Enhanced photoluminescence intensity of Y2O3: Eu3+ Sheets by codoping Pr3+ and involved energy transfer mechanisms

Y2O3: Eu3+ has been widely applied as red phosphors in the fields of displaying and illumination. Here, we report the enhanced luminescence intensity of Y2O3: Eu3+ by codoping Pr3+ ion. The Pr3+ and Eu3+ doped Y2O3 microsheets with high aspect ratio were synthesized by a simple route combining chemical precipitation and pyrolysis, which could emit intense red light centered at 610 nm under the 254 and 365 nm UV excitation. The fluorescence measurement indicated that the luminescence intensity of Y2O3: Eu3+, Pr3+ did not increase monotonously with increasing Pr3+ concentration. The highest improvement of the photoluminescence intensity of Y2O3:Eu3+ was realized in the sample doped with 2 mol% Pr3+, which was of 17.8% higher than the whole intensity of only Eu3+ doped Y2O3.The mechanism analysis based on SEM, XRD, fluorescence spectra, and simplified energy level diagram indicated that (1) energy transfer process between Pr3+ and Eu3+, (2) crystallinity, and (3) symmetry should respond for this nonmonotonous variation phenomenon by competition with each other. For energy transfer process between Pr3+ and Eu3+, it was suggested that the cross relaxation of 5D0 + 7F1(Eu3+)↔3P0 + 3H6(Pr3+) and the efficient energy transfer from 3P0 state of Pr3+ to 5D1 energy level of Eu3+ lead to the improvement of the population of the 5D0 state of Eu3+ so that the 610 red emission of Eu3+ ion was accordingly enhanced.