First-principles study on electronic and optical properties of Cu-doped LiF with Li vacancy

Taken into account the presences of Li vacancy (VLi), we calculate the formation energy, electronic structure and optical properties of Cu doped LiF (LiF:Cu) by using the density functional theory. The presence of VLi leads to a decrease of the formation energies of Cu, in favor of Cu doping into LiF. Due to Cu doping, an impurity band of Cu-3d states is formed at the Fermi level, which is then split by the introduction of VLi. A wide absorption band and some new absorption peaks are obtained in LiF:Cu with an adjacent VLi to Cu. There appears an absorption peak at 9.3 eV, which is consistent with the experiment observation (133 nm). The results are useful for understanding of the optical properties of the doped systems.