HIGH QUALITY METALLIC GRID PREPARATION ON LARGE AREA ITO-COATED PLASTIC SUBSTRATES

ITO-coated plastic substrates have a variety of applications in solar energy conversion systems, optoelectronic devices, touch panels, flat-panel displays and others. ITO is one of the most used materials for these applications. However, conductivity of ITO is not enough to produce efficient large area devices. The problem can be solved with high conductivity metallic grids embedded in ITO. We propose the electrochemical method for such metallic grids preparation.

We have developed a new electrochemical method to deposit different metals and alloys (e.g. silver, copper, nickel) on large area ITO-coated glass and plastic substrates. Our method is noted by a very high adhesion and Ohmic contact to the ITO. The sheet resistance of ITO-PET can be decreased more than in 75 times by electrodeposited silver or copper meshes. The electrodeposited metallic layers possess dense structure and low specific resistance.

120 mm*120 mm samples of copper and silver meshes on ITO-PET with sheet resistance less than 1 Ohm/sq and excellent metal adhesion to ITO were prepared. The electrochemical metal plating is the method which is widely used in industry. This method is roll-to-roll compatible (for flexible, plastic based substrates), relatively low cost, high speed and can be performed under ambient conditions. It is direct method, no expensive metal inks are required. Patterning of ITO-PET before the metal electrodeposition was performed by gravure printing or by photolithography with a low cost resist which can be easily removed after electrodeposition.

Based on sol-gel electrophoretic deposition we further developed insulating coating of the metallic grid to avoid electric shorts. This process is performed from transparent solutions under an applied electric field and results in transparent or slightly opaque dense uniform conformal metal oxide coatings on top of metallic layers.