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

The formation energies and transition levels of point defects V-Cu, V-In, V-S, In-Cu, Cu-In, and O-S 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. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4762001]