Pr3+-doped Li2SrSiO4 red phosphor for white LEDs

Novel red phosphors, Li2Sr1-1.5xSiO4:xPr(3+) (x=0.002, 0.003, 0.004, 0.005, 0.006 and 0.008), were synthesized by conventional solid state reaction and the luminescent properties were investigated. The as-prepared phosphors showed red emission at 610 nm under excitation of blue light at 452 nm, indicating that they were promising candidates for red phosphors in the fabrication of white LEDs via blue LED chips. Their excitation bands at 452, 476 and 487 nm were attributed to transitions of H-3(4)-> P-3(2), H-3(4)-> P-3(1)+I-1(6), H-3(4)-> P-3(0) of Pr3+ ion. The red emissions at 606 and 610 nm were originated from the P-3(0)-H-3(6) and D-1(2)-H-3(4) transitions of Pr3+. The optimum doping concentration of Pr3+ in Li2Sr1-1.5xSiO4:xPr(3+) was determined to be x=0.004. With the concentration of Pr3+ over x=0.004, the fluorescence intensity of Li2Sr1-1.5xSiO4:xPr(3+) decreased, indicating the concentration quenching occurred.