Electrodeposition of CuInSe2 thin films in a glycine acid medium

CuInSe₂ polycrystalline thin films were potentiostatically electrodeposited on titanium and conducting glass substrates from an aqueous solution containing CuCl₂, InCl₃, SeO₂ in a glycine acid medium, pH around 2 adjusted with HCl. The effect of adding EDTA as a complexing agent was also studied. These films were then submitted to different post-deposition treatments: annealing at temperatures up to about 400°C in an Ar flowing stream, chemical etching in a 0.5 M KCN solution and in some cases room temperature air oxidation. The as-grown and treated layers were characterized by X-ray energy dispersive analysis, X-ray diffraction, scanning electron microscopy and photoelectrochemical studies. Annealing improves the crystallinity of electrodeposited films and the effective grain size increased, resulting in the formation of CuInSe₂ chalcopyrite structure. Photoelectrochemical measurements of the films revealed p-type behaviour, and better photoresponse was observed for the films obtained from EDTA based solutions. Room temperature air oxidation of the CuInSe₂ films improves the photocurrent response.