The photoluminescence properties of Eu3+,Bi3+ co-doped yttrium oxysulfide phosphor under vacuum ultraviolet excitation

Y2O2S co-doped with Bi3+,Eu3+ phosphors were prepared and their luminescence properties under vacuum ultraviolet (VUV) excitation were investigated. Much stronger red emission for Y2O2S:Eu3+,Bi3+ were observed under 147 nm excitation than that for Y2O2S:Eu3+. Investigation on photoluminescence and calculation of electronic structure of Y2O2S:Eu3+,Bi3+ revealed that the Bi3+ acts as a medium in energy transfer process and the great VUV luminescence enhancement of Y2O2S:Eu3+ by doping Bi3+ is due to effective energy transfer process: charge transfer (CT) transition of Y3+–O2− → Bi3+ → Eu3+. The Y2O2S:Eu3+,Bi3+ showed excellent optical properties when compared with the commercial (Y,Gd)BO3:Eu3+. Thus, the Y2O2S:Eu3+,Bi3+ would be a promising VUV-excited red phosphor.