JP2004164970A - Electrode substrate and photoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain corrosion of a metal wiring layer 12 and degradation of a characteristic due to leakage current from the metal wiring layer 12 in an electrode substrate 1 having the metal wiring layer 12 and a transparent conductive layer 11. <P>SOLUTION: The surface of each metal wiring layer 12 is insulated and covered with an insulating layer 14. By composing this photoelectric conversion element by using such an electrode substrate 1, the wiring layer 12 is surely shielded from an electrolyte solution or the like to effectively restrain its corrosion and leakage current, so that the photoelectric conversion element having high photoelectric conversion efficiency can be provided. The insulating layer 14 is preferably formed of a material containing a glass constituent, and it is particularly preferable to form it by printing of paste containing a glass frit. The wiring layer 12 is preferably formed by a printing method. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrode substrate used for a photoelectric conversion element such as a solar cell.
[0002]
[Prior art]
Dye-sensitized solar cells have been developed by Gretzel et al. In Switzerland and have advantages such as high photoelectric conversion efficiency and low manufacturing cost. Reference 1, Non-Patent Document 1, Japanese Patent Application No. 2001-400593, etc.).
[0003]
FIGS. 8A and 8B show an example of a conventional dye-sensitized solar cell. The dye-sensitized solar cell has a working electrode 3 having an oxide semiconductor porous film 2 made of oxide semiconductor fine particles such as titanium oxide and carrying a photosensitizing dye on an electrode substrate 1; And a counter electrode 4 provided to face the counter electrode. The electrolyte layer 5 is formed between the working electrode 3 and the counter electrode 4 by filling with an electrolytic solution.
[0004]
The electrode substrate 1 is formed by forming a transparent conductive layer 11 made of tin-added indium oxide (ITO) or fluorine-added tin oxide (FTO) on a base material 10 such as a glass plate. Further, in order to improve current collection efficiency from the oxide semiconductor porous film 2, a lattice-shaped metal wiring layer 12 made of gold, platinum, silver, or the like is provided on the transparent conductive layer 11. Further, the surfaces of the metal wiring layer 12 and the transparent conductive layer 11 are provided with ITO, in order to suppress inconveniences such as corrosion of the metal wiring layer 12, short-circuit with the electrolyte layer 5, and output reduction due to leakage current (reverse electron transfer). It is covered with a shielding layer 13 made of an oxide semiconductor such as FTO, titanium oxide, and zinc oxide.
Further, instead of the electrolyte layer 5, a solid charge transfer layer 6 made of a p-type semiconductor or the like may be used.
In this dye-sensitized solar cell, when light such as sunlight enters from the base material 10 side, an electromotive force is generated between the working electrode 3 and the counter electrode 4.
[0005]
[Patent Document 1]
JP-A-01-220380
[Non-patent document 1]
Michael Graetzel et al., Nature, (UK), 1991, 737, p. 353
[0006]
[Problems to be solved by the invention]
The shielding layer 13 can be formed by forming a film made of an oxide semiconductor on the metal wiring layer 12 by using a thin film forming method such as a sputtering method or a spray pyrolysis method (SPD). However, since the surfaces of the transparent conductive layer 11 and the metal wiring layer 12 have fine irregularities (profiles) such as voids, cracks, and grain boundaries, it is difficult to form the dense shielding layer 13 uniformly, Due to the formation failure of the layer 13, an uncovered portion where the metal wiring layer 12 is exposed may occur. In this case, the effect of suppressing inconveniences such as corrosion of the metal wiring layer 12 and output reduction due to generation of leakage current due to reverse electron transfer from the metal wiring layer 12 to the electrolyte layer 5 and the like is reduced, and the solar cell (cell) ) May be significantly impaired.
If the coating thickness of the shielding layer 13 is increased in order to suppress the formation failure of the shielding layer 13, there is a possibility that the transfer of photoelectrons is hindered, or the photoelectric conversion efficiency is reduced due to a decrease in light transmittance.
[0007]
For example, when the metal wiring layer 12 is formed using a conductive paste mainly containing conductive particles such as metal fine particles and a binder such as glass frit, the conductivity of the metal wiring layer 12 is reduced. Although it is better that the compounding ratio of the binder is small, fine and sharp irregularities and shadows such as voids and pinholes are easily generated inside and on the surface of the metal wiring layer 12, and it is difficult to form a shielding layer. When the mixing ratio of the binder is increased, the conductivity of the metal wiring layer 12 is reduced, so that the current collection efficiency is reduced and the cell characteristics may be significantly impaired.
[0008]
Further, when the metal wiring layer 12 is not provided on the electrode substrate 1 and the current collection from the oxide semiconductor porous film 2 is performed only by the transparent conductive layer 11, the specific resistance of the semiconductor such as FTO forming the transparent conductive layer 11 is reduced. 10^-4-10^-3Since it is about Ω · cm, which is 100 times or more that of a metal such as gold or silver, the reduction in photoelectric conversion efficiency becomes remarkable especially in a large-area cell. When the thickness of the transparent conductive layer 11 is increased in order to reduce the resistance, the light transmittance of the transparent conductive layer 11 is significantly reduced, and the photoelectric conversion efficiency is also reduced.
The present invention has been made in view of the above circumstances, and in an electrode substrate having a metal wiring layer and a transparent conductive layer, suppressing deterioration of characteristics due to corrosion of the metal wiring layer and leakage current from the metal wiring layer. As an issue.
[0009]
[Means for Solving the Problems]
The present invention, in order to solve the above problems, an electrode substrate having a metal wiring layer and a transparent conductive layer on a base material, wherein the metal wiring layer and the transparent conductive layer are electrically connected, at least An electrode substrate, wherein the surface of the metal wiring layer is insulated and covered with an insulating layer.
According to such an electrode substrate, the metal wiring layer is reliably shielded from the electrolyte solution and the like, and its corrosion and leakage current can be effectively suppressed. Therefore, the electrode substrate has excellent conductivity.
The insulating layer is preferably formed from a material containing a glass component, and is particularly preferably formed by printing a paste containing glass frit. Thus, an insulating layer capable of reliably insulating and shielding the metal wiring layer can be easily formed.
Further, the metal wiring layer is preferably formed by a printing method. Thereby, a metal wiring layer having a desired pattern can be easily formed.
Further, the present invention provides a photoelectric conversion element having the above-mentioned electrode substrate. Thus, a decrease in output due to corrosion of the metal wiring layer of the electrode substrate or leakage current can be suppressed, and a photoelectric conversion element having high photoelectric conversion efficiency can be obtained.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1A is a cross-sectional view illustrating an example of the photoelectric conversion element of the present invention, and FIG. 1B is a cross-sectional view illustrating an electrode substrate 1 used in the photoelectric conversion element.
In FIG. 1, the same reference numerals as those used in FIG. 8 indicate the same components as those in FIG. This photoelectric conversion element generates an electromotive force between the working electrode 3 and the counter electrode 4 when light such as sunlight enters from the substrate 10 side by the same operation and effect as the conventional one, thereby obtaining electric power. Is a dye-sensitized solar cell.
The difference between the photoelectric conversion element of the present embodiment and the conventional one is that, as shown in FIG. 1B, an electrode substrate 1 is formed by disposing a transparent conductive layer 11 on a base material 10 and a transparent conductive layer 11 A metal wiring layer 12 formed thereon and an insulating layer 14 covering the surface of the metal wiring layer 12 are provided, and the insulating layer 14 covers the metal wiring layer 12. .
[0011]
As a material of the base material 10, a material having high light transmittance is preferable in terms of application, and in addition to glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyether sulfone (PES), and the like. A transparent plastic sheet, a polished plate of ceramics such as titanium oxide and alumina, or the like can be used.
[0012]
The transparent conductive layer 11 is formed on the base material 10 over an area wider than the area where the metal wiring layer 12 is formed, and the material thereof is not particularly limited. For example, tin-added indium oxide ( ITO), tin oxide (SnO)₂) And conductive metal oxides such as fluorine-added tin oxide (FTO).
As a method for forming the transparent conductive layer 11, a known appropriate method according to the material of the transparent conductive layer 11 may be used, and examples thereof include a sputtering method, an evaporation method, an SPD method, and a CVD method. The thickness is usually about 0.001 μm to 10 μm in consideration of light transmittance and conductivity.
[0013]
The metal wiring layer 12 is formed by forming a metal, such as gold, silver, platinum, aluminum, nickel, or titanium, as a wiring in a lattice, stripe, or comb pattern as shown in FIG. In order not to significantly impair the light transmittance of the electrode substrate 1, the width of each wiring is preferably reduced to 1000 μm or less. The thickness (height) of each wiring of the metal wiring layer 12 is not particularly limited, but is preferably 0.1 to 10 μm.
[0014]
As a method of forming the metal wiring layer 12, for example, a paste is prepared by mixing a metal powder to be conductive particles and a binder such as glass fine particles, and the paste is formed by a printing method such as a screen printing method, a metal mask method, and an inkjet method. A method in which a coating film is formed so as to form a predetermined pattern by using a method, and the conductive particles are fused by heating and firing. The firing temperature is, for example, preferably 600 ° C. or less, more preferably 550 ° C. or less when the substrate 10 is glass. In addition, a forming method such as a sputtering method, an evaporation method, and a plating method can be used.
From the viewpoint of conductivity, the volume resistivity of the metal wiring layer 12 is 10^-5It is preferably Ω · cm or less. The surface of the metal wiring layer 12 is preferably smooth, but some undulations and unevenness may be present.
[0015]
The insulating layer 14 is formed by using one or more kinds of insulating materials such as resin, ceramics, and glass, and forming one or more layers and a layer on the region where the metal wiring layer 12 is formed. be able to. The region where the insulating layer 14 is formed may protrude to the periphery of the pattern of the metal wiring layer 12 as long as it does not hinder light incidence or charge transfer to the transparent conductive layer 11.
[0016]
The method for forming the insulating layer 14 is not necessarily limited, but a screen printing method using a glass paste obtained by mixing a suitable thickener, a binder, a dispersant, and a solvent with glass frit, A method in which a coating method is applied so as to overlap the pattern of the metal wiring layer 12 by a printing method such as a metal mask method or an ink jet method, and then heated and baked is preferable from the viewpoint of ease of pattern formation, cost, and the like. The firing temperature is preferably 600 ° C. or lower, more preferably 550 ° C. or lower. Glasses that can be fired at such temperatures include commercially available lead-containing solder glasses such as lead oxide, lead borate, and bismuth lead borate as amorphous or crystalline glass, as well as non-lead glass. Solder glass or the like can be used. The number of layers of the insulating layer 14 may be one or plural, and in the case of plural layers, one kind of glass paste may be formed two or more times, or two or more kinds having different melting temperatures. May be used.
[0017]
An oxide semiconductor porous film 2 carrying a sensitizing dye is formed on the surface of the electrode substrate 1 manufactured as described above, and the photoelectric conversion is performed by the electrode substrate 1 and the oxide semiconductor porous film 2. The working electrode 3 of the conversion element is configured.
[0018]
The porous oxide semiconductor film 2 is made of titanium oxide (TiO 2).₂), Tin oxide (SnO)₂), Tungsten oxide (WO₃), Zinc oxide (ZnO), niobium oxide (Nb)₂O₅) Is a porous thin film composed of oxide semiconductor fine particles having an average particle diameter of 1 to 1000 nm obtained by combining one or two or more of them, and having a thickness of about 0.5 to 50 μm.
[0019]
In order to form the oxide semiconductor porous film 2, for example, a dispersion obtained by dispersing commercially available oxide semiconductor fine particles in a desired dispersion medium or a colloid solution that can be adjusted by a sol-gel method is used, if necessary. After adding a desired additive, the electrode substrate 1 is coated by a known coating method such as a screen printing method, an inkjet printing method, a roll coating method, a doctor blade method, a spin coating method, or a spray coating method, and the electrode substrate 1 is immersed in a colloid solution. Electrophoresis to deposit oxide semiconductor fine particles on the electrode substrate 1 by electrophoresis, a method of mixing and applying a foaming agent to a colloid solution or dispersion, and then sintering the mixture to make it porous. After mixing and applying the beads, the polymer microbeads are removed by heat treatment or chemical treatment to form voids and make them porous. It is possible to apply.
[0020]
The sensitizing dye supported on the oxide semiconductor porous film 2 is not particularly limited, and may be, for example, a ruthenium complex or an iron complex having a ligand having a bipyridine structure, a terpyridine structure, or the like, a porphyrin-based or phthalocyanine-based complex. A metal complex, an organic dye such as eosin, rhodamine, and merocyanine, and the like can be appropriately selected and used depending on the application and the material of the oxide semiconductor porous film.
[0021]
As an electrolytic solution for forming the electrolyte layer 5, an organic solvent containing a redox couple, a room temperature molten salt, or the like can be used. Examples of the organic solvent include acetonitrile, methoxyacetonitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, and γ-butyrolactone. Examples of the room temperature molten salt include salts composed of a quaternized imidazolium-based cation and an iodide ion or a bistrifluoromethylsulfonylimide anion.
[0022]
The redox couple contained in the electrolytic solution is not particularly limited, and can be obtained by adding a pair of iodine / iodide ion, bromine / bromide ion, and the like. As a source of iodide ion or bromide ion, lithium salt, quaternized imidazolium salt, tetrabutylammonium salt, or the like can be used alone or in combination.
Additives such as tert-butylpyridine can be added to the electrolyte as needed. Further, a material which is gelled by an appropriate gelling agent to suppress fluidity may be used.
[0023]
Further, instead of the electrolyte layer 5, a solid charge transfer layer 6 made of a p-type semiconductor or the like can be used. As the p-type semiconductor, for example, a monovalent copper compound such as copper iodide or copper thiocyanate can be suitably used. The method for forming the charge transport layer 6 is not particularly limited, and a known method can be applied, and examples thereof include a casting method, a sputtering method, and a vapor deposition method. Further, the charge transfer layer 6 may contain an additive as necessary for forming the layer.
[0024]
As the counter electrode 4, for example, a thin film made of a conductive oxide semiconductor such as ITO or FTO is formed on a substrate made of a non-conductive material such as glass, or a gold, platinum, or carbon-based material is formed on the substrate. A material in which an electrode is formed by depositing or applying a conductive material such as a material can be used. Alternatively, a layer of platinum, carbon, or the like can be formed over a thin film of a conductive oxide semiconductor such as ITO or FTO.
[0025]
As a method of manufacturing such a counter electrode 4, for example, a method of forming a platinum layer by applying a heat treatment after application of chloroplatinic acid can be mentioned. Alternatively, an electrode may be formed over a substrate by an evaporation method or a sputtering method.
When the charge transport layer 6 is used in place of the electrolyte layer 5, a method is used in which a conductive material serving as an electrode of the counter electrode 4 is directly formed on the charge transport layer 6 by a method such as sputtering or coating. You can also.
[0026]
According to the electrode substrate of the present embodiment, since transparent conductive layer 11 and metal wiring layer 12 are in contact with and electrically connected to each other, electrons from oxide semiconductor porous film 2 are The power collection efficiency can be improved through the metal wiring layer 12 through the current collection by the metal wiring layer 12. Further, the metal wiring layer 12 is reliably shielded from the solution of the electrolyte layer 5 and the like, so that corrosion and leakage current thereof can be effectively suppressed. Therefore, since the electrode substrate 1 having excellent conductive properties can be obtained, the contact between the metal wiring layer 12 and the electrolyte layer 5 is formed by forming the working electrode of the photoelectric conversion element using the electrode substrate of the present embodiment. And a reduction in output due to corrosion and leakage current can be suppressed, and a photoelectric conversion element with high photoelectric conversion efficiency can be manufactured.
[0027]
FIG. 3 is a schematic sectional view showing a second embodiment of the electrode substrate of the present invention. In the electrode substrate 1 of this example, the metal wiring layer 12 is provided on the substrate 10, and the transparent conductive layer 11 extends over the metal wiring layer 12 and is formed in a region where the metal wiring layer 12 is formed. It is formed over a wider area. The insulating layer 14 is formed on the transparent conductive layer 11 so as to overlap the pattern of the metal wiring layer 12 so as to cover the upper surface and side surfaces of the metal wiring layer 12. That is, the insulating layer 14 is provided on the metal wiring layer 12 via the transparent conductive layer 11.
According to such an electrode substrate 1, as in the electrode substrate 1 of the first embodiment, the metal wiring layer 12 can be insulated and shielded by the insulating layer 14, so that the occurrence of leakage current can be suppressed. The electrode substrate 1 having excellent conductive properties can be obtained. Further, even with the use of the electrode substrate 1, a photoelectric conversion element having high photoelectric conversion efficiency can be manufactured.
[0028]
7 shows another embodiment of the electrode substrate of the present invention.
In the electrode substrate according to the third embodiment, as shown in FIG. 4, a transparent conductive layer 11 is formed on a base material 10, and a metal wiring is formed on the transparent conductive layer 11 as a pattern such as a lattice. Layer 12 has been formed. Then, a shielding layer 13 made of an oxide semiconductor thin film is provided on the transparent conductive layer 11, and an insulating layer 14 is formed on the metal wiring layer 12.
In the electrode substrate according to the fourth embodiment, as shown in FIG. 5, a metal wiring layer 12 is formed on a base material 10 as a pattern such as a grid pattern. Further, the transparent conductive layer 11 is formed over a region wider than the region where the metal wiring layer 12 is formed. Then, a shielding layer 13 made of a thin film of an oxide semiconductor is provided on the transparent conductive layer 11. Further, an insulating layer 14 is formed on the shielding layer 13 so as to overlap the pattern of the metal wiring layer 12 so as to cover the upper surface and side surfaces of the metal wiring layer 12.
Although the problem is small compared with the metal wiring layer 12, since the reverse electron transfer from the transparent conductive layer 11 has been pointed out, the shielding layer 13 is formed on the transparent conductive layer 11 as shown in FIGS. , A higher shielding effect can be obtained.
[0029]
As a material of the shielding layer 13, a compound having a low electron transfer reaction rate with an electrolytic solution containing a redox species, a high light transmission property, and a high ability to transfer photoelectrons is selected, and titanium oxide, zinc oxide, niobium oxide, Examples include tin oxide, fluorine-added tin oxide (FTO), and tin-added indium oxide (ITO).
The shielding layer 13 needs to be formed thin enough not to hinder electron transfer to the transparent conductive layer 11, and preferably has a thickness of about 10 to 3000 nm. Examples of a method for forming the shielding layer 13 include a sputtering method, an evaporation method, an SPD method, a spin coating method, a dipping method, and a doctor blade method. However, according to these methods, the density of the shielding layer 13 and the adaptability to the surface shape of the base material 10 are not always sufficient, and it is difficult to sufficiently obtain the shielding performance of the metal wiring layer 12. For this reason, even when the shielding layer 13 is formed, it is necessary to form the insulating layer 14 directly on the metal wiring layer 12 or via the transparent conductive layer 11, the shielding layer 13, and the like. Thereby, the insulation shielding of the metal wiring layer 12 can be sufficiently performed.
[0030]
The method for forming the shielding layer 13 is not particularly limited. For example, an oxide semiconductor or a precursor thereof as a target compound is formed by a dry method (vapor phase method) such as a sputtering method, an evaporation method, and a CVD method. Method. For example, when a precursor such as a metal is formed into a film, the shielding layer 13 can be obtained by oxidizing the precursor by heat treatment or chemical treatment.
In the case of the wet method, a liquid containing the target compound or its precursor is applied by a method such as spin coating, dipping, or blade coating, and then chemically changed to the target compound by heat treatment or chemical treatment. And the shielding layer 13 can be obtained. Examples of the precursor include salts and complexes having the constituent metal element of the target compound. In order to obtain a dense film, a solution is more preferable than a dispersion.
As another method for forming the shielding layer 13, for example, a spray pyrolysis method (SPD) is used, and while the substrate 10 having the transparent conductive layer 11 is heated, the precursor of the shielding layer 13 is directed toward the substrate 10. A method of forming the shielding layer 13 by spraying and thermally decomposing a substance serving as a body to change into a target oxide semiconductor can also be used.
By providing the shielding layer 13 for shielding the transparent conductive layer 11 in this manner, the transfer of reverse electrons from the transparent conductive layer 11 can be suppressed. Therefore, by using the electrode substrate of the present embodiment, Thus, a photoelectric conversion element with high photoelectric conversion efficiency can be manufactured.
[0031]
Further, the shielding layer 13 can have an effect as a protective layer for a purpose different from that of the insulating layer 14, for example, if necessary in terms of characteristics.
For example, FIG. 6 shows an electrode substrate according to a fifth embodiment of the present invention. In this electrode substrate 1, the shielding layer 13 is formed not only on the transparent conductive layer 11 but also on the metal wiring layer 12 and the insulating layer 14. Thereby, the shielding layer 13 can be used as a protective layer for the metal wiring layer 12 and the insulating layer 14.
[0032]
9 shows still another embodiment of the electrode substrate of the present invention. FIG. 7 is a schematic sectional view showing an electrode substrate according to a sixth embodiment of the present invention. In the electrode substrate 1, a metal wiring layer 12 is formed on a first transparent conductive layer 11 a as a wiring pattern such as a grid, a stripe, or a comb, and the metal wiring layer 12 is formed on the metal wiring layer 12. An insulating layer 14 for covering the metal wiring layer 12 is provided. Further, a second transparent conductive layer 11b is formed over the metal wiring layer 12 and the insulating layer 14. That is, the metal wiring layer 12 and the insulating layer 14 are sandwiched between the first transparent conductive layer 11a and the second transparent conductive layer 11b. The first and second transparent conductive layers 11a and 11b are the same as the above-described transparent conductive layer 11, and are thin films made of a conductive metal oxide such as ITO and FTO.
According to such an electrode substrate 1, the metal wiring layer 12 can be insulated and shielded by the insulating layer 14, and the metal wiring layer 12 and the insulating layer 14 can be protected by the second transparent conductive layer 11b. In addition, by having the second transparent conductive layer 11b in addition to the first transparent conductive layer 11a, improvement in current collection efficiency can be expected.
[0033]
As described above, the present invention has been described based on the preferred embodiments. However, the present invention is not limited to only the embodiments, and various modifications can be made without departing from the gist of the present invention.
For example, the electrode substrate of the present invention can be applied to photoelectric conversion elements other than solar cells, such as photochemical cells and optical sensors. Also in this case, since the metal wiring layer 12 of the electrode substrate 1 is covered with the insulating layer 14 and the contact of the metal wiring layer 12 with the electrolyte solution or the like is prevented, inconveniences such as corrosion and short circuit are suppressed, and the quality is improved. Degradation and deterioration of photoelectric conversion characteristics, optical responsiveness and the like can be suppressed.
[0034]
Hereinafter, the present invention will be described in detail with reference to specific examples.
<Example 1>
(Preparation of electrode substrate)
A 100 mm × 100 mm glass substrate with an FTO film was used as the transparent conductive layer 11 (11 a) and the substrate 10, and a silver paste for printing (volume resistivity after sintering was 3 × 10^-6Ω) is screen-printed in a grid pattern, leveled for 10 minutes, dried in a hot air circulating oven at 135 ° C. for 20 minutes, and baked at 550 ° C. for 15 minutes to form a metal wiring layer 12 composed of a silver circuit. Formed. The circuit width of the metal wiring layer 12 was 150 μm, and the film thickness was 5 μm.
While performing alignment using a CCD camera, the glass paste is printed by overlapping with the metal wiring layer 12 by screen printing, and after leveling for 10 minutes, drying is performed in a hot air circulating furnace at 135 ° C. for 20 minutes and then at 550 ° C. The insulating layer 14 was formed by baking for 15 minutes. The width of the obtained insulating layer 14 was 250 μm, and the film thickness from the surface of the glass substrate was 10 μm. Thus, the insulating layer 14 is formed on the metal wiring layer 12 to a thickness of about 5 μm.
When the surface of the insulating layer 14 was observed with a scanning electron microscope (SEM), the glass frit particles were melted and fused together, and the surface of the insulating layer 14 was dense and had remarkable defects such as pinholes. It turned out there was no.
Further, an FTO film serving as the second transparent conductive layer 11b also serving as the protective layer and the shielding layer 13 is formed by the SPD method so as to straddle over the metal wiring layer 12 and the insulating layer 14, and FIG. An electrode substrate 1 having the configuration shown in FIG. 7) was manufactured.
[0035]
(Preparation of photoelectric conversion element)
On the obtained electrode substrate 1, an aqueous dispersion of titanium oxide (average particle diameter: 25 nm) is applied, dried, and then heat-treated at 450 ° C. for 1 hour to form an oxide semiconductor porous film 2 having a thickness of 10 μm. Was formed. Further, the electrode was immersed in an ethanol solution of a ruthenium bipyridine complex (N3 dye) for 8 hours to carry the dye, thereby preparing a working electrode 3. As a counter electrode 4, a platinum sputtered FTO glass electrode substrate was used. The counter electrode 4 and the working electrode 3 were opposed to each other with a thermoplastic polyolefin resin sheet having a thickness of 50 μm interposed therebetween as a spacer. And both electrodes 3 and 4 were fixed. At this time, a part on the counter electrode 4 side was left open to serve as an electrolyte injection port. A methoxyacetonitrile solution containing 0.5M iodide salt and 0.05M iodine as a main component was injected from the injection port to form an electrolyte layer 5, and then the peripheral portion and the injection port were connected with an epoxy-based liquid. This was completely sealed with a sealing resin, and a silver paste was applied to the current collector to prepare a photoelectric conversion element serving as a test cell.
When the photoelectric conversion characteristics of this test cell were evaluated using pseudo sunlight having an air mass (AM) of 1.5, the conversion efficiency was 3.0%.
[0036]
<Example 2>
(Preparation of electrode substrate)
A 100 mm × 100 mm heat-resistant glass substrate was used as the base material 10, and a metal wiring layer 12 having a circuit width of 50 μm and a film thickness of 5 μm was formed on the surface of the substrate by using a printing silver paste by the same procedure as in Example 1. After that, an FTO film to be the transparent conductive layer 11 was formed on the metal wiring layer 12 by the SPD method. Further, the insulating layer 14 was formed in accordance with the pattern of the metal wiring layer 12 by printing a glass paste by using the same method as in Example 1, and the electrode substrate 1 having the configuration shown in FIG. 3 was manufactured.
(Preparation of photoelectric conversion element)
Using this electrode substrate 1, a photoelectric conversion element serving as a test cell was manufactured in the same procedure as in Example 1. When the photoelectric conversion characteristics of this test cell were evaluated using pseudo sunlight with an air mass (AM) of 1.5, the conversion efficiency was 2.5%.
[0037]
<Example 3>
(Preparation of electrode substrate)
A 100 mm × 100 mm glass substrate with an FTO film was used as the transparent conductive layer 11 and the substrate 10, and a metal wiring layer 12 made of a gold circuit having a circuit width of 50 μm and a film thickness of 5 μm was formed on the surface by an additive plating method. . An insulating layer 14 is formed on the metal wiring layer 12 in accordance with the pattern of the metal wiring layer 12 by printing a glass paste using the same method as in the first embodiment, and the structure shown in FIG. The electrode substrate 1 was produced.
(Preparation of photoelectric conversion element)
Using this electrode substrate 1, a photoelectric conversion element serving as a test cell was manufactured in the same procedure as in Example 1. When the photoelectric conversion characteristics of this test cell were evaluated using pseudo sunlight having an air mass (AM) of 1.5, the conversion efficiency was 3.3%.
[0038]
<Comparative Example 1>
(Preparation of electrode substrate)
A 100 mm × 100 mm heat-resistant glass substrate was used as the base material 10, and a metal wiring layer 12 having a circuit width of 100 μm and a film thickness of 5 μm was formed on the surface of the substrate by using the same procedure as in Example 1 using a silver paste for printing. After that, an FTO film to be the transparent conductive layer 11 and the shielding layer 13 was formed on the metal wiring layer 12 in the same procedure as in Example 2, and the electrode substrate 1 was manufactured.
(Preparation of photoelectric conversion element)
Using this electrode substrate 1, a photoelectric conversion element serving as a test cell was manufactured in the same procedure as in Example 1. Observation of the electrolyte injected into the test cell showed that the electrolyte had a brown color immediately after the injection, but turned almost transparent several minutes later. This is because I in the electrolyte₃ ⁻The ions react with the exposed silver due to insufficient shielding of the silver circuit,⁻It is thought that it was reduced to. When the photoelectric conversion characteristics of this test cell were evaluated using simulated sunlight having an air mass (AM) of 1.5, the photoelectric conversion efficiency was 0.24%.
This indicates that when the insulating layer 14 is not provided, the silver circuit is insufficiently shielded, and the photoelectric conversion efficiency of the photoelectric conversion element is likely to be reduced.
[0039]
<Comparative Example 2>
(Preparation of electrode substrate)
A 100 mm × 100 mm glass substrate with an FTO film was used as the transparent conductive layer 11 and the substrate 10, and a metal wiring layer 12 made of a gold circuit having a circuit width of 50 μm and a film thickness of 5 μm was formed on the surface by an additive plating method. . On the metal wiring layer 12, a 300 nm-thick FTO film serving as the transparent conductive layer 11 and the shielding layer 13 was formed by using the same method as in Example 2, and the electrode substrate 1 was manufactured.
Observation of the surface of the electrode substrate 1 formed in this manner by SEM and EDX revealed that there was a dive at the bottom of the metal wiring layer 12 which was thought to be caused by the tailing of the plating resist. Was not formed.
(Preparation of photoelectric conversion element)
Using this electrode substrate 1, a photoelectric conversion element serving as a test cell was manufactured in the same procedure as in Example 1. When the photoelectric conversion characteristics of this test cell were evaluated using simulated sunlight having an air mass (AM) of 1.5, the conversion efficiency was 0.30%. For this reason, when only the shielding layer 13 is provided and the insulating layer 14 is not provided for shielding the conductive layer, the metal wiring layer 12 is easily exposed, and when the metal wiring layer 12 is exposed, the photoelectric conversion element is formed. It can be seen that the photoelectric conversion efficiency of the sample may be significantly reduced, which is a problem.
[0040]
<Comparative Example 3>
(Preparation of electrode substrate)
Example 1 A glass substrate with an FTO film of 100 mm × 100 mm was used as the transparent conductive layer 11 and the substrate 10, and the glass substrate with the FTO film itself was used as the electrode substrate 1 without providing the metal wiring layer 12 on the surface. According to the same procedure as in 1, a photoelectric conversion element serving as a test cell was manufactured. When the photoelectric conversion characteristics of this test cell were evaluated using pseudo sunlight having an air mass (AM) of 1.5, the conversion efficiency was 0.11%. This indicates that when the metal wiring layer 12 is not provided, the photoelectric conversion efficiency of the photoelectric conversion element is low because the resistance of the electrode substrate 1 is large.
[0041]
【The invention's effect】
As described above, the electrode substrate of the present invention has a metal wiring layer and a transparent conductive layer electrically connected to the metal wiring layer on a base material, and the metal wiring layer is insulated by an insulating layer. Since it is covered, the metal wiring layer is reliably shielded from the electrolyte solution or the like, and its corrosion and leakage current can be effectively suppressed. Further, as compared with the case where only the transparent conductive layer is used as the conductor of the electrode, the resistance can be reduced and an electrode substrate having excellent conductivity can be obtained.
[0042]
When such an electrode substrate is used for a photoelectric conversion element, electrons which pass through the oxide semiconductor porous film are collected through the transparent conductive layer, and the current collection efficiency is further improved by the metal wiring layer. Can be. For this reason, while reducing the resistance of the electrode substrate, it is possible to suppress inconveniences such as deterioration of quality due to corrosion of the metal wiring layer and a decrease in output due to leakage current and the like. In comparison with, for example, even in a large area cell of a 100 mm square class, the photoelectric conversion efficiency can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of (a) a photoelectric conversion element and (b) an electrode substrate of the present invention.
FIG. 2 is a partial plan view showing an example of a schematic shape of a metal wiring layer.
FIG. 3 is a sectional view showing a second embodiment of the electrode substrate of the present invention.
FIG. 4 is a sectional view showing a third embodiment of the electrode substrate of the present invention.
FIG. 5 is a sectional view showing a fourth embodiment of the electrode substrate of the present invention.
FIG. 6 is a sectional view showing a fifth embodiment of the electrode substrate of the present invention.
FIG. 7 is a sectional view showing a sixth embodiment of the electrode substrate of the present invention.
FIG. 8 is a cross-sectional view illustrating an example of a conventional photoelectric conversion element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... electrode board, 10 ... base material, 11 ... transparent conductive layer, 12 ... metal wiring layer, 13 ... shielding layer, 14 ... insulating layer.

Claims (6)

On a substrate, having a metal wiring layer and a transparent conductive layer electrically connected to the metal wiring layer,
An electrode substrate, wherein the metal wiring layer is insulated and covered with an insulating layer. The electrode substrate according to claim 1, wherein the insulating layer is formed of a material containing a glass component. The electrode substrate according to claim 2, wherein the insulating layer is formed by printing a paste containing glass frit. The electrode substrate according to any one of claims 1 to 3, wherein the metal wiring layer is formed by a printing method. A photoelectric conversion element comprising the electrode substrate according to claim 1. The photoelectric conversion device according to claim 5, wherein the photoelectric conversion device is a dye-sensitized solar cell.

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