JPS619471A - Ink for formation of transparent electrode - Google Patents

Abstract

PURPOSE:To provide an ink for the formation of a transparent electrode, which has good workability in printing and gives an electrode having a good film surface, containing an indium compd. contg. a tin compd., a specified thickener and a solvent. CONSTITUTION:Ink is obtd. by blending an indium compd. contg. a tin compd. as an additive, hydroxypropylcellulose as a thickener and a solvent capable of dissolving the above components. By incorporating hydroxypropylcellulose as a thickener, there can be obtd. an ink which has good workability in printing and gives a transparent electrode having good smoothness and little unevenness in surface resistance. After a pattern is printed on a substrate in said ink by screen printing, the printed pattern is fired to obtain a transparent electrode. The ink is mainly used in the field of electronics industry.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ink for forming transparent electrodes that can be printed in a pattern on a substrate by screen printing and then baked to obtain a transparent electrode. , which can be used primarily in the electronics industry.

Conventional Structure and Problems A thin film of an oxide such as indium or tin formed on a transparent substrate has excellent performance as a transparent electrode. Demand for transparent electrodes made of such metal oxides has been increasing in recent years as one of the important constituent materials of display elements, solar cells, and the like.

The mainstream of this is an indium oxide film doped with tin, and its formation methods include vacuum evaporation, spraying, CVD, and screen printing.
Among these methods, the screen printing method is particularly advantageous in terms of the complexity of the manufacturing process and the ease of mass production.

In other words, in the screen printing method, an ink containing a compound of indium and tin can be formed into a pattern on the substrate, so there is no need for the etching process that is required with other methods. It has the advantage of being easy to manufacture and has high mass productivity.In addition, since only a screen printing machine and a firing furnace are required as manufacturing equipment, it is advantageous in terms of equipment costs compared to methods using a vacuum system. be.

However, conventional inks of this type have many problems in terms of chemical stability, resulting in drawbacks such as poor workability during printing operations and a short pot life of the ink itself. In addition, many of them had problems with the smoothness of the printed film surface, swelling and bleeding of pattern edges, and the surface of the fired transparent electrode was likely to have unevenness due to variations in film thickness. For this reason, the electrodes had the disadvantage of poor appearance and large variations in surface resistance.

On the other hand, methods using ethylcellulose or nitrocellulose as thickeners seem to have yielded relatively good results, but these products tend to leave residue in the transparent electrode even after firing due to thermal stability. Object of the Invention The object of the present invention is to overcome the above-mentioned drawbacks and to provide an ink for forming transparent electrodes that has good printing workability and a good film surface. It is about providing.

Structure of the Invention To achieve this object, the ink for forming transparent electrodes of the present invention contains an indium compound as a main ingredient, contains a tin compound as an additive thereto, and hydroxybrobyl cellulose as a thickener, and It is constructed by containing a solvent for dissolving these.

Description of examples Examples of the present invention will be described below.

[Example 1] The ink was adjusted to have the following composition.

Indium acetyl decetonate) 6.51g Tin 2-ethylhexanoate 0.49g Isophorone
40g cyclohexanone
26g Benzyl acetate 13g
Hydroxypropylcellulose' 14g [Nippon Soda@Fusa, trade name: 1 Soda HPC-L] Using this ink,
320 mesh polyester net, emulsion thickness 7μ
Printed on a soda-lime glass plate using a screen plate.

At this time, printing was performed 50 times in a row. After drying this at 60°C for 15 minutes, it was held in the air at 50°C for 60 minutes to form a transparent electrode.0 When these were evaluated, the film surface was smooth regardless of the number of times it was printed.1. No bleeding of the C-turn edge was observed. When the surface resistance was measured, it was found to be within the narrow range of 0.8 to 1.2 Ω/hole, and the light transmittance of the film alone was over 80%.

[Example 2] The ink was adjusted to have the following composition.

Indium 2-ethylhexanoate 14.4g Tin 2-ethylhexanoate 0.6g Mixed xylene
13g benzyl alcohol
28g isophorone
28g n-butyl acetate 13g hydroxypropylcellulose 3g [Nippon Soda (
Stock product name: Nisso HPC-M] Using this ink, 25
It was printed on a soda lime glass plate using a screen plate with a 0 mesh polyester net and an emulsion thickness of 10 μm. At this time as well, printing was performed 60 times in a row. After processing these in the same manner as in Example 1, the film was evaluated. Regardless of the number of printings, the film surface was smooth and there was no bleeding at the pattern edges. I couldn't see it. Further, when the surface resistance was measured, it was found to be between 0 and 0.9 ohms, and the light transmittance was also 80 or more.

Note that in the above examples, an indium compound is used.

The mixed xylene used as a solvent to dissolve the tin compound and hydroxyglobil cellulose as a thickener is an aromatic hydrocarbon, teisophorone and cyclohexanone are ketones with a boiling point of 100℃ or higher, and benzyl alcohol has a boiling point of 100℃ or higher. Alcohols, benzyl acetate and n-butyl acetate are esters with a boiling point of 100°C or higher, and other solvents include kerosene and hexane.

Aliphatic hydrocarbons such as octane can also be used,
One or more of these bag materials may be used as a solvent.

Effects of the Invention As can be seen from the above examples, the ink for forming transparent electrodes of the present invention has good printing workability and good smoothness due to the inclusion of hydroxybutylene cellulose as a thickener. , a transparent i-electrode with less variation in surface resistance can be obtained, and its effects are significant in practical use.

Claims (1)

[Claims] 1. An ink for forming a transparent electrode, comprising an indium compound as a main ingredient, a tin compound as an additive, hydroxypropyl cellulose as a thickener, and a solvent for dissolving these.