JPH0433213A - Formation of transparent conductive film - Google Patents

Abstract

PURPOSE:To ensure lower resistance and higher transparency, and to improve doping efficiency by spraying a tin compound and solvent including antimony and fluorine on a heated substrate. CONSTITUTION:A tin compound and solvent including antimony and fluorine are sprayed on a heated substrate. It is recommended to use antimony trichloride as the antimony resource and at least one is selected from ammonium hydrogen fluoride and ammonium fluoride as the fluorine resource. A comparatively stable tin compound is thus formed, and problems such as unstableness of the solvent when only antimony is used, or fluorine evaporation when only fluorine is used, are solved. By synergism of them, the film with lower resistance and higher transparency can be obtained with less quantity than that obtained by conventional methods.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a transparent conductive tin oxide film that can be used in devices such as solar cells, liquid crystals, and electroluminescence.

[Conventional technology]

Conventionally, as one method for forming a transparent conductive tin oxide film, a transparent conductive tin oxide film containing antimony (hereinafter referred to as Snug
: For example, a solution of tin chloride (SnC1=・5820) and antimony trichloride (SnCI3) dissolved in a solvent such as water is used to form a Sb film on the surface.
A known method is to heat soda-lime glass coated with a coating to 400° C. or higher and then apply the coating using a spray coating method. Another fluorine-containing transparent conductive tin oxide film (hereinafter referred to as SnO:F film) can be made by using stannic chloride (SnCI) in a solvent such as water.
5820) and ammonium fluoride (NH4F), hydrogen fluoride (I(F)), ammonium hydrogen fluoride (Ni
A method is known in which a solution containing 14FHF) or the like is applied onto soda lime glass whose surface is coated with 5iOz by spray coating on heated to 400° C. or higher.

[Problem that the invention seeks to solve]

However, the former method, i.e., using dichloride in a solvent such as water,
Tin (SnCI4.5HzO) and antimony trichloride (
When a solution containing SbC1s) is prepared, it becomes a colloidal solution, and unless constant stirring is carried out, there is a problem in that it sediments and separates over time and lacks stability. Also,
When a film with a constant thickness is formed on the substrate surface, the sheet resistance value decreases as the amount of sb doped is increased, but the substrate is colored blue and the light transmittance is greatly reduced. In addition, in the case of the latter method, that is, doping with fluorine, ammonium fluoride (NH4F) and ammonium hydrogen fluoride (N) 14F instead of antimony trichloride (SbCls) are used.
), hydrogen fluoride (HF), etc. are used as doping agents, but they volatilize during the reaction, lowering the doping efficiency, so it is necessary to add an excess amount to the amount required in the film, and unreacted fluorine compounds Problems such as disposal will arise. In addition, when a film with a constant thickness is formed on the surface of the substrate,
As the amount of F doping is increased, the sheet resistance value decreases, but the substrate is colored yellow and the light transmittance is greatly reduced.

Compared to transparent conductive tin oxide films produced by these conventional methods, the present invention exhibits lower resistance and higher transparency when the film thickness is the same, and is also superior in doping efficiency. It is an object of the present invention to provide a forming method that requires a smaller amount of doping agent than conventional methods.

[Means for solving problems]

As mentioned above, when producing a transparent conductive tin oxide film using the spray method, a solvent solution containing water as a living body is used to avoid risks such as explosions. Antimony trichloride (SbCl2) is used as a doping agent in the production, but antimony trichloride does not become a transparent solution in water but becomes a colloidal solution, and sedimentation and separation occurs over time.

However, as a result of intensive research, the present inventors found that by adding, for example, ammonium hydrogen fluoride (NHJFT (F), ammonium fluoride (N114F), etc.) to this solution, a stable transparent solution was created instead of a colloidal solution. In addition, this solution also contains fluorine as a doping agent, forming a relatively stable complex, and in the conventional method, when fluorine is doped,
Fluorine volatilizes at high temperatures and requires a large amount of fluorine compound, but in the case of this solution, doping is carried out efficiently without such problems, so only a small amount of fluorine compound is required, and the reason is clear. However, by doping with antimony and fluorine at the same time,
The present invention has obtained the knowledge that when a film having the same thickness as each single-element doped film of the conventional method is produced, it is possible to produce a film with lower resistance and higher transparency than the conventional method. It was completed based on.

That is, the present invention is directed to a method for forming a transparent conductive tin oxide film, which comprises applying a solution containing a tin compound, antimony, and fluorine onto a heated substrate by a spray method.

Antimony compounds, which are the source of antimony, include:
Antimony chloride (SbCls) and the like are preferred.

Further, as the fluorine compound which is the source of fluorine, ammonium hydrogen fluoride (NH, FHF), ammonium fluoride (NH4F), etc. are suitable, and these may be used alone or in combination. In addition, pentafluoroantimony is a water-soluble complex compound containing fluorine and antimony.
III) ammonium acid ((N)l-)z(SbFs)
1 can also be used alone or in combination with the above antimony compounds and fluorine compounds.

The ratio of antimony in the antimony compound to fluorine in the fluorine compound is preferably 1 part antimony to 5 parts fluorine or more by weight.

The tin compound used in the present invention includes stannous chloride (S
nCI z), tin chloride (SnCI a ・5HzO
), stannous bromide (SnBrz), etc. can be used, and suitable solvents include water, a mixed solvent of water and ethanol, and a mixed solvent of water and hydrochloric acid. The total amount of fluorine and antimony in the solution is preferably 0.1 to 30% by weight based on tin, and within this range, the ratio of antimony to fluorine is 5 or more by weight to 1 antimony as described above. It is preferable to adjust as follows.

The substrate temperature during film formation is preferably 400 to 500°C.

〔Example〕

Next, the present invention will be explained in more detail by giving Examples and Comparative Examples, but these are not intended to limit the present invention.

Example 1 100 g of stannic chloride (SnCIa, 5HzO), 0.64 g of antimony trichloride (SnCIs), and 2.67 g of ammonium hydrogen fluoride (N)IJ)IF)
A solution was prepared by dissolving these in a mixed solvent containing 50 g of 35% hydrochloric acid in 1000 jd of water. The amount of antimony with respect to tin in this solution is 1% by weight, and the amount of fluorine with respect to tin is 5% by weight.
% by weight. This solution was then spray applied onto one surface of a 1.1aa++ thick substrate of surface Sing (500 people) coated soda lime glass heated to 450°C to form a transparent conductive oxide film with a film thickness of 4000 people. A tin film was obtained.

Example 2 0.32 g of antimony trichloride (SbC1s) and 1.57 g of ammonium hydrogen fluoride (NH4FHF)
The same operation as in Example 1 was performed except that the amount of antimony was 0.5% by weight relative to tin, and the amount of fluorine was 3% by weight relative to tin.

Example 3 In place of ammonium hydrogen fluoride (NH, FHF) in Example 2, ammonium fluoride (Nl(,F) was 2.04
The same operation as in Example 2 was performed except that g was used.

Example 4 Antimony trichloride (SbC1s) and ammonium hydrogen fluoride (N) of Example 11. Ammonium pentafluoroantimonyate (I[[)ate ((NO
4) Using 1.43g of z(SbFs), the amount of antimony relative to tin was 2% by weight, and the amount of fluorine relative to tin was 1.43g.
The same operation as in Example 1 was performed except that the weight was 57%.

Example 5 After storing the solution of Example 1 in a room at 25°C for 14 days, Example 1
Treatment was carried out using the same spray method.

Comparative Example 1 3.46 g of ammonium fluoride (N144F) was used instead of antimony trichloride (SbC1ff) and ammonium hydrogen fluoride (NFl, F) iF) in Example 1, and the amount of antimony with respect to tin was 0% by weight. The same operation as in Example 1 was performed except that the amount of fluorine relative to tin was changed to 5% by weight.

Comparative Example 2 7.29 g of ammonium fluoride (NH4F) was used instead of antimony trichloride (SbC1 and ammonium hydrogen fluoride CNH4FHF) in Example 1, and the amount of antimony with respect to tin was 0% by weight, and the amount of fluorine with respect to tin was The same operation as in Example 1 was performed except that the amount was changed to 10% by weight.

Comparative Example 3 Antimony trichloride (5bCJ, ) of Example I was added to 1.96
The same operation as in Example 1 was performed except that ammonium hydrogen fluoride (NHaFHF) was not used, the amount of antimony was 3% by weight relative to tin, and the amount of fluorine was 3% by weight relative to tin.

To evaluate each of the transparent conductive tin oxide films obtained in Examples 1 to 4 and Comparative Examples 1 to 3, specific resistance and visible light transmittance were measured, and the results are shown in Table 1.

Table 1 * In the solution of Comparative Example 3, precipitation of a white substance was observed 1 hour after the liquid preparation.

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

[Action/Effect]

In the present invention, a relatively stable complex compound is formed by containing antimony and fluorine, and problems such as instability of the solution when using antimony alone and problems such as fluorine volatilization when using fluorine alone are solved. In addition, it is presumed that both of them act synergistically to produce a remarkable effect of providing a film with low resistance and high transparency with a smaller amount than in the case of the conventional method.

As described above, according to the present invention, a transparent conductive tin oxide film having a lower resistance and an equivalent or higher light transmittance can be obtained with a smaller amount of doping agent than in the conventional method. In addition, the solution is stable and the amount of unreacted doping agent disposed of is small, making it extremely suitable for raising seedlings in industry.

Claims (5)

[Claims] 1. A method for forming a transparent conductive tin oxide film, comprising applying a solution containing a tin compound, antimony and fluorine onto a heated substrate by a spray method. 2. Antimony trichloride (SbC) as an antimony source
ammonium hydrogen fluoride (NH_4FHF) and ammonium fluoride (N
The forming method according to claim 1, wherein at least one selected from H_4F) is used. 3. Ammonium pentafluoroantimony(III) {(NH_4)_2 as antimony and fluorine source
(SbF_5)}. The method according to claim 1. 4. 2. The method of claim 1, wherein the total amount of antimony and fluorine relative to tin in the solution is 0.1 to 30% by weight. 5. The weight ratio of antimony and fluorine is 1 antimony.
The forming method according to claim 1 or 4, wherein the fluorine content is adjusted to 5 or more.