for bringing the treatment liquid into contact with the surface is performed, and water, an aqueous solution, an organic solvent, or a mixed solvent of water and an organic solvent is used as the treatment liquid. When the above aqueous solution is used for 0.5 to 1440 minutes of contact treatment with water at ˜70 ° C., the contact treatment is carried out with an aqueous solution of 0 to 60 ° C. for 0.5 to 280 minutes and when the above organic solvent is used, 0.5 to 1440 minutes in organic solvent at 50 ° C Touch processing, when using the mixed solvent, characterized in that it is carried out by contact treatment 5-720 minutes with a mixed solvent of 25 to 50 ° C..

  The second aspect of the present invention is the invention based on the first aspect, wherein the aqueous solution is one kind compound selected from the group consisting of water, nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid, or two or more kinds. It is a combination with a mixture of compounds.

  The third aspect of the present invention is the invention based on the first aspect, wherein the organic solvent further comprises alcohols, ketones, hydrocarbons, carboxylic acid, sulfonic acid, glycols and glycol ethers. It is characterized by being a single solvent composed of one compound selected from the above or a mixed solvent composed of two or more compounds.

  A fourth aspect of the present invention is the invention based on the first aspect, further drying is performed after the treatment liquid contact treatment and before forming the back side transparent electrode layer, and drying is performed under reduced pressure, It is characterized by being carried out by natural drying, air drying or heat drying.

  A fifth aspect of the present invention is the invention based on the first aspect, and further, after forming the back side transparent electrode layer, either one of Ag or Al is formed as a reflective electrode layer on the back side transparent electrode layer. A metal film made of is formed.

  A sixth aspect of the present invention is the invention based on the first aspect, wherein the silicon-based power generation layer is a multi-junction type of two or more layers by a combination of amorphous silicon and microcrystalline silicon. To do.

  In the manufacturing method according to the first aspect of the present invention, a silicon-based power generation layer is formed on the surface-side electrode layer of the transparent substrate having the surface-side electrode layer formed on the surface, and a wet coating method is applied on the power generation layer. In the method of manufacturing a solar cell for forming a backside transparent electrode layer according to the above, after forming the power generation layer and before forming the backside transparent electrode layer, at least the surface of the power generation layer has water, an aqueous solution, an organic solvent, or water. A treatment liquid contact treatment is performed in which a treatment liquid composed of a mixed solvent with an organic solvent is brought into contact under specific conditions. In order to improve the work function of the surface of the power generation layer by adsorbing solvent molecules or solute molecules on the surface of the power generation layer 13 by this treatment liquid contact treatment, the work function of the surface of the power generation layer and the work function of the back side transparent electrode layer Can be reduced. Thereby, the conversion efficiency of a solar cell can be improved by reducing the contact resistance between the electric power generation layer in the case of electric power generation, and a back surface side transparent electrode layer, and reducing the series resistance in the solar cell in the case of an electric power generation. Moreover, since it forms by the wet coating method, it does not require vacuum processes, such as a vacuum evaporation method and a sputtering method, and it can manufacture more cheaply.

It is a figure showing process drawing of the manufacturing method of the solar cell of this invention.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the solar cell manufacturing method of the present invention forms a silicon-based power generation layer 13 on the surface-side electrode layer 12 of the transparent substrate 11 having the surface-side electrode layer 12 formed on the surface. The back side transparent electrode layer 14 is formed on the power generation layer 13. And it has the structure which provided the back surface side reflective electrode layer 16 on this back surface side transparent electrode layer 14. FIG.

  The transparent substrate 11 is made of a light transmissive substrate made of glass, ceramics or a polymer material, or two or more types of light transmissive laminates selected from the group consisting of glass, ceramics, a polymer material and silicon. Can be used. Examples of the polymer substrate include a substrate formed of an organic polymer such as polyimide or PET (polyethylene terephthalate).

The front-side electrode layer 12 is a transparent and conductive film that transmits light incident from the substrate 11 side to the silicon-based power generation layer 13 and functions as an electrode. As this surface side electrode layer 12, for example, ITO (indium oxide-tin oxide composite oxide), ATO (antimony oxide-tin oxide composite oxide), SnO ₂ (tin oxide), ZnO (zinc oxide), Examples of the film include IZO (indium oxide-zinc oxide composite oxide) and AZO (aluminum oxide-zinc oxide composite oxide). The surface-side electrode layer 12 is made of ZnO, In ₂ O ₃ , SnO ₂ , CdO, TiO ₂ , CdIn ₂ O ₄ , Cd ₂ SnO ₄ or Zn ₂ SnO ₄ , and Sn, Sb, F or Al. You may comprise by the 1 type (s) or 2 or more types of metal oxide chosen from the group of the metal oxide which doped any. The surface side electrode layer 12 may be formed by a conventionally known method such as a thermal CVD method, a sputtering method, a vacuum deposition method, or a wet coating method, and is not particularly limited. When forming the surface side electrode layer 12 by the wet coating method, it is performed similarly to the case where the below-mentioned back side transparent electrode layer 14 is formed by the wet coating method. The ZnO is suitable as a material for the surface-side electrode layer 12 because it has high light transmittance, low resistance, and plasticity and is inexpensive.

  On the surface-side electrode layer 12, a silicon-based power generation layer 13 that generates power by light is formed. The power generation layer 13 is composed of one or both of amorphous silicon and microcrystalline silicon. In this embodiment, the power generation layer 13 has a first power generation layer formed of an amorphous silicon semiconductor and a second power generation layer formed of a microcrystalline silicon semiconductor. Specifically, the first power generation layer is p in which p-type a-Si (amorphous silicon), i-type a-Si (amorphous silicon) and n-type a-Si (amorphous silicon) are stacked in order from the substrate 11 side. -I-n type amorphous silicon layer. The second power generation layer is formed by sequentially stacking p-type μc-Si (microcrystalline silicon), i-type μc-Si (microcrystalline silicon), and n-type μc-Si (microcrystalline silicon) from the first power generation layer side. It is a pin type microcrystalline silicon layer.

  As described above, the tandem solar cell using i-type a-Si (first power generation layer) and i-type μc-Si (second power generation layer) for the power generation layer 13 includes two types of semiconductors having different light absorption wavelengths. It is a laminated structure and can effectively use the sunlight spectrum. Here, in this specification, “microcrystal” means not only a complete crystal state but also a partially amorphous (amorphous) state.

  Note that the power generation layer may take either a single-junction type consisting of either an amorphous silicon layer or a microcrystalline silicon layer, or a multi-junction type including a plurality of either one or both of an amorphous silicon layer and a microcrystalline silicon layer. obtain. Also, a structure such as p-type a-SiC: H (amorphous silicon carbide) / i-type a-Si / n-type μc-Si can be used. Although they are not particularly limited, they can be formed by a conventionally known method such as a plasma CVD method. Further, for example, in the example of the tandem structure, an intermediate layer may be formed between the first power generation layer (amorphous silicon power generation unit) and the second power generation layer (microcrystalline silicon power generation unit). The intermediate layer is preferably made of a material used for the front-side electrode layer 12 and the back-side transparent electrode layer 14.

  On the power generation layer 13, a back surface side transparent electrode layer 14 is formed by a wet coating method. However, the work function of the back side transparent electrode layer 14 formed by the wet coating method tends to be higher than that of the surface of the power generation layer 13 due to the characteristics of the substance. For this reason, a difference arises between the work function of the surface of the back surface side transparent electrode layer 14 and the work function of the surface of the power generation layer 13, and when these differences increase, the contact between the power generation layer 13 and the back surface side transparent electrode layer 14 is increased. The resistance increases and the series resistance of the solar cell during power generation increases. As a result, improvement in the conversion efficiency of the solar cell is hindered.

  Therefore, in the manufacturing method of the present invention, after the formation of the silicon-based power generation layer 13 and before the formation of the back-side transparent electrode layer 14, a treatment liquid contact treatment in which a treatment liquid is brought into contact with at least the surface of the silicon-based power generation layer 13. It is set as a characteristic structure. As the treatment liquid, water, an aqueous solution, an organic solvent, or a mixed solvent of water and an organic solvent is used. And when using the above water, contact treatment with 10 to 70 ° C. water for 0.5 to 1440 minutes, and when using the above aqueous solution, contact treatment with 0 to 60 ° C. aqueous solution for 0.5 to 280 minutes, When using the above organic solvent, contact treatment with an organic solvent at 10 to 50 ° C. for 0.5 to 1440 minutes, and when using the above mixed solvent, contact treatment with a mixed solvent at 25 to 50 ° C. for 5 to 720 minutes. Is done.

  In order to improve the work function of the surface of the power generation layer 13 by adsorbing solvent molecules or solute molecules on the surface of the power generation layer 13 by the treatment liquid contact treatment under the above specific conditions, The difference from the work function of the back side transparent electrode layer can be reduced.

  The work function on the surface of the power generation layer 13 and the work function on the surface of the back electrode layer 14 can be measured by using a Kelvin probe or the like.

  If the temperature of each treatment liquid is less than the lower limit, the work function of the surface of the power generation layer 13 cannot be sufficiently increased, and if the upper limit is exceeded, the power generation layer is damaged, resulting in an increase in electrical resistance. Therefore, the improvement in power generation efficiency of solar cells cannot be expected. In addition, if the contact time of each treatment liquid is less than the lower limit value, the work function of the surface of the power generation layer 13 cannot be sufficiently increased, and if the upper limit value is exceeded, the power generation layer is damaged, resulting in electrical resistance. Therefore, the power generation efficiency of the solar cell cannot be improved.

  Among these, when the contact treatment is performed with water having a lower temperature of 10 to 25 ° C., the contact time is 1 to 1440 minutes, and when the contact treatment is performed with water having a higher temperature of 25 to 70 ° C., the contact time is 0. 5 to 120 minutes is preferable. When the contact treatment is performed with an aqueous solution having a lower temperature of 0 to 25 ° C., the contact time is 1 to 280 minutes, and when the contact treatment is performed with an aqueous solution having a higher temperature of 25 to 60 ° C., the contact time is set to 0. It is preferable to set it for 5 to 60 minutes. Further, when the contact treatment is performed with an organic solvent having a lower temperature of 10 to 25 ° C., the contact time is 0.5 to 1440 minutes, and when the contact treatment is performed with an organic solvent having a higher temperature of 25 to 50 ° C., the contact is performed. The time is preferably 0.5 to 720 minutes. Furthermore, when the contact treatment is performed with a mixed solvent having a lower temperature of 25 to 30 ° C., the contact time is 0.5 to 720 minutes, and when the contact treatment is performed with a mixed solvent having a higher temperature of 30 to 50 ° C., the contact is performed. The time is preferably 5 to 120 minutes.

Examples of the aqueous solution include a combination of water and one compound selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, and phosphoric acid, or a mixture composed of two or more compounds. A nitric acid aqueous solution has a concentration of 1.0 × 10 ^{−4 to} 1.0 × 10 ⁻¹ mass%, a hydrochloric acid aqueous solution has a concentration of 1.0 × 10 ^{−4 to} 1.0 × 10 ⁻¹ mass%, and a sulfuric acid aqueous solution has a concentration of 1 .0 × 10 ^-4 ~1.0 × 10 ^-1 wt% concentration, aqueous phosphoric acid, respectively preferably 1.0 × 10 ^-4 ~1.0 × 10 ^-1 wt% concentration.

  As the organic solvent, a single solvent composed of one compound selected from the group consisting of alcohols, ketones, hydrocarbons, carboxylic acids, sulfonic acids, glycols and glycol ethers, or two or more compounds A mixed solvent consisting of Specifically, as alcohols, methanol, ethanol, 1-butanol, 2-butanol, 1-propanol, 2-propanol, and as ketones, dimethylformamide, acetylacetone, acetone, 2-butanone, cyclohexanone, Hydrocarbons include n-octane, cyclohexane, and n-hexane, carboxylic acids include formic acid and acetic acid, sulfonic acids include benzene sulfonic acid and methane sulfonic acid, and glycols include ethylene glycol and propylene. Examples of glycol ethers include ethylene glycol monoisopropyl ether and diethylene glycol monohexyl ether. Examples of the mixed solvent composed of two or more compounds include a combination of methanol and ethanol and a combination of ethanol and acetylacetone.

  Examples of the mixed solvent of water and an organic solvent include a combination of water, methanol and ethanol, and a combination of water and acetone. The mixing ratio of water and the organic solvent is preferably 1 to 1: 1 to 4 by mass ratio.

  As the method for contacting the treatment liquid, a dipping method, a spray method, a spin method, and the like are particularly preferable. However, the method is not limited to this, and any method can be used. Further, ultrasonic treatment may be combined with the dipping method.

  After the treatment liquid contact treatment, drying is performed before the back side transparent electrode layer is formed. As the drying method, reduced pressure drying, natural drying, blow drying or heat drying is particularly preferable. The degree of chemical modification, that is, the amount of adsorbed material changes depending on the difference in the drying method.

  Next, the back-side transparent electrode layer 14 is formed on the power generation layer 13 that has been subjected to the treatment liquid contact treatment by a wet coating method. The back side transparent electrode layer 14 is provided to suppress mutual diffusion between the power generation layer 13 and the back side reflective electrode layer 16 and to increase the reflection efficiency of the back side reflective electrode layer 16.

  As a first method using the wet coating method, a composition for transparent conductive film prepared by containing conductive fine particles and a binder component together on the power generation layer 13 is applied using the wet coating method, and thereafter The back side transparent electrode layer 14 is formed by baking.

  In addition, as a second method using the wet coating method, a conductive fine particle coating film is formed by applying a conductive fine particle dispersion containing no binder component on the power generation layer 13 using the wet coating method. Then, the back side transparent electrode layer 14 is formed by impregnating the binder dispersion liquid containing no conductive fine particles on the coating film of the conductive fine particles using a wet coating method and baking.

  The composition for transparent conductive film in the first method is a composition containing conductive fine particles, and the conductive fine particles are dispersed in a dispersion medium. As the conductive fine particles contained in the composition for transparent conductive film, oxidation of ITO (Indium Tin Oxide: indium oxide-tin oxide composite oxide) and ATO (Antimony Tin Oxide: antimony oxide-tin oxide composite oxide) Tin powder and zinc oxide powder containing one or more metals selected from the group consisting of Al, Co, Fe, In, Sn, Ga and Ti are preferred. Of these, ITO, ATO, AZO (Aluminum Zinc Oxide), IZO (Indium Zinc Oxide), TZO (Tin Zinc Oxide: Tin-containing zinc oxide composite oxide) Is particularly preferred.

  The dispersion medium contained in the transparent conductive film composition includes water, alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, ketones such as acetone, methyl ethyl ketone, cyclohexanone, and isophorone, toluene, xylene, and hexane. Hydrocarbons such as cyclohexane, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, glycols such as ethylene glycol, glycol ethers such as ethyl cellosolve, etc. It is done.

  Moreover, it is preferable that the content rate of the electroconductive fine particle which occupies for the solid content contained in the composition for transparent conductive films 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 is lowered if the content is less than the lower limit value, and the adhesiveness is lowered if the upper limit value is exceeded. 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 composition for transparent conductive film is a composition containing one or both of a polymer binder and a non-polymer binder that are cured by heating. Examples of the polymer binder include acrylic resin, polycarbonate, polyester, alkyd resin, polyurethane, acrylic urethane, polystyrene, polyacetal, polyamide, polyvinyl alcohol, polyvinyl acetate, cellulose, and siloxane polymer. Polymeric binders include aluminum, silicon, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum or tin metal soaps, metal complexes or metal alkoxide hydrolysates. It is preferable. The hydrolyzate of the metal alkoxide includes sol-gel. Examples of the non-polymer type binder include metal soap, metal complex, metal alkoxide, halosilanes, 2-alkoxyethanol, β-diketone, and alkyl acetate. The metal contained in the metal soap, metal complex or metal alkoxide is aluminum, silicon, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium or antimony. These polymer-type binder and non-polymer-type binder are cured by heating, thereby enabling formation of the back-side transparent electrode layer 14 having a low haze ratio and volume resistivity at low temperatures. The content of these binders is preferably in the range of 5 to 50% by mass, particularly preferably in the range of 10 to 30% by mass, as a proportion of the solid content in the transparent conductive film composition.

  It is preferable to add a coupling agent to the composition for transparent conductive films according to the other components used. This is to improve the adhesion between the conductive fine particles and the binder and the adhesion between the backside transparent electrode layer 14 formed of the transparent conductive film composition and the power generation layer 13 or the backside reflective electrode layer 16. Examples of the coupling agent include a silane coupling agent, an aluminum coupling agent, and a titanium coupling agent.

  Examples of the silane coupling agent include vinyltriethoxyxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. Examples of the aluminum coupling agent include an aluminum coupling agent containing an acetoalkoxy group represented by the following formula (1). Further, as a titanium coupling agent, a titanium coupling agent having a dialkyl pyrophosphite group represented by the following formulas (2) to (4), or a titanium having a dialkyl phosphite group represented by the following formula (5): A coupling agent is mentioned.

上記透明導電膜用組成物を用いて裏面側透明電極層１４を形成するには、先ず透明導電膜用組成物を発電層１３上に湿式塗工法により塗布して焼成後の厚さが０．０３〜０．５μｍ、好ましくは０．０５〜０．３μｍの範囲内となるように成膜する。ここで、裏面側透明電極層１４の厚さを０．０３〜０．５μｍの範囲に限定したのは、０．０３μｍ未満又は０．５μｍを越えると増反射効果が十分に得られないからである。次にこの積層体を大気中若しくは窒素やアルゴンなどの不活性ガス雰囲気中で１２０〜４００℃の温度に５〜６０分間保持して焼成することにより裏面側透明電極層１４が形成される。

In order to form the back surface side transparent electrode layer 14 using the said composition for transparent conductive films, first, the composition for transparent conductive films is apply | coated by the wet coating method on the electric power generation layer 13, and the thickness after baking is 0.00. The film is formed in a range of 03 to 0.5 μm, preferably 0.05 to 0.3 μm. Here, the reason why the thickness of the back surface side transparent electrode layer 14 is limited to the range of 0.03 to 0.5 μm is that if the thickness is less than 0.03 μm or exceeds 0.5 μm, the enhanced reflection effect cannot be obtained sufficiently. is there. Next, the back surface side transparent electrode layer 14 is formed by baking this laminated body at 120 to 400 ° C. for 5 to 60 minutes in the atmosphere or in an inert gas atmosphere such as nitrogen or argon.

  The wet coating method is particularly preferably a spray coating method, a dispenser coating method, a spin coating method, a knife coating method, a slit coating method, an inkjet coating method, a screen printing method, an offset printing method or a die coating method. However, 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.

  The conductive fine particle dispersion containing no binder component in the second method is a dispersion in which conductive fine particles are dispersed in a dispersion medium. The conductive fine particles and the dispersion medium used for the preparation of the conductive fine particle dispersion may be the same type as the conductive fine particles and the dispersion medium used in the transparent conductive film composition in the first method. it can.

  It is preferable to add a coupling agent to the conductive fine particle dispersion according to other components to be used. This is to improve the bonding between the conductive fine particles and the binder and the adhesion between the backside transparent electrode layer 14 formed of the conductive fine particle dispersion and the binder dispersion and the power generation layer 13 or the backside reflective electrode layer 16. It is. In addition, the coupling agent used for preparation of electroconductive fine particle dispersion can use the same kind as the coupling agent used with the composition for transparent conductive films in the said 1st method.

  Moreover, the binder dispersion liquid which does not contain electroconductive fine particles contains either one or both of the polymer type binder and the non-polymer type binder which harden | cure by heating as a binder component. These polymer-type binder and non-polymer-type binder are cured by heating, thereby enabling formation of the back-side transparent electrode layer 14 having a low haze ratio and volume resistivity at low temperatures. The content of these binders in the binder dispersion is preferably in the range of 0.01 to 50% by mass, and particularly preferably in the range of 0.5 to 20% by mass. The polymer type binder and non-polymer type binder used for preparing the binder dispersion are the same type as the polymer type binder and non-polymer type binder used in the transparent conductive film composition in the first method. be able to.

  In preparing the binder dispersion, it is preferable to use a dispersion medium of the same type as the dispersion medium used in the preparation of the conductive fine particle dispersion. 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.

  Moreover, it is preferable to add a low resistance agent, a water-soluble cellulose derivative, etc. according to the component to be used. The low resistance agent is preferably one or more selected from the group consisting of cobalt, iron, indium, nickel, lead, tin, titanium and zinc mineral salts and organic acid salts. For example, a mixture of nickel acetate and ferric chloride, zinc naphthenate, a mixture of tin octylate and antimony chloride, a mixture of indium nitrate and lead acetate, a mixture of titanium acetyl acetate and cobalt octylate, and the like can be mentioned. The content ratio of these low resistance agents is preferably 0.1 to 10% by mass. Moreover, the transparency in the formed transparent electrode layer is also improved by the addition of the water-soluble cellulose derivative. Examples of the water-soluble cellulose derivative include hydroxypropyl cellulose and hydroxypropyl methylcellulose. The addition amount of the water-soluble cellulose derivative is preferably in the range of 0.1 to 10% by mass.

  In the method of forming the back side transparent electrode layer 14 using the conductive fine particle dispersion and the binder dispersion, the first layer containing both the conductive fine particles and the binder component is the lower layer, and the first layer mainly composed of the binder component is used. There are a method of forming two layers as an upper layer and a method of forming a first layer containing both conductive fine particles and a binder component as a lower layer and a second layer not containing a binder component as an upper layer.

  The back side transparent electrode layer formed by the former forming method is formed in a state in which the entire surface of the conductive oxide fine particle layer is covered with the binder layer, and thus has an advantage of little change with time. In this formation method, first, the conductive fine particle dispersion is applied onto the power generation layer 13 by a wet coating method, and the temperature is 20 to 120 ° C., preferably 25 to 60 ° C., for 1 to 30 minutes, preferably 2 to 10 minutes. By drying for a minute, a coating film of conductive fine particles is formed.

  Next, it coat | covers so that the whole surface of the coating film of electroconductive fine particles may be coat | covered completely with a binder dispersion liquid. Moreover, the coating here is such that the mass of the binder component in the binder dispersion to be applied is 0.5 to 10 mass ratio with respect to the total mass of the fine particles contained in the coating film of the applied conductive oxide fine particles. It is preferable to apply so as to be (mass of binder component / mass of conductive oxide fine particles in binder dispersion to be applied). If it is less than the lower limit, sufficient adhesion is difficult to obtain, and if it exceeds the upper limit, the surface resistance tends to increase. When the conductive oxide fine particle dispersion and the binder dispersion are applied, the back-side transparent electrode layer after firing has a thickness of 0.01 to 0.5 μm, preferably 0.03 to 0.1 μm. Apply as follows. After impregnating the binder dispersion, the transparent conductive coating film is formed by drying at a temperature of 20 to 120 ° C., preferably 25 to 60 ° C. for 1 to 30 minutes, preferably 2 to 10 minutes.

  Finally, the substrate having the coating film is heated to 130 to 400 ° C., preferably 150 to 350 ° C. in the air or in an inert gas atmosphere such as nitrogen or argon, for 5 to 60 minutes, preferably 15 to 40 minutes. The back side transparent electrode layer 14 is formed by holding and firing.

  On the other hand, the back side transparent electrode layer formed by the latter forming method is effective in increasing the fill factor, which is one of the factors that determine the conversion efficiency. In this forming method, first, the conductive fine particle dispersion is applied onto the power generation layer 13 by a wet coating method to form a coating film of conductive fine particles. The application here is such that the back side transparent electrode layer after firing has a thickness of 0.01 to 0.5 μm, preferably 0.05 to 0.1 μm, and a temperature of 20 to 120 ° C., preferably Is formed by drying at 25 to 60 ° C. for 1 to 30 minutes, preferably 2 to 10 minutes.

  Next, the binder dispersion liquid is impregnated on the coating film of conductive fine particles by a wet coating method. At this time, the binder dispersion liquid is coated with conductive fine particles so that the second layer that does not contain the binder component of the back-side transparent electrode layer 14 formed after firing is exposed 1 to 30% of the volume of the first layer. Complete impregnation to a predetermined depth of the membrane. In addition, the coating here is such that the mass of the binder component in the binder dispersion to be coated is a mass ratio of 0.05 to 0.5 with respect to the total mass of the fine particles contained in the coating film of the applied conductive fine particles. It is preferable to apply so that it becomes (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. After impregnating the binder dispersion, the transparent conductive coating film is formed by drying at a temperature of 20 to 120 ° C., preferably 25 to 60 ° C. for 1 to 30 minutes, preferably 2 to 10 minutes.

  Finally, the substrate having the coating film is heated to 130 to 400 ° C., preferably 150 to 350 ° C. in the air or in an inert gas atmosphere such as nitrogen or argon, for 5 to 60 minutes, preferably 15 to 40 minutes. The back side transparent electrode layer 14 is formed by holding and firing.

  On the back side transparent electrode layer 14, the back side reflective electrode layer 16 is formed. Since this back surface side reflective electrode layer 16 plays the role which improves the electric power generation efficiency by reflecting the light which could not be absorbed but permeate | transmitted the electric power generation layer 13, and returning to the electric power generation layer 13 again, a high diffuse reflectance is requested | required. For this reason, the back side reflective electrode layer 16 is preferably a metal having a high reflectance. Examples of the metal include metals such as silver, iron, chromium, tantalum, molybdenum, nickel, aluminum, cobalt, and titanium, alloys of these metals, and alloys such as nichrome and stainless steel. Of these, silver and aluminum are particularly preferable. The backside reflective electrode layer 16 is not particularly limited, but may be formed by a conventionally known method such as a thermal CVD method, a sputtering method, a vacuum deposition method, or a wet coating method. When the back side reflective electrode layer 16 is formed by a wet coating method, an electrode composition in which metal nanoparticles are dispersed in a dispersion medium is used. This electrode composition is a composition prepared by dispersing metal nanoparticles in a dispersion medium. In the metal nanoparticles, the proportion of silver in the metal element is 75% by mass or more, preferably 80% by mass or more. The reason why the ratio of silver in the metal element is in the range of 75% by mass or more is that if it is less than 75% by mass, the reflectance of the back-side reflective electrode layer 16 formed using this electrode composition decreases. It is. The metal nanoparticles are chemically modified with a protective agent having an organic molecular main chain having a carbon skeleton of 1 to 3 carbon atoms. The reason why the number of carbon atoms in the carbon skeleton of the organic molecule main chain of the protective agent for chemically modifying the metal nanoparticles is in the range of 1 to 3 is that the protective agent is desorbed or decomposed (separated) by heating when the carbon number is 4 or more This is because it is difficult to burn), and a large amount of organic residue remains in the back side reflective electrode layer 16, which deteriorates or deteriorates, and the conductivity and reflectivity of the back side reflective electrode layer 16 decrease.

  The metal nanoparticles preferably contain 70% or more, preferably 75% or more of the number average of metal nanoparticles having a primary particle size of 10 to 50 nm. When the content of the metal nanoparticles within the range of the primary particle size of 10 to 50 nm is less than 70% by mass with respect to 100% of all the metal nanoparticles, the specific surface area of the metal nanoparticles is increased and The proportion occupied is increased. For this reason, even if it is an organic molecule that is easily desorbed or decomposed (separated / burned) by heating, a large proportion of the organic molecule occupies it, so that a large amount of organic residue remains in the back-side reflective electrode layer 16. This residue may be altered or deteriorated to reduce the conductivity and reflectance of the back-side reflective electrode layer 16, or the particle size distribution of the metal nanoparticles may be widened to reduce the density of the back-side reflective electrode layer 16. Moreover, it is because the electroconductivity and reflectance of the back surface side reflective electrode layer 16 will fall. Furthermore, the primary particle size of the metal nanoparticles was set within the range of 10 to 50 nm based on the correlation between the primary particle size and the stability over time (aging stability) of the metal nanoparticles.

  The electrode composition containing the metal nanoparticles further includes one or more additives selected from the group consisting of organic polymers, metal oxides, metal hydroxides, organometallic compounds, and silicone oils. It is preferable. As the additive, an organic polymer, metal oxide, metal hydroxide, organometallic compound, or silicone oil contained in the electrode composition is used. Thereby, the chemical bond with the base material or the anchor effect is increased, or the wettability between the metal nanoparticles and the base material is improved in the process of heating and firing, and the base material is not impaired. Adhesiveness can be improved. Moreover, when the back surface side reflective electrode layer 16 is formed using this composition for electrodes, the grain growth by sintering between metal nanoparticles can be adjusted. The formation of the back-side reflective electrode layer 16 using this electrode composition does not require a vacuum process at the time of film formation, so that the process restrictions are small and the running cost of manufacturing equipment can be greatly reduced.

The content of the additive is 0.1 to 20%, preferably 0.2 to 10% of the mass of the silver nanoparticles constituting the metal nanoparticles. If the content of the additive is less than 0.1%, pores having a large average diameter may appear or the pore density may be increased. When the content of the additive exceeds 20%, the conductivity of the back-side reflective electrode layer 16 formed is adversely affected, and the volume resistivity exceeds 2 × 10 ⁻⁵ Ω · cm.

  As the organic polymer used as the additive, one or more selected from the group consisting of polyvinylpyrrolidone (hereinafter referred to as PVP), a PVP copolymer and water-soluble cellulose is used. Specifically, examples of the PVP copolymer include a PVP-methacrylate copolymer, a PVP-styrene copolymer, and a PVP-vinyl acetate copolymer. Examples of the water-soluble cellulose include cellulose ethers such as hydroxypropylmethylcellulose, methylcellulose, and hydroxyethylmethylcellulose.

  The metal oxide used as an additive is at least selected from the group consisting of aluminum, silicon, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and antimony An oxide or composite oxide containing one kind is preferable. Specifically, the composite oxide is ITO (Indium Tin Oxide), ATO (Antimony Tin Oxide), IZO (Indium Zic Oxide). Indium-zinc oxide composite oxide), AZO (Aluminum Zinc Oxide: aluminum oxide-zinc oxide composite oxide) and the like.

  The metal hydroxide used as an additive was selected from the group consisting of aluminum, silicon, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and antimony. A hydroxide containing at least one kind is preferred.

  As an organometallic compound used as an additive, a metal soap containing at least one selected from the group consisting of silicon, titanium, zirconium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum and tin Metal complexes or metal alkoxides are preferred. Examples of the metal soap include chromium acetate, manganese formate, iron citrate, cobalt formate, nickel acetate, silver citrate, copper acetate, copper citrate, tin acetate, zinc acetate, zinc oxalate, and molybdenum acetate. Examples of the metal complex include an acetylacetone zinc complex, an acetylacetone chromium complex, and an acetylacetone nickel complex. Examples of the metal alkoxide include titanium isopropoxide, methyl silicate, isoanatopropyltrimethoxysilane, aminopropyltrimethoxysilane and the like.

  As the silicone oil used as the additive, both straight silicone oil and modified silicone oil can be used. The modified silicone oil further has an organic group introduced into part of the side chain of the polysiloxane (side chain type), an organic group introduced into both ends of the polysiloxane (both end type), and both ends of the polysiloxane. Those having an organic group introduced into one of them (one end type) and those having an organic group introduced into a part of both side chains and both ends of the polysiloxane (both side chain end type) can be used. The modified silicone oil includes a reactive silicone oil and a non-reactive silicone oil. Both types can be used as the additive of the present invention. Reactive silicone oil means amino modification, epoxy modification, carboxy modification, carbinol modification, mercapto modification, and heterogeneous functional group modification (epoxy group, amino group, polyether group). Indicates polyether modification, methylstyryl group modification, alkyl modification, higher fatty acid ester modification, fluorine modification, and hydrophilic special modification.

  On the other hand, among the metal nanoparticles constituting the electrode composition, the metal nanoparticles other than silver nanoparticles are composed of gold, platinum, palladium, ruthenium, nickel, copper, tin, indium, zinc, iron, chromium and manganese. It is preferable to further contain metal nanoparticles composed of one kind of particles selected from the group or two or more kinds of mixed compositions or alloy compositions. The metal nanoparticles other than silver nanoparticles are preferably 0.02% by mass or more and less than 25% by mass with respect to 100% by mass of all metal nanoparticles, and 0.03% by mass to 20% by mass. Is more preferable. When the content of particles other than silver nanoparticles is in the range of 0.02% by mass or more and less than 25% by mass, it is maintained in a constant temperature and humidity chamber having a temperature of 100 ° C. and a humidity of 50% for 1000 hours. This is because the conductivity and reflectance of the back electrode layer 16 after the test) are not deteriorated as compared with those before the weather resistance test.

  Moreover, content of the metal nanoparticle containing the silver nanoparticle in an electrode composition should contain 2.5-95.0 mass% with respect to 100 mass% of electrode compositions which consist of a metal nanoparticle and a dispersion medium. Is preferable, and it is further more preferable to contain 3.5-90 mass%. This is because if the content ratio with respect to 100% by mass of the electrode composition exceeds 95.0% by mass, the required fluidity as an ink or paste is lost during wet coating of the electrode composition.

  Moreover, the dispersion medium which comprises the composition for electrodes for forming the back surface side reflective electrode layer 16 is 1 mass% or more with respect to 100 mass% of all the dispersion media, Preferably it is 2 mass% or more of water, 2 It is preferable to contain a solvent that is compatible with water in an amount of not less than mass%, preferably not less than 3 mass%, such as alcohols. For example, when the dispersion medium is composed of only water and alcohols, it contains 98% by mass of alcohol when it contains 2% by mass of water, and 98% by mass of water when it contains 2% by mass of alcohol. Further, the dispersion medium, that is, the protective molecule chemically modified on the surface of the metal nanoparticles contains one or both of a hydroxyl group (—OH) and a carbonyl group (—C═O). The water content is preferably in the range of 1% by mass or more with respect to 100% by mass of all the dispersion media. This is because if the water content is less than 2% by mass, it becomes difficult to sinter the film obtained by applying the electrode composition by a wet coating method at a low temperature. Furthermore, the conductivity and reflectance of the back-side reflective electrode layer 16 after firing are reduced. In addition, when a hydroxyl group (—OH) is contained in a protective agent that chemically modifies metal nanoparticles such as silver nanoparticles, it is excellent in dispersion stability of the electrode composition and effective for low-temperature sintering of the coating film. There is an effect. In addition, when a carbonyl group (—C═O) is contained in a protective agent that chemically modifies metal nanoparticles such as silver nanoparticles, it is excellent in dispersion stability of the electrode composition as described above, and the coating film has a low temperature. Sintering also has an effective action. As the solvent compatible with water used for the dispersion medium, alcohols are preferable. Among these, as the alcohols, it is particularly preferable to use one or more selected from the group consisting of methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, isobornyl hexanol and erythritol. preferable.

A method for producing an electrode composition containing metal nanoparticles for forming the back side reflective electrode layer 16 is as follows.
(a) When the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying the silver nanoparticles is set to 3 First, silver nitrate is dissolved in water such as deionized water to prepare an aqueous metal salt solution. On the other hand, the aqueous solution of sodium citrate having a concentration of 10 to 40% obtained by dissolving sodium citrate in deionized water or the like is mixed with granular or powdered sulfuric acid in a stream of inert gas such as nitrogen gas. Iron is directly added and dissolved to prepare an aqueous reducing agent solution containing citrate ions and ferrous ions in a molar ratio of 3: 2. Next, the aqueous metal salt solution is added dropwise to and mixed with the reducing agent aqueous solution while stirring the reducing agent aqueous solution in the inert gas stream. Here, by adjusting the concentration of each solution so that the addition amount of the metal salt aqueous solution is 1/10 or less of the amount of the reducing agent aqueous solution, the reaction temperature is 30 to 30 even when the metal salt aqueous solution at room temperature is dropped. It is preferable to keep the temperature at 60 ° C. The mixing ratio of the two aqueous solutions is adjusted so that the equivalent of ferrous ions added as a reducing agent is three times the equivalent of metal ions. That is, the number of moles of metal ions in the aqueous solution of metal salt × (valence of metal ions) = 3 × (number of moles of ferrous ions in the aqueous reducing agent solution) is adjusted. After the dropping of the aqueous metal salt solution is completed, the mixture is further stirred for 10 to 300 minutes to prepare a dispersion composed of metal colloid. This dispersion is allowed to stand at room temperature, and the aggregates of the precipitated metal nanoparticles are separated by decantation, centrifugation, etc., and then water such as deionized water is added to the separation to form a dispersion, followed by ultrafiltration. Demineralize by. Further, it is subsequently substituted and washed with alcohols so that the metal (silver) content is 2.5 to 50% by mass. Thereafter, by adjusting the centrifugal force of the centrifuge using a centrifuge to separate coarse particles, the silver nanoparticles having a primary particle size in the range of 10 to 50 nm are 70% or more in average number of silver nanoparticles. Prepare to contain. That is, the ratio of the silver nanoparticles in the range of the primary particle diameter of 10 to 50 nm with respect to 100% of all silver nanoparticles is adjusted so that the number average is 70% or more. Thereby, a dispersion in which the carbon skeleton of the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying the silver nanoparticles is 3 is obtained.

Subsequently, the obtained dispersion is adjusted so that the final metal content (silver content) with respect to 100% by mass of the dispersion is in the range of 2.5 to 95% by mass. When the dispersion medium is an alcohol-containing aqueous solution, it is preferable to adjust the solvent water and the alcohol to 1% or more and 2% or more, respectively. In addition, when an additive is further included in the electrode composition, the dispersion is one or more selected from the group consisting of organic polymers, metal oxides, metal hydroxides, organometallic compounds, and silicone oils. It is carried out by adding two or more additives in a desired ratio. Content of an additive is adjusted so that it may become in the range of 0.1-20 mass% with respect to 100 mass% of composition for electrodes obtained. As a result, an electrode composition in which silver nanoparticles chemically modified with a protective agent for an organic molecular main chain having 3 carbon skeletons is dispersed in a dispersion medium is obtained.
(b) When the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent that chemically modifies the silver nanoparticles is 2, except that the sodium citrate used when preparing the reducing agent aqueous solution is replaced with sodium malate A dispersion is prepared in the same manner as in the above (a). As a result, a dispersion having 2 carbon atoms in the carbon skeleton of the organic molecular main chain that chemically modifies the silver nanoparticles can be obtained.
(c) When the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying the silver nanoparticles is 1, except that sodium citrate used when preparing the reducing agent aqueous solution is replaced with sodium glycolate A dispersion is prepared in the same manner as in the above (a). Thereby, a dispersion in which the carbon skeleton of the carbon skeleton of the organic molecular main chain for chemically modifying the silver nanoparticles is 1 is obtained.
(d) When the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying metal nanoparticles other than silver nanoparticles is 3, the metal constituting the metal nanoparticles other than silver nanoparticles is gold, Examples include platinum, palladium, ruthenium, nickel, copper, tin, indium, zinc, iron, chromium and manganese. The silver nitrate used to prepare the aqueous metal salt solution is chloroauric acid, chloroplatinic acid, palladium nitrate, ruthenium trichloride, nickel chloride, cuprous nitrate, tin dichloride, indium nitrate, zinc chloride, iron sulfate, sulfuric acid A dispersion is prepared in the same manner as in the above (a) except that it is replaced with chromium or manganese sulfate. Thereby, the dispersion whose carbon number of the carbon skeleton of the organic molecular principal chain of the protective agent which chemically modifies metal nanoparticles other than silver nanoparticles is 3 is obtained.

  In addition, when the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent that chemically modifies the metal nanoparticles other than the silver nanoparticles is 1 or 2, the silver nitrate used when preparing the metal salt aqueous solution is the above kind. A dispersion is prepared in the same manner as in the above (b) and (c) except that the metal salt is replaced. Thereby, the dispersion whose carbon number of carbon skeleton of the organic molecular principal chain of the protective agent which chemically modifies metal nanoparticles other than silver nanoparticles is 1 or 2 is obtained.

  When the metal nanoparticles include metal nanoparticles other than silver nanoparticles together with silver nanoparticles, for example, a dispersion containing silver nanoparticles produced by the method of (a) is used as the first dispersion, When the dispersion containing metal nanoparticles other than the silver nanoparticles produced by the method (d) is used as the second dispersion, 75% by mass or more of the first dispersion and less than 25% by mass of the second dispersion are obtained. Mixing is performed so that the total content of the first and second dispersions is 100% by mass. The first dispersion is not limited to the dispersion containing the silver nanoparticles produced by the method (a), but the dispersion containing the silver nanoparticles produced by the method (b) or the above (c). You may use the dispersion containing the silver nanoparticle manufactured by the method.

  In order to form the back-side reflective electrode layer 16 using the electrode composition, first, the electrode composition is applied onto the back-side transparent electrode layer 14 by a wet coating method, and the thickness after baking by heating is applied. Is formed to have a thickness of 0.05 to 2.0 μm, preferably 0.1 to 1.5 μm. Next, this electrode coating layer is kept in the atmosphere or in an inert gas atmosphere such as nitrogen or argon at a temperature of 130 to 400 ° C., preferably 150 to 350 ° C. for 5 minutes to 1 hour, preferably 15 to 40 minutes. And fired. Here, the thickness of the back-side reflective electrode layer 16 after firing was limited to a range of 0.05 to 2.0 μm. This is because if it is less than 0.05 μm, the surface resistance value of the electrode necessary for the solar cell becomes insufficient. Moreover, the heating temperature of the coating layer for electrodes was made into the range of 130-400 degreeC. This is because if the temperature is lower than 130 ° C., the metal nanoparticles are not sufficiently sintered and are not easily detached or decomposed (separated / burned) by heating the protective agent. That is, a large amount of organic residue remains in the back-side reflective electrode layer 16 after firing, and the residue is altered or deteriorated, so that the conductivity and reflectance of the back-side reflective electrode layer 16 are reduced. Moreover, if it exceeds 400 degreeC, the merit in a low temperature process cannot be utilized. That is, the manufacturing cost is increased and the productivity is lowered, and this affects the light wavelength range of photoelectric conversion particularly in amorphous silicon, microcrystalline silicon, or a hybrid silicon solar cell using these. Further, the heating time of the electrode coating layer was set in the range of 5 minutes to 1 hour. This is because the sintering between the metal nanoparticles becomes insufficient for less than 5 minutes, and it is difficult to desorb or decompose (separate / burn) by heating the protective agent. This is because a large amount of residue remains, and the residue is altered or deteriorated, so that the conductivity and reflectance of the back-side reflective electrode layer 16 are lowered.

When the back-side reflective electrode layer 16 is formed by the wet coating method in this way, a simple process can be completed in a short time, and a vacuum process is not required at the time of film formation. It can be greatly reduced. In the back-side reflective electrode layer 16 obtained by this method, the average diameter of pores appearing on the contact surface on the power generation layer 13 side of the layer is 100 nm or less, the average depth at which pores are located is 100 nm or less, and the number density of pores is 30. Pieces / μm ² or less. Thereby, when a translucent substrate having a transmittance of 98% or more is used, a high diffuse reflectance of 80% or more of the theoretical reflectance can be achieved in the wavelength range of 500 to 1200 nm. This wavelength range of 500 to 1200 nm almost covers the convertible wavelengths when polycrystalline silicon is used as the power generation layer. Moreover, the said back surface side reflective electrode layer 16 has the specific resistance close | similar to the specific resistance which the metal itself which comprises the metal nanoparticle contained in the composition for electrodes has. That is, it shows a specific resistance as low as a bulk that can be used as an electrode for a solar cell module. Moreover, the back surface side reflective electrode layer 16 of this invention is excellent in long-term stability, such as a reflectance of a film | membrane, adhesiveness, and a specific resistance compared with the film | membrane formed into a film by vacuum processes, such as a sputtering method. The reason for this is that the back-side reflective electrode layer 16 of the present invention formed in the atmosphere is less susceptible to moisture intrusion and oxidation than a film formed in vacuum.

  A barrier film may be formed on the back-side reflective electrode layer 16 via a back electrode reinforcing film (not shown) or without a back electrode reinforcing film.

  As described above, since the work function of the surface of the power generation layer 13 is improved by the manufacturing method of the present invention, the difference between the work function of the surface of the power generation layer 13 and the work function of the back side transparent electrode layer can be reduced. Thereby, the conversion efficiency of a solar cell can be improved by reducing the contact resistance between the electric power generation layer in the case of electric power generation, and a back surface side transparent electrode layer, and reducing the series resistance in the solar cell in the case of an electric power generation.

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

<Example 1>
First, as shown in FIG. 1, a glass plate having 10 cm square and 4 mm thickness 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, as shown in Table 1 and Table 3 below, an amorphous silicon layer is formed with a thickness of 300 nm on the surface-side electrode layer 12 using a plasma CVD method, and then on the amorphous silicon layer. In addition, a silicon-based power generation layer 13 was formed by forming a microcrystalline silicon layer with a thickness of 1.7 μm using a plasma CVD method. The work function of the formed power generation layer surface was measured using a Kelvin probe (manufactured by KP Technology; model SKP020).

  Subsequently, ion-exchanged water having a liquid temperature of 25 ° C. is prepared as a treatment liquid, the treatment liquid is stored in a liquid tank, the substrate is immersed in the treatment liquid in the liquid tank, and the surface of the power generation layer 13 on the substrate is covered. A treatment liquid contact treatment by a dipping method in which the treatment solution was brought into contact with the treatment liquid for 0.5 minutes was performed. The substrate after the treatment liquid contact treatment was left to dry at room temperature. The work function of the surface of the power generation layer 13 after the dry treatment liquid contact treatment was measured using the Kelvin probe. And the difference of the work function of the electric power generation layer 13 surface measured before the process liquid contact process and the work function of the electric power generation layer 13 surface measured after the process liquid contact process was calculated | required.

  Next, the composition for transparent conductive films used for formation of the back surface side transparent electrode layer 14 was prepared as follows. As shown in Tables 1 and 4 below, 1.0 part by mass of ITO powder with Sn / (Sn + In) = 0.1 and particle size of 0.03 μm in terms of atomic ratio as conductive fine particles, and ethyl silicate as a binder are added. 0.2 parts by mass of the decomposed siloxane polymer, 0.01 parts by mass of the organic titanium coupling agent represented by the above formula (3) as a coupling agent are added, and ethanol is added as a dispersion medium, so that the total is 100 parts by mass. The part.

  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 with a dyno mill (horizontal bead mill) for 2 hours using zirconia beads having a diameter of 0.3 mm to disperse fine particles in the mixture, thereby obtaining a transparent conductive film composition.

  Next, on the power generation layer 13 subjected to the treatment liquid contact treatment, the transparent conductive film composition prepared above was applied by spin coating so that the film thickness after firing was 80 nm, and the coating film was coated at 200 ° C. The back side transparent electrode layer 14 was formed by baking for 30 minutes. The film thickness after firing was measured by a photograph of the cross section taken by SEM. The fine particle / binder ratio in the back-side transparent electrode layer 14 obtained by firing was 2/1 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.

  Further, an Ag nano ink in which an Ag colloid having an average particle size of 0.03 μm is dispersed in an ethanol solvent is applied onto the formed back surface side transparent electrode layer 14 so that the film thickness after baking is 200 nm by a spin coating method. By baking the coating film at 200 ° C. for 30 minutes to form the back surface side reflective electrode layer 16, an evaluation multi-junction thin film silicon solar cell was obtained. did. The composition of the Ag nanoink used was 10 parts by mass of Ag colloid and 90 parts by mass of ethanol.

Thereafter, for this multi-junction thin film silicon solar cell for evaluation, lead wires were routed on the substrate after the line processing of the solar cells, and using a solar simulator and a digital source meter, AM 1.5, 100 mW / cm ² An IV (current-voltage) curve was obtained when irradiated with light. Further, the current value (I) in the obtained IV (current-voltage) curve is divided by the surface area of the solar battery cell to obtain a JV curve (current density-voltage). The reciprocal of the slope in the vicinity of the voltage at 0) was taken as the series resistance. The results are shown in Table 1 below.

<Example 2>
In the treatment liquid contact treatment, a multijunction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the contact time with the treatment liquid was changed to 1 minute.

<Example 3>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that the temperature of the treatment liquid was changed to 70 ° C. and the contact time with the treatment liquid was changed to 60 minutes.

<Example 4>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that the contact time with the treatment liquid was changed to 5 minutes.

<Example 5>
In the treatment liquid contact treatment, a multijunction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the contact time with the treatment liquid was changed to 60 minutes.

<Example 6>
In the treatment liquid contact treatment, the temperature of the treatment liquid is changed to 50 ° C., the contact time with the treatment liquid is changed to 720 minutes, and in the drying method, the substrate after the treatment liquid contact treatment is changed to heat drying to heat to 50 ° C. Obtained a multijunction thin film silicon solar cell for evaluation in the same manner as in Example 1.

<Example 7>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that the contact time with the treatment liquid was changed to 1440 minutes.

<Example 8>
In the treatment liquid contact treatment, the dipping method is combined with ultrasonic treatment as the contact method, the contact time with the treatment liquid is changed to 5 minutes, and the substrate after the treatment liquid contact treatment is 1.0 × 10 ⁻ in the drying method. ^A multi-junction thin-film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the drying was performed under reduced pressure held in a reduced pressure atmosphere of ⁵ MPa.

<Example 9>
In the treatment liquid contact treatment, a spray method in which the treatment liquid is sprayed at a flow rate of 100 ml / min is used as a contact method, the temperature of the treatment liquid is changed to 10 ° C., and the contact time with the treatment liquid is changed to 10 minutes. A multi-junction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the substrate after the liquid contact treatment was changed to blow drying which blows air at room temperature.

<Example 10>
In the treatment liquid contact treatment, a multijunction thin film silicon solar cell for evaluation was used in the same manner as in Example 1 except that a 0.01 mol / L nitric acid aqueous solution was used as the treatment liquid and the contact time with the treatment liquid was changed to 60 minutes. Got.

<Example 11>
In the treatment liquid contact treatment, a spray method in which the treatment liquid is sprayed at a flow rate of 100 ml / min as a contact method, a 0.01 mol / L nitric acid aqueous solution is used as the treatment liquid, the temperature of the treatment liquid is 0 ° C., and the treatment liquid The contact time was changed to 280 minutes, and the drying method was the same as in Example 1 except that the substrate after the treatment liquid contact treatment was changed to reduced-pressure drying that was held in a reduced-pressure atmosphere of 1.0 × 10 ⁻⁵ MPa. A multi-junction thin film silicon solar cell for evaluation was obtained.

<Example 12>
In the treatment liquid contact treatment, a spray method in which the treatment liquid is sprayed at a flow rate of 100 ml / min as the contact method, a 0.01 mol / L nitric acid aqueous solution is used as the treatment liquid, the temperature of the treatment liquid is changed to 50 ° C., and drying is performed. In the method, an evaluation multi-junction thin-film silicon solar cell was prepared in the same manner as in Example 1 except that the substrate after the treatment liquid contact treatment was changed to reduced-pressure drying which was held in a reduced-pressure atmosphere of 1.0 × 10 ⁻⁵ MPa. Obtained.

<Example 13>
In the treatment liquid contact treatment, a spray method in which the treatment liquid is sprayed at a flow rate of 100 ml / min is used as the contact method, a 0.01 mol / L hydrochloric acid aqueous solution is used as the treatment liquid, and the contact time with the treatment liquid is changed to 10 minutes. In the drying method, a multijunction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the substrate after the treatment liquid contact treatment was changed to heat drying where the substrate was heated to 50 ° C.

<Example 14>
In the treatment liquid contact treatment, 0.01 mol / L sulfuric acid aqueous solution is used as the treatment liquid, the contact time with the treatment liquid is changed to 10 minutes, and air at room temperature is blown onto the substrate after the treatment liquid contact treatment in the drying method. A multijunction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the air knife method was used.

<Example 15>
In the treatment liquid contact treatment, a multi-junction thin film silicon solar cell for evaluation was used in the same manner as in Example 1 except that a 0.01 mol / L phosphoric acid aqueous solution was used as the treatment liquid and the contact time with the treatment liquid was changed to 60 minutes. A battery was obtained.

<Example 16>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that ethanol was used as the treatment liquid and the contact time with the treatment liquid was changed to 5 minutes.

<Example 17>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that ethanol was used as the treatment liquid and the contact time with the treatment liquid was changed to 60 minutes.

<Example 18>
In the treatment liquid contact treatment, ethanol is used as the treatment liquid, the temperature of the treatment liquid is changed to 50 ° C., the contact time with the treatment liquid is changed to 720 minutes, and the substrate after the treatment liquid contact treatment is heated to 50 ° C. in the drying method. A multi-junction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the drying was changed to heat drying.

<Example 19>
In the treatment liquid contact treatment, ethanol was used as the treatment liquid, the evaluation was performed in the same manner as in Example 1 except that the temperature of the treatment liquid was changed to 10 ° C. and the contact time with the treatment liquid was changed to 60 minutes. A battery was obtained.

<Example 20>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that ethanol was used as the treatment liquid and the contact time with the treatment liquid was changed to 1440 minutes.

<Example 21>
In the treatment liquid contact treatment, as a contact method, a spin method is used in which the treatment liquid is dropped onto the surface of the power generation layer at a flow rate of 100 ml / min while rotating the substrate at 300 rpm, and the power generation layer surface is dried by centrifugal force generated by the rotation. A multi-junction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that ethanol was used.

<Example 22>
In the treatment liquid contact treatment, an evaluation multijunction thin film silicon solar cell was obtained in the same manner as in Example 1 except that methanol was used as the treatment liquid and the contact time with the treatment liquid was changed to 1 minute.

<Example 23>
In the treatment liquid contact treatment, an evaluation multijunction thin film silicon solar cell was obtained in the same manner as in Example 1 except that methanol was used as the treatment liquid and the contact time with the treatment liquid was changed to 60 minutes.

<Example 24>
In the treatment liquid contact treatment, a solvent mixed so that ethanol and methanol are in a mass ratio of 9: 1 was used as the treatment liquid, and the contact time with the treatment liquid was changed to 60 minutes. Thus, a multi-junction thin film silicon solar cell for evaluation was obtained.

<Example 25>
In the treatment liquid contact treatment, a spray method in which the treatment liquid is sprayed at a flow rate of 100 ml / min is used as the contact method, and the treatment liquid is treated using a solvent in which ethanol and methanol are mixed at a mass ratio of 9: 1. The temperature of the liquid was changed to 50 ° C., the contact time with the treatment liquid was changed to 10 minutes, and the drying method was the same as in Example 1 except that the drying was performed by blowing air at room temperature to the substrate after the treatment liquid contact treatment. Thus, a multi-junction thin film silicon solar cell for evaluation was obtained.

<Example 26>
In the treatment liquid contact treatment, a dipping method is combined with ultrasonic treatment as the contact method, and a solvent in which ethanol and methanol are mixed at a mass ratio of 9: 1 is used as the treatment liquid, and the contact time with the treatment liquid is used. Was changed to 5 minutes, and in the drying method, evaluation was performed in the same manner as in Example 1 except that the substrate after the treatment liquid contact treatment was changed to reduced-pressure drying in which the substrate was held in a reduced-pressure atmosphere of 1.0 × 10 ⁻⁵ MPa. A multi-junction thin film silicon solar cell was obtained.

<Example 27>
In the treatment liquid contact treatment, a solvent in which water, ethanol, and methanol are mixed at a mass ratio of 1: 2.7: 0.3 is used as the treatment liquid, and the contact time with the treatment liquid is changed to 720 minutes. Then, in the drying method, the multi-junction thin film silicon for evaluation was evaluated in the same manner as in Example 1 except that the substrate after the treatment liquid contact treatment was changed to reduced-pressure drying which was held in a reduced-pressure atmosphere of 1.0 × 10 ⁻⁵ MPa. A solar cell was obtained.

<Example 28>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that ethylene glycol monoisopropyl ether was used as the treatment liquid and the contact time with the treatment liquid was changed to 60 minutes. .

<Example 29>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that acetylacetone was used as the treatment liquid and the contact time with the treatment liquid was changed to 60 minutes.

<Example 30>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that dimethylformamide was used as the treatment liquid and the contact time with the treatment liquid was changed to 60 minutes.

<Example 31>
In the treatment liquid contact treatment, 1-butanol was used as the treatment liquid, the contact time with the treatment liquid was changed to 60 minutes, and the substrate after the treatment liquid contact treatment was reduced to 1.0 × 10 ⁻⁵ MPa in the drying method. A multi-junction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the drying under reduced pressure was changed to hold under an atmosphere.

<Example 32>
In the treatment liquid contact treatment, ethylene glycol is used as the treatment liquid, the contact time with the treatment liquid is changed to 60 minutes, and in the drying method, the substrate after the treatment liquid contact treatment is changed to heat drying to heat to 50 ° C. Obtained a multijunction thin film silicon solar cell for evaluation in the same manner as in Example 1.

<Example 33>
In the treatment liquid contact treatment, a solvent in which ethanol and methanol are mixed at a mass ratio of 9: 1 is used as the treatment liquid, the contact time with the treatment liquid is changed to 60 minutes, and the reflective electrode layer is formed. A multi-junction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that the metal species of the reflective electrode layer was changed to an aluminum film.

<Comparative Example 1>
An evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that the treatment liquid contact treatment and the drying treatment were not performed.

<Comparative example 2>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that the temperature of the treatment liquid was changed to 75 ° C. and the contact time with the treatment liquid was changed to 300 minutes.

<Comparative Example 3>
In the treatment liquid contact treatment, an evaluation multi-junction thin film silicon solar cell was obtained in the same manner as in Example 1 except that the temperature of the treatment liquid was changed to 85 ° C. and the contact time with the treatment liquid was changed to 60 minutes.

<Comparative example 4>
In the treatment liquid contact treatment, a multijunction thin film silicon solar cell for evaluation was used in the same manner as in Example 1 except that a 0.01 mol / L nitric acid aqueous solution was used as the treatment liquid and the contact time with the treatment liquid was changed to 300 minutes. Got.

<Comparative Example 5>
In the treatment liquid contact treatment, evaluation was performed in the same manner as in Example 1 except that a 0.01 mol / L aqueous nitric acid solution was used as the treatment liquid, the temperature of the treatment liquid was changed to 70 ° C., and the contact time with the treatment liquid was changed to 60 minutes. A multi-junction thin-film silicon solar cell was obtained.

<Comparative Example 6>
In the treatment liquid contact treatment, a solvent mixed so that ethanol and methanol are in a mass ratio of 9: 1 is used as the treatment liquid, and the contact time with the treatment liquid is changed to 14400 minutes. Thus, a multi-junction thin film silicon solar cell for evaluation was obtained.

<Comparative Example 7>
In the treatment liquid contact treatment, a solvent in which ethanol and methanol are mixed at a mass ratio of 9: 1 is used as the treatment liquid, the temperature of the treatment liquid is changed to 70 ° C., and the contact time with the treatment liquid is changed to 720 minutes. A multijunction thin film silicon solar cell for evaluation was obtained in the same manner as in Example 1 except that.

<Comparative Example 8>
In the treatment liquid contact treatment, the contact time with the treatment liquid was changed to 5 minutes, and in the formation of the back surface side transparent electrode layer, the formation method was changed to the vacuum film formation method, and the evaluation was performed in the same manner as in Example 1. A junction-type thin film silicon solar cell was obtained.

表１及び表２から明らかなように、処理液接触処理を施さない比較例１では直列抵抗が１４．５Ω／ｃｍ²であったのに対し、実施例１〜３３では処理液接触処理前後の仕事関数の差が向上しており、直列抵抗が抑制された結果が得られた。また、裏面側透明電極層を真空成膜法により形成した比較例８の結果と比べても、遜色のない抵抗値を得ることができた。

As is clear from Tables 1 and 2, in Comparative Example 1 in which no treatment liquid contact treatment was performed, the series resistance was 14.5 Ω / cm ² , whereas in Examples 1 to 33, before and after the treatment liquid contact treatment. The difference in work function was improved, and the result that the series resistance was suppressed was obtained. Moreover, even if it compared with the result of the comparative example 8 which formed the back surface side transparent electrode layer by the vacuum film-forming method, the comparable resistance value was able to be obtained.

  When comparing Examples 1 to 9 using water as the treatment liquid, the result that the series resistance was suppressed as the temperature of the treatment liquid was higher or the contact time was longer was obtained. However, in Example 7, which had a long time of 1440 minutes, the suppression width of the series resistance value tended to be small. In Examples 10 to 15 where an aqueous solution was used as the treatment liquid, the results of Examples 13 and 14 using an aqueous hydrochloric acid solution and an aqueous sulfuric acid solution were particularly excellent. When Examples 16 to 26 and 28 to 33 using an organic solvent as the treatment liquid were compared, the result that the series resistance was suppressed as the temperature of the treatment liquid was higher or the contact time was longer was obtained. However, in Example 20, where the contact time was as long as 1440 minutes, the suppression width of the series resistance value tended to be small.

  Moreover, in Examples 17, 23, and 31 in which only the type of the treatment liquid was different under the same treatment conditions, the lower the resistance value was, the higher the number of carbons was. Further, in Examples 24 and 33 in which only the metal type of the reflective electrode layer was different, the resistance value of Ag was lower than that of Al.

  On the other hand, in Comparative Examples 2 to 7 under conditions where the temperature of the treatment liquid was high or the contact time was long, the result was that the series resistance was high, or the power generation layer was peeled off, making measurement impossible.

  From this result, in the production of solar cells, after the treatment liquid is brought into contact with the surface of the power generation layer under predetermined conditions, the back side transparent electrode layer is formed, thereby reducing the electrical resistance during power generation and improving the power generation efficiency. It was confirmed that the solar cell made can be manufactured.

DESCRIPTION OF SYMBOLS 11 Transparent substrate 12 Front surface side electrode layer 13 Power generation layer 14 Back side transparent electrode layer 16 Back side reflective electrode layer

Claims (6)

A solar cell in which a silicon-based power generation layer is formed on the surface-side electrode layer of a transparent substrate having a surface-side electrode layer formed on the surface, and a back-side transparent electrode layer is formed on the power generation layer by a wet coating method. In the manufacturing method,
After the formation of the power generation layer and before the formation of the back side transparent electrode layer, at least a treatment liquid contact treatment for bringing a treatment liquid into contact with the surface of the power generation layer is performed,
For the treatment liquid, water, an aqueous solution, an organic solvent, or a mixed solvent of the water and the organic solvent is used,
When using the water, it is contact-treated with water at 10 to 70 ° C. for 0.5 to 1440 minutes,
When using the aqueous solution, contact treatment with an aqueous solution at 0 to 60 ° C. for 0.5 to 280 minutes,
When using the organic solvent, contact treatment with an organic solvent at 10 to 50 ° C. for 0.5 to 1440 minutes,
When using the said mixed solvent, it is performed by carrying out contact processing for 5 to 720 minutes with a mixed solvent of 25-50 degreeC. The manufacturing method of the solar cell characterized by the above-mentioned.   The method for producing a solar cell according to claim 1, wherein the aqueous solution is a combination of water and a mixture of one compound or two or more compounds selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid and phosphoric acid.   The organic solvent is a single solvent consisting of one compound selected from the group consisting of alcohols, ketones, hydrocarbons, carboxylic acids, sulfonic acids, glycols and glycol ethers, or two or more compounds The method for producing a solar cell according to claim 1, which is a mixed solvent comprising:   2. The solar cell according to claim 1, wherein drying is performed after the treatment liquid contact treatment and before forming the back-side transparent electrode layer, and the drying is performed by reduced-pressure drying, natural drying, air drying, or heat drying. Manufacturing method.   The method for manufacturing a solar cell according to claim 1, wherein after the formation of the back surface side transparent electrode layer, a metal film made of either Ag or Al is formed as a reflective electrode layer on the back surface side transparent electrode layer.   The method for manufacturing a solar cell according to claim 1, wherein the silicon-based power generation layer is a multi-junction type of two or more layers by a combination of amorphous silicon and microcrystalline silicon.

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