Effect of Crystal Symmetry on Electronic Structures of CuInSe₂ and Related Compounds

The first-principles band calculations by using the full-potential linearized augmented plane wave method have been used to understand the electronic structures of the chalcopyrite CuInSe 2 and the defect stannite CuIn 3 Se 5 . It is found that the symmetrized wave function and the d - d mixing as well as the p - d hybridization play important roles in causing the anomalous large band gap of CuIn 3 Se 5 . The valence band offset between CuInSe 2 and CuIn 3 Se 5 is evaluated to be 0.52 eV. This value is in good agreement with the observed value.