JP4892197B2 - Electrode substrate for dye-sensitized solar cell, photoelectrode and counter electrode for dye-sensitized solar cell, and dye-sensitized solar cell - Google Patents

Description

  The present invention relates to a dye-sensitized solar cell, and more particularly to an electrode substrate used for a photoelectrode or a counter electrode of the solar cell.

  In recent years, research and development have been actively conducted toward full-scale practical application of solar cells using clean and non-depleting solar energy.

  Solar cells are classified into silicon-based, compound semiconductor-based, organic semiconductor-based, dye-sensitized type (metal oxide semiconductor-based), etc., depending on the semiconductor material used. Of these, silicon solar cells are most practically used, but have a problem of high price and have not yet been widely used.

  Dye-sensitized solar cells have gained worldwide attention as a result of the development of the so-called “Gretzel cell” announced by Professor Graetzel of Lausanne Institute of Technology (Switzerland) in 1991 (Patent Literature) 1). This Gretzel cell is made by sealing an electrolyte solution between a photoelectrode in which a ruthenium metal complex dye is fixed on a nanoporous titania semiconductor film and a counter electrode having a platinum layer. Many research institutes and companies are engaged in research and development because there is a possibility that a significant reduction in cost can be achieved while securing high photoelectric conversion efficiency without requiring equipment.

In a dye-sensitized solar cell, a metal oxide semiconductor film such as titania (TiO ₂ ) constituting a photoelectrode is formed on a transparent plate such as a glass plate by FTO (fluorine-doped tin oxide) or ITO (indium-doped tin oxide). It is formed on an electrode substrate formed by laminating transparent conductive films made of, for example. However, since FTO and ITO have a large electric resistance value, the output current density per unit area is low. Therefore, if the resistance of the electrode substrate can be reduced, the photoelectric conversion efficiency is improved and the cell is increased in size.

  As a means for reducing the resistance of the electrode substrate, a method of forming a current collecting circuit with a silver paste or copper tape on the surface of a transparent conductive film is known. However, these methods have problems that the material cost is high and the process of forming the current collecting circuit is complicated, leading to an increase in manufacturing cost.

Further, as a means other than the above, a current collecting electrode (current collecting circuit) is formed by sputtering a conductive metal material such as Au, Al, Cr after applying a photomask on the surface of a transparent conductive film such as ITO. ), And a method for dissolving and removing the photomask is disclosed (see Patent Document 2).
Even in the above method, the process of forming the current collecting circuit is complicated, which may increase the manufacturing cost.
In addition, the current collector circuit formed on the surface of the transparent conductive film is exposed to the electrolyte through the nanoporous titania semiconductor film. Since the electrolyte uses an iodine solution, the current collector circuit is configured. The metal such as Au or Al corrodes and the current collecting function is impaired, and there is a problem that it cannot be put into practical use as it is.
Japanese Patent Laid-Open No. 1-220380 JP 2005-11609 A

  An object of the present invention is to effectively reduce the resistance value of a transparent conductive film as an electrode substrate for a dye-sensitized solar cell in which a transparent conductive film is laminated on one side of a transparent plate, and has corrosion resistance to an electrolyte. In addition, it is to provide a product having excellent durability at a lower price.

The electrode substrate for a first dye-sensitized solar cell according to the present invention is provided with a current collecting circuit formed by vacuum-depositing Al in a predetermined pattern on at least one of one surface of a transparent plate and the surface of a transparent conductive film. The surface of the current collecting circuit is covered with an oxide film.
In the first electrode substrate, a current collecting circuit is formed by vacuum-depositing Al in a predetermined pattern on one side of the transparent plate and / or the surface of the transparent conductive film and covering the surface with an oxide film. Therefore, although the resistance value of the transparent conductive film is effectively reduced, the material cost is lower and the manufacturing process is simpler than that of the conventional technique, so that the manufacturing cost can be reduced. . In addition, in the case of the first electrode substrate, since the Al vapor deposition film constituting the current collecting circuit is covered with an oxide film, the first electrode substrate is excellent in corrosion resistance to the electrolyte and also improved in durability.

The second dye-sensitized solar cell electrode substrate according to the present invention is a current collecting circuit formed by vacuum-depositing Al in a predetermined pattern on at least one of one surface of a transparent plate and the surface of a transparent conductive film. And the surface of the current collecting circuit is covered with any one film of Ti, Ni, Nb, Ta, W, SUS and ITO.
Even in the second electrode substrate, the resistance value of the transparent conductive film is effectively reduced by the current collecting circuit provided on one surface of the transparent plate and / or the surface of the transparent conductive film, and the manufacturing cost is also reduced. Be lowered. In the case of the second electrode substrate, the Al vapor deposition film constituting the current collecting circuit is covered with any one film of Ti, Ni, Nb, Ta, W, SUS, and ITO. Excellent corrosion resistance and improved durability.

Next, the third electrode substrate for a dye-sensitized solar cell according to the present invention is made of Nb, Ta, W, Ti, Ni, SUS on at least one of one surface of the transparent plate and the surface of the transparent conductive film. A current collecting circuit formed by vacuum-depositing any one of them in a predetermined pattern is provided.
In the third electrode substrate, one of Nb, Ta, W, Ti, Ni, and SUS excellent in corrosion resistance is predetermined on one surface of the transparent plate and / or the surface of the transparent conductive film. Since the current collection circuit is formed by vacuum deposition on the pattern, the material cost is low compared to the conventional technology, even though the resistance value of the transparent conductive film is effectively reduced by the circuit. However, the manufacturing cost can be reduced and the corrosion resistance and durability against the electrolyte can be improved, so that it can be sufficiently put into practical use.

In the first to third dye-sensitized solar cell electrode substrates according to the present invention, the thickness of the current collecting circuit is preferably 1 to 30 μm.
When the thickness of the current collecting circuit is less than 1 μm, the original purpose of sufficiently reducing the sheet resistance is diminished. On the other hand, when the thickness of the current collecting circuit exceeds 10 μm, it cannot be covered with a metal oxide semiconductor film such as TiO ₂ and is likely to be short-circuited with the counter electrode. More preferably, the thickness of the current collecting circuit is 5 to 10 μm.

In the first to third dye-sensitized solar cell electrode substrates according to the present invention, the width of the current collecting circuit is preferably 0.01 to 5 mm.
When the width of the current collecting circuit is less than 0.01 mm, the surface resistance reduction effect is reduced. On the other hand, when the thickness of the current collecting circuit exceeds 5 mm, the light shielding ratio increases, and the photoelectric conversion efficiency may be impaired. Note that the width of the current collecting circuit is normally 0.05 to 1 mm due to restrictions on the apparatus.

Further, in the first to third dye-sensitized solar cell electrode substrates according to the present invention, the current collecting circuit pattern is a parallel line type, and an Amida lottery type in which horizontal lines are arranged discontinuously between the parallel lines. And a spiral wire type.
In the case of each of the above patterns, the current collecting circuit can be formed by a single Al vacuum vapor deposition process using a metal mask, so that the cost can be reduced accordingly.

Next, the photoelectrode for dye-sensitized solar cell according to the present invention was laminated on any one of the first to third electrode substrates according to the present invention described above and the surface of the transparent conductive film in the electrode substrate. It comprises a metal oxide semiconductor film and a sensitizing dye held on the metal oxide semiconductor film.
According to the above-mentioned photoelectrode, the resistance value of the transparent conductive film can be effectively reduced by the current collecting circuit provided on the electrode substrate, the manufacturing cost can be suppressed, and the corrosion resistance and durability against the electrolyte can be reduced. Is also excellent.

The counter electrode for a dye-sensitized solar cell according to the present invention includes any one of the first to third electrode substrates according to the present invention described above.
According to the above counter electrode, the current collector circuit provided on the electrode substrate can effectively reduce the resistance value of the transparent conductive film, reduce the manufacturing cost, and provide corrosion resistance and durability to the electrolyte. Is also excellent.

The present invention also includes a dye-sensitized solar cell comprising the above-described photoelectrode according to the present invention, a counter electrode, and an electrolyte layer interposed between the two electrodes. The counter electrode is preferably constituted by the counter electrode according to the present invention described above.
According to the solar cell, the resistance value of the transparent conductive film is reduced by the current collecting circuit, so that the photoelectric conversion efficiency is improved and the cell can be enlarged. Moreover, according to said solar cell, since the corrosion resistance of the current collection circuit with respect to an electrolyte layer is improving, durability and stability are also improved.

  An embodiment of the present invention will be described with reference to FIGS. In the following description, “upper and lower” means the upper and lower sides of FIGS. 1 to 3, and light is applied from above.

  FIG. 1 is a partial cross-sectional view showing an embodiment of a dye-sensitized solar cell according to the present invention. The illustrated solar cell (1) includes a photoelectrode (2), a counter electrode (3) disposed at a predetermined interval below the photoelectrode (2), and an electrode between the electrodes (2) and (3). An electrolyte layer (4).

  The photoelectrode (2) consists of an electrode substrate (21) in which a transparent conductive film (21B) is laminated on the lower surface of a transparent plate (21A), and a metal oxide layered on the lower surface (front surface) of the transparent conductive film (21B). A physical semiconductor film (22), and a sensitizing dye (23) held on the metal oxide semiconductor film (22). On the lower surface of the transparent conductive film (21B) in the electrode substrate (21), a current collector circuit (21C) is provided, which is obtained by vacuum-depositing Al in a predetermined pattern.

  The counter electrode (3) includes an electrode substrate (31) in which a transparent conductive film (31B) is laminated on the lower surface of the transparent plate (31A), and a reduction film laminated on the upper surface (front surface) of the transparent conductive film (31B). (32).

  As the transparent plates (21A) and (31A), a glass plate is usually used, but a transparent plastic film such as a PET film may be used.

  Examples of the material for the transparent conductive films (21B) and (31B) include ITO and FTO.

In addition to titania (TiO ₂ ), the metal oxide semiconductor film (22) is formed of ZnO ₂ , SnO ₂ , ZrO ₂ , a composite system between these oxides, or the like. As a film forming means of these metal oxide semiconductors, for example, a method of applying a wet process such as a spin coating method, a doctor blade method, a screen printing method, a squeegee method, and sintering at about 450 ° C., a sputtering method, Examples include a dry process such as a CVD method and a vapor deposition method.

  As the sensitizing dye (23), a ruthenium-based dye is usually used, and is carried in the pores of the metal oxide semiconductor film (22) made of nano-sized titania or the like.

  The reducing film (32) of the counter electrode (3) is usually formed by vapor deposition of platinum (Pt), but carbon, rhodium, ruthenium or the like may be used instead of platinum. Note that the reduction film (32) of the counter electrode (3) may not be formed, for example, when the entire solar cell (1) is formed transparently.

  The electrolyte layer (4) is formed by sealing an electrolyte made of an iodine solution or the like in a space provided between the photoelectrode (2) and the counter electrode (3).

  Although not shown in the drawing, the electrodes (2) and (3) are integrated by joining the peripheral portions with a sealant or the like with an electrolyte interposed therebetween. Then, a lead wire is connected to one end of the transparent conductive film (21B) (31B) in both electrodes (2) (3).

  FIG. 2 is an enlarged partial sectional view showing the electrode substrate (21) of the photoelectrode (2) in the solar cell (1) of FIG. As shown in the figure, the surface of the current collector circuit (21C) formed on the transparent conductive film (21B) is covered with an oxide film (21D). The oxide film (21D) is formed by heat-treating or electrically or chemically oxidizing the surface of the Al vapor deposition film (21C). In the case of heat treatment, it is usually preferable to carry out at 300 to 600 ° C. for 0.2 to 12 hours in the air. Examples of the electrical method include alumite treatment and anodization treatment. Chemical methods include the formation of hydrated oxides by hydrolysis. Among these methods, the heat treatment is particularly advantageous in that it does not require special equipment and can suppress the production cost. The thickness of the current collector circuit (21C) is 1 to 30 μm.

  Further, instead of the oxide film (21D), the surface of the current collecting circuit (21C) may be covered with any one film of Ti, Ni, Nb, Ta, W, SUS and ITO. These films are formed by vacuum-depositing Ti, Ni, Nb, Ta, W, SUS or ITO on the surface of the Al deposited film constituting the current collecting circuit (21C). In the case of ITO, Furthermore, a sintering process is required.

  FIG. 3 is a partial cross-sectional view showing another embodiment of the electrode substrate (21). In this electrode substrate (21), a current collector circuit (21C) formed by vacuum-depositing Al in a predetermined pattern is provided on the lower surface of the transparent plate (21A), and the surface of the current collector circuit (21C) is an oxide film (21D ). In the case of this embodiment, the transparent conductive film (21B) is advantageously formed of an ITO film. This is because the oxide film (211) is formed on the surface of the current collecting circuit (21C) at the same time as the sintering process for forming the ITO film, thereby reducing the number of steps.

Although not shown, the current collector circuit (21C) may be formed on both the lower surface of the transparent plate (21A) and the lower surface of the transparent conductive film (21B).
Further, a current collecting circuit similar to the current collecting circuit (21C) of the electrode substrate (21) of the photoelectrode (2) may be formed on the electrode substrate (31) of the counter electrode (3). In this case, the current collecting circuit is formed on at least one of the upper surface of the transparent plate (31A) and the upper surface (surface) of the transparent conductive film (31B) in the electrode substrate (31).

  FIG. 4 is a bottom view showing a pattern of the current collecting circuit (21C) formed on the electrode substrate (21). The current collecting circuit (21C) in FIG. 4 has a parallel line pattern in which six vertical lines (211) are arranged in parallel, and extends almost over the entire surface of the transparent conductive film (21B). The width of each vertical line (211) is 0.01 to 5 mm.

  FIG. 5 is a bottom view of the electrode substrate (21) showing another pattern of the current collecting circuit (21C). In FIG. 5, the current collecting circuit (21C) has an “Amidakuji” pattern in which horizontal lines (212) are arranged discontinuously between six parallel vertical lines (211).

  FIG. 6 is a bottom view of the electrode substrate (21) showing still another pattern of the current collecting circuit (21C). The current collecting circuit (21C) of FIG. 6 has a spiral pattern in which the broken lines (213) are continuous so as to draw a spiral from the outer peripheral portion to the center portion of the transparent conductive film (21B).

  When the current collector circuit (21C) having the pattern as shown in FIGS. 4 to 6 is formed on the surface of the transparent conductive film (21B), for example, the pattern of the current collector circuit (21C) to be formed in the deposition chamber is used. After the corresponding metal mask is overlaid on the lower surface of the transparent conductive film (21B), Al is vacuum-deposited on the lower surface portion of the transparent conductive film (21B) not covered with the metal mask, and then the metal mask is removed. Good. Note that the pattern of the current collecting circuit (21C) is not limited to that shown in FIGS. 4 to 6, and for example, the number of steps may be increased, but may be a lattice shape.

Example 1
Prepare a glass plate with an ITO film thickness of about 2400 mm (Sanyo Vacuum Industry, 80 mm x 90 mm), vacuum-deposit Al on the ITO film surface of the glass plate, and then oxidize the surface of the Al deposited film Then, an electrode substrate was manufactured by forming a current collecting circuit having a parallel line pattern (see FIG. 4). The current collecting circuit had a width of 0.2 mm and a pitch of 10 mm. Moreover, the oxidation treatment of the Al deposited film was performed by heating at 300 ° C. for 3 hours in the air.
(Example 2)
An electrode substrate was produced in the same manner as in Example 1 except that the current collector circuit pitch was 5 mm.
(Example 3)
An electrode substrate was fabricated in the same manner as in Example 1 except that the current collecting circuit pattern was an amide lottery type (see FIG. 5) having a width of 0.2 mm and a pitch of 10 mm.
Example 4
An electrode substrate was fabricated in the same manner as in Example 1 except that the current collecting circuit pattern was a spiral type (see FIG. 6) having a width of 0.2 mm and a pitch of 10 mm.
(Comparative Example 1)
The same glass plate with an ITO film as used in Example 1, in which an Al vapor deposition film (current collecting circuit) was not formed on the surface of the ITO film, was used as an electrode substrate.

  For each of the electrode substrates of Examples 1 to 4 and Comparative Example 1, the surface resistance between 100 mmL diagonal was measured with a tester. The results are as shown in Table 1 below.

  As can be seen from Table 1, in Examples 1 to 4 having a current collecting circuit made of a surface-oxidized Al vapor deposition film, the surface resistance was about as compared with Comparative Example 1 having no such current collecting circuit. It decreased by 38 to 47%.

(Example 5)
A glass plate with an FTO film thickness of 9500 mm (Asahi Glass Co., Ltd., 80 mm x 80 mm) is prepared. After Al is vacuum-deposited on the surface of the FTO film on the glass plate, the surface of the Al vapor-deposited film is oxidized to produce a parallel line type. An electrode substrate was produced by forming a current collecting circuit having the pattern (see FIG. 4). The current collecting circuit had a width of 0.2 mm and a pitch of 10 mm. Moreover, the oxidation treatment of the Al deposited film was performed by heating at 300 ° C. for 3 hours in the air.
(Example 6)
An electrode substrate was fabricated in the same manner as in Example 5 except that the current collector circuit pitch was 5 mm.
(Example 7)
An electrode substrate was fabricated in the same manner as in Example 5 except that the current collecting circuit pattern was an amide lottery type (see FIG. 5) having a width of 0.2 mm and a pitch of 10 mm.
(Example 8)
An electrode substrate was fabricated in the same manner as in Example 5 except that the current collecting circuit pattern was a spiral wire type having a width of 0.2 mm and a pitch of 10 mm (see FIG. 6).
(Comparative Example 2)
The same glass plate with an FTO film as used in Example 5 and having no Al deposited film (current collector circuit) formed on the surface of the FTO film was used as an electrode substrate.

  For each of the electrode substrates of Examples 5 to 8 and Comparative Example 2, the surface resistance between 100 mmL diagonal was measured by a tester. The results are as shown in Table 2 below.

  As is apparent from Table 2, in Examples 5 to 8 having a current collecting circuit made of an Al deposited film subjected to surface oxidation treatment, the surface resistance was about as compared with Comparative Example 2 having no such current collecting circuit. It decreased by 32-42%.

1 is a partial sectional view of a dye-sensitized solar cell according to an embodiment of the present invention. It is a fragmentary sectional view which expands and shows the electrode substrate of the photoelectrode in the solar cell of FIG. It is a fragmentary sectional view showing other embodiments of an electrode substrate. It is a bottom view of the electrode substrate which shows the pattern of a current collection circuit. It is a bottom view of the electrode substrate which shows the other pattern of a current collection circuit. It is a bottom view of the electrode substrate which shows another pattern of a current collection circuit.

Explanation of symbols

(1): Dye-sensitized solar cell
(2): Photoelectrode
(21): Electrode substrate
(21A): Transparent plate
(21B): Transparent conductive film
(21C): Current collector circuit
(21D): Oxide film
(22): Metal oxide semiconductor layer
(23): Sensitizing dye
(3): Counter electrode
(31): Electrode substrate
(31A): Transparent plate
(31B): Transparent conductive film
(32): Reduction layer
(4): Electrolyte layer

Claims (9)

In the electrode substrate for a dye-sensitized solar cell in which a transparent conductive film is laminated on one side of the transparent plate, a plurality of parallel Al are provided on at least one of the one side of the transparent plate and the surface of the transparent conductive film . A current collecting circuit is formed by vacuum deposition on an Amida lottery or spiral line pattern in which horizontal lines are arranged discontinuously between vertical lines, and the surface of the current collecting circuit is covered with an oxide film An electrode substrate for a dye-sensitized solar cell, characterized in that. In the electrode substrate for a dye-sensitized solar cell in which a transparent conductive film is laminated on one side of the transparent plate, a plurality of parallel Al are provided on at least one of the one side of the transparent plate and the surface of the transparent conductive film . A current collecting circuit is provided by vacuum deposition on an Amida lottery or spiral pattern in which horizontal lines are arranged discontinuously between vertical lines, and the surface of the current collecting circuit is formed of Ti, Ni, Nb, Ta An electrode substrate for a dye-sensitized solar cell, which is covered with any one film of W, SUS, and ITO. In the dye-sensitized solar cell electrode substrate in which a transparent conductive film is laminated on one side of the transparent plate, at least one of the one side of the transparent plate and the surface of the transparent conductive film has Nb, Ta, W, A current collecting circuit is provided, in which any one of Ti, Ni, and SUS is vacuum-deposited into an Amida lottery or spiral line pattern in which horizontal lines are discontinuously arranged between a plurality of parallel vertical lines. A dye-sensitized solar cell electrode substrate, wherein:   The dye-sensitized solar cell electrode substrate according to any one of claims 1 to 3, wherein the current collecting circuit has a thickness of 1 to 30 µm.   The electrode substrate for a dye-sensitized solar cell according to any one of claims 1 to 4, wherein the current collecting circuit has a width of 0.01 to 5 mm. An electrode substrate according to any one of claims 1 to 5 , a metal oxide semiconductor film laminated on a surface of a transparent conductive film in the electrode substrate, and a sensitizing dye held on the metal oxide semiconductor film A photoelectrode for a dye-sensitized solar cell, comprising: A counter electrode for a dye-sensitized solar cell, comprising the electrode substrate according to any one of claims 1 to 5 . A dye-sensitized solar cell comprising the photoelectrode according to claim 6 , a counter electrode, and an electrolyte layer interposed between the two electrodes. Counter electrode consists of opposing electrodes according to claim 7, dye-sensitized solar cell of claim 8.

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