Photoluminescence properties of Sr1–xSi2O2N2: Eu2+x as green to yellow-emitting phosphor for blue pumped white LEDs Original Research Article

This study evaluated potential applications of green to yellow-emitting phosphors (Sr1−xSi2O2N2: Eu2+x) in blue pumped white light emitting diodes. Sr1–xSi2O2N2: Eu2+x was synthesized at different Eu2+ doping concentrations at 1450 °C for 5 h under a reducing nitrogen atmosphere containing 5% H2 using a conventional solid reaction method. The X-ray diffraction patterns of the prepared phosphor (Sr1–xSi2O2N2: Eu2+x) were indexed to the SrSi2O2N2 phase and an unknown intermediate phase. The photoluminescence properties of these phosphors (Sr1−xSi2O2N2: Eu2+x) 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: Eu2+x phosphor can be used in blue-pumped white light emitting diodes.