JPH0353723B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a transparent conductive film for photovoltaic devices, particularly for solar cells, having a two-layer structure containing tin oxide as a main component. [Prior art] In recent years, amorphous silicon (a-
A photoelectric conversion element is formed using Al (Si), and then Al
Low-cost solar cells with electrodes such as these are known. Since the photoelectric conversion efficiency of such a-Si solar cells is lower than that of solar cells using other crystalline semiconductors, various measures have been taken to increase the photoelectric conversion efficiency. One of its features is low resistance and high optical transparency. One example of this is to use a fluorine-containing tin oxide film as a transparent conductive film. As a transparent conductive film containing tin oxide as a main component other than the fluorine-containing tin oxide film, an antimony-containing tin oxide film is known. [Problems to be solved by the invention] However, antimony-containing tin oxide films have higher resistance than fluorine-containing tin oxide films, and are not often used as transparent conductive films for photoelectric conversion elements using amorphous silicon. It had not been done. [Means for Solving the Problems] The present invention has been made to solve the above problems, and provides a transparent conductive film for photoelectric devices suitable for increasing the photoelectric conversion efficiency of photoelectric devices. It is. That is, the present invention deposits a fluorine-containing tin oxide film by bringing a tin compound and a fluorine-containing compound into contact with a transparent substrate heated to a high temperature through a thermal decomposition oxidation reaction, and further deposits this fluorine-containing tin oxide film. A transparent conductive film having a two-layer structure in which an antimony-containing tin oxide film is deposited on a fluorine-containing tin oxide film by heating a transparent substrate to a high temperature, bringing a tin compound and an antimony-containing compound into contact, and depositing an antimony-containing tin oxide film through a thermal decomposition oxidation reaction. . Tin compounds that can be used in the present invention are:
C ₄ H ₉ SnCl ₃ , SnCl ₄ , (CH ₃ ) ₂ SnCl ₂ , (CnH _2o+1 )
₄ Sn (however, n=1 to 4), (CH ₃ ) ₂ SnH ₂ ,
(C ₄ H ₉ ) ₃ SnH and (C ₄ H ₉ ) ₂ Sn(COOCH ₃ ) ₂ , etc. Compounds containing fluorine include CH ₃ CHF ₂ ,
CH ₃ CClF ₂ , CHClF ₂ , CHF ₃ , CF ₂ Cl ₂ , CF ₃ Cl,
CF ₃ Br etc. can be used, and as the antimony-containing compound, SbCl ₅ , SbCl ₃ etc. can be used. In the present invention, these tin compounds and a compound containing fluorine or a compound containing antimony (hereinafter referred to as
These two are collectively called dopants. ) to cause a thermal decomposition oxidation reaction by contacting the heated transparent substrate with a vapor phase chemical reaction method (CVD method) in which tin compound vapor, oxidizing gas, and dopant are brought into contact with the high-temperature transparent substrate, or a solution of the tin compound. This can be carried out by a spray method, etc., in which a spray is applied to a high-temperature transparent substrate. Among these, the CVD method is preferred, in which a transparent conductive film having a two-layer structure of a fluorine-containing tin oxide film and an antimony-containing tin oxide film is deposited by vaporizing a tin compound and a dopant onto a transparent substrate heated to 400°C to 600°C. It is used in [Function] By forming the transparent conductive film into a two-layer structure having a fluorine-containing tin oxide film layer, the resistance of the transparent conductive film can be lowered, and the transparent conductive film in contact with the p-type semiconductor layer of the photoelectric conversion element can be lowered. By changing the film from fluorine-containing tin oxide to antimony-containing tin oxide, the bonding property between the transparent conductive film and the photoelectric conversion element is improved, and the conversion efficiency of the photoelectric element can be increased. Example 1 Soda lime glass with a silicon oxide coating having a size of 25 (mm) x 30 (mm) and a thickness of 1.1 (mm) was thoroughly washed and dried to obtain a glass substrate. A transparent conductive film was attached onto this glass substrate in the following manner. Monobutyltin trichloride vapor, water vapor,
by CVD method using a adjusted gas mixture of oxygen gas 1.1-difluoroethane gas and nitrogen gas.
A fluorine-containing tin oxide film was formed on a glass substrate heated to 550°C. The thickness of the obtained fluorine-containing tin oxide film was 0.33 μm. The glass substrate on which this fluorine-containing tin oxide film was deposited was heated to 550°C, and then the glass substrate was heated to 550°C, and the film was impregnated by CVD using a controlled gas mixture of tin tetrachloride vapor, oxygen gas, methyl alcohol, antimony pentachloride, and nitrogen gas. An antimony-containing tin oxide film was formed on a fluorine tin oxide film. The thickness of the obtained antimony-containing tin oxide film was 0.07 μm. The sheet resistance of this two-layer film having a total film thickness of 0.4 μm was 11.0 Ω/hole as shown in Table 1. Using this, an amorphous silicon solar cell was created according to the following procedure. (1) A p-type semiconductor layer (boron _- doped a-SiC:
H, approximately 0.015 μm thick) (2) Intrinsic semiconductor layer (a-Si: H, approximately 0.5 μm thick) (3) N-type semiconductor layer (phosphorus-doped microcrystalline Si (μc-Si): H, approximately 0.050 μm thick) ) are deposited in turn, and finally an Al electrode (approximately
0.1 μm thick) in vacuum (approximately 10 ⁻⁴ Pa) by vapor deposition. When creating the above Al electrode, a mask with a hole of 2 mm in diameter was placed on the substrate, and 16 solar cells with a diameter of 2 mm were created. The obtained solar cell was irradiated with AM1 light of 100 mW/cm ² and the energy conversion efficiency was measured. The measurement results obtained are shown in Table 1. In addition, as Comparative Example 1, by the same method as Example 1, on soda lime glass with silicon oxide coating,
A fluorine-containing tin oxide film with a thickness of 0.4 μm was formed and the sheet resistance was measured, and as shown in Table 1, it was 10.0Ω/
mouth

[Table] An amorphous silicon solar cell was prepared on this fluorine-containing tin oxide film by the same method as in Example 1, and the energy conversion efficiency was measured. Table 1 shows the results. Example 2 Soda lime glass with a silicon oxide coating having a size of 25 (mm) x 30 (mm) and a thickness of 1.1 (mm) was thoroughly washed and dried to be used as a glass substrate. A transparent conductive film was deposited on this glass substrate in the same manner as in Example 1. The transparent conductive film is 0.22μm attached on the glass substrate.
It was a two-layer film in which a 0.25 μm antimony-containing tin oxide film was deposited on a fluorine-containing tin oxide film with a film thickness, and the sheet resistance was 14.5 Ω/hole as shown in Table 2. An amorphous silicon solar cell was fabricated on this antimony-containing tin oxide film in the same manner as in Example 1, and the resulting solar cell was irradiated with AM light of 100 mW/cm ² to measure energy conversion efficiency. Table 2 shows the measurement results obtained.

〔Effect of the invention〕

According to the present invention, as is clear from the examples,
A solar cell transparent conductive film that contributes to improving energy conversion efficiency can be obtained. Furthermore, it is clear that the present invention can be used as a transparent conductive film for photoelectric devices other than solar cells.

Claims (1)

[Scope of Claims] 1. A two-layer structure consisting of a transparent conductive film mainly composed of tin oxide containing fluorine, and a transparent conductive film mainly composed of tin oxide containing antimony attached to the transparent conductive film. transparent conductive film. 2. The method according to claim 1, wherein a transparent conductive film mainly composed of tin oxide containing antimony is formed on a transparent conductive film mainly composed of tin oxide containing fluorine attached to a transparent substrate. Transparent conductive film.