Understanding native defect induced photoluminescence in Zn2SnO4

Simulation of photoluminescence spectroscopy from first principles provides a powerful approach for pre-dicting the experimental spectrum and understanding the origin of the luminescence of materials. We show here that the use of the hybrid-exchange correlation functional combined with first-principles molecular dynamics can simulate the defect-induced photoluminescence spectrum of zinc stannate (Zn2SnO4) in good agreement with the experiment. The calculations were carried out for 12 different point defects of Zn2SnO4, and show that the green-to-red photoluminescence emissions obtained in the experiment are mainly contributed by the oxygen vacancy defects. These defect states play the roles of deep donors and radiative recombination centers during the photoluminescence mechanism. In particular, their electronic properties are significantly affected by temperature, which is related to the strong fluctuation of the nearest-neighbor Sn atoms relative to the vacancy center.