Optical enhancement brought by doping Gd(3+) ions into Ce: YAG ceramics for indoor white light-emitting diodes.

We dope Gd(3+) ions into Ce: YAG ceramics to induce red-shift in the photoluminescence, of which the degree is proportional to the Gd(3+) doping concentration. This kind of ceramic, when collaborating with InGaN blue chips, proves to be a promising fluorescent material of white light-emitting diodes, for not only its high in-line transmittance and decent quantum yield, but also the improvement in color rendering ability brought by the red-shift, which enhances the ratio of red portion in spectra. We demonstrate that 10% is the optimized value of Gd(3+) doping concentration, as it provides the maximum color rendering index of ~78 with luminous efficiency as high as 128 lm/W.