In situ growth of CuSbS2 thin films by reactive co-sputtering for solar cells

Abstract

CuSbS2 thin films were in situ grown by reactive co-sputtering and the effects of the growth temperature on film composition, structure and morphology were investigated. It is demonstrated that orthorhombic chalcostibite CuSbS2 thin films with uniform morphology, pure phase and grain size over 2 µm can be obtained for growth temperature of 300 ℃, while higher growth temperature results in the formation of Cu3SbS4 phase and lower growth temperature leads to Sb2S3 secondary phase. The grown CuSbS2 film shows an optical absorption coefficient of higher than 104 cm−1, an optical band gap of 1.52 eV and p-type conductivity. Solar cell devices with configuration of glass/Mo/CuSbS2/CdS/i-ZnO/ITO/Ag were fabricated and yield power conversion efficiency of 0.52%. The incompatible interfaces including absorber/back contact (the absence of beneficial MoS2 interface layer) and absorber/buffer layer (unfavorable “cliff”-like conduction band offset) interfaces have been considered as the key factor limiting efficiency.