The effect of thermal evaporated MoO3 intermediate layer as primary back contact for kesterite Cu2ZnSnS4 solar cells

Abstract In this research, we present thermal evaporated MoO 3 layer as a primary back contact for pure sulphide Cu 2 ZnSnS 4 solar cells. The effects of incorporating MoO 3 in primary back contact and its thickness on the Cu 2 ZnSnS 4 device performance are investigated. The MoO 3 layer acts as enhancing sodium diffusion site where sodium is more effectively diffused into CZTS absorber, facilitating the formation of larger CZTS grains during sulfurization process compared to the reference absorber. The power conversion efficiency is improved from 5.2% to 6.2% on average, yielding the highest efficiency of 6.52% by the insertion of 10 nm MoO 3 layer between Cu 2 ZnSnS 4 absorber and molybdenum contact. The major efficiency enhancement arises from open circuit voltage which is improved from 530 to 615 mV.