The electronic structures and optical properties of yttrium-doped zinc oxide with zinc interstitial defects calculated by first-principles

The geometric structures of ZnO, yttrium doped ZnO (YZO), ZnO with Zn interstitial (ZIO) and yttrium doped ZnO with Zn interstitial (YZIO) systems are investigated using the first-principle method based on density functional theory. The results show that doping yttrium ions can decrease the formation energy of Zni defects adjacent to yttrium ions. The electronic structures and absorption spectra of these systems are further obtained after revising the value of bandgap. Compared with ZnO, YZO and ZIO systems, there is an impurity level (Er) near the center of the forbidden band in YZIO, which will enhance the luminescence peak in yellow region. Besides, the bandgap of YZIO will increase with the increase of yttrium doping concentration, which suggests that the UV emission of YZIO would have a blue shift. In addition, the absorption property of YZIO system is also improved in both the visible and UV regions, which can be used in converting solar energy into electricity.