Investigation into the photoluminescence and energy levels in bismuth-doped Sr3MgSi2O8 through first principles calculations

Abstract

In this paper, influences of Bi3+ doping on the crystal structure and electronic band structure of Sr3MgSi2O8, and charge transfer process from the valence band to Bi3+ (CT) and from Bi3+ to the conduction band in Sr3MgSi2O8 (MMCT) have been investigated through first principles calculations. The total energy calculations make clear the location of the doped Bi3+ in Sr3MgSi2O8 that the doped Bi3+ preferred to take up the Mg2+ sites and form BiO6. The calculated results of electronic band structure and density of states reveal the constituents that make up the conduction band and valence band of Sr3MgSi2O8 and Sr3Mg0.875Bi0.125Si2O8, respectively. In addition, a defect level appears in the band gap of Sr3Mg0.875Bi0.125Si2O8, which is originated from the p orbit of the doped Bi3+. Also, the calculated absorptions of Sr3MgSi2O8 and Sr3Mg0.875Bi0.125Si2O8 show a gradually shifted absorption band from deep UV region to the blue area with increasing absorption intensity. The above results make clear of the fact that first principles calculations can be useful in investigating the properties of Bi3+ doped luminescent materials and designing new kinds of luminescent host materials.