Effects of strains on the electronic structure and optical properties of Ce-doped ZnO with interstitial H

Abstract

The electronic structure and optical properties of Ce-doped ZnO systems have been widely studied, but the effects of different strains of Ce-doped ZnO or Ce- doped ZnO with interstitial H systems remain unclear. To solve these problems, this study identified the effects of biaxial strain on the electronic structure and absorption spectrum of Ce-doped ZnO with interstitial H systems through a generalized gradient approximation + U (GGA + U) with plane wave pseudopotential. The formation energy of Zn15CeHiO16 decreased with the distance between Ce and H. At a close distance between Ce atom and H atom (i.e., 0.1876 nm), Zn15CeHiO16 showed the lowest formation energy and best stability among the doping systems. The formation energy of Zn15CeHiO16 decreased when the compressive strain increased but increased when the tensile strain increased. All doping systems did not change the ZnO direct band gap. Zn15CeO16 band gap without strain decreased, and the absorption spectrum red shifted compared with that of Zn16O16. Zn16HiO16 and Zn15CeHiO16 band gaps without strain increased, and the absorption spectrum blue shifted. Zn15CeHiO16 band gap increased as the compressive strain increased. The static dielectric constant decreased, and the absorption spectrum blue shifted. These findings were valuable for the design and preparation of new ZnO-based short-wavelength light-emitting diodes. The band gap of Zn15CeHiO16 decreased as the tensile strain increased; the static dielectric constant increased, and the absorption spectrum red shifted. Trap effect was significant regardless of the compressive strain or the tensile strain and was beneficial for prolonging the electron lifetime. These findings are valuable for the design and preparation of novel ZnO-based photocatalysts.