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 (2V_Cu+In_Cu) CuInGaSe₂/CdS interfaces theoretically, especially the interface states. We find that the local lattice structure of (2V_Cu+In_Cu) 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 (2V_Cu+In_Cu) interface the interface states near the Fermi level in CuInGaSe₂ and 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 CuInGaSe₂ region but only some interface states which are mainly composed of S-3p orbitals in the valance band of CdS region.