Energy transfer properties and enhanced color rendering index of chromaticity tunable green-yellow-red-emitting Y_3Al_5O_12: Ce^3+, Cr^3+ phosphors for white light-emitting diodes

Abstract

White light-emitting diodes using YAG: Ce3+ phosphors suffer from the deficiency of red component, leading to a low color rendering index (CRI) and a high correlated color temperature (CCT). Herein, a yellow-red single-phase YAG: Ce3+, Cr3+ phosphor was synthesized by a traditional solid-state reaction. Compared with Cr3+ ion single-doped YAG phosphor, the emission intensity in the far-red region of the co-doped YAG: Ce3+, Cr3+ sample increases because of the energy transfer from Ce3+ ions to Cr3+ ions. For sample Y3Al5O12: 0.02Ce3+, 0.008Cr3+ phosphor, the internal and external quantum efficiencies are 58.9% and 46.7%, respectively. And, the fabricated white LED shows a CCT of 6085 K at CIE 1931 coordinate (0.3208, 0.3273). Moreover, the CRI is as high as 77.9 while that of the corresponding Ce3+ single-doped YAG phosphor is only 63.2. Thus, the Ce3+ and Cr3+ co-doped YAG phosphors are suitable for white light-emitting diodes (WLEDs).