Density functional theory study on two-peak emission of Eu2+ activators in Sr2SiO4

The supercells of pure and Eu-doped Sr2SiO4 were theoretically analyzed by density functional theory (DFT) calculations to investigate the typical two-peak emission of Sr2SiO4:Eu2+, which originates from two different Sr2+ (or Eu2+) sites in the Sr2SiO4 host structure. The Perdew–Wang generalized-gradient approximation (GGA) functional and the double numerical plus d-functions (DND) basis set with effective core potentials (ECP) were employed in the calculations of electronic properties. The electron transfer between Eu2+ ions placed at two different crystallographic Sr2+ sites was understood based on the accurate assignment of deconvoluted peaks of the two-peak emission to their corresponding crystallographic sites. This study ought to be instructive as a basic guideline to improve the color chromaticity of Sr2SiO4:Eu2+ for use in white light emitting diodes (WLEDs).