First-principles study of point defects in solar cell semiconductor CuInS2

The formation energies and transition levels of point defects VCu, VIn, VS, InCu, CuIn, and OS in CuInS2 are studied using the hybrid density functional theory. It is found that the Heyd-Scuseria-Ernzerhof method can accurately describe the electronic structure and gives a band gap of 1.40 eV, in good agreement with the experimental value. On the other hand, we conclude that p-type semiconductor CuInS2 can be obtained under sulfur-rich condition with a certain copper and indium content, while n-type semiconductor CuInS2 can be easily obtained under the copper-rich, indium-rich, sulfur-poor, and non-oxygen conditions. These results provide an excellent account for the modification of the structural and electronic properties of CuInS2.