Efficient energy transfer induced tunable emission in Ce3+ and Eu2+ co-doped Ba1.2Ca0.8SiO4 phosphor

Abstract

A series of Ce3+ and/or Eu2+ doped T-phase orthosilicate Ba1.2Ca0.8SiO4 (BCS) phosphors were synthesized by conventional solid state reaction. The as-synthesized samples were investigated by X-ray diffraction (XRD), photoluminescence spectroscopy, and fluorescence decay curve. The red shifts of emission peak were observed in Ce3+ and/or Eu2+ doped BCS phosphors. The possible rationalization for the red shift was discussed. The emission color for BCS:Ce3+, Eu2+ phosphors can be turned from deep blue to bluish green by varying Eu2+ concentration. The efficient energy transfer from Ce3+ to Eu2+ is responsible for this phenomenon. The energy transfer mechanism was validated and demonstrated to be a resonant type via a dipole–dipole interaction by using Inokuti–Hirayama model and Dexter's energy transfer theory. In addition, the thermal stability of the phosphors is also investigated. Furthermore, the quantum efficiency (QE) of Ba1.15Ca0.8SiO4:0.02Ce3+, 0.02Na+, 0.01Eu2+ phosphor was found to be 38.77%. Finally, to explore the practical applications of obtained compounds for indoor illumination, a white light-emitting-diode (LED) device which contained a n-UV chip, prepared phosphors, and green emitting and red emitting phosphors was packaged. The packaged white LEDs device can emit dazzling white light with satisfied color coordinate of (0.350, 0.335), Ra (84), and correlated color temperature (4744 K).