Efficient green phosphor realized by Ce3+→Tb3+ energy transfer in Li3Sc2(PO4)3 for ultraviolet white light-emitting diodes.

A series of Ce3+/Tb3+ doped Li3Sc2(PO4)3 phosphors has been obtained using high temperature solid state reactions. Density functional theory (DFT) calculations using the CASTEP module have given an insight into the bandgap and electronic structures of the hosts. The phase formation and the crystal structure of the prepared samples were verified using X-ray diffraction and Rietveld structure refinement analysis. Samples singly doped with Ce3+ ions had an intense emission centered at 350 nm under UV light irradiation, while samples singly doped with Tb3+ ions exhibited a typical green emission under 230 nm irradiation. Efficient Ce3+→Tb3+ energy transfer can cause the Li3Sc2(PO4)3:Ce3+,Tb3+ samples to have an intense green emission at very low Tb3+ concentrations under 285 nm excitation, making Li3Sc2(PO4)3:Ce3+,Tb3+ an efficient UV-excited green phosphor. The mechanism and critical distance for Ce3+→Tb3+ energy transfer in the phosphor were determined by detailed luminescence decay curve analysis utilizing the I-H model. Moreover, a WLED device was fabricated using our prepared green phosphor.