Density functional theory study on two-peak emission of Eu 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).