JP2005324435A - Transparent conductive laminated film and optical action electrode for photochemical cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive laminated film which is good in coating properties and adhesion in relation to a porous titanium dioxide layer used as the semiconductor layer of a photogalvanic cell optical action electrode and makes a transparent conductive layer resistant to corrosion by iodine ions contained in an electrolytic solution and an optical action electrode using the film. <P>SOLUTION: In the transparent conductive laminated film, the transparent conductive layer is formed on one side of a transparent plastic substrate. In the transparent conductive laminated film for an optical action electrode, a transparent barrier layer having a contact angle with water of 45° or below and a thickness of 1-50 nm is formed on the surface of the transparent conductive layer of the transparent conductive laminated film. The laminated film is used in the optical action electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transparent conductive laminated film, and more particularly to a transparent conductive laminated film used as a photoworking electrode of a photochemical battery and a photoworking electrode using the same.

  There are several types of solar cells that convert light energy into electrical energy, but silicon semiconductors are the mainstream. Currently, these solar cells are expensive to manufacture and are a factor that hinders their spread. A photochemical battery is known as a low-cost solar battery. Dye-sensitized solar cells announced in 1991 by O'Regan and Graetzel are attracting attention [B. O'Regan and Graetzel, Nature, 353, 737 (1991)]. This battery is expected to be put to practical use because of its low conversion efficiency and manufacturing cost comparable to silicon solar batteries. The basic structure of a dye-sensitized solar cell consists of a photoactive electrode in which a porous semiconductor layer is formed on a transparent conductive substrate, a photosensitizing dye such as ruthenium complex adsorbed on the surface, and a redox pair. It consists of an electrolyte and a counter electrode. Titanium dioxide is generally used as a material for the porous semiconductor layer.

  As a method for forming the porous titanium dioxide layer, the above-mentioned B.I. The method devised by O'Regan and Graetzel is generally used, but it is necessary to calcinate at a temperature of 400 ° C. or higher in the process of forming the porous titanium dioxide layer. Accordingly, the substrate is limited to those having heat resistance such as transparent conductive glass, and a substrate having low heat resistance such as a transparent conductive film cannot be used.

  However, recently, a technique for forming a porous titanium dioxide layer at a low temperature has been invented and proposed. In JP-A-2003-282160, when a titania sol solution, a titania gel body, or a titania sol-gel mixture is applied as a coating liquid on a substrate to form a coating film, and the coating film is heated in a sealed container A thin film forming method characterized by obtaining a titanium dioxide film by simultaneously performing pressure treatment and crystallization has been proposed, and a transparent conductive film can be used as a substrate. D. Zhang et al. Used an aqueous solution of titanium inorganic salt (titanium tetrachloride or titanyl sulfate) or an aqueous solution of titanium alkoxide (titanium tetraisopropoxide) dispersed in crystalline titanium dioxide as a coating solution. It has been reported that a porous titanium dioxide layer having an excellent photoelectrode function can be formed by applying a hydrothermal reaction at 100 ° C. in an autoclave [D. Zhang, T .; Yoshida and H.K. Minoura, Chemistry Letters, 874-875 (2002)], it is possible to produce a dye-sensitized solar cell using a transparent conductive film having no heat resistance as a substrate. More recently, pastes for forming a porous titanium dioxide layer at a low temperature have come to the market, and the expectation of a film-type lightweight and flexible dye-sensitized solar cell is increasing.

  As described above, the porous titanium dioxide layer can be formed at a low temperature, but when using a transparent conductive film in which tin-doped indium oxide (hereinafter, ITO) is formed on a transparent plastic film as a base material, Since the surface energy on the surface of the ITO layer is low, there are problems such that it is easy to repel the coating liquid and it is difficult to form a uniform porous titanium dioxide layer over a large area, and the adhesion between the porous titanium dioxide layer and ITO is weak. Furthermore, the dye-sensitized solar cell is filled with an electrolyte solution containing iodine ions between the photoactive electrode and the counter electrode, and the ITO layer is easily corroded when it comes into contact with iodine ions that have passed through the porous titanium dioxide layer. There is also a problem that the battery characteristics deteriorate in a short time. Although it is conceivable to use materials other than ITO, there is no low resistance material comparable to ITO in other materials, and good battery characteristics cannot be expected.

JP 2003-282160 A B. O'Regan and Graetzel, Nature, 353, 737 (1991) D. Zhang, T .; Yoshida and H.K. Minoura, Chemistry Letters, 874-875 (2002)

  The present invention solves the problems of the prior art as described above, and when used as a photoactive electrode of a dye-sensitized solar cell, a porous titanium layer used as a semiconductor layer without lowering the photoelectric conversion efficiency Transparent conductive laminated film that has good coating properties when forming and adhesion with the porous titanium dioxide layer after being formed, and that the transparent conductive layer is less likely to be corroded by iodine ions contained in the electrolyte solution Is to provide.

  As a result of intensive studies to solve the above-mentioned problems, a transparent conductive layer made of an ITO thin film is formed on a transparent plastic substrate, and a transparent barrier layer having an extremely thin water contact angle of 45 ° or less is further formed thereon. This improves the corrosion resistance of the transparent conductive layer by iodine ions while improving the coating properties for forming the porous titanium dioxide layer and the adhesion between the porous titanium dioxide layer and the transparent conductive film. We have found out that we can do it and have reached the present invention.

  Thus, according to the present invention, an object of the present invention is a transparent conductive laminated film in which a transparent conductive layer is formed on one side of a transparent plastic substrate, and water is applied to the surface of the transparent conductive layer of the transparent conductive laminated film. Is achieved by a transparent conductive laminated film for a photoactive electrode provided with a transparent barrier layer having a contact angle of 45 ° or less and a film thickness (tb) of 1 to 50 nm.

Further, according to the present invention, as a preferred embodiment of the transparent conductive laminated film for photoactive electrodes of the present invention, the surface resistance of the transparent conductive layer before forming the transparent barrier layer is R ₀ , and the transparent barrier layer is formed. When the surface resistance of the subsequent transparent barrier layer is R ₁ , R ₁ / R ₀ is 1.5 at most, the transparent conductive layer is made of tin-doped indium oxide, and the transparent barrier layer is a thin film made of titanium oxide. The transparent barrier layer is formed by a vapor phase method typified by a physical vapor phase method or a chemical vapor phase method, or the transparent barrier layer is a tetramer solution or titanium from a monomer of titanium alkoxide. The transparent plastic base material and the transparent conductive layer are stacked from the transparent plastic base material side through the hard coat layer and the anchor layer in this order. As a photo-working electrode of a photochemical cell, that an anti-reflection layer is formed on the surface of the transparent plastic film substrate that is not in contact with the transparent conductive layer or that an anti-reflection film is bonded. There is also provided a photoconductive electrode transparent conductive laminated film comprising at least one of the above. In particular, the adhesion of the transparent conductive layer can be improved by laminating a hard coat and an anchor layer sequentially from the transparent plastic substrate side between the transparent plastic substrate and the transparent conductive layer. By forming an antireflection layer on the surface opposite to the surface on which the conductive layer is formed, or by sticking an antireflection film, reflection of external light can be suppressed and battery characteristics can be further improved. .

  Furthermore, according to this invention, the photoworking electrode for photochemical cells which consists of the transparent conductive laminated film of this invention and the porous semiconductor layer formed in the surface of the transparent barrier layer is also provided.

  According to the present invention, when forming a porous titanium dioxide layer used as a semiconductor layer of a dye-sensitized solar cell photoactive electrode, the coating property is good, the adhesion with the porous titanium dioxide layer is good, and It is possible to provide a transparent conductive laminated film for a photoactive electrode of a dye-sensitized solar cell in which the transparent conductive layer is hardly corroded by iodine ions contained in the electrolyte solution.

  A preferred example of the layer structure of the transparent conductive laminated film of the present invention is shown in FIG. In addition, this invention is not limited to the transparent conductive laminated film of this figure. 1, reference numeral 1 is a transparent plastic substrate, reference numeral 2 is a hard coat layer, reference numeral 3 is an anchor layer, reference numeral 4 is a transparent conductive layer, reference numeral 5 is a transparent barrier layer, reference numeral 6 is an antireflection film, and reference numeral 7 is The transparent conductive laminated film with an antireflection function is shown. In the transparent conductive laminated film of the present invention shown in FIG. 1, a hard coat layer 2, an anchor layer 3, a transparent conductive layer 4, and a transparent barrier layer 5 are laminated in this order on one surface of a transparent plastic substrate 1. A transparent conductive laminated film with an antireflection function in which an antireflection film 6 is bonded to the other surface of the transparent plastic substrate 1.

  Moreover, sectional drawing of the dye-sensitized solar cell using the photoactive electrode of this invention is shown in FIG. In addition, this invention is not limited to the dye-sensitized solar cell of this figure. In FIG. 2, reference numeral 8 denotes a dye-adsorbing porous titanium dioxide layer, reference numeral 9 denotes a counter electrode, reference numeral 10 denotes a spacer, reference numeral 11 denotes an electrolyte solution, and reference numeral 12 denotes a transparent conductive laminated film with an antireflection function. In the dye-sensitized solar cell shown in FIG. 2, the transparent conductive laminated film 12 with antireflection function and the counter electrode 9 face each other so that the respective electrodes are inside, and a spacer 10 is interposed therebetween. In the space surrounded by the transparent conductive laminated film 12 with antireflection function, the counter electrode 9 and the spacer 10, the dye-adsorbing porous titanium dioxide layer 8 is placed on the transparent conductive laminated film 12 side with antireflection function on the side of the counter electrode 9 The electrolyte solution 11 is arranged on the side.

  The transparent plastic base material which comprises the transparent conductive laminated film of this invention is so preferable that the transmittance | permeability of visible light is high. Visible light as used herein means light having a wavelength of 380 to 780 nm, and the transmittance means an average transmittance in the wavelength region. The visible light transmittance of the transparent plastic substrate is preferably 50% or more, particularly preferably 75% or more. The transparent plastic substrate in the present invention is preferably an organic polymer film excellent in industrial productivity. Examples of the organic polymer include polyester (for example, polyethylene terephthalate (PET) and polyethylene naphthalate), poly (meth) acryl (for example, polymethyl methacrylate (PMMA)), polycarbonate (PC), polystyrene, polyvinyl alcohol, Examples include polyvinyl chloride, polyvinylidene chloride, polyethylene, ethylene-vinyl acetate copolymer, polyurethane, triacetate, cellophane and the like. Among these, PET, PC, and PMMA are preferable.

  The transparent plastic substrate may be an unstretched film or a stretched film depending on the type of polymer. For example, a polyester film such as a PET film is usually a biaxially stretched film, and a PC film, a triacetate film, a cellophane film and the like are usually unstretched films. The thickness of the transparent plastic substrate is usually preferably 10 to 500 μm. In addition, the transparent plastic substrate can be subjected to an easy adhesion treatment in order to enhance the adhesion to other functional layers. These easy adhesion treatments may be performed at the time of film formation, You may carry out after a film | membrane.

  The transparent conductive layer in the present invention is preferably an ITO thin film, and the tin concentration is preferably in the range of 5 atomic% to 10 atomic% with respect to indium atoms. Even if the concentration of tin is higher or lower than this range, it becomes difficult to obtain sufficient conductivity as a photoactive electrode. The thickness of the transparent conductive layer depends on the surface resistance and light transmittance of the target transparent conductive laminated film, but is generally preferably in the range of 100 nm to 500 nm. A more preferable thickness of the transparent conductive layer is in the range of 250 to 450 nm. When the thickness of the transparent conductive layer is thinner than the lower limit, it becomes difficult to obtain a sufficiently low surface resistance. On the other hand, when the film thickness is thicker than the upper limit, the transparent conductive layer is liable to break or light rays. Or decrease the transmittance.

  The formation of the transparent conductive layer is preferably performed by a physical vapor phase method. Of the physical vapor phase methods, the sputtering method is most preferable. The sputtering method can cope with the formation of a uniform film thickness on a large-area substrate simply by increasing the size of the target, and further, compared with other physical vapor phase methods, the formed film and substrate It is characterized by excellent adhesion to the material. Although there is no restriction | limiting in the acquisition method at the time of forming an ITO thin film by sputtering method, DC discharge is preferable from a viewpoint of discharge stability. The target to be used is preferably an ITO target, and the concentration of tin in the target is preferably 5 atomic percent to 10 atomic percent with respect to indium, like the tin concentration in the ITO thin film. A reactive sputtering method can be used, in which an ITO thin film is formed while introducing a small amount of oxygen during sputtering using an alloy of indium and tin as a target. It is not preferable from the viewpoint of sex.

  The transparent barrier layer provided on the transparent conductive layer in the present invention needs to be transparent and have a surface water contact angle of 45 ° C. or less. The term “transparent” as used herein means that the total light average transmittance of light having a wavelength of 380 to 780 nm is 60% or more, preferably 70% or more, as viewed in the entire transparent conductive laminated film. As the transparent barrier layer, a known material can be used as long as it is transparent, has a water contact angle of 45 ° or less, and has sufficient corrosion resistance against iodine ions. As the transparent barrier layer having such characteristics, a barrier layer mainly composed of silicon oxide or titanium oxide can be exemplified. In addition, since a porous semiconductor layer made of titanium dioxide is preferably used as the porous semiconductor layer, a barrier layer is particularly preferable from the viewpoint of adhesion. The barrier layer containing titanium oxide as a main component only needs to contain titanium oxide as a main component. For example, even in a mixture of titanium oxide and silicon oxide of 30 mol% or less, the titanium alkoxide is hydrolyzed to change into titanium oxide. An intermediate may be used.

  When the contact angle of water on the surface of the transparent barrier layer exceeds 45 °, in order to form a porous semiconductor layer of a dye-sensitized solar cell, a coating in which fine particles forming the porous semiconductor are dispersed in water or alcohol When applying the liquid, the coating liquid cannot be applied uniformly, or the formed porous semiconductor layer is peeled off, that is, the adhesion is impaired. Moreover, in order to solve these problems, when surfactant etc. are added to a coating liquid, although a coating property and adhesiveness will improve, photoelectric conversion efficiency will be impaired.

The thickness of the transparent barrier layer needs to be in the range of 1 to 50 nm, and preferably in the range of 5 to 30 nm. When the thickness of the transparent barrier layer is thinner than the lower limit, the transparent conductive layer made of the ITO thin film is corroded by iodine ions after assembling the dye-sensitized solar cell. On the other hand, if the thickness of the transparent barrier layer is larger than the upper limit, the transparent barrier layer is insulative, so that sufficient surface conductivity cannot be obtained, or the transmittance decreases due to light interference. Thus, the photoelectric conversion efficiency is impaired. Further, when R _{0 is} the surface resistance before forming the transparent barrier layer and R ₁ is the surface resistance after forming the transparent barrier layer, R ₁ / R ₀ is preferably 1.5 or less. The lower limit of R ₁ / R ₀ is not particularly limited, and is preferably as close to 1 as possible. To suppress the increase in surface resistance due to such a transparent barrier layer, the thickness of the transparent barrier layer described above is 50 nm or less. It is done. Moreover, when the thickness of the transparent conductive layer is tc and the thickness of the transparent barrier layer is tb, it is also preferable to set tb / tc to 0.3 or less. Preferred tb / tc is in the range of 0.01 to 0.2.

  The method for forming the transparent barrier layer may be a vapor phase method or a coating method. The vapor phase method can be divided into a physical vapor phase method and a chemical vapor phase method. Furthermore, examples of the physical vapor phase method include a vacuum vapor deposition method, an ion plating method, and a sputtering method, and examples of the chemical vapor phase method include a CVD method and a spray pyrolysis method. On the other hand, the coating method can include a method of applying a tetramer solution or a titanium inorganic salt solution from a monomer of titanium alkoxide and hydrolyzing it. The method used can be used, for example, spin coating method, dip method, spray method, roll coater method, meniscus coater method, flexographic printing method, screen printing method, beat coater method, micro gravure coater method, etc. it can.

  Examples of the titanium alkoxide include titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetra-i-propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium tetra-tert-butoxide. Furthermore, chelate compounds such as diethoxytitanium bisacetylacetonate, dipropoxytitanium bisacetylacetonate, and dibutoxytitanium bisacetylacetonate can also be mentioned. Examples of the titanium inorganic salt include titanium tetrachloride, titanium trichloride, titanyl sulfate, and the like.

  In the transparent conductive laminated film of the present invention, another layer may be provided between the transparent plastic substrate and the transparent conductive layer. It is preferable to provide a hard coat and an anchor layer from the transparent plastic substrate side. In the process of assembling the photochemical battery, the photoactive electrode and the counter electrode face each other, and a hard gap spacer such as silica beads with a particle size of several tens of microns is used as the photoactive electrode for the purpose of gap adjustment to prevent a short circuit. It may be inserted between the counter electrodes. Without a hard coat layer, when a compressive force is applied while using the battery, the transparent conductive layer is cracked or damaged by hard silica beads, and the battery characteristics deteriorate. Because there is. The reason for providing the anchor layer is to improve the adhesion of the transparent conductive layer to the transparent plastic substrate.

  It is preferable to form a layer having transparency and appropriate hardness as the hard coat layer. The forming material is not particularly limited, and for example, a curable resin or a thermosetting resin by ionizing radiation or ultraviolet irradiation can be used. In particular, an ultraviolet irradiation curable acrylic or organic silicon resin or a thermosetting polysiloxane resin is suitable. Known resins can be used for these resins. Furthermore, it is more preferable that the refractive index of the hard coat layer is equal to or close to that of the transparent film substrate, but this point is not particularly necessary when the film thickness is 3 μm or more. The anchor layer is preferably an oxide or nitride or oxynitride of one or more metals selected from the group consisting of silicon, aluminum, and titanium. There are no particular limitations on the anchor layer and the method of forming the anchor layer, and anchor layers and methods of formation known per se can be used. Specific examples of the anchor layer include a silicon dioxide thin film. The thickness of the anchor layer is not limited, but is preferably in the range of 10 nm to 50 nm.

  In the transparent conductive laminated film of the present invention, an antireflection layer is formed on the surface opposite to the surface on which the transparent conductive layer is formed, or an antireflection film is bonded to prevent reflection of external light. can do. By preventing reflection of external light, sunlight can be efficiently introduced into the solar cell. There are no particular limitations on the material and formation method of the antireflection layer, and materials and methods known per se, for example, the materials and methods described in JP-A-2002-264242 can be used.

  Hereinafter, the present invention will be described by way of examples. In addition, the evaluation item and the evaluation method in an Example were performed as follows.

 (1) Surface resistance value: An arbitrary five points were measured using a 4-probe type surface resistivity measuring device [Mitsubishi Chemical Corporation, Loresta GP], and the average value was used as a representative value.

 (2) Contact angle of water: 0.05 ml of distilled water was dropped with a microsyringe and allowed to stand for 30 seconds, and then a surface droplet was photographed with a CCD camera and directly read from a photograph.

 (3) Corrosiveness: A transparent conductive laminated film is cut into a size of 10 mm × 10 mm, and a porous titanium dioxide layer is formed in the center of the outermost surface on the transparent conductive layer side so as to form a photoactive electrode. . To this porous semiconductor layer, a 3-methoxypropionitrile solution containing 0.5 M lithium iodide and 0.05 M iodine is dropped and left at room temperature for 30 minutes. After that, as shown in FIG. 3, the positive and negative poles of the digital multimeter 13 (Yokogawa Electric Co., Ltd., model 753501) are brought into contact with two opposite sides 10 mm apart where the porous semiconductor layer is not formed. The resistance was measured. When the electrical resistance before dropping the solution is Rb, and the electrical resistance 30 minutes after dropping the solution is Ra, the change rate of the electrical resistance represented by the following formula, (Ra−Rb) / Rb is: The case where it was smaller than 0.3 was marked with ◯, and the case where it was 0.3 or larger was marked with ×.

 (4) Adhesiveness of porous titanium dioxide layer: evaluated by a cross-cut tape peeling test in accordance with JIS D0202-1988. The grid size was 1 mm × 1 mm square, and the number of grids was 100. Cellophane adhesive tape used Nichiban Co., Ltd. CT405A-18. The case where the number of peeled grids was 10 or less was marked with ◯, and the case where the number of peeled grids exceeded 10 was marked with x.

(5) Battery characteristics: The obtained 25 mm ² large dye-sensitized solar cell was subjected to IV measurement under irradiation of AM 1.5 pseudo-sunlight 100 mW / cm ² , and the open circuit voltage, short-circuit current density, fill factor, The conversion efficiency was calculated. In addition, the spectrophotometer CEP-2000 type | mold spectral sensitivity measuring apparatus was used for the measurement.

[Reference Example 1] Preparation of antireflection film An easy-adhesion-treated biaxially oriented PET film (OPFW-188 μm, manufactured by Teijin DuPont Film) was used as a transparent film substrate, and a UV curable hard coating agent (Desolite manufactured by JSR) was formed on one side R7501) was applied to a thickness of about 5 μm and UV cured to form a hard coat layer.

Next, a tetrabutyl titanate tetramer (manufactured by Nippon Soda TBT B-4) in a ligroin / n-butanol (3/1) solution is added to a SiO ₂ particle (AEROSIL R972 manufactured by Nippon Aerosil Co., Ltd., average particle size 20 nm). ) Was added by 0.5% by weight to the alkoxide and dispersed by coating with microgravure coating and dried at 150 ° C. for 2 minutes to form a film (refractive index of 1.85) having a thickness of about 80 nm. Further on this, a TiO ₂ layer (refractive index 2.2) was formed to a thickness of 65 nm by sputtering. Thus, an antireflection layer composed of two or more layers having different refractive indexes was formed.

Finally, tetraethyl silicate is dissolved in ethanol, water and hydrochloric acid are added to hydrolyze it, and the SiO ₂ sol is applied and heat treated at 100 ° C. for 2 minutes to form a gel film (refractive index as an antifouling water repellent layer). 1.45) was formed.

[Example 1]
An easy-adhesion-treated biaxially oriented PET film (O3PF8W-100 μm, Teijin DuPont Film, 1 in FIG. 1) is used as a transparent film substrate, and a UV curable hard coat agent (Desolite R7501 from JSR) is about 5 μm thick on one side. And hardened by UV curing to form a hard coat layer (2 in FIG. 1).

An anchor layer (3 in FIG. 1) made of silicon dioxide having a thickness of 30 nm was provided on one surface on which the hard coat layer (2 in FIG. 1) was formed by high-frequency magnetron sputtering using a silicon dioxide target. The formation of the anchor layer (3 in FIG. 1) by sputtering is performed by evacuating the chamber to 5 × 10 ⁻⁴ Pa before plasma discharge, and then introducing argon gas into the chamber to a pressure of 0.3 Pa. This was performed by applying a 1000 W high frequency to the silicon dioxide target.

A transparent conductive layer made of ITO having a film thickness of 450 nm (FIG. 1) is formed by DC magnetron sputtering using an ITO target (tin concentration is 10% by weight in terms of tin dioxide) on the anchor layer (3 in FIG. 1). 4) was formed. Formation of the transparent conductive layer (4 in FIG. 1) by sputtering is performed by evacuating the chamber to 5 × 10 ⁻⁴ Pa before plasma discharge, and then mixing a mixed gas of argon and oxygen (the oxygen concentration is 0. 0). 5 vol%) was introduced to a pressure of 0.3 Pa, and 1000 W was applied to the ITO target. Thus, the surface resistance value _R0 when the transparent conductive layer (4 in FIG. 1) was formed was 14Ω / □. Moreover, the contact angle of water on the surface of the transparent conductive layer was 87 °. Regarding the corrosivity due to iodine ions, the transparent conductive layer (4 in FIG. 1) was completely dissolved, and the evaluation was x.

Next, a transparent barrier layer (5 in FIG. 1) made of titanium dioxide with a thickness of 30 nm is formed on the transparent conductive layer (4 in FIG. 1) by high-frequency magnetron sputtering using a titanium dioxide target. The laminated film was made. tb / tc is 0.07. In the formation of the transparent barrier layer (E in FIG. 1) by sputtering, the inside of the chamber is evacuated to 5 × 10 ⁻⁴ Pa before plasma discharge, and then a mixed gas (oxygen) of argon and oxygen is placed in the chamber. The concentration was 1.0 vol%), the pressure was 0.3 Pa, and a 1000 W high frequency was applied to the titanium dioxide target. When the transparent barrier layer (5 in FIG. 1) was formed as described above, the surface resistance value R ₁ was 16Ω / □, R ₁ / R ₀ was 1.14, and the surface resistance hardly changed. The contact angle of water on the surface of the transparent barrier layer was 32 °, and the surface energy could be increased without almost increasing the surface resistance by forming the transparent barrier layer.

  Furthermore, the antireflection film (6 in FIG. 1) prepared in Reference Example 1 was applied to the surface of the antireflection film (6 in FIG. 1) on which the antireflection layer was not provided and the transparent barrier layer of the transparent conductive laminated film. The surface on the side where (5 in FIG. 1) is not formed was bonded to create a transparent conductive laminated film (7 in FIG. 1) with an antireflection function.

  On the transparent barrier layer (5 in FIG. 1) of the transparent conductive laminated film with antireflection function prepared in this way, a commercially available paste for forming a low temperature forming porous titanium dioxide layer (SP made by Showa Denko) -200) was applied with a bar coater and heat-treated at 120 ° C. for 30 minutes in the atmosphere to form a porous titanium dioxide layer (8 in FIG. 2) to a thickness of 3 μm. A photoactive electrode was prepared. When the corrosivity was evaluated, Rb and Ra were both 16Ω and the rate of change in electrical resistance was 0. There was no increase in electrical resistance due to corrosion of the transparent conductive layer, and the evaluation of corrosiveness was good. When the adhesion was evaluated, the number of peeled grids was 3, and the evaluation was good. It was confirmed that the adhesion of the porous titanium dioxide layer and the corrosion resistance of the transparent conductive layer were improved by forming the barrier layer.

A dye-sensitized solar cell was prepared using the photoactive electrode thus prepared (FIG. 2). The creation procedure is as follows. The above-described photoactive electrode was immersed in a 300 μM ethanol solution of a ruthenium complex (Ru535bisTBA, manufactured by Solaronix) for 24 hours to adsorb the ruthenium complex on the surface of the photoactive electrode. A counter electrode (9 in FIG. 2) was prepared by depositing a Pt film on a glass substrate with an ITO film having a surface resistance of 10Ω / □ by sputtering. Both substrates of these photoactive electrode and counter electrode are overlapped via a spacer (10 in FIG. 2), and an electrolyte solution (0.5M lithium iodide, 0.05M iodine and 0.5M tert-butylpyridine) is used. After injecting 3-methoxypropionitrile solution containing 11) in FIG. 2, it was sealed with an adhesive. As a result of performing IV measurement of the completed dye-sensitized solar cell, the open circuit voltage, the short circuit current density, and the fill factor were 0.69 V, 4.6 mA / cm ² and 0.76, respectively. The conversion efficiency was 2.4%.

[Example 2]
Except that the transparent barrier layer was formed by the following coating method, the same operation as in Example 1 was repeated to produce a transparent conductive laminated film, a photoactive electrode, and a dye-sensitized solar cell. The procedure for forming the transparent barrier layer is as follows. The coating solution was adjusted by adding tetrabutyl titanate tetramer to a mixed solvent of tert-butanol and 2-butanol in a volume ratio of 3: 1 to 0.1 M, and a transparent conductive layer (FIG. 1) was prepared using a bar coater. A transparent barrier layer mainly composed of titanium oxide was formed so as to have a film thickness of 30 nm by being heat-treated at 150 ° C. for 1 minute in the atmosphere and then hydrolyzing. tb / tc is 0.07. The surface resistance R ₀ before forming the transparent barrier layer is 14 Ω / □ as in Example 1, the surface resistance R ₁ after forming the transparent barrier layer is 15 Ω / □, and R ₀ / R ₁ is 1.07. It was. The contact angle of water on the surface of the transparent conductive layer before the formation of the transparent barrier layer was 87 ° as in Example 1, and the contact angle of water on the surface of the transparent barrier layer was 41 °. Even when the transparent barrier layer was formed by a coating method, the surface energy could be increased with almost no increase in surface resistance as in Example 1.

In the evaluation of adhesion of the porous titanium dioxide layer, the number of peeled grids was 0, and the evaluation was ○. When the corrosive evaluation of the photoactive electrode was performed, Rb was 15Ω, Ra was 17Ω, the rate of change in electrical resistance was 0.13, and the evaluation was good. There was almost no increase in electrical resistance due to corrosion of the transparent conductive layer, and the evaluation of corrosivity was ○. It was confirmed that the adhesion of the porous titanium dioxide layer and the corrosion resistance of the transparent conductive layer were improved by forming the barrier layer. A dye-sensitized solar cell was prepared and subjected to IV measurement. The result was an open circuit voltage of 0.68 V, a short-circuit current density of 4.2 mA / cm ² , a fill factor of 0.77, and a conversion efficiency of 2.2%. It was.

[Comparative Example 1]
Except not forming a transparent barrier layer, the same operation as Example 1 was repeated, and the transparent conductive laminated film and the photoactive electrode were created. The surface resistance value at this time and the contact angle of water on the surface of the transparent conductive layer were 14Ω / □ and 87 °, respectively, as in Example 1. Regarding the corrosivity due to iodine ions, the transparent conductive layer (4 in FIG. 1) was completely dissolved, and the evaluation was x.

  A commercially available paste for forming a low temperature forming porous titanium dioxide layer (SP-200 manufactured by Showa Denko) was applied on a transparent conductive layer on which a transparent barrier layer was not formed with a bar coater. It was impossible to apply to. In the evaluation of adhesion, the number of peeled grids was 43, and the evaluation was x. When the corrosive evaluation of the photoactive electrode was performed, Rb was 16Ω, Ra was 140Ω, the rate of change in electrical resistance was 7.75, and the evaluation was x. Since no barrier layer was formed, no further evaluation was performed.

[Comparative Example 2]
When a commercially available paste for forming a low temperature forming porous titanium dioxide layer (SP-200 made by Showa Denko) is applied on the transparent conductive layer (E in FIG. 1) with a bar coater, A transparent conductive laminated film and a photoactive electrode were prepared by repeating the same operation as in Comparative Example 1 except that 1.0% of Triton (manufactured by Aldridge) as a surfactant was added. When the corrosive evaluation of the photoactive electrode was performed, Rb was 15Ω, Ra was 16Ω, and the rate of change in electrical resistance was 0.07. There was almost no increase in electrical resistance due to corrosion of the transparent conductive layer, and the evaluation of corrosivity was ○. In addition, using the obtained photoactive electrode, the same operation as in Example 1 was repeated to prepare a dye-sensitized solar cell. Coating is possible by adding 1.0% of Triton (manufactured by Aldridge) as a surfactant to the paste for forming a low temperature forming porous titanium dioxide layer, and the porous titanium dioxide is formed to a film thickness of 3 μm. A photoworking electrode was prepared. The evaluation of adhesion was ○. A dye-sensitized solar cell was prepared using this photoactive electrode, and the results of IV measurement were as follows: open circuit voltage, short circuit current density, fill factor, and conversion efficiency were 0.60 V and 1.7 mA, respectively. / Cm ² , 0.70, and 0.71%. Even if a transparent barrier layer is not formed, the coating property and adhesion can be improved by adding a surfactant to the paste, but this addition reduces the conversion efficiency.

An example of the layer structure of the transparent conductive laminated film of this invention. Sectional drawing of a dye-sensitized solar cell. Electrical resistance measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent plastic base material 2 Hard-coat layer 3 Anchor layer 4 Transparent conductive layer 5 Transparent barrier layer 6 Antireflection film 7 Transparent electroconductive laminated film with an antireflection function 8 Dye adsorption | suction porous titanium dioxide layer 9 Counter electrode 10 Spacer 11 Electrolyte solution 12 Transparent conductive laminated film with antireflection function 13 Digital Multimeter

Claims (10)

  A transparent conductive laminated film in which a transparent conductive layer is formed on one side of a transparent plastic substrate, and the surface of the transparent conductive layer of the transparent conductive laminated film has a water contact angle of 45 ° or less and a film thickness (tb ) Is provided with a transparent barrier layer having a thickness of 1 to 50 nm. When the surface resistance of the transparent conductive layer before forming the transparent barrier layer is R ₀ and the surface resistance of the transparent barrier layer after forming the transparent barrier layer is R ₁ , R ₁ / R ₀ is at most 1.5. The transparent conductive laminated film according to claim 1.   The transparent conductive laminated film according to claim 1, wherein the transparent conductive layer is made of tin-doped indium oxide.   The transparent conductive laminated film according to claim 1, wherein the transparent barrier layer is a thin film made of titanium oxide.   The transparent conductive laminated film according to claim 1, wherein the transparent barrier layer is formed by a vapor phase method typified by a physical vapor phase method or a chemical vapor phase method.   The transparent conductive laminated film according to claim 4, wherein the transparent barrier layer is formed by a coating method in which a tetramer solution or a titanium inorganic salt solution is coated from a titanium alkoxide monomer and hydrolyzed.   The transparent conductive film according to claim 1, wherein the transparent plastic substrate and the transparent conductive layer are laminated from the transparent plastic substrate side through a hard coat layer and an anchor layer in this order.   The transparent conductive laminated film according to claim 1, wherein an antireflection layer is formed on the surface of the transparent plastic film substrate that is not in contact with the transparent conductive layer, or an antireflection film is bonded.   The transparent conductive laminated film according to any one of claims 1 to 8, which is used as a photoactive electrode of a photochemical battery.   The photoactive electrode for photochemical cells which consists of the transparent conductive laminated film in any one of Claims 1-8, and the porous semiconductor layer formed in the surface of the transparent barrier layer.

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