Sol–gel assisted synthesis and photoluminescence property of Sr2Si5N8:Eu2+, Dy3+ red phosphor for white light emitting diodes

Eu2+, Dy3+ co-doped Sr2Si5N8 red phosphors were prepared using a sol–gel-nitridation method at a lower temperature comparing with traditional solid state reaction. Effects of synthesis process, Eu2+ and Dy3+ doping concentration on the crystal structure and luminescence property of as-prepared phosphors were investigated. X-ray diffraction patterns indicated that all Sr2Si5N8:Eu2+, Dy3+ phosphors have the standard phase of Sr2Si5N8 structure. With a broad excitation from UV to blue light, a strong emission of Sr2Si5N8:Eu2+, Dy3+ with 4f65d1→4f7 transition of Eu2+ ions was obtained at red region in photoluminescence spectra. Emission peaks in spectra were red-shifted from 611 to 632 nm for all Sr2Si5N8:xEu2+ as Eu2+ ion concentrations increased, which due to Eu2+ ions occupying from the tenfold coordinated site (Sr1) to the eightfold coordinated site (Sr2). These Sr2Si5N8:Eu2+ phosphors with Dy3+ co-doping showed excellent luminescence properties, included emission intensity and luminescence quenching. It is potential that Sr2Si5N8:Eu2+, Dy3+ phosphors can be applied in white LEDs combining with blue InGaN LEDs.