Luminescence Characteristics of Ce: YAG Ceramic Phosphors with Gd3+Doping for White Light-emitting Diodes

Ce:YAG ceramic phosphor has outstanding thermal conductivity and chemical stability for application in white light-emitting diodes (WLEDs), thus has a broader application than organic packaging in high-power WLEDs. (Gd,Y)(3)Al5O12:Ce ceramic phosphors of varying Gd3+ concentrations were fabricated through solid-state reactive sintering method. Through X ray diffraction, scanning electron microscopy, and fluorescence spectroscopy, the crystal structures, influence of the Gd concentration on fluorescence spectra of Ce:YAG, and luminescence properties of WLEDs with (Gd,Y)(3)Al5O12:Ce ceramic phosphors were investigated. As Gd content increased, the Gd3+ replaced the lattice position of y(3+) into the lattice. The absorption of blue light and relative photoluminescence (PL) intensity of the (Gd,Y)(3)Al5O12:Ce ceramic phosphors decreased as Gd content increased, leading to a reduction in the luminous efficacy from 81.451 m/W to 63.701 m/W. Moreover, the PL emission bands of (Gd,Y)(3)Al5O12:Ce exhibited redshift from 534 nm toward 564 nm and resulted in increase of the color, rendering index from 61.3 to 70.2. Although doping of Gd decreases the luminous efficacy, the color rendering index of the (Gd,Y)(3)Al5O12:Ce sample is significantly increased, and the performance of the yellow YAG ceramic phosphor applied to the white LED is improved.