Effects of additional Ce~(3+) doping on the luminescence of Li_2SrSiO_4:Eu~(2+) yellow phosphor

摘要

Additional Ce~(3+) doping improves the luminescence of Li_2SrSiO_4:Eu~(2+), a yellow phosphor for ultraviolet or blue light-emitting diodes. By examining the photoluminescence of Li_2SrSiO_4:Eu~(2+), Li_2SrSiO_4:Ce~(3+), and Li_2SrSiO_4:Ce~(3+),Eu~(2+), it was confirmed that the energy transfer from Ce~(3+) to Eu~(2+) ions contributes little to the enhanced luminescence of Li_2SrSiO_4:Ce~(3+),Eu~(2+). Alternatively, we suggested that Ce~(3+) ions could stabilize the Li vacancies, inhibit the oxidization of Eu~(2+) to Eu~(3+), and consequently increase emission intensity, based on the characterizations with decay time and synchrotron light source x-ray absorption measurements. The proposed argument was validated with first principle calculations of the defect formation energies.