Solar cells based on CuInS2 thin films through sulfurization of precursors prepared by reactive sputtering with H2S gas

CuInS2 films were prepared using a two-stage process in which Cu-In-S precursors were sputtered in H2S/Ar with metal targets (Cu and In) and then annealed in H2S atmosphere. Control of S content in the precursor is essential for fabricating high-quality CuInS2 films and achieving high-efficiency solar cells. When S/(Cu+In) ratio in the precursor was about 0.3; CuInS2 films with good crystallinity and smooth surface were obtained, and consequently a CuInS2 solar cell with an efficiency of 6.3% has been achieved without KCN treatment.