JP2003203683A - Conductive glass for photoelectronic conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive glass for a photoelectronic conversion element used for a dye sensitive solar cell or the like of which, surface resistivity is reduced to a great extent and photoelectric conversion efficiency is heightened so as not to reduce the transmission quantity of light. <P>SOLUTION: The conductive glass for a photoelectric conversion element is formed by forming a transparent conductive film 12 made of FTO or the like on a glass plate 11, and forming a grid 13 made of metal thin film on the transparent conductive film 12, and covering the grid 13 and the transparent conductive film 12 by a protection thin film 17 with a thickness of 50 nm or less, made of tin oxide or the like. The grid 13 made of gold, silver, platinum, or the like with a thickness of 1-20 μm, of which, the plane shape is formed into a grid-shape, a comb tooth-shape or the like, and the open area ratio is 90-99%, is formed by a plating method. The sheet resistivity of the conductive glass is 1-0.01 Ω/square and the light transmission rate at the wave length of 550 nm is 60-90%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive glass used for a photoelectric conversion element such as a dye-sensitized solar cell.

[0002]

2. Description of the Related Art A dye-sensitized solar cell, which was developed by Gretzell et al. In Switzerland, has advantages such as high photoelectric conversion efficiency and low manufacturing cost, and is attracting attention as a new type of solar cell. FIG. 10 shows an example of this dye-sensitized solar cell (Japanese Patent Publication No. 8-15097).

In the figure, reference numeral 1 is a glass plate serving as a transparent substrate, and one surface of the glass plate 1 is transparent such as indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO) having a thickness of about 1 μm. The conductive film 2 is formed and becomes the conductive glass 3. On the transparent conductive film 2 of the conductive glass 3, an oxide semiconductor porous film 4 made of oxide semiconductor fine particles such as titanium oxide and niodymium oxide and carrying a photosensitizing dye is formed.

Reference numeral 5 is a conductive glass serving as a counter electrode, and a space between the conductive glass and the oxide semiconductor porous film 4 is filled with an electrolytic solution composed of a non-aqueous solution containing a redox pair such as iodine / iodine ion. The electrolyte layer 6 is formed. Also, instead of the electrolyte layer 6, there is also one in which a hole transport layer made of a solid p-type semiconductor such as copper iodide or thiocyanate copper is provided. In this dye-sensitized solar cell, when light such as sunlight enters from the conductive glass 3 side, an electromotive force is generated between the transparent conductive film 2 and the counter electrode 5.

By the way, in such a dye-sensitized solar cell, the conductive glass 3 usually has a thickness of 0.5 to 1 to form the transparent conductive film 2 on the surface of a heat-resistant glass plate as a glass plate.
Commercially available transparent conductive glass coated with ITO or FTO of about μm in advance by a thin film forming method such as vapor deposition or sputtering is used.

However, this transparent conductive glass has high material cost and processing cost, and the specific resistance of ITO and FTO forming the transparent conductive film 2 is about 10 ⁻⁴ to 10 ⁻³ Ω · cm, and silver, Since it exhibits a value about 100 times the specific resistance of metal such as gold, there is a problem that the resistance value of the transparent conductive film 2 is high, which lowers the photoelectric conversion efficiency of the solar cell.

Therefore, the transparent conductive film 2 of transparent conductive glass is used.
It is conceivable to increase the thickness of the transparent conductive film 2 in order to reduce the resistance of the transparent conductive film 2. However, if the thickness of the transparent conductive film 2 is increased to about 5 μm, the light absorption by the transparent conductive film 2 becomes large, which causes Light transmittance of transparent conductive glass is about 75
% To about 20%, the light reaching the oxide semiconductor porous film 3 is reduced, and this also reduces the photoelectric conversion efficiency of the solar cell.

[0008]

Therefore, an object of the present invention is to provide a conductive glass for a photoelectric conversion element, which is provided on the glass surface and has a low electric resistance value of a conductive layer which functions as an electron passage and has high transparency. Is to get.

[0009]

In order to solve such a problem, the invention according to claim 1 provides a transparent conductive film on a glass surface, and a grid made of a metal thin film is provided on the transparent conductive film. At least the grid is coated with a protective thin film, which is a conductive glass for a photoelectric conversion element.

According to a second aspect of the present invention, the conductive glass for a photoelectric conversion element according to the twelfth aspect is characterized in that the planar shape of the grid is a lattice shape or a comb tooth shape. In the invention according to claim 3, the grid aperture ratio is 90 to 99.
% Is the conductive glass for a photoelectric conversion element according to claim 1. The invention according to claim 4 is characterized in that the metal forming the grid is any one of gold, silver, platinum, chromium, nickel, or an alloy of two or more kinds of these, for the photoelectric conversion element according to claim 1. It is a conductive glass.

The invention according to claim 5 is the conductive glass for a photoelectric conversion element according to claim 1, characterized in that the grid is formed by a plating method. In the invention according to claim 6, the grid has a thickness of 1 to 20 μm.
The conductive glass for a photoelectric conversion element according to claim 1, wherein

The invention according to claim 7 is the conductive glass for a photoelectric conversion element according to claim 1, wherein the protective thin film is made of tin oxide or titanium oxide. The invention according to claim 8 is the conductive glass for a photoelectric conversion element according to claim 1, characterized in that the thickness of the titanium oxide forming the protective thin film is 50 nm or less.

According to a ninth aspect of the invention, the sheet resistance is
It is 1-0.01 ohms / square, It is the electroconductive glass for photoelectric conversion elements of Claim 1 characterized by the above-mentioned. The invention according to claim 10 has a light transmittance of 60 at a wavelength of 550 nm.
The conductive glass for a photoelectric conversion element according to claim 1, wherein the conductive glass is about 90%.

The invention according to claim 11 is a photoelectric conversion element comprising the conductive glass for photoelectric conversion element according to any one of claims 1 to 10. The invention according to claim 12 is the photoelectric conversion element according to claim 11, which is a dye-sensitized solar cell.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments. FIG. 1 shows an example of the conductive glass for a photoelectric conversion element of the present invention. In FIG. 1, reference numeral 11 indicates a glass plate. This glass plate 11 has a thickness of 1
It is made of glass such as soda glass, heat resistant glass, and quartz glass having a size of about 5 mm.

A transparent conductive film 12 is provided on the glass plate 11 to cover the entire surface of the glass plate 11. The transparent conductive film 12 is made of a transparent and conductive thin film such as ITO or FTO and has a thickness of 0.
It has a thickness of about 2 to 1 μm and is formed by a thin film forming method such as a sputtering method or a CVD method.

On the transparent conductive film 12, a grid 13 made of a metal thin film is provided in close contact with it. The grid 13 works together with the transparent conductive film 12 as a passage for electrons generated in the oxide semiconductor porous film when the conductive glass is used in a dye-sensitized solar cell or the like.

The grid 13 has a planar shape, for example, a grid shape as shown in FIG. 2 or a comb tooth shape as shown in FIG. The grid 1 shown in FIG.
3, the vertical length is 450 to 2000 μm and the horizontal width is 2000 to 200.
A large number of 00 μm rectangular openings 14, 14, ... Are formed, and a line 1 made of a metal thin film in the vertical and horizontal directions forming a lattice.
The line width of 5 is 10 to 1000 μm. In addition, a wide collector electrode 16 for collecting current is formed on one side thereof so as to extend in the vertical direction.

In the comb-tooth-shaped grid 13 shown in FIG. 3, the wire 1 having a width of 10 to 1000 μm and made of a metal thin film forming the comb teeth.
5, 15 ... Infinitely parallel to each other 450-2000
Innumerable openings 14, 1 formed at intervals of μm
4 are formed, and a wide collector electrode 16 for collecting current is formed at one end thereof. It goes without saying that the planar shape of the grid 13 is not limited to the lattice shape and the comb tooth shape shown in FIGS. 2 and 3.

As will be described later, the grid 13 is formed by, for example, a plating method, and is made of one or more alloys of metals such as gold, silver, platinum, chromium, nickel, etc. The thickness of 15 is 1 to 20 μm, preferably 3 to 10 μm. This thickness is 1 μm
If it is less than 20 μm, the effect of improving the conductivity is small, and even if it exceeds 20 μm, such an effect is reached, and it is not preferable because it becomes thicker than the oxide semiconductor porous film provided thereon.

The aperture ratio of the grid 13 is 90
~ 99%. The aperture ratio here is defined by the ratio of the total area of the line 15 occupied in the unit area. If the aperture ratio is less than 90%, the light transmittance is reduced and the amount of incident light is reduced, and if it exceeds 99%, the improvement in conductivity becomes insufficient.

Furthermore, the transparent conductive film 12 and the grid 1
3 is entirely covered with a protective thin film 17. This protective thin film 17 has a function of a barrier for preventing the grid 13 from being eroded by an electrolytic solution when this conductive glass is used for a dye-sensitized solar cell or the like, and also transmits light. This is for ensuring that a sufficient amount of light reaches the internal oxide semiconductor porous film.

The protective thin film 17 is a transparent thin film made of a ceramic such as tin oxide, titanium oxide, silicon oxide or zinc oxide and has a thickness of 50 nm or less, preferably 20 to 50 nm.
50 nm. If this thickness is less than 20 nm, the protective effect is insufficient. Further, even if the thickness exceeds 50 nm, the protective effect reaches a peak and the current hardly flows. Protective thin film 17
When is made of tin oxide, its thickness may be 50 nm or more. This protective thin film 17 is formed by CVD method, SPD
Method, a sputtering method, a vapor deposition method, or the like. The protective thin film 17 may be a transparent polymer thin film other than ceramic.

FIG. 4 shows another example of the conductive glass of the present invention. The same components as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In this example, the protective thin film 17 covers only the grid 13, that is, the upper surface and both side surfaces of each line 15, 15 ... Of the grid 13 are covered with the protective thin film 17, and the surface of the transparent conductive film 12 is the protective thin film. It is different from the previous example in that it is not covered with 17.

In the conductive glass having such a structure, the grid 13 and the transparent conductive film 12 on the entire surface thereof.
The total surface resistance that takes into account (and called sheet resistance)
Is 1 to 0.01 Ω / □, and conventional ITO and FTO
It is about 10 to 1/1000 of the transparent conductive glass provided with the transparent conductive film. Therefore, it can be said to be a conductive glass having extremely high conductivity.

Furthermore, in this conductive glass, the average light transmittance of the entire surface can be increased. That is, since the conductivity is remarkably improved by the existence of the grid 13, the thickness of the transparent conductive film 12 having poor transparency can be reduced, and the aperture ratio of the grid 13 is 90 to 99%.
Therefore, the existence of the grid 13 hardly blocks the incident light, and the thickness of the protective thin film 17 is extremely thin. Therefore, the light transmittance at a wavelength of 550 nm is 9
It can be increased to about 0%.

Next, an example of a method for producing such a conductive glass will be described. First, the commercially available I shown in FIG.
A transparent conductive glass 18 provided with a transparent conductive film 12 such as TO or FTO is prepared. Such a transparent conductive glass 1
8 can be obtained from Asahi Glass Co., Ltd., Nippon Sheet Glass Co., Ltd., etc.

The transparent conductive film 12 of this transparent conductive glass 18
After the surface of is cleaned by plasma cleaning or the like, silver, chromium, nickel or gold is sputtered thereon to form a seed layer 19 (FIG. 5). Then, a dry resist film is attached on the seed layer 19, exposed and developed, and then, as shown in FIG.
As shown in FIG. 5, a mask 20 having a planar pattern of the grid 13 is formed, and baking and activation processing are further performed.

After that, gold plating with a thickness of 1 to 20 μm is applied to the seed layer 19 exposed from the mask 20 using this seed layer 19 as one electrode, and as shown in FIG.
A gold layer 21 to be the grid 13 is formed. For this gold plating, first strike plating with a high current density,
Then, a method of plating at a normal current density is preferable because the adhesion is improved.

Thereafter, as shown in FIG. 8, the remaining mask 20 is peeled off and removed, and the seed layer 19 remaining under the mask 20 is removed by etching. Then, the entire surface is thickened by atmospheric pressure CVD or the like. By forming a protective thin film 17 by depositing a film of tin oxide having a thickness of 20 to 50 nm and cleaning the whole,
A conductive glass having the structure shown in is produced.

FIG. 9 shows an example of a dye-sensitized solar cell as a photoelectric conversion element using the conductive glass of the present invention. In FIG. 9, reference numeral 31 is the conductive glass shown in FIG. An oxide semiconductor porous film 32 is provided on the protective thin film 17 of the conductive glass 31.

The oxide semiconductor porous film 32 is formed by combining metal oxide fine particles having semiconductivity such as titanium oxide, tin oxide, tungsten oxide, zinc oxide, zirconium oxide, niobium oxide, etc. A porous body having innumerable fine pores and fine irregularities on the surface,
The thickness is 5 to 50 μm. As shown in FIG. 9, the oxide semiconductor porous film 32 fills the concave portions corresponding to the openings 14, 14, ... Of the grid 13 and covers the entire surface of the protective thin film 17 to form the protective thin film. It is integrally connected with 17.

This oxide semiconductor porous film 32 is formed by
A colloidal liquid or dispersion liquid in which fine particles of the metal oxide having an average particle diameter of 5 to 50 nm are dispersed is applied to the surface of the protective thin film 17 by a coating means such as screen printing, inkjet printing, roll coating, doctor coating, or spray coating. Then, it is performed by a method such as sintering at 300 to 800 ° C.

Further, the oxide semiconductor porous film 32 carries a photosensitizing dye. As the photosensitizing dye, ruthenium complexes containing ligands such as bipyridine structure and terpyridine structure, metal complexes such as porphyrin and phthalocyanine, and organic dyes such as eosin, rhodamine, and merocyanine are used. It can be appropriately selected depending on the type of semiconductor and the like.

Reference numeral 33 is a counter electrode. The counter electrode 33 in this example is a metal foil laminated film 33 in which a metal foil such as a copper foil or a nickel foil is laminated on one surface of a plastic film such as polyimide or polyethylene terephthalate.
A conductive thin film 33b made of platinum, gold or the like is formed on the surface of the metal foil a by vapor deposition, sputtering, or the like, and the conductive thin film 33b is arranged so as to be on the inner surface side of the solar cell. It is an example of dye-sensitized solar cell.

In addition, as the counter electrode 33, a conductive substrate such as a metal plate or a non-conductive substrate 33a such as a glass plate on which a conductive film 33b such as platinum, gold or carbon is formed is used. Good. Further, when the p-type semiconductor is used as the hole transport layer, since the p-type semiconductor is solid,
It is also possible to directly form a conductive thin film of platinum or the like by vapor deposition, sputtering or the like, and use this conductive thin film as the counter electrode 23.

An electrolytic solution is filled between the counter electrode 33 and the oxide semiconductor porous film 32 of the conductive glass 21 to form an electrolyte layer 34. The electrolytic solution is not particularly limited as long as it is a non-aqueous electrolytic solution containing a redox couple. As the solvent, for example, acetonitrile, methoxyacetonitrile, propionitrile, ethylene carbonate, propylene carbonate, γ-butyrolactone, etc. are used.

As the redox pair, for example, a combination of iodine / iodine ion, bromine / bromine ion and the like can be selected. When adding this as a salt, the counter ion is a lithium ion or a tetraalkyl ion in addition to the above redox pair. , Imidazolium ions, etc. can be used. Further, iodine or the like may be added if necessary. Further, a solid electrolyte obtained by gelling such an electrolytic solution with an appropriate polymer matrix may be used.

Instead of the electrolyte layer 34, a hole transport layer made of a p-type semiconductor may be used. For this p-type semiconductor, for example, a monovalent copper compound such as copper iodide or copper thiocyanate or a conductive polymer such as polypyrrole can be used, and among them, copper iodide is preferable. With a solid hole transport layer made of this p-type semiconductor or a gelled electrolyte, there is no risk of electrolyte leakage.

In the conductive glass having such a structure, since the grid 13 made of a metal thin film having high electric conductivity is provided, the electric resistance value of the conductive glass as a whole becomes low, and the dye sensitization is performed. When used in a photoelectric conversion element such as a solar cell, the photoelectric conversion efficiency is high.

Further, since the grid 13 having a low resistance is present, the thickness of the transparent conductive film 12 having poor transparency can be reduced and the transparency thereof can be enhanced, and the existence of the grid 13 blocks light. Also, the amount of light transmitted is increased, and the amount of light incident on the oxide semiconductor porous film 22 is increased when the dye-sensitized solar cell is used. Also improves the photoelectric conversion efficiency. further,
When used in a dye-sensitized solar cell or the like, since the protective thin film 17 is provided, the grid 13 made of metal is not corroded by the electrolytic solution.

Specific examples will be shown below. A transparent conductive glass (manufactured by Asahi Glass Co., Ltd.) in which an FTO having a thickness of 0.5 μm was provided on a glass plate having a thickness of 2 mm was prepared. On the FTO of this transparent conductive glass, a grid-like grid made of an alloy of gold and silver as shown in FIG. 2 was provided by the above-described manufacturing method.

The line thickness of this grid was 5 μm, the line width was 40 μm, the size of the opening was a rectangle of 860 μm in length and 5000 μm in width, and the aperture ratio was 95%. Then, a protective thin film made of tin oxide having a thickness of 30 nm was formed on the entire glass plate from above this grid by atmospheric pressure CVD method to obtain a conductive glass. The sheet resistance of the conductive glass thus obtained is 0.1 Ω / □, the wavelength is 550.
The light transmittance in nm was 75%.

Then, an oxide semiconductor porous film was formed on the protective conductive film of the conductive glass. This porous oxide semiconductor film is formed by dispersing fine particles of titanium oxide having a particle diameter of about 20 nm in acetyl nitrile to form a paste, which is applied to the grid by a barcode method to a thickness of 15 μm, and dried at 400 ° C. It was heated and baked for 1 hour.
A ruthenium dye was supported on the baked oxide semiconductor porous film.

As a counter electrode, a transparent conductive glass (commercially available) having a glass plate having a thickness of 2 mm and FTO having a thickness of 5 μm was prepared, the conductive glass and the counter electrode were bonded together, and iodine / iodide was placed in the gap. A dye-sensitized solar cell was prepared by filling the electrolytic solution of No. 1 with an electrolyte layer. The planar dimension of the obtained solar cell was 100 mm × 100 mm.

About this solar cell, artificial sunlight (AM
1.5) was irradiated, the current-voltage characteristic was measured, and the power generation efficiency (η) was obtained. As a result, the power generation efficiency was 5%. For comparison, a commercially available transparent conductive glass without a grid and a protective thin film was used as it was to assemble a dye-sensitized solar cell, and the power generation efficiency was calculated to be 0.07%.

[0047]

As described above, in the conductive glass for photoelectric conversion element of the present invention, a transparent conductive film is provided on the glass surface, a grid made of a metal thin film is provided on the transparent conductive film, and at least the grid is protected. Since it is coated with a thin film, it has extremely high electrical conductivity as conductive glass, and the thickness of the transparent conductive film can be made thin, so there is almost no blocking of light in the grid, so light transmission is possible. The photoelectric conversion element has a high rate, and thus a photoelectric conversion element having a high photoelectric conversion efficiency can be obtained.

When this conductive glass is used in a dye-sensitized solar cell, the grid made of a metal thin film is covered with the protective thin film, so that it is not eroded by the electrolytic solution of the battery.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a conductive glass for a photoelectric conversion element of the present invention.

FIG. 2 is a plan view showing an example of a grid according to the present invention.

FIG. 3 is a plan view showing another example of the grid according to the present invention.

FIG. 4 is a schematic cross-sectional view showing another example of the conductive glass of the present invention.

FIG. 5 is a schematic sectional view showing a method for producing a conductive glass for a photoelectric conversion element of the present invention.

FIG. 6 is a schematic cross-sectional view showing a method for producing a conductive glass for a photoelectric conversion element of the present invention.

FIG. 7 is a schematic cross-sectional view showing a method for producing a conductive glass for a photoelectric conversion element of the present invention.

FIG. 8 is a schematic sectional view showing a method for producing a conductive glass for a photoelectric conversion element of the present invention.

FIG. 9 is a schematic sectional view showing an example of a dye-sensitized solar cell using the conductive glass for a photoelectric conversion element of the present invention.

FIG. 10 is a schematic cross-sectional view showing a conventional dye-sensitized solar cell.

[Explanation of symbols]

11 ... Glass plate, 12 ... Transparent conductive film, 13 ...
-Grid, 17 ... Protective thin film, 32 ... Oxide semiconductor porous film, 33 ... Counter electrode, 34 ... Electrolyte layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuo Tanabe             1-5-1 Kiba Stock Market, Koto-ku, Tokyo             Inside Fujikura F-term (reference) 5F051 AA14 FA02 FA06 GA03                 5H032 AA06 AS06 AS16 CC09 CC13                       CC16 EE01 EE02 EE07 EE16                       HH01 HH04 HH07 HH08

Claims (12)

[Claims] 1. A transparent conductive film is provided on a glass surface, and a grid made of a metal thin film is provided on the transparent conductive film.
At least the grid is covered with a protective thin film, which is a conductive glass for a photoelectric conversion element. 2. The conductive glass for a photoelectric conversion element according to claim 1, wherein the planar shape of the grid is a lattice shape or a comb tooth shape. 3. The conductive glass for a photoelectric conversion element according to claim 1, wherein the grid has an aperture ratio of 90 to 99%. 4. The conductive glass for a photoelectric conversion element according to claim 1, wherein the metal forming the grid is any one of gold, silver, platinum, chromium, nickel, or an alloy of two or more of these. . 5. The conductive glass for a photoelectric conversion element according to claim 1, wherein the grid is formed by a plating method. 6. The conductive glass for a photoelectric conversion element according to claim 1, wherein the grid has a thickness of 1 to 20 μm. 7. The conductive glass for a photoelectric conversion element according to claim 1, wherein the protective thin film is made of tin oxide or titanium oxide. 8. The titanium oxide forming the protective thin film has a thickness of 50.
The conductive glass for a photoelectric conversion element according to claim 1, wherein the conductive glass has a thickness of not more than nm. 9. The conductive glass for a photoelectric conversion element according to claim 1, which has a sheet resistance of 1 to 0.01 Ω / □. 10. The light transmittance at a wavelength of 550 nm is 60.
It is -90%, The electroconductive glass for photoelectric conversion elements of Claim 1 characterized by the above-mentioned. 11. A photoelectric conversion element comprising the conductive glass for a photoelectric conversion element according to claim 1. 12. The photoelectric conversion element according to claim 11, which is a dye-sensitized solar cell.