JP5545796B2 - Transparent conductive substrate, transparent conductive substrate for dye-sensitized solar cell, and method for producing transparent conductive substrate - Google Patents

Description

  The present invention relates to a transparent conductive substrate having low resistance and excellent transparency and a method for producing the same, and particularly suitable as a transparent conductive substrate for a dye-sensitized solar cell having a first conductive layer and a second conductive layer. The present invention relates to a usable transparent conductive substrate and a manufacturing method thereof.

  In recent years, solar cells, an energy creation method using sunlight, have been against the backdrop of environmental problems such as soaring and depleting fossil fuels, increasing power consumption accompanying economic growth in Asian countries, and increasing carbon dioxide from fossil fuels. It is attracting attention and active research and development.

  Among them, solar cells using crystalline silicon or amorphous silicon are the mainstream. However, a large amount of energy is required to produce crystalline silicon and the like, and the use of silicon is contrary to the original intention of the solar cell in order to save energy. In addition, since silicon is also a basic material for integrated circuits, there is a shortage of silicon due to an increase in silicon demand and an increase in the price of silicon.

  For these reasons, attention has been given to dye-sensitized solar cells that can be manufactured with lower energy and can be manufactured at lower costs than silicon solar cells.

  A typical dye-sensitized solar cell has a transparent oxide electrode (ITO: composite oxide of tin oxide and indium oxide) formed on one side of a glass substrate, and a porous oxide containing the dye on it. Titanium is formed, an electrolyte solution containing iodine and an iodine compound is used as an electrolyte, and a counter electrode (platinum electrode or platinum-carbon electrode) is disposed thereon.

  In general, a glass substrate is used as the substrate, but by using a transparent resin substrate, a light-weight and flexible dye-sensitized solar cell can be produced. It can be enlarged.

The reason why iodine and an iodine compound are used for the electrolyte is that I ⁻ / I ₃ ⁻ is used as a bearer of the redox reaction during power generation. The iodine system is generally used because it is efficient as an electrolyte, but there is a problem that the metal electrode is corroded when a metal material having a lower resistance is used instead of the transparent oxide. Therefore, in order to protect the metal material which corrodes, the method of plating with the metal with corrosion resistance, the method of protecting with a conductive resin, etc. are examined (for example, refer patent document 1, 2).

JP 2008-66212 A JP 2008-226753 A

  The technique described in Patent Document 1 is a configuration in which a conductive resin is formed so as to cover the network-like first conductive portion, and in this configuration, the total light transmittance is reduced due to an excessive conductive resin. At the same time, since a conductive resin that hardly contributes to conductivity is required, it is difficult to say a technique for obtaining a low-cost substrate.

  The technique described in Patent Document 2 has a configuration in which an opening of a mesh-like first conductive layer is embedded with an intermediate resin having a high transmittance and a conductive resin is further coated thereon as a means for solving the above-described problem. It has become. In this configuration, it is not necessary to use a conductive resin that hardly contributes to conductivity, and the total light transmittance is not lowered by the conductive resin, so that it can be said to be an effective configuration.

  In order to obtain sufficient effects of both high transmittance and low resistance with the configuration described in Patent Document 2, a network-like first conductive layer and second conductive layer are shown in the drawing of Patent Document 2. The configuration described in FIG. A schematic diagram is shown in FIG. That is, it is preferable that the surface of the network-like first conductive layer 3 and the intermediate resin layer 4 has the same height and no step. In the case of a dye-sensitized solar cell, since a semiconductor layer such as titanium oxide is further laminated on the transparent conductive substrate 1, the flatness of the surface of the second conductive layer 5 is also important. Also from this point, it is preferable that the surfaces of the network-like first conductive layer 3 and the intermediate resin layer 4 have the same height and no step.

  On the other hand, when there is a step in the vertical height of the mesh-like first conductive layer 3, the structure shown in FIG. 2B or FIG. 2C can be considered. In the case of FIG. 2B, in order to obtain uniform thickness control and flatness of the second conductive layer 5, a large amount of conductive resin is required, and there is a concern that the transmittance is reduced. Further, in order to embed the intermediate resin only in the opening, a mesh-like masking is used so that the intermediate resin is not covered on the mesh-like first conductive layer 3 or the intermediate resin is applied to the entire surface and then the mesh is formed. It is easily conceivable that a process of chemically or physically removing only the intermediate resin 4 on the first conductive layer 3 having a shape is required. In the case of the configuration of FIG. 2C, it is difficult to electrically connect the mesh-like first conductive layer 3 and the second conductive layer 5 and it is difficult to obtain low resistance. it is obvious.

  In the description of Patent Document 2, there is a description that “the intermediate resin layer 4 may be 5Ω / □ in a state where the intermediate resin layer 4 is laminated on the first conductive layer 3”. The formation state of the intermediate resin layer 4 depends on the structure (specifically, variation in height), and the first conductive layer 3 must be formed strictly in order to achieve the stated 5Ω / □ or less. It may be important.

  Considering the importance of the structural control of the first conductive layer (the uniformity of the height in the vertical direction) as described above, a method for producing the first conductive layer will be examined.

  By using the screen printing method described in the example of Patent Document 2, it can be said that the vertical height of the mesh-like first conductive layer can be controlled to some extent. However, this method remains a problem for forming a network-like first conductive layer on a large-area substrate at a low cost. In addition, there is a method of applying a metal fine particle described in the text of Patent Document 2 on the entire surface of the substrate and then performing an etching process in a mesh shape, a method of digging a groove in the substrate, and filling the groove with the metal fine particle, etc. It can be said that there remains a problem in producing a network-like first conductive layer in a large area at a low cost.

  As a method for forming a network-like first conductive layer, a method using a metal fine particle dispersion is disclosed as a method capable of increasing the area at low cost (see, for example, Patent Documents 3 and 4). In this method, simply by applying a dispersion solution of metal fine particles onto a substrate and drying, the metal fine particles form a network structure due to the self-organization phenomenon, and then conducting high heat transmission and low resistance by heat treatment and chemical treatment. It is possible to form a conductive layer.

  However, when the inventors conducted a supplementary examination with reference to Patent Documents 3 and 4 described above, the aggregation of the metal fine particles due to the self-organization phenomenon does not occur uniformly in each location. It turned out to be difficult to control the height in the vertical direction.

As described above, at present, after the first conductive layer is formed, the opening is embedded with an intermediate resin having a high transmittance, and finally the second conductive layer is covered, thereby having a high transmittance. It is difficult to produce a low-resistance transparent conductive substrate at low cost.
WO2005 / 115070 JP 2007-234299 A

  Furthermore, in order to reduce the resistance value of the first conductive layer of the metal fine particles as much as possible, it is necessary to promote the sintering of the metal fine particles by heating as much as possible. The softening temperature is limited. For this reason, it is necessary to use metal fine particles that are restricted in heat resistance of the substrate or that are sintered at a low temperature, whether it is screen printing or application of the metal fine particle dispersion solution, in order to form the network-like first conductive layer.

  An object of the present invention is to provide a transparent conductive substrate having a first conductive layer and a second conductive layer, which has low resistance and excellent transparency, and a manufacturing method capable of manufacturing the transparent conductive substrate at low cost. is there.

The present invention according to claim 1 is a method for manufacturing a transparent conductive substrate, wherein the transparent conductive substrate is manufactured by the following manufacturing steps 1 to 4.
1. A metal fine particle dispersion solution is applied on a substrate and dried, and a first conductive layer forming step 2 for forming a network-like first conductive layer on the substrate. The first conductive layer is completely covered. Adhesive layer laminating step 3 for laminating a transparent adhesive layer, the pressure-sensitive adhesive layer surface and the substrate to be transferred are bonded and pressed, then the substrate is peeled off, and the first conductive layer and the adhesive layer are integrated. Transfer step 4 for transferring the transfer layer to the substrate to be transferred, second conductive layer forming step for laminating the second conductive layer on the surface of the transferred transfer layer

According to a second aspect of the present invention, in the method for manufacturing a transparent conductive substrate, the transparent conductive substrate is manufactured by the following manufacturing steps 1 to 4.
1. A metal fine particle dispersion solution is applied on a substrate and dried, and a first conductive layer forming step 2 for forming a network-like first conductive layer on the substrate. A transparent adhesive layer is formed on the substrate to be transferred. Lamination adhesive layer laminating step 3, the first conductive layer surface and the substrate to be transferred are bonded, heated and pressurized, then the substrate is peeled off, and the first conductive layer and the adhesive layer are integrated into a transfer layer Transfer step 4 for transferring the substrate to the transfer substrate, and a second conductive layer forming step for laminating the second conductive layer on the surface of the transferred transfer layer

  According to a third aspect of the present invention, in the first conductive layer forming step, after a metal salt solution, which is a precursor of metal fine particles, is applied to a substrate and dried, the precursor of the metal fine particles is heated. Alternatively, the transparent conductive layer according to claim 1 or 2, wherein the transparent conductive layer is a first conductive layer forming step in which a net-like first conductive layer is formed on a substrate by reduction deposition with ultraviolet irradiation or a reducing gas. It is a manufacturing method of a conductive substrate.

  The present invention according to claim 4 includes a step of performing heat treatment and / or chemical treatment on the first conductive layer between the first conductive layer forming step and the adhesive layer laminating step. The method for producing a transparent conductive substrate according to any one of claims 1 to 3.

  The present invention according to claim 5 is characterized in that the substrate is subjected to a surface treatment prior to applying the metal fine particle dispersion solution or the metal salt solution to the substrate. It is a manufacturing method of the transparent conductive substrate given in any 1 paragraph.

  The present invention described in claim 6 is characterized in that the thickness of the adhesive layer is higher than the height of the first conductive layer, and the first conductive layer is not in contact with the transfer substrate. It is a manufacturing method of the transparent conductive substrate of any one of 1-5.

  The present invention according to claim 7 is a transparent conductive substrate obtained by the method for producing a transparent conductive substrate according to any one of claims 1 to 6.

  The present invention according to claim 8 is characterized in that the maximum step between the first conductive layer and the adhesive layer is 300 nm or less, and the surface resistance value of the surface is 5 Ω / □ or less. It is a transparent conductive substrate of description.

The present invention of claim 9 is a transparent conductive substrate according to claim 7 or 8, wherein the adhesive layer is acrylic Le viscosity adhesive.

  A tenth aspect of the present invention is the transparent conductive substrate according to any one of the seventh to ninth aspects, wherein the second conductive layer is resistant to an electrolyte solution. This is a transparent conductive substrate for a dye-sensitized solar cell.

  According to the method for producing a transparent conductive substrate according to the present invention, since the method for forming the first conductive layer using a dispersion solution of metal fine particles or a metal salt solution that is a precursor of metal fine particles is used, the cost is low. A large-area network-like first conductive layer can be formed. Furthermore, by using a heat-resistant substrate, a heat treatment sufficient for sintering the metal fine particles can be performed, and a low-resistance transparent conductive film can be obtained. Subsequently, the surface of the transfer layer in which the first conductive layer and the adhesive layer are integrated is obtained by transferring the network-like first conductive layer onto a desired substrate via a highly transparent adhesive layer. It becomes flat, the thickness of the second conductive layer covering the surface can be controlled, the electrical connectivity is improved, and high transmittance and low resistance can be satisfied at the same time.

  Moreover, by making the thickness of the adhesive layer higher than the height of the first conductive layer, the adhesive layer can be brought into contact with the entire surface of the substrate, and the adhesive force is improved.

  Further, according to the method for producing a transparent conductive substrate according to the present invention, high transmittance and low resistance are satisfied at the same time, and the flatness of the surface of the second conductive layer is high. It can be suitably used as a conductive substrate.

It is a figure which shows typically the manufacturing method of the transparent conductive substrate 20 as one Embodiment of this invention. It is a figure which shows the manufacturing method of the conventional transparent conductive substrate 1 typically.

  The method for producing a transparent conductive substrate according to the present invention generally includes applying a dispersion of metal fine particles on a substrate in advance and drying to form a network-like first conductive layer, and then if necessary. The first conductive layer is subjected to heat treatment and / or chemical treatment, and then the network-like first conductive layer is transferred onto the transfer substrate via a highly transparent adhesive layer, and after the transfer The surface of the transfer layer is coated with a second conductive layer to produce a transparent conductive substrate.

  FIG. 1 is a diagram schematically showing a method for producing a transparent conductive substrate as one embodiment of the present invention. Hereinafter, the manufacturing method will be described using the transparent conductive substrate 20 for a dye-sensitized solar cell as an example.

  First, a dispersion solution of metal fine particles is applied on the substrate 2 and dried to form the first conductive layer 3 made of a network structure on the substrate 2. Further, heat treatment and / or chemical treatment is performed on the first conductive layer 3 as necessary. Thereby, the base material 2 on which the first conductive layer 3 made of a network structure is laminated can be obtained. FIG. 1A shows a base material 2 on which a first conductive layer 3 is laminated.

  The metal fine particle dispersion solution that can be used here forms a network structure by self-organization after coating and drying on the base material 2, and heat treatment and chemical treatment of the laminated base material as necessary. Any metal fine particle dispersion solution may be used as long as the network structure exhibits low resistance and high transmittance by performing the treatment or any treatment. In place of the metal fine particle dispersion solution, a metal salt solution (hereinafter referred to as a metal fine particle precursor solution) that is a precursor of metal fine particles capable of forming a network structure can also be used. In the case of a metal fine particle precursor solution, after applying to the substrate 2 having heat resistance and / or chemical resistance and drying, the metal fine particle precursor is reduced or precipitated by heating, ultraviolet irradiation or a reducing gas. A shaped structure can be obtained.

  The metal fine particles contained in the metal fine particle dispersion solution or the metal fine particle precursor solution are Au, Ag, Cu, Ni, Co, Fe, Cr, Zn, Al, Sn, Pd, Ti, Ta, W, Mo, In, Metal fine particles such as Pt and Ru, metal alloy fine particles, metal oxide fine particles or metal sulfide fine particles, carbon fine particles containing carbon, so-called nanocarbon materials such as carbon nanotubes, fullerenes, and carbon nanohorns, or silicon fine particles containing silicon Silicon alloy fine particles, silicon oxide fine particles, silicon carbide fine particles, or silicon nitride fine particles of silicon and other metals can be used. In consideration of obtaining oxidation resistance and a low-cost conductive substrate, a metal fine particle dispersion of Au or Ag or a metal fine particle precursor solution is preferable.

  Methods for preparing fine metal particles include conventional gas phase methods (evaporation in gas, etc.), liquid phase methods (liquid phase reduction methods using metal salts and reducing agents), and thermal decomposition methods (thermal decomposition of metal complexes). Or the like) can be used.

  The average particle diameter of the metal fine particles is preferably 10 nm or more and 1 μm or less. More preferably, the average particle size is 10 nm to 500 nm. More preferably, the average particle size is 50 nm to 200 nm. When the average particle diameter exceeds 1 μm or less than 10 nm, a well-developed network structure is difficult to obtain, and as a result, low resistance and high transmittance are difficult to obtain.

As the metal fine particle dispersion solution or the metal fine particle precursor solution as described above, for example, a metal fine particle dispersion solution or a metal fine particle precursor solution prepared with reference to Patent Documents 5 to 7 can be used.
JP 2007-234299 A JP 2005-530005 Gazette Japanese Patent Laid-Open No. 10-312715

  The base material 2 is for applying a metal fine particle dispersion solution or a metal fine particle precursor solution to stably form a network structure, and does not corrode or dissolve in an organic solvent contained in the metal fine particle dispersion solution. There is no particular limitation as long as the electrical properties (resistance value) and optical properties (transmittance) of the network structure are not deteriorated by the subsequent heat treatment or chemical treatment. In addition, after apply | coating and drying a metal fine particle precursor solution on the base material 2, when carrying out reduction | restoration precipitation of the metal fine particle precursor with heating, ultraviolet irradiation, or a reducing gas, it has resistance to these operation. It goes without saying that there must be.

  Further, the smoothness of the surface 6 is important for the substrate 2. Since the first conductive layer 3 made of a network structure formed on the base material 2 is transferred onto the transfer substrate 8 via the adhesive layer 7, the first conductive layer on the base material 2 The bottom surface 9 is a surface on the transfer substrate 8. For this reason, when the smoothness of the surface 6 of a base material is low, the smoothness of the surface 11 of the transparent conductive substrate 20 finally obtained will become low.

  Further, the surface of the base material 2 to which the metal fine particle dispersion solution or the metal fine particle precursor solution is applied is preliminarily formed with a reproducible network structure by the metal fine particles or the metal fine particle precursor. It is preferable to perform cleaning by alkali treatment. Although the said method is not specifically limited, It is preferable to perform the process suitable for each metal fine particle dispersion solution or metal fine particle precursor solution.

  Moreover, it is preferable to provide a release layer (not shown) on the base material 2 in advance so that the first conductive layer 3 on the base material 2 can be smoothly transferred to the transfer substrate 8 without being broken. The release layer is formed by coating with a dry thickness of 0.01 to 1.0 μm as a coating liquid such as a silicone polymer or a fluorine polymer. The release layer is treated to such an extent that it does not interfere with the self-organization phenomenon of the metal fine particles or metal fine particle precursor.

  As the base material 2, it is preferable to use a less expensive resin film industrially. Specifically, a resin film of polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, polyphenylene sulfide, or the like can be used. In consideration of operability during transfer, the substrate 2 preferably has flexibility. The substrate 2 can be used repeatedly. As for the thickness of the base material 2, 6-200 micrometers is preferable. Further, preferably, a thickness of 12 to 150 μm is used. Particularly preferably, one having a thickness of 25 to 125 μm is used.

  As a method for applying the metal fine particle dispersion solution or the metal fine particle precursor solution onto the base material 2, for example, a bar coater, a dip coater, a spray coater, a die coater, a spin coater, or the like, generally used by those skilled in the art at the time of coating I can do it.

  After the application, it is possible to use a stationary drying method, a method of drying while passing a gas such as air at a constant flow rate, or a method of combining heating.

  After the metal fine particle dispersion is applied and dried, the network structure is preferably subjected to heat treatment and / or chemical treatment. The chemical treatment is mainly intended to remove the dispersant or resin contained in the metal fine particles and lower the resistance value of the network structure, and is immersed in an organic solvent and an inorganic acid or an organic acid. It is preferable. Examples of the organic solvent include ketones such as acetone and methyl ethyl ketone, and alcohols such as methanol, ethanol and isopropanol. Ketones such as acetone are preferred. Examples of the inorganic acid or organic acid include hydrochloric acid, nitric acid, formic acid, and acetic acid, and hydrochloric acid or formic acid is preferable. After the immersion, it is preferable to rinse with pure water or ethanol and then dry by standing drying or heat drying.

  Furthermore, it is more preferable to perform heat treatment for the purpose of promoting the sintering of the metal fine particles and lowering the resistance value. Although heat processing temperature changes with the base materials 2 to be used, in order to obtain sufficient electroconductivity, the range of 100-300 degreeC is preferable. More preferably, it is 100-200 degreeC.

  In the case of reducing the metal fine particle precursor, heating, light irradiation such as ultraviolet rays or radiation, or a reducing gas method can be combined.

  The total light transmittance of the first conductive layer 3 made of the network structure described above is 70% or more, more preferably 80% or more.

  Next, in order to transfer the first conductive layer 3 made of a network structure formed on the base material 2 to a desired substrate 8 to be transferred, the first conductive layer 3 is formed as shown in FIG. The entire surface of the laminated substrate 2 is covered with a highly transparent adhesive to form an adhesive layer 7. At this time, it is important that all the openings 12 of the first conductive layer 3 are filled with the adhesive and the openings 12 are embedded with the adhesive. Since the first conductive layer 3 is transferred integrally with the adhesive layer 7 in the next step, the surface of the first conductive layer that is the bottom surface 9 on the substrate 2 becomes the surface after transfer. (FIGS. 1C and 1D). For this reason, if the opening 12 of the first conductive layer 3 is not completely buried with the adhesive, the surface 14 of the transfer layer 10 (the first conductive layer and the adhesive layer) after the transfer is locally perforated. Opened. In the next step, the surface of the transfer layer 10 is further coated with a resin that forms the second conductive layer 5. Therefore, if a hole is locally formed in the surface of the transfer layer 10, the surface of the second conductive layer 5 Is not preferable because the resin does not become flat or the resin forming the second conductive layer 5 enters the hole and lowers the transmittance.

  Further, the thickness of the pressure-sensitive adhesive layer 7 is set to a height slightly exceeding the height of the first conductive layer 3. In the present invention, the height of the first conductive layer 3 refers to the maximum height in the first conductive layer 3. The adhesive layer 7 is transferred integrally with the first conductive layer 3 to the transfer substrate 8 in the next step. For this reason, the surface 13 of the pressure-sensitive adhesive layer 7 which is the surface on the base material 2 becomes a surface in contact with the substrate to be transferred 8 after the transfer. For this reason, if the first conductive layer 3 on the substrate 2 is not completely covered with the adhesive layer 7, sufficient adhesive strength cannot be obtained after transfer. If the height of the pressure-sensitive adhesive layer 7 is the same as the height of the first conductive layer 3, it is not preferable because a portion where no pressure-sensitive adhesive is locally present on the adhesive surface with the substrate 8 to be transferred after transfer. On the other hand, if the thickness of the pressure-sensitive adhesive layer 7 is increased more than necessary, the transmittance decreases, which is not preferable.

  The adhesive layer 7 may be provided on one surface of the transfer substrate 8 instead of being provided on the substrate 2 side.

Various adhesives including acrylic Le viscosity Chakuzai as adhesives used in the adhesive layer 7 is available and then butyl acrylate, ethyl acrylate, the low Tg monomers, such as 2-ethylhexyl acrylate as a main monomer, Acrylic copolymers obtained by copolymerizing with functional monomers such as acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide, and acrylonitrile can be used as known crosslinking agents such as isocyanates, melamines, and epoxies. And can be obtained by crosslinking.

  Moreover, an ultraviolet absorber, a color pigment, an antistatic agent, an antioxidant, a silane coupling agent, and the like can be appropriately used as necessary for the adhesive layer 7 as additives.

  The pressure-sensitive adhesive layer 7 is formed by preparing a coating agent in which the above-mentioned pressure-sensitive adhesive material is dissolved in an organic solvent or water or dispersed in water to adjust the viscosity, and is applied and dried by a conventionally known coating method such as gravure coating or spin coating. Can be used. The thickness of the adhesive layer 7 is preferably 0.5 to 50 μm, more preferably 1 to 30 μm. When the thickness of the pressure-sensitive adhesive layer 7 is less than 0.5 μm, the opening 12 of the first conductive layer 3 is not completely embedded with the pressure-sensitive adhesive, and the surface 14 of the transfer layer 10 after the transfer is locally perforated. It becomes. In the next step, the surface 14 of the transfer layer 10 is further coated with a resin that forms the second conductive layer 5. Therefore, if a hole is locally formed in the surface 14 of the transfer layer 10, the second conductive layer 5 This is not preferable because the surface is not flat, or the resin forming the second conductive layer 5 enters the hole and lowers the transmittance. Moreover, since the transmittance | permeability of the transparent conductive substrate 20 will fall when the thickness of the adhesion layer 7 is thicker than 50 micrometers, it is unpreferable.

  Next, as shown in FIG. 1 (c), after the base material 2 and the substrate 8 to be transferred are bonded together, heat treatment, pressure treatment, etc. are performed as necessary, and the base material 2 is peeled off. The conductive layer 3 is transferred to the transfer substrate 8 through the adhesive layer 7. A known transfer method can be used as the transfer method, and it may be appropriately selected according to the base material 2 and the material of the substrate 8 to be transferred and the adhesive layer. For example, a method of transferring through a laminator, a method of transferring with a press machine, or the like can be used.

  The surface 14 of the transfer layer 10 on the transfer substrate 8 obtained as described above is very flat because the substrate 2 is peeled after the substrate 2 and the transfer substrate 8 are bonded together. Yes (FIG. 1 (d)), the step difference between the first conductive layer 3 and the adhesive layer 7 after transfer is 300 nm or less so that the surface resistance value of the surface of the transfer layer 10 is 5Ω / □ or less. To do. It is preferable to perform transfer so that the rate of increase of the surface resistance value after transfer is 10% or less with respect to the surface resistance value of the first conductive layer 3 prepared by the above-described manufacturing method. When the rate of increase in the surface resistance value after transfer is 10% or more, the adhesive layer 7 is inserted between the first conductive layer 3 and the second conductive layer 5 and includes the second conductive layer 5. Further, the surface resistance value of the transparent conductive substrate 20 is increased, which is not preferable.

  Even when the adhesive layer 7 is provided on the transfer substrate 8 instead of the substrate 2 and the first conductive layer 3 is transferred to the transfer substrate 8, the first conductive layer surface of the substrate 2 and the transfer substrate 8 The first conductive layer 3 is embedded in the adhesive layer 7 with the bottom surface 9 of the first conductive layer 3 left, and after transfer, the base material 2 is peeled off, whereby the adhesive layer is applied to the base material 2. The same state as when 7 is provided can be obtained.

  The substrate 8 to be transferred can be selected widely depending on each application. Examples thereof include glass, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, polyphenylene sulfide, polyethylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, acrylic resin, Si substrate, porous ceramics, and the like. Among these, it is preferable to use a resin film such as polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, polyphenylene sulfide and the like because it can be produced at low cost by roll-to-roll.

  Next, a resin containing a conductive resin is applied to the surface 14 of the transfer layer after transfer to form the second conductive layer 5 (FIG. 1 (e)).

  The second conductive layer 5 is preferably formed by applying and drying a coating liquid mainly composed of a conventionally known conductive polymer. Although there is no restriction | limiting in particular in the kind of electrically conductive polymer, Polythiophene, polyaniline, polypyrrole, its derivative (s), and mixtures thereof can be mentioned as a preferable electrically conductive polymer. Among them, a complex of poly (3,4-dialkoxythiophene) and polyanion is particularly preferable because of its excellent transparent conductivity. The solvent or dispersion medium contained in the conductive polymer coating solution is not particularly limited as long as it can dissolve or disperse the conductive polymer, and any of water, aqueous solvents, and organic solvents can be used.

  As a method for applying and drying the conductive polymer, a coating agent in which the above-mentioned pressure-sensitive adhesive material is dissolved in an organic solvent or water or dispersed in water to adjust the viscosity is prepared and applied by a conventionally known coating method such as gravure coating or spin coating. A drying method can be used.

  In the case of an aqueous solvent, a mixed solvent of water and an organic solvent miscible with water can be used. The organic solvent miscible with water is not particularly limited, and examples thereof include the following solvents: alcohols such as methanol, ethanol, 2-propanol, 1-propanol, n-butanol; ethylene glycol, diethylene glycol, triethylene Ethylene glycols such as glycol and tetraethylene glycol; glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether and diethylene glycol dimethyl ether; ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, Glycol ethers such as diethylene glycol monobutyl ether acetate Acetates; propylene glycols such as propylene glycol, dipropylene glycol, tripropylene glycol; propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, propylene glycol dimethyl ether, dipropylene glycol Propylene glycol ethers such as dimethyl ether, propylene glycol diethyl ether, dipropylene glycol diethyl ether; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether Propylene glycol ether acetates such as Tate; N- methylformamide, N, N- dimethylformamide, N- methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, acetone, acetonitrile and their blends.

  When the solvent or dispersion medium is an organic solvent system, the above-mentioned solvents that are miscible with water and the solvents that are immiscible with water may be mentioned. The latter includes toluene, xylene (o-, m-, or p-xylene). ), Benzene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, diethyl ether, diisopropyl ether, methyl-t-butyl ether, hexane, heptane, and the like. Normally, when the conductive polymer and the additive contained as necessary are completely dissolved in the solvent, the solvent is a “solvent” and any component is not dissolved but is dispersed. The case is described as “dispersion medium”.

  When the second conductive layer 5 of the present invention is a conductive polymer, a conductivity improver can be included for the purpose of improving the conductivity. As such a conductivity improver, an organic solvent miscible with water is used. For example, ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, catechol, cyclohexanediol, diethylene glycol monoethyl Examples include ether, cyclohexanedimethanol, glycerin, dimethyl sulfoxide, N-methylpyrrolidone, N-methylformamide, N, N-dimethylformamide, γ-butyrolactone, isophorone, propylene carbonate, and cyclohexanone. These may be used individually by 1 type and may use 2 or more types together. These organic solvents may be used also as a solvent or a dispersion medium. When the conductivity improver is contained, the amount is not particularly limited, but it is usually contained in the composition at a ratio of 95% by mass or less.

The conductive polymer coating liquid preferably contains a binder because scratch resistance and surface hardness of the coating film are increased, and resistance to the electrolyte solution is improved.
The binder may be a thermosetting resin or a thermoplastic resin. For example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyimides; polyamide imides; polyamides such as polyamide 6, polyamide 6, 6, polyamide 12, and polyamide 11; polyvinylidene fluoride, polyvinyl fluoride, polytetrafluoroethylene Fluoropolymers such as ethylene tetrafluoroethylene copolymer and polychlorotrifluoroethylene; vinyl resins such as polyvinyl alcohol, polyvinyl ether, polyvinyl butyral, polyvinyl acetate, and polyvinyl chloride; epoxy resins; xylene resins; aramid resins; Polyurea; polyurea; melamine resin; phenol resin; polyether; acrylic resin and copolymers thereof. These binders may be dissolved in an organic solvent, may be provided with a functional group such as a sulfonic acid group or a carboxylic acid group, may be formed into an aqueous solution, or may be dispersed in water such as emulsification.

  The content of the binder is preferably 0.1 to 1000 times, more preferably 1 to 100 times the amount of the conductive polymer. When the content of the binder is less than the lower limit, the film strength of the resulting conductive coating film tends to be low. When the content exceeds the upper limit, there is a decrease in conductivity due to a decrease in the conductive polymer concentration. May happen.

  The thickness of the second conductive layer 5 is preferably 0.1 to 10 μm, more preferably 0.2 to 3.5 μm. When it is less than 0.1 μm, iodine resistance is lowered. If it exceeds 10 μm, the transparency deteriorates.

  The transparent conductive substrate 20 obtained by the above manufacturing method is transparent for a dye-sensitized solar cell because the second conductive layer 5 has resistance to an electrolyte solution, and has low resistance and excellent transparency. It can be suitably used as a substrate.

  The measurement of the electrical resistance of the transparent conductive substrate was measured in accordance with JIS-K-7194 using a series 4-probe probe (ASP) in Loresta-GP (manufactured by Dia Instruments, model number: MCP-T610). The four-terminal four-probe method was used.

  The optical transmittance was evaluated as the total light transmittance. The transparent conductive substrate was measured according to JIS K-7105 using a haze meter (model number: NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

  The iodine electrolyte solution used for evaluation was the content of a commercially available dye-sensitized solar cell production kit (manufactured by Nishinoda Electric Co., Ltd.). The iodine electrolyte solution was applied onto the produced transparent conductive substrate, and allowed to stand in the dark at room temperature for 24 hours. The iodine electrolyte solution was washed with pure water and ethanol and then dried, and the surface resistance value was compared after the transparent conductive substrate was produced and after the iodine resistance test.

Example 1
<Preparation method of silver fine particles 1>
The liquid phase reduction preparation method of silver fine particles will be described as an example of the metal fine particles, but the type and production method of the metal fine particles are not limited.
40 g of silver nitrate, 37.9 g of butylamine, and 200 mL of methanol were added and stirred for 1 hour to prepare solution A. Separately, 62.2 g of isoascorbic acid was taken, 400 mL of water was added and dissolved by stirring, and then 200 mL of methanol was added to prepare solution B. B liquid was stirred well and A liquid was dripped at B liquid over 1 hour and 20 minutes. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid. After removing the supernatant by decantation, 500 mL of water was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times. The settled solid was dried in a dryer at 40 ° C. to remove moisture. Furthermore, 20 g of the obtained silver fine particles and 0.2 g of DISPERBYK-106 (manufactured by Big Chemie Japan) were mixed in a mixed solution of 100 mL of methanol and 5 mL of pure water, mixed for 1 hour, and then 100 mL of pure water was added. After filtering the slurry, the slurry was dried in a dryer at 40 ° C. to obtain silver fine particles 1. Silver fine particles had an average primary particle diameter of 60 nm as observed with an electron microscope.

<Preparation of silver fine particle dispersion 2>
The dispersion of silver fine particles was prepared with reference to Patent Document 6 (prepared with reference to JP 2005-530005 A).
That is, 4 g of the silver fine particles 1, 30 g of toluene, and 0.2 g of BYK-410 (manufactured by Big Chemie Japan) were mixed, and subjected to a dispersion treatment for 1.5 minutes with an ultrasonic disperser with an output of 180 W to obtain 15 g of pure water. Was added, and the obtained emulsion was subjected to a dispersion treatment for 30 seconds with an ultrasonic disperser with an output of 180 W to prepare a silver fine particle dispersion solution 2.

<Method for forming first conductive layer>
The silver fine particle dispersion 2 was coated on a polyethylene terephthalate substrate having a thickness of 100 μm having a silicone release treatment on the surface using a bar coater. Subsequently, by spontaneous drying in the air, the silver fine particles formed a network structure by the self-organization phenomenon. Next, after heating at 150 ° C. for 2 minutes, each was immersed in acetone and 1N hydrochloric acid, and then heated and dried at 150 ° C. for 5 minutes to form a first conductive layer. After the first conductive layer was formed on the substrate, the total light transmittance was 85%, and the surface resistance value was 4.5Ω / □.

<Formation of adhesive layer>
The thickness after drying the following adhesive layer coating solution 1 on the first conductive layer surface side of the substrate on which the first conductive layer is formed is 5.1 μm (Example 1), 6.0 μm (Example 2). , 6.5 μm (Example 3), and dried at a temperature of 100 ° C. for 5 minutes to form an adhesive layer.

<Adhesive layer coating solution 1>
An adhesive layer coating solution 1 was prepared by dissolving in 30 g of a copolymer of butyl acrylate and hydroxybutyl acrylate, 1 g of an isocyanurate of tolylene diisocyanate and 69 g of ethyl acetate.

<Transfer>
A hot laminator (manufactured by Taisei Laminator, Taisei First Laminator) is made to face the surface of the polyethylene terephthalate substrate having a thickness of 100 μm on which the first conductive layer and the adhesive layer are formed on the surface of a polyethylene terephthalate substrate having a thickness of 125 μm. VAII-700) was pressed at room temperature, the polyethylene terephthalate substrate was peeled off, and the first conductive layer and the adhesive layer were transferred onto the polyethylene terephthalate substrate.

<Formation of second conductive layer>
Conductive polymer coating liquid (manufactured by TAEI Chemical, BaytronP) and thermosetting melamine resin (manufactured by Sanwa Chemical Co., Ltd., Nicalac MW-30) are solid on the surface of the transfer layer. Weight: The solid coating weight of the thermosetting melamine resin = 40: 60 The coating solution mixed at a ratio of 40:60 was applied with an applicator so that the thickness of the second conductive layer after drying was 1 μm. A transparent conductive substrate was produced by drying for a minute.

<Iodine resistance evaluation results>
Table 1 shows the surface resistance value and total light transmittance of the produced transparent conductive substrate and the iodine resistance of the transparent conductive substrate produced in Examples 1 to 3.

Comparative Example 1
The first conductive layer was formed on the polyethylene terephthalate substrate by the method of Example 1. When the cross section of the substrate was observed by SEM, the height of the first conductive layer had a width of 2 μm to 5 μm. The surface resistance value was 4.5Ω / □, and the total light transmittance was 85%. On the substrate on which the first conductive layer was produced, the pressure-sensitive adhesive layer coating solution 1 was formed by applying and drying with an applicator so as to have a thickness of 3 μm. The surface resistance value of the coating layer of the obtained substrate was 5.5Ω / □, and the total light transmittance was 85%. Subsequently, the same conductive coating liquid as in Examples 1 to 3 was applied as the second conductive layer so that the thickness after drying was 1 μm, and then dried. The surface resistance value of the obtained base material was 5.8 Ω / □, which was 24% higher than that of the first conductive layer. The total light transmittance was 81%.

Comparative Example 2
As in Example 1, a first conductive layer was formed on a polyethylene terephthalate substrate. When the cross section of the substrate was observed by SEM, the height of the first conductive layer had a width of 2 μm to 5 μm. The surface resistance value was 4.5Ω / □, and the total light transmittance was 85%. On the substrate on which the first conductive layer was produced, the adhesive layer coating solution 1 was applied with an applicator so as to have a thickness of 1 μm and dried to form an adhesive layer. The surface resistance value of the coating layer of the obtained base material was 4.5Ω / □, and the total light transmittance was 83%. Subsequently, the same conductive coating liquid as in Examples 1 to 3 was applied as the second conductive layer so that the thickness after drying was 4 μm, and then dried. The obtained substrate had a surface resistance of 4.6Ω / □ and a total light transmittance of 66%, which was deteriorated in transparency.

2 Substrate 3 First conductive layer 5 Second conductive layer 7 Adhesive layer 8 Substrate to be transferred 10 Transfer layer 14 Transfer layer surface 20 Transparent conductive substrate

Claims (9)

In the manufacturing method of a transparent conductive substrate, it manufactures in the manufacturing process of the following 1 to 4, The manufacturing method of the transparent conductive substrate characterized by the above-mentioned.
1. A metal fine particle dispersion solution is applied on a substrate and dried, and a first conductive layer forming step 2 for forming a network-like first conductive layer on the substrate. The first conductive layer is completely covered. A pressure-sensitive adhesive layer laminating step for laminating a transparent pressure-sensitive adhesive layer, wherein the thickness of the pressure-sensitive adhesive layer is higher than the height of the first conductive layer, and the first conductive layer is not in contact with the substrate to be transferred; The pressure-sensitive adhesive layer laminating step 3 in which the difference between the thickness of the pressure-sensitive adhesive layer and the height of the first conductive layer is 1.5 μm or less, the pressure-sensitive adhesive layer surface and the substrate to be transferred are bonded, heated and pressurized, Transfer step 4 for transferring the transfer layer in which the first conductive layer and the adhesive layer are integrated to the substrate to be transferred, and the second conductive layer for laminating the second conductive layer on the surface of the transferred transfer layer. Layer formation process In the manufacturing method of a transparent conductive substrate, it manufactures in the manufacturing process of the following 1 to 4, The manufacturing method of the transparent conductive substrate characterized by the above-mentioned.
1. A metal fine particle dispersion solution is applied on a substrate and dried, and a first conductive layer forming step 2 for forming a network-like first conductive layer on the substrate. A transparent adhesive layer is formed on the substrate to be transferred. A pressure-sensitive adhesive layer laminating step in which the thickness of the pressure-sensitive adhesive layer is higher than the height of the first conductive layer, the first conductive layer is not in contact with the substrate to be transferred, and the thickness of the pressure-sensitive adhesive layer Adhesive layer laminating step 3 in which the height difference between the first conductive layer and the first conductive layer is 1.5 μm or less, the first conductive layer surface and the substrate to be transferred are bonded and pressed, and then the substrate is peeled off. , A transfer step 4 for transferring the transfer layer in which the first conductive layer and the adhesive layer are integrated to the substrate to be transferred, a second conductive layer forming step for laminating the second conductive layer on the surface of the transferred transfer layer In the first conductive layer forming step, a solution of a metal salt, which is a precursor of metal fine particles, is applied to a substrate and dried, and then the metal fine particle precursor is reduced or precipitated by heating, ultraviolet irradiation or a reducing gas. 3. The method for producing a transparent conductive substrate according to claim 1, wherein the first conductive layer is formed by forming a network-like first conductive layer on a base material. 4. The method according to claim 1, further comprising a step of performing heat treatment and / or chemical treatment on the first conductive layer between the first conductive layer forming step and the adhesive layer laminating step. The manufacturing method of the transparent conductive substrate of any one of Claims 1. 5. The transparent conductive material according to claim 1, wherein a surface treatment is applied to the base material prior to applying the metal fine particle dispersion solution or the metal salt solution to the base material. 6. A method for manufacturing a substrate. It is a transparent conductive substrate obtained by the manufacturing method of the transparent conductive substrate of any one of Claim 1 to 5, Comprising: A to-be-transferred substrate, an adhesion layer, a mesh-shaped 1st conductive layer, and a 2nd conductive The adhesive layer is laminated in order, the thickness of the adhesive layer is higher than the height of the first conductive layer, the first conductive layer is not in contact with the substrate to be transferred, the thickness of the adhesive layer A transparent conductive substrate in which a difference in height of the first conductive layer is 1.5 μm or less. The transparent conductive substrate according to claim 6, wherein a maximum level difference between the first conductive layer and the adhesive layer is 300 nm or less, and a surface resistance value of the surface is 5Ω / □ or less. The transparent conductive substrate according to claim 6, wherein the adhesive layer is an acrylic adhesive. The transparent conductive substrate according to any one of claims 6 to 8, wherein the second conductive layer is resistant to an electrolyte solution. Substrate.

Images