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

Hybrid density functional theory is used to study the formation energies and transition levels of point defects VCu, VI, ICu, CuI, and OI in CuI. It is shown that the Heyd-Scuseria-Ernzerhof (HSE06) method can accurately describe the band gap of bulk CuI. As a solar cell material, we find that p-type semiconductor CuI can be obtained under the iodine-rich and copper-poor conditions. Our results are in good agreement with experiment and provide an excellent account for tuning the structural and electronic properties of CuI.