PREPARATION OF DEVICE-QUALITY CUINSE2 BY SELENIZATION OF SE-CONTAINING PRECURSORS IN H2SE ATMOSPHERE

Efficient thin-film photovoltaic cells were fabricated, using CuInSe2 absorber films obtained from the selenization (in H2Se/Ar) of InSe/Cu and InSe/Cu/InSe metallic precursors. The material properties of the C uInSe2 layers were critically influenced by the kinetics of the seleni zation process and the nature of the precursor films before the reacti on step. Selenization of InSe/Cu precursors resulted in layers with po or morphological features (droplet formation) and in cells with relati vely low conversion efficiencies (eta = 3-5%). Optimal material proper ties were obtained when InSe/Cu/InSe precursors were selenized in H2Se /Ar (atmospheric pressure) while ramping the temperature slowly betwee n 200 degrees C and 400 degrees C. This process produced relatively un iform and dense films which exhibited large crystallites of high cryst alline quality. Preliminary CuInSe2/CdS/ZnO heterojunction solar cell devices were fabricated using these films, and conversion efficiencies exceeding 10% (total area) were obtained without the use of an antire flective coating.