Structural and electronic properties of CuI doped with Zn, Ga and Al

• The substitutional Zn is predicted to be preferred in CuI lattice.
• The substitutional Zn introduces some additional states in the band gap of CuI.
• Zn is expected to enhance the concentration of copper vacancies in CuI.

The structural and electronic properties of CuI doped with Zn, Ga and Al are investigated using density functional theory. The calculated results find that the solubility of the cation dopants considered is primarily determined by the difference in the electronic configurations between host and dopants. The order of the formation energy of the dopants is predicted to be E(ZnCu)>E(AlCu)>E(GaCu) in CuI. Furthermore, dopants at the octahedral interstitial sites have lower formation energies as compared to dopants located at the tetrahedral interstitial sites in the lattice. The defect complex consisting of ZnCu and the copper vacancy (ZnCu+VCu) is predicted to be preferred in the lattice, suggesting that incorporation of Zn is expected to enhance the concentration of copper vacancies in CuI.