Lattice structures and electronic properties of CIGS/CdS interface:First-principles calculations

Using first-principles calculations within density functional theory, we study the atomic structures and electronic properties of the perfect and defective(2VCu+ InCu) CuInGaSe2/CdS interfaces theoretically, especially the interface states.We find that the local lattice structure of(2VCu+ InCu) interface is somewhat disorganized. By analyzing the local density of states projected on several atomic layers of the two interfaces models, we find that for the(2VCu+ InCu) interface the interface states near the Fermi level in CuInGaSe2and CdS band gap regions are mainly composed of interfacial Se-4p,Cu-3d and S-3p orbitals, while for the perfect interface there are no clear interface states in the CuInGaSe2region but only some interface states which are mainly composed of S-3p orbitals in the valance band of CdS region.