JP3004679B2 - Method of forming transparent conductive film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a transparent conductive tin oxide film used for devices such as solar cells, liquid crystals, and electroluminescence.

[Prior Art] Conventionally, as one method of forming a transparent conductive tin oxide film,
A transparent conductive tin oxide film containing antimony (hereinafter, SnO ₂ : Sb
As a film, for example, soda-lime glass having a surface coated with SiO ₂ with a solution obtained by dissolving stannic chloride (SnCl ₄ .5H ₂ O) and antimony trichloride (SnCl ₃ ) in a solvent such as water Is heated to 400 ° C. or higher, and then applied by a spray coating method to form the film. Further, another transparent conductive tin oxide film containing fluorine (hereinafter referred to as Sn
O ₂ : F film) is also used in a solvent such as water.
Tin (SnCl ₄ · 5H ₂ O) and ammonium fluoride (NH ₄ F),
Hydrogen fluoride (HF), ammonium hydrogen fluoride (NH ₄ FHF)
A method is known in which a solution prepared by dissolving the above is heated to 400 ° C. or higher on soda lime glass whose surface is coated with SiO _2, and then applied by spray coating to form a soda lime glass.

[INVENTION A problem to be solved] However乍Ra, the former method, i.e., a solvent such as water stannic chloride (SnCl ₄ · 5H ₂ O) and Oyobi antimony trichloride (SbCl ₃₎
When a solution prepared by dissolving is prepared, it becomes a colloid solution,
If the stirring is not carried out constantly, there is a problem that sedimentation and separation occur with the lapse of time and stability is lacking. In addition, when a film having a constant thickness is formed on the substrate surface, the sheet resistance value decreases as the doping amount of Sb increases, but the substrate is colored blue,
Light transmittance is greatly reduced. In the latter method, that is, when doping with fluorine, antimony trichloride (Sb
Ammonium fluoride (NH ₄ F), ammonium hydrogen fluoride (NH ₄ FHF), hydrogen fluoride (HF), etc. are used as doping agents instead of Cl ₃ ), but volatilization occurs during the reaction and the doping efficiency decreases. Therefore, it is necessary to add an excess amount to the necessary amount in the membrane, and a problem such as disposal of unreacted fluorine compound occurs. Further, when a film having a constant thickness is formed on the surface of the substrate, the sheet resistance value decreases as the doping amount of F increases, but the substrate is colored yellow and the light transmittance greatly decreases.

The present invention, when compared with the transparent conductive tin oxide films manufactured by these conventional methods, shows lower resistance and higher transparency when they have the same film thickness, and also has excellent doping efficiency, thus It is another object of the present invention to provide a forming method which requires a smaller amount of a doping agent than a conventional method.

[Means for solving the problem]

As described above, when producing a transparent conductive tin oxide film by the spray method, as a solvent, in order to avoid the danger of explosion and the like, a solvent solution mainly composed of water is used, and a SnO ₂ : Sb film is used. Antimony trichloride (SbCl ₃ ) is used as a doping agent for the preparation, but antimony trichloride does not become a transparent solution in water but a colloidal solution, and sedimentation occurs with the passage of time.

However, the present inventors have made intensive studies and found that a stable transparent solution can be obtained without adding a colloid solution by adding a water-soluble complex compound containing fluorine and antimony to this solution. In addition, this solution also contains fluorine as a doping agent, and a relatively stable complex compound is formed.In the conventional method, when doping with fluorine, fluorine volatilization is large at high temperatures and a large amount of fluorine compound is formed. However, in the case of this solution, doping is efficiently performed without such a problem, so that only a small amount of a fluorine compound is sufficient.Moreover, although the reason is not clear, antimony and fluorine are simultaneously doped. As a result, it has been found that when a film having the same thickness as each single element doping film of the conventional method is manufactured, a film having lower resistance and higher transparency than the conventional method can be manufactured. The present invention has been completed based on such findings.

That is, in the present invention, a solution containing a tin compound and ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )} as a source of antimony and fluorine is applied to a heated substrate by a spray method. A method for forming a transparent conductive tin oxide film, characterized in that:

As a source of antimony and fluorine in the present invention, ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )}, which is a water-soluble complex compound containing fluorine and antimony, is used alone or It can be used in combination with other antimony compounds and fluorine compounds. As such an antimony compound, antimony chloride (SbCl ₃ ) is suitable. As also fluorine compounds, ammonium hydrogen fluoride (NH ₄ FHF), ammonium fluoride (NH ₄ F) and the like.

As the tin compound used in the present invention, stannous chloride (SnCl ₂ ), stannic chloride (SnCl ₄ .5H ₂ O), stannous bromide (SnBr ₂ ) and the like can be used. Water, a mixed solvent of water and ethanol, a mixed solvent of water and hydrochloric acid, and the like are suitable. The total amount of fluorine and antimony in the solution is preferably 0.1 to 30% by weight based on tin. The substrate temperature during film formation is preferably from 400 to 500 ° C.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but these do not limit the present invention.

Example 1 1.43 g of ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )} was added to 35% hydrochloric acid in 1000 ml of water.
A solution dissolved in a mixed solvent containing 50 g was prepared. In this solution, the amount of antimony based on tin was 2% by weight, and the amount of fluorine based on tin was 1.57% by weight. Next, this solution is
Soda lime glass with a surface SiO ₂ (500 mm) coat heated to 450 ° C. was spray-coated on one surface of a 1.1 mm thick substrate to obtain a transparent conductive tin oxide film having a thickness of 4000 mm.

Comparative Example 1 Instead of ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )} of Example 1, 3.46 g of ammonium fluoride (NH ₄ F) was used, and the amount of antimony with respect to tin was 0 weight. %, And the same operation as in Example 1 except that the amount of fluorine based on tin was 5% by weight.

Comparative Example 2 Instead of ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )} of Example 1, 7.29 g of ammonium fluoride (NH ₄ F) was used, and the amount of antimony with respect to tin was 0 weight. %, And the same operation as in Example 1 except that the amount of fluorine based on tin was 10% by weight.

Comparative Example 3 Instead of ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )} of Example 1, 1.96 g of antimony trichloride (SbCl ₃ ) was used, and the amount of antimony with respect to tin was 3% by weight. The same operation as in Example 1 was performed except that the amount of fluorine based on tin was 0% by weight.

As evaluation of each transparent conductive tin oxide film obtained in Example 1 and Comparative Examples 1 to 3, specific resistance and visible light transmittance were measured, and the results are shown in Table 1.

As is clear from the results in Table 1 above, in this example, a transparent conductive tin oxide film having low resistance and light transmittance equal to or higher than that of the comparative example was formed with a small amount of the doping agent. It was also confirmed that the stability of the solution was good.

[Action / Effect]

The present invention uses ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )}, which is a water-soluble complex compound containing antimony and fluorine,
The problem of instability of the solution in the case of antimony alone and the problem of the volatilization of fluorine in the case of fluorine alone are eliminated, and a low-resistance and high-transparency film is provided in a smaller amount than in the conventional method. This has a remarkable effect.

As described above, according to the present invention, a transparent conductive tin oxide film having low resistance and light transmittance equal to or higher than that of the conventional method can be obtained with a smaller amount of the doping agent. In addition, the solution is stable, and the amount of unreacted doping agent disposed of is small, which is extremely useful in industry.

Claims (2)

(57) [Claims] A solution containing a tin compound and ammonium pentafluoroantimonate (III) {(NH ₄ ) ₂ (SbF ₅ )} as a source of fluorine and antimony is applied on a heated substrate by a spray method. A method for forming a transparent conductive tin oxide film. 2. The method according to claim 1, wherein the total amount of antimony and fluorine based on tin in the solution is 0.1 to 30% by weight.