The luminescence properties of Sr2-1.5x-1.5yP2O7:xDy3+,yCe3+ phosphor for near-UV-based white LEDs synthesized by a chemical co-precipitation method

A series of Sr2P2O7:Dy3+, Sr2P2O7:Ce3+ and Sr2P2O7:Dy3+,Ce3+ phosphors was synthesized via the one-step calcination process for the precursors prepared by co-precipitation methods. The phases, morphology, quantum efficiency and photoluminescence properties of the obtained phosphors were characterized systematically. These results show that the near-spherical particles prepared through calcining the precursors by means of ammonium dibasic phosphate co-precipitation (method 3) have the smallest particle size and strongest emission intensity among the three methods in the paper. With Dy3+ concentration increasing in Sr2P2O7:Dy3+ phosphors, the luminescence intensity first increases, reaches maximum, and then decreases. A similar trend was followed by Sr2P2O7:Ce3+ with Ce(3+)concentration increasing. A successful attempt was made to initiate the energy transfer mechanism from Ce3+ to Dy3+ in the host lattice and an overlap between the emission band of Ce3+ and the excitation band of Dy3+ indicated that the Ce3+Dy3+ energy transfer may indeed exist. It is clear that the photoluminescence intensity of Dy3+ as well as the quantum efficiency of the phosphor can be enhanced markedly by co-doping Ce3+. Sr2P2O7:Dy3+,Ce3+ has its (CIE) chromaticity coordinates in the bluish-white-light region, near the standard illuminant D-65. The CIE 1913 chromaticity coordinates of Sr2P2O7:Dy3+ phosphors fall in the white-light region, and are adjacent to the ideal white-light coordinates. In addition, the colour temperature and colour tone of Sr2P2O7:Dy3+ could be adjusted by changing the relative concentration of Dy3+. In short, Sr2P2O7:Dy3+ can be a promising single-phased white-light emitting phosphor for near-UV (NUV) w-LEDs.