JP2011003399A - Method of manufacturing transparent conductive film, and transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a transparent conductive film, in which the transparent conductive film having a double texture structure in a desired shape can be easily manufactured.SOLUTION: The method of manufacturing the transparent conducive film includes a step (S10) of fabricating a forming die having a uneven shape on the surface, a step (S20) of preparing a substrate, a step (S30) of forming a transparent conductive precursor layer including a transparent conductive precursor material and a volatile material on the substrate, a step (S40) of pressing the uneven shape of the forming die against the transparent conductive precursor layer, a step (S50) of volatilizing the volatile material, a step (S60) of releasing the forming die from the transparent conductive precursor layer, and a step (S70) of giving heat treatment to the transparent conductive precursor layer.

Description

  The present invention relates to a transparent conductive film and a method for producing the same, and more particularly to a transparent conductive film used for a solar cell and the like and a method for producing the same.

  In recent years, in order to achieve both cost reduction and high efficiency of a photoelectric conversion device, a thin film solar cell that is preferable from the viewpoint of resources has attracted attention and its development has been vigorously performed.

  Incidentally, one of the important technologies for realizing a highly efficient thin film solar cell is a light confinement effect. The light confinement effect means that the surface of the transparent conductive layer or metal layer in contact with the photoelectric conversion layer is roughened and light is scattered at the interface to extend the optical path length, increasing the amount of light absorbed by the photoelectric conversion layer. It is something to be made.

  There is an effect of reducing the film thickness of the photoelectric conversion layer by improving the photoelectric conversion efficiency by the light confinement effect. Thereby, especially in the case of an amorphous silicon solar cell, light deterioration can be suppressed. In addition, in the case of crystalline silicon solar cells that require thicknesses on the order of several μm, which is several to tens of times that of amorphous silicon due to light absorption characteristics, the film formation time is greatly shortened. Can be In other words, the light confinement can improve all of the high efficiency, stabilization, and cost reduction, which are major issues for the practical application of thin film solar cells.

  For example, Patent Document 1 has, on a glass substrate, a macro unevenness (texture) due to a plurality of discontinuous peaks, and a plurality of flat portions that lie between the peaks, A substrate with a transparent conductive oxide film having a structure (so-called double texture structure) having a large number of micro irregularities (textures) on the outer surface of the flat part is disclosed. By making the outer surfaces of the ridges and the flat part unevenness (micro unevenness) smaller than the unevenness (macro unevenness) by the ridges, it is possible to strongly scatter short-wavelength light and wide as a whole. It becomes possible to effectively scatter the light in the region.

  That is, light having a long wavelength can be scattered by a peak having large unevenness, and light having a short wavelength can be scattered by a small uneven surface, so that a high light scattering property can be achieved as a whole. When such a substrate with a transparent conductive oxide film is used for a thin film solar cell, a solar cell with high photoelectric conversion efficiency can be manufactured. In addition, it is described that all of the irregularities are formed by an atmospheric pressure CVD method.

  In Patent Document 2, a film of a transparent conductive solution to which a metal organic compound or an organic metal complex and, if necessary, an organic compound is added is formed on a substrate, and a stamper having an arbitrary shape is pressed onto the film. A method of manufacturing a transparent electrode having a plurality of protrusions by molding a plurality of protrusions having an uneven shape and heat-treating the film is disclosed.

JP 2005-347490 A Japanese Patent Laying-Open No. 2005-310387

  If the unevenness formed on the glass substrate is too small, the light scattering effect cannot be expected, and if it is too large, the reflection component of the incident light increases and the incident light to the photoelectric conversion layer decreases. Therefore, in order to make the best use of the light confinement effect, it is necessary to precisely control the size and shape of the unevenness and the film thickness of the transparent conductive film.

  However, in the method described in Patent Document 1, since the size of the unevenness changes according to the film thickness of the transparent conductive film, there is a limitation on the combination of the film thickness and the uneven shape. Moreover, it was necessary to form two layers of macro unevenness and micro unevenness, and there was a problem of film peeling at these interfaces. As described above, in the method described in Patent Document 1, there are limitations on the uneven shape and film thickness that can be realized from the viewpoints of film peeling, film forming conditions, and the like, and there are problems in shape controllability and reproducibility. .

  In addition, Patent Document 2 mentions that a film with a metal-organic compound or organometallic complex added with an organic compound can be coated on a film surface on which a concavo-convex pattern has been formed in advance to form a structure with concavo-convex in the order of nm. However, there is no description about the specific method. Moreover, although it is described that a stamper is used as a means for forming unevenness, there is no description about the material and the pressing method. Therefore, in the method described in Patent Document 2, it is difficult to form a transparent conductive film having a double texture structure.

  That is, with the conventional method, it has been difficult to manufacture a transparent conductive film having a desired shape and having a double texture structure with good controllability.

  The present invention has been made in view of the above problems, and a main object thereof is to provide a method for producing a transparent conductive film, which makes it possible to produce a transparent conductive film having a double texture structure of a desired shape by a simple method. It is to be.

  The method for producing a transparent conductive film according to the present invention includes a step of producing a mold having an undulating shape on a surface, a step of preparing a substrate, and a transparent precursor material and a volatile material having conductivity on the substrate. A step of forming a precursor layer including: a step of pressing the undulating shape of the mold against the precursor layer; a step of volatilizing the volatile material; a step of releasing the mold from the precursor layer; Heat-treating the body layer.

  Preferably, for the method for producing the transparent conductive film, the mold includes a first member having an undulating shape and a second member having a Young's modulus smaller than that of the first member, and the first member and the second member are laminated. Has been formed.

  Preferably about the manufacturing method of the said transparent conductive film, a 1st member contains a silicone resin material or a fluorine compound resin material.

  In the step of volatilizing the transparent conductive film, preferably, in the step of volatilizing the precursor layer, the lower limit temperature at which the volatile material volatilizes is Ts, and the lower limit temperature at which the precursor material is crystallized is Tc. <Tc is heated to a temperature T represented by Tc.

  Regarding the method for producing the transparent conductive film, preferably, in the pressing step, undulations reflecting the undulation shape of the molding die are formed on the contact surface that contacts the molding die of the precursor layer. In the heat treatment step, irregularities having a height difference smaller than the undulation are formed on the contact surface so as to overlap the undulation.

  Preferably, the method for producing the transparent conductive film has a relief height difference of 100 nm or more and 15 μm or less, and an uneven height difference of 10 nm or more and 200 nm or less.

  Regarding the method for producing the transparent conductive film, preferably, the precursor material is an element selected from the group consisting of Zn, Sn, Pb, Sb, Cd, Mg, In, Ga, Te, Ag, Cu, Al, and Sr. At least one oxide is included.

Regarding the method for producing the transparent conductive film, the precursor material preferably contains a UV curable material.
About the manufacturing method of the said transparent conductive film, Preferably, the process of repressing a shaping | molding die to a precursor layer is provided between the process of pressing and the process of volatilizing.

  The transparent conductive film according to the present invention is manufactured by the manufacturing method according to any one of the above aspects.

  According to the method for producing a transparent conductive film of the present invention, a transparent conductive film having a double texture structure having a desired shape can be easily produced.

It is a flowchart which shows the manufacturing method of the transparent conductive film of this Embodiment. It is a flowchart which shows the manufacturing method of the shaping | molding die used for manufacture of the transparent conductive film of this Embodiment. It is a cross-sectional schematic diagram which shows the structure of a master type | mold. It is a cross-sectional schematic diagram which shows the state which apply | coated the solution of the rubber raw material to the master type | mold. It is a cross-sectional schematic diagram which shows the state by which the rubber layer was peeled from the master type | mold. It is a cross-sectional schematic diagram which shows the structure of a shaping | molding die. It is a cross-sectional schematic diagram which shows the state which formed the transparent conductive precursor layer on the board | substrate. It is a cross-sectional schematic diagram which shows the state which pressed the shaping | molding die to the transparent conductive precursor layer. It is a cross-sectional schematic diagram which shows the state which released the shaping | molding die from the transparent conductive precursor layer. It is a cross-sectional schematic diagram which shows the transparent conductive film formed by heat processing. It is a cross-sectional schematic diagram which expands and shows the area | region XI vicinity shown in FIG. It is a cross-sectional schematic diagram which expands and shows the area | region XII vicinity shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  In the embodiments described below, each component is not necessarily essential for the present invention unless otherwise specified. In the following embodiments, when referring to the number, amount, etc., unless otherwise specified, the above number is an example, and the scope of the present invention is not necessarily limited to the number, amount, etc.

  FIG. 1 is a flowchart showing a method for manufacturing a transparent conductive film of the present embodiment. With reference to FIG. 1, the manufacturing method of the transparent conductive film of this Embodiment is demonstrated. As shown in FIG. 1, first, in a process (S10), a shaping | molding die is produced.

  FIG. 2 is a flowchart showing a manufacturing method of a mold used for manufacturing the transparent conductive film of the present embodiment. With reference to FIG. 2, the detail of the process (S10) which produces a shaping | molding die is demonstrated. As shown in FIG. 2, the master mold 2 is prepared in the step (S11). FIG. 3 is a schematic cross-sectional view showing the configuration of the master mold 2. As shown in FIG. 3, an undulating shape 24 is formed on the surface 21 of the master mold 2. The undulating shape 24 has a crest 22 with a protruding surface 21 and a trough 23 with a recessed surface 21. A large number of peaks 22 and valleys 23 are alternately formed on the surface 21.

  As the master mold 2, for example, a substrate on which irregularities are formed in advance by single crystal crystal anisotropic etching, thermal chemical vapor deposition (thermal CVD), or the like may be used. Alternatively, a substrate may be prepared, and irregularities may be formed on the substrate by etching using photolithography, electroforming, or the like.

  Subsequently, in the step (S12), an appropriate release agent is applied to the surface 21 of the master mold 2. By applying the release agent, the releasability from the master mold 2 of the rubber layer 4 formed on the surface 21 described later is enhanced, and the rubber layer 4 can be easily peeled from the master mold 2.

  Subsequently, in the step (S13), the solution 3 in which the rubber raw material is dissolved is applied onto the surface 21 of the master mold 2. FIG. 4 is a schematic cross-sectional view showing a state in which the rubber raw material solution 3 is applied to the master mold 2. As shown in FIG. 4, the rubber raw material solution 3 is applied along the undulating shape 24 so as to cover the entire surface 21 of the master mold 2. The rubber raw material solution 3 is applied so that the rubber raw material is filled in all the valleys 23 of the undulating shape 24.

  Subsequently, in the step (S14), the rubber raw material solution 3 is dried and solidified to form the rubber layer 4. When the rubber raw material is solidified to obtain the rubber layer 4, heating, light irradiation, and pressurization steps may be included in order to stably maintain the shape of the rubber layer 4. Moreover, it is preferable that the rubber layer 4 contains a silicone resin material or a fluorine compound resin material from a viewpoint of improving mold release property.

  Subsequently, in the step (S15), the rubber layer 4 is peeled off from the master mold 2. FIG. 5 is a schematic cross-sectional view showing a state where the rubber layer 4 is peeled from the master mold 2. On the surface 41 of the rubber layer 4, an undulating shape 44 that is a reverse pattern of the uneven texture structure of the surface 21 of the master mold 2 is formed. That is, in the undulation shape 24 of the surface 21 of the master mold 2, the valley portion 43 of the undulation shape 44 of the surface 41 of the rubber layer 4 is formed corresponding to the position where the peak portion 22 is formed. Further, a crest 42 is formed on the surface 41 of the rubber layer 4 in correspondence with the position where the trough 23 is formed on the surface 21 of the master mold 2.

  Subsequently, in step (S <b> 16), the cushion layer 5 is bonded to the back surface opposite to the front surface 41 of the rubber layer 4 to obtain the mold 1. FIG. 6 is a schematic cross-sectional view showing the configuration of the mold 1. The forming material of the cushion layer 5 is preferably foamed rubber, cotton cloth, woven cloth, non-woven cloth or the like from the viewpoint of improving poor contact between the rubber layer 4 and the substrate during pressing. In this way, the mold 1 having the undulating shape 44 on the surface 41 is produced. The mold 1 includes a rubber layer 4 as an example of a first member having an undulating shape 44 and a cushion layer 5 as an example of a second member, and is formed by laminating the rubber layer 4 and the cushion layer 5. Yes. The cushion layer 5 is formed with a Young's modulus smaller than that of the rubber layer 4.

  Returning to FIG. 1, in the next step (S20), a substrate 6 having a main surface is prepared. Subsequently, in the step (S30), the transparent conductive precursor layer 7 as an example of the precursor layer is formed on the main surface of the substrate 6. FIG. 7 is a schematic cross-sectional view showing a state in which the transparent conductive precursor layer 7 is formed on the substrate 6. The transparent conductive precursor layer 7 is formed by applying a forming material for forming the transparent conductive precursor layer 7 to the main surface of the substrate 6. This forming material includes a transparent conductive precursor material as an example of a transparent and conductive precursor material, and a volatile material. The transparent conductive precursor material is crystallized by heating to form a transparent conductive film. Volatile materials volatilize when heated.

  The coating method for applying the forming material for forming the transparent conductive precursor layer 7 can be appropriately selected from known methods such as dipping, spin coating, and screen printing. In order to maintain the shape of the forming material applied in the form of a film, a drying process such as heat treatment or hot air blowing may be provided as necessary.

The transparent conductive precursor material contains at least one oxide of an element selected from the group consisting of Zn, Sn, Pb, Sb, Cd, Mg, In, Ga, Te, Ag, Cu, Al, and Sr. The transparent conductive precursor material includes a conductive material selected from one or a combination of oxides of the above element group. In particular, it is desirable to include ZnO, SnO ₂ , ITO (Indium Tin Oxide), etc. having excellent conductivity. The transparent conductive precursor material may include a UV (ultraviolet) curable material that is cured by being irradiated with ultraviolet rays. In this case, in the subsequent step of volatilizing the volatile material, the transparent conductive precursor layer 7 can be cured while irradiating UV light, so that the processing time can be shortened.

  Next, in the step (S40), the mold 1 produced in the step (S10) is pressed against the transparent conductive precursor layer 7. FIG. 8 is a schematic cross-sectional view showing a state in which the mold 1 is pressed against the transparent conductive precursor layer 7. The thickness of the transparent conductive precursor layer 7 can be adjusted by adjusting the pressure applied from the mold 1 to the transparent conductive precursor layer 7 when the mold 1 is pressed against the transparent conductive precursor layer 7. .

  As shown in FIG. 8, when the molding die 1 is pressed against the transparent conductive precursor layer 7, the contact surface 71 of the transparent conductive precursor layer 7 that comes into contact with the molding die 1 is undulated. A undulation 74 reflecting the shape 44 is formed. That is, in the undulation shape 44 of the surface 41 of the rubber layer 4 of the mold 1, the valley portion 73 of the undulation 74 of the contact surface 71 is formed corresponding to the position where the peak portion 42 is formed. Further, a crest portion 72 is formed on the contact surface 71 corresponding to the position where the trough portion 43 is formed on the surface 41 of the rubber layer 4.

  As a method of pressing the mold 1, a method in which the mold 1 is attached to a thin metal plate in order from the end of the substrate 6 or a method in which the mold 1 is wound around a roller is used on the substrate 6. For example, a method of pressing while rolling.

  As described above, the mold 1 is formed as a laminate of the rubber layer 4 and the cushion layer 5 having a Young's modulus smaller than that of the rubber layer 4. When the highly rigid rubber layer 4 is pressed against the transparent conductive precursor layer 7 having high rigidity, uneven printing pressure occurs, and in-plane distribution occurs in the texture shape of the undulation 74 or the film thickness of the transparent conductive film. End up. This effect is particularly noticeable when a large-area press is performed. Therefore, by providing a cushion layer 5 made of a material having a Young's modulus, which is an index of hardness in the printing pressure direction, smaller than that of the rubber layer 4 on the back side of the rubber layer 4, the mold 1 (rubber layer) 4) can be prevented and the uneven printing pressure can be suppressed.

  Here, after forming the undulations 74, the mold 1 is once released from the transparent conductive precursor layer 7, and then the relative position of the mold 1 with respect to the transparent conductive precursor layer 7 is shifted so that the transparent conductive The mold 1 may be pressed again against the precursor layer 7. By shifting the pressing position of the molding die 1 and pressing it again, the undulations 74 corresponding to the undulating shape 44 of the molding die 1 are superimposed, and undulations having different shapes before and after being pressed again are obtained. By pressing a plurality of times while changing the position in this way, undulations of various shapes can be formed using the single mold 1. Therefore, undulations having a desired shape can be obtained without increasing the manufacturing cost of the mold 1. That is, it is possible to obtain the transparent conductive film 9 having a desired light scattering effect corresponding to solar cells having various specifications.

  Next, in the step (S50), the mold 1 is held for a predetermined time while being pressed against the transparent conductive precursor layer 7, and a part or all of the volatile material contained in the transparent conductive precursor layer 7 is volatilized. Let

  At this time, the transparent conductive precursor layer 7 may be heated. That is, the lower limit temperature at which a part of the volatile material contained in the transparent conductive precursor layer 7 starts to volatilize is Ts, and the lower limit temperature at which the transparent conductive precursor material contained in the transparent conductive precursor layer 7 starts to crystallize. When Tc is set, the transparent conductive precursor layer 7 is heated at a temperature T represented by Ts <T <Tc. In this way, the volatilization of the volatile material can be accelerated, so that the processing time can be shortened.

  Below Ts, when the mold 1 is released, the hardness of the transparent conductive precursor layer 7 is too small, and the shape of the portion pressed and deformed by the undulating shape 44 of the mold 1 is not maintained. Above Tc, during the pressing of the mold 1 to the transparent conductive precursor layer 7, the transparent conductive precursor material starts to crystallize and becomes a single texture reflecting the undulating shape 44 of the mold 1. Cannot be obtained.

  Next, in the step (S60), the mold 1 is released from the transparent conductive precursor layer 7. FIG. 9 is a schematic cross-sectional view showing a state in which the mold 1 is released from the transparent conductive precursor layer 7. After volatilizing at least a part of the volatile material and drying the transparent conductive precursor layer 7, the mold 1 is released so that the undulation 74 reflecting the undulation shape 44 of the mold 1 is formed on the contact surface 71. The transparent conductive precursor layer 7 formed and provided with an uneven (texture) structure is obtained.

  Next, in step (S70), the transparent conductive precursor layer 7 is heat-treated. The heat treatment temperature is set to be equal to or higher than the lower limit temperature Tc at which the transparent conductive precursor material is crystallized. By this heat treatment, the remaining volatile material is volatilized, and the transparent conductive precursor material is crystallized and denatured, whereby the transparent conductive film 9 exhibiting excellent conductivity is obtained. FIG. 10 is a schematic cross-sectional view showing the transparent conductive film 9 formed by heat treatment. FIG. 11 is an enlarged schematic cross-sectional view of the vicinity of the region XI shown in FIG. FIG. 12 is an enlarged schematic cross-sectional view showing the vicinity of the region XII shown in FIG.

  As shown in FIGS. 10 to 12, as a result of the heat treatment, the surface 91 of the transparent conductive film 9 has a texture (undulation 74) formed by pressing the mold 1, and the surface of the undulation 74 has an undulation 74. Unevenness 94, which is a finely shaped texture, is formed. In this way, a so-called double texture in which the fine texture (unevenness 94) is superimposed on the texture (undulation 74) is formed.

  By heat-treating the transparent conductive precursor material, fine crystal grains grow, and as a result, a fine texture (unevenness 94) is formed. A texture (undulation 74) is formed by pressing the mold 1 against the transparent conductive precursor layer 7, and then this heat treatment is performed to cause nucleation and growth from the slope of the undulation 74. A double texture shape in which the unevenness 94 is superimposed on the surface can be obtained.

  When the mold 1 is heat-treated while being pressed against the transparent conductive precursor layer 7, crystal grains do not grow on the slope of the undulation 74, and only the undulation 74 reflecting the undulation shape 44 of the mold 1 can be obtained. As described above, the unevenness 94 is formed on the undulation 74 for the first time by performing heat treatment in a free state where the mold 1 is not pressed against the slope of the undulation 74.

  The height difference H1 between the peak portion 72 and the valley portion 73 of the undulation 74 shown in FIG. 11 is larger than the height difference H2 between the convex portion 92 and the concave portion 93 of the unevenness 94 shown in FIG. On the surface 91 of the transparent conductive film 9, an unevenness 94 having a height difference smaller than that of the undulation 74 is formed so as to overlap the undulation 74 formed by pressing the mold 1. For example, the undulation 74 and the unevenness 94 can be formed so that the height difference H1 of the undulation 74 is 100 nm or more and 15 μm or less and the height difference H2 of the unevenness 94 is 10 nm or more and 200 nm or less.

  The undulation 74, which is a large texture, improves the scattering of light having a particularly long wavelength. The undulation 74 results in long wavelength scattering up. If the height difference H1 of the undulation 74 is too small, the effect of improving the scattering of light having a long wavelength cannot be obtained, and if the height difference H1 is too large, the reflection component of incident light increases and absorption by the transparent conductive film accompanying an increase in film thickness. This results in increased loss and insufficient coverage of the upper layer of the transparent conductive film. On the other hand, the unevenness 94, which is a small texture, improves the scattering of light having a short wavelength. The unevenness 94 causes an increase in short wavelength scattering. If the height difference H2 of the unevenness 94 is too small, the effect of improving the short wavelength light cannot be obtained, and if the height difference H2 is too large, the difference from the undulation 74 is reduced, so that the effect of improving the short wavelength scattering is also obtained. There is no problem. Thus, by setting the height differences H1 and H2 within the above range, light scattering can be improved in a wide range of wavelengths.

  By the manufacturing method of the present embodiment described above, the transparent conductive film 9 having a double texture in which the unevenness 94 is superimposed on the undulation 74 can be produced. The transparent conductive film 9 manufactured by the method of the present embodiment can exhibit a high light scattering effect in a wide wavelength range from a long wavelength to a short wavelength, and as a result, the transparent conductive film 9 in a wide wavelength range. Spectral sensitivity increases (that is, photocurrent increases).

  In the manufacturing method of the present embodiment, the press conditions for pressing the mold 1 against the substrate 6, the specifications of the master mold 2 (press master specifications) when the mold 1 is manufactured, the heat treatment conditions, etc. are appropriately set. By adjusting, the controllability of the texture shape can be expanded as compared with the case where a transparent conductive film having a double texture is formed by another transparent conductive film manufacturing method such as a CVD method. Therefore, it is possible to realize the transparent conductive film 9 having various texture shapes.

  A power generation layer made of pin is formed on the textured transparent conductive film 9 obtained as described above, and a take-out electrode is formed thereon, thereby completing a solar battery cell. The solar cell obtained in this way can achieve high conversion efficiency because the light confinement effect is improved by the double texture of the transparent conductive film 9.

  In the description so far, the method for forming the transparent conductive film 9 on the substrate 6 has been described. The manufacturing method of the transparent conductive film 9 of the invention can be applied. For example, the transparent conductive material of the present invention can be applied to the surface shape of a back surface conductive layer formed between the power generation layer and the back electrode, or an intermediate layer formed between different power generation layers when a plurality of power generation layers are joined by direct iron. The manufacturing method of the film 9 can be applied.

  Hereinafter, the Example of the manufacturing method of the transparent conductive film of this invention is described in detail. A mold was prepared in advance. The mold was prepared by applying silicone rubber to a master mold, drying and solidifying to form a rubber layer.

  Here, as the master mold, an Si wafer was etched using an alkaline solution such as KOH to form an uneven texture structure having a height difference of several μm to several tens of μm. . Further, in order to improve the releasability from the master mold, a fluorine-based mold release agent (for example, Daikin Kasei OPTOOL HD-1100) was coated on the master surface.

  Thereafter, the rubber layer was peeled from the master mold to obtain a rubber layer in which a reverse pattern of the textured texture structure of the master mold was formed. A cushion layer was bonded to the opposite side of the obtained rubber layer pattern to form a mold. As the cushion layer, porous urethane having a thickness of 1 mm was used.

  Next, a transparent conductive precursor layer was formed on a glass substrate by spin coating. The rotation speed of the spin coat was 1000 rpm. The transparent conductive precursor layer is formed by dissolving zinc acetate at a concentration of 0.3 mol / L, monoethanolamine at 0.3 mol / L, and acetylmethylcarbinol at a concentration of 0.15 mol / L in an isopropyl alcohol solvent. Solution. Moreover, 1% of aluminum nitrate was added with respect to Zn concentration as a dopant for adjusting resistance.

Thereafter, the produced mold was pressed against the substrate coated with the transparent conductive precursor material. Here, as a method of pressing the molding die, a method in which a molding plate wound around a roller is pressed while rolling on the substrate. The pressure for pressing the mold against the substrate was 200 gf / cm ² .

  With the substrate pressed, the transparent conductive precursor layer is heated to 300 ° C. and held at 300 ° C. for 60 minutes, then the mold is released, and the transparent conductive having a texture structure reflecting the unevenness of the master mold Sex precursor layer was obtained.

Finally, the transparent conductive precursor layer was heated to 600 ° C. in an N ₂ atmosphere, and heat treatment was performed at 600 ° C. for 30 minutes. As a result, the transparent conductive precursor material contained in the transparent conductive precursor layer was crystallized and transformed into a transparent conductive film. At the same time, unevenness having a height difference of about 10 to 200 nm was formed on the surface of the transparent conductive film so as to be superimposed on the texture structure previously formed by the mold.

  Although the embodiments of the present invention have been described above, the embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The method for producing a transparent conductive film according to the present invention can be particularly advantageously applied to a method for producing a transparent conductive film having a double texture structure of a desired shape for forming a solar cell having high conversion efficiency. .

  1 Mold, 2 Master, 3 Solution, 4 Rubber layer, 5 Cushion layer, 6 Substrate, 7 Transparent conductive precursor layer, 9 Transparent conductive film, 21, 41, 91 Surface, 22, 42, 72 Mountains, 23, 43, 73 Valley, 24, 44 Relief shape, 71 Contact surface, 74 Relief, 92 Protrusion, 93 Concavity, 94 Concavity and convexity.

Claims (10)

Producing a mold having an undulating shape on the surface;
Preparing a substrate;
Forming a precursor layer including a conductive transparent precursor material and a volatile material on the substrate;
Pressing the undulating shape of the mold against the precursor layer;
Volatilizing the volatile material;
Releasing the mold from the precursor layer;
A process for heat-treating the precursor layer.   The mold includes a first member having the undulating shape and a second member having a Young's modulus smaller than that of the first member, and the first member and the second member are laminated. The manufacturing method of the transparent conductive film of Claim 1.   The method for producing a transparent conductive film according to claim 2, wherein the first member includes a silicone resin material or a fluorine compound resin material. In the step of volatilizing, the precursor layer has the following formula: Ts <T <Tc, where Ts is a lower limit temperature at which the volatile material volatilizes and Tc is a lower limit temperature at which the precursor material is crystallized.
The manufacturing method of the transparent conductive film in any one of Claims 1-3 heated to the temperature T represented by these. In the pressing step, a undulation reflecting the undulation shape of the mold is formed on the contact surface of the precursor layer that contacts the mold.
5. The transparent conductive film according to claim 1, wherein, in the heat treatment step, unevenness having a height difference smaller than the undulation is formed on the contact surface so as to overlap the undulation. Production method.   The method for producing a transparent conductive film according to claim 5, wherein a difference in height of the undulations is from 100 nm to 15 μm, and a difference in height of the irregularities is from 10 nm to 200 nm.   The precursor material includes at least one oxide of an element selected from the group consisting of Zn, Sn, Pb, Sb, Cd, Mg, In, Ga, Te, Ag, Cu, Al, and Sr. The manufacturing method of the transparent conductive film in any one of Claim 1-6.   The method for producing a transparent conductive film according to claim 1, wherein the precursor material includes a UV curable material.   The manufacturing method of the transparent conductive film of Claim 1 provided with the process of repressing the said shaping | molding die to the said precursor layer between the said process to press and the process to volatilize.   The transparent conductive film manufactured by the manufacturing method of the transparent conductive film in any one of Claims 1-9.

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