Red enhanced YAG:Ce, Pr nanophosphor for white LEDs

Abstract

Rare earth ion Pr<sup>3+</sup> was co doped in yellow emitting YAG:Ce nanophosphor to introduce red emission for improving colour rendering property of white LED. Nanocrystalline YAG:Ce, YAG:Ce, Pr was synthesised by a single step auto combustion process. Photoluminescence (PL) emission spectra of YAG:Ce, Pr nanophosphor, when excited by 460nm blue light, exhibited sharp red emission peaks at 610nm from Pr<sup>3+</sup> ions in addition to broad yellow emission from Ce<sup>3+</sup> peaking at 540nm due to charge transfer from excited Ce<sup>3+</sup> 5d band to 3PJ/1D2 level of Pr<sup>3+</sup>. Ce<sup>3+</sup> (yellow) and Pr<sup>3+</sup> (red) emission decays in tens of nanoseconds and microseconds, respectively. Electroluminescence spectra of blue LED with developed phosphor layer shows colour coordinates (0.30, 0.39) close to ideal white light.