Effect of crystal symmetry on electronic structures of CuInSe2 and CuIn3Se5

First-principles band calculations have been used to understand the electronic structures of the chalcopyrite CuInSe₂ and the stannite CuIn₃Se₅. 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 larger band gap of CuIn₃Se₅ than that of CuInSe₂. The band lineup between CuInSe₂ and CuIn3Se₅ is also presented.