METHOD FOR PRODUCING A MULTI-CRYSTALLINE CHROMIUM LAYER AS A SUBSTRATE LAYER FOR THE ASSEMBLY OF SOLAR CELLS ON A METAL CARRIER

摘要

The invention relates to a method for producing a multi-crystalline chromium layer as a substrate layer for the assembly of solar cells on a metal carrier, particularly for producing thin-film solar cells on galvanic strip processing systems, wherein the chromium layer is applied by electrochemical deposition with the aid of a tetrachromate electrolyte having the following composition: 350 - 400 g*l-1 CrO3, 40 - 50 g*l-1 NaOH, 2.5 - 2.7 g*l-1 H2SO4, 5 - 10 g*l-1 Cr-III, wherein the current yield is 25 - 30% and the deposition rate is 0.5 - 1 µm*min-1. Thereafter, the surface of the chromium layer is smoothed by polishing to a hardness Ra of < 15 nanometers and gas nitriding. With the method according to the invention, a uniform application of the layer for layer thickness of preferably 5 - 8 µm is achieved, and also that the chromium layer is completely tight and free of pores. A corresponding chromium layer has a high barrier effect against the diffusion of iron atoms.