Photoluminescence properties of Sr1-xSi2O2N2: Eux2+ as green to yellow-emitting phosphor for blue pumped white LEDs

This study evaluated potential applications of green to yellow-emitting phosphors (Sr1-xSi2O2N2: Eu-x(2+)) in blue pumped white light emitting diodes. Sr1-xSi2O2N2: Eu-x(2+) was synthesized at different Eu2+ doping concentrations at 1450 degrees C for 5 h under a reducing nitrogen atmosphere containing 5% H-2 using a conventional solid reaction method. The X-ray diffraction patterns of the prepared phosphor (Sr1-xSi2O2N2: Eu-x(2+)) were indexed to the SrSi2O2N2 phase and an unknown intermediate phase. The photoluminescence properties of these phosphors (Sr1-xSi2O2N2: Eu-x(2+)) showed that the samples were excited from the UV to visible region due to the strong crystal field splitting of the Eu2+ ion. The emission spectra under excitation of 450 nm showed a bright color at 545-561 nm. The emission intensity increased gradually with increasing Eu2+ doping concentration ratio from 0.05 to 0.15. However, the emission intensity decreased suddenly when the Eu2+ concentration ratio was > 0.2. As the doping concentration of Eu2+ was increased, there was a red shift in the continuous emission peak. These results suggest that Sr1-xSi2O2N2: Eu-2(+) phosphor can be used in blue-pumped white light emitting diodes. (C) 2009 Elsevier Ltd. All rights reserved.