ELECTRODISSOLUTION AND CORROSION OF CUINS2 PHOTOANODES WITH LAMELLAR MORPHOLOGY

Crystals of n-CuInS2 grown in a steep temperature gradient show lamell ar morphology, prone to cleavage, and inclusions of copper-poor phases like CuIn5S8. Photoelectrooxidation of n-CuInS2 in 1 M HClO4, a non-p rotective electrolyte, results in massive dissolution of the metal ion s and deposition of sulfur, with marked photocurrent quenching. Operat ion of n-CuInS2 (photo)anodes in acidic polyiodide medium causes signi ficant corrosion and decay of photocurrent output. Micrographs of corr oded areas show progressive and irregular etching of the CuInS2 layers , which appear strongly polycristalline. EDX microanalyses show very s imilar composition before and after corrosion, suggesting that the lat ter causes stoichiometric removal and dissolution of the components an d does not form new phases of significant thickness.