JPS5923403B2 - Method for manufacturing transparent conductive film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a transparent conductive film,
In particular, it is characterized in that indium oxide, indium oxide, and tin oxide are obtained from organic indium or a mixture of organic indium and organic tin, respectively.

An object of the present invention is to obtain a transparent conductive film that is stable, has a low specific resistance, and has a high transmittance at a low cost and with good mass productivity.

Conventionally, transparent conductive films include indium oxide, tin oxide, or a mixture of both, tin oxide, antimony oxide mixture,
Metal oxides such as titanium oxide, rhodium oxide, platinum oxide,
Alternatively, a thin film of metal such as gold has been used.

The coating method differs depending on the type of transparent conductive film, but generally, sputtering method, vacuum evaporation method, C
VD method, spray method, etc. are used.

The drawbacks of these coating methods, ie, methods of manufacturing transparent conductive films, are listed in Table 1, taking commonly used transparent conductive films as an example. Indium oxide or indium oxide/tin oxide mixture transparent conductive films have low resistivity, low surface reflectance, and high transmittance, and are useful for CVD.
At present, a suitable source that can be mass-produced using methods such as the method and the spray method has not yet been discovered.

The present invention is a novel technique for obtaining a transparent conductive film by decomposing organic indium or organic tin as a source.

The organic indium and organic tin used in the present invention are represented by In(0R)3 and Sn(0R)4, respectively. Here, R is a straight chain or side chain alkyl, generally having 1 to 2 carbon atoms.
A value up to 0 is used, but more preferably a value of 1 to
It is 8. These organic indium and organic tin are used after being dissolved in an appropriate amount in an organic solvent such as alcohol ethers, ketones, esters, or a mixed solvent thereof. Further, in order to promote hydrolysis, a small amount of acid, alkaline water, salt, etc. may be added. The substrate covering the transparent conductive film may be made of glass, ceramic, or the like, as long as it has heat resistance of 350° C. or higher.

An appropriate amount of the organic indium or organic indium/organotin mixture of the present invention is mixed and dissolved in the above-mentioned heating medium, and the mixture is applied to a substrate.
If the solvent is removed at 00 to 150°C and then baked at 350°C or higher, a colorless and transparent transparent conductive film can be obtained.

The chemical reaction at this time can be imagined as shown in the following equation.

Possible coating methods include a constant-velocity pulling method, a spraying method, etc., but the constant-velocity pulling method is advantageous in terms of both uniformity of the coating and mass productivity. The object of claim 2 is to further reduce the resistivity of indium oxide9, and generally, tin oxide has a minimum resistivity of around 5(f).

It can be used appropriately depending on the purpose of the transparent conductive film.
The transparent conductive film thus obtained according to the present invention can be used for displays, resistance heating, optical applications, etc. The present invention will be described below with reference to Examples.

Example 1 Using isopropyl alcohol (500t) and ethyl acetate (50%) as a solvent, In(0C4H,)3 was adjusted to 5ωt%, and Sn(0C4H,)3 was further added to In(0C4H9)3.
Table 2 shows the changes in resistance when the amount of H, )I was changed and the coating was applied by a constant speed pulling method using soda-based glass as a substrate.

The film thickness can be freely controlled by the concentration of the solution and the pulling rate, and therefore the specific resistance can also be freely changed by changing the film thickness.

However, if it exceeds 2000A0, a crack will occur. S
It was found that a minimum resistivity can be obtained with n(0C4H,)4/In(0C4H9) of 3-5%. From the above, the resistivity can be freely controlled by changing the proportion of tin added and the film thickness.

There is almost no effect of firing temperature, 1 hour at 500℃ or higher
At this point, the resistivity became constant. When the firing temperature was low, the adhesion with the substrate was slightly reduced. Further, when the firing temperature was low or the firing time was short, sufficient transparency could not be obtained. In addition, it is generally known that indium oxide-based transparent conductive films have low surface reflectance, but the transparent conductive film obtained by this method has extremely low reflectance and is no different from conventional products. Ta. It was found that it is particularly suitable for use as a transparent conductive film for displays.

As described above, the present invention relates to a method for obtaining a transparent conductive film from organic indium or a mixture of organic indium and organic tin by hydrolysis, thermal decomposition, etc.; Processing conditions such as solvent, firing temperature, time, substrate, intended use, etc. are not in question.

Claims (1)

[Scope of Claims] 1. A solution of an organic indium compound having the general formula In(OR)_3 (R: alkyl group) dissolved in an organic solvent is applied to a substrate, and then heated to remove the solvent. A method for producing a transparent conductive film, which comprises obtaining a conductive film of indium oxide on a substrate by post-baking. 2 General formulas In(OR)_3 and Sn(OR)_4(R:
A solution of an organic indium compound (alkyl group) and an organic tin compound dissolved in an organic solvent is applied to the substrate, then heated to remove the solvent, and then baked to form an indium oxide/tin oxide mixture on the substrate. A method for producing a transparent conductive film, characterized by obtaining a conductive film.