Photoluminescence and energy transfer in Sr3La(BO3)3:Ce, Sm and Sr2TiO4:Sm, Eu phosphors

Sr3La(BO3)3:Ce, Sm and Sr2TiO4:Sm, Eu phosphors were prepared via solid-state reaction method. The X-ray diffraction patterns, photoluminescence, diffuse reflectance spectra, decay curves and energy transfer mechanism of phosphors were investigated in detail. The photoluminescence properties of the phosphors indicated the Ce → Sm energy transfer in Sr3La(BO3)3:Ce, Sm and Sm → Eu in Sr2TiO4:Sm, Eu. With the activator concentration increase, the characteristic emission intensity of activators increased firstly and then decreased. However, the emission intensity and the average decay times of the sensitizer gradually decreased, which was a strong evidence for energy transfer. The energy transfer efficiency of Ce → Sm in Sr3La(BO3)3:0.03Ce, ySm were calculated to be 59.49% when y = 0.03 and Sm → Eu in Sr2TiO4:0.01Sm, yEu were calculated to be 90.51% when y = 0.03. The energy transfers Ce → Sm in Sr3La(BO3)3 and Sm → Eu in Sr2TiO4 were both demonstrated to be dipole-dipole interactions. The quantum efficiency of Sr3La(BO3)3:0.03Ce, 0.03Sm and Sr2TiO4:0.01Sm, 0.03Eu reached 45.5% and 19.1%, respectively, which indicated they could serve as efficient n-UV excitation blue-emitting and orange-emitting phosphors applied in w-LEDs, respectively.