Enriching Red Emission of Y\u3csub\u3e3\u3c/sub\u3eAl\u3csub\u3e5\u3c/sub\u3eO\u3csub\u3e12\u3c/sub\u3e: Ce\u3csup\u3e3+\u3c/sup\u3e by Codoping Pr\u3csup\u3e3+\u3c/sup\u3e and Cr\u3csup\u3e3+\u3c/sup\u3e for Improving Color Rendering of White LEDs

Triply doped Y3Al5O12: Ce3+, Pr3+, Cr3+ phosphors are prepared by solid state reaction. The emission spectra are enriched in the red region with the luminescence of both Pr3+ and Cr3+through Ce3+→Cr3+ and Ce3+→Pr3+→Cr3+ energy transfers. The properties of photoluminescence and fluorescence decay indicates larger macroscopic Ce3+→Cr3+ transfer rates in the triply doped phosphors in comparison to Ce3+ and Cr3+ doubly doped one, reflecting the effect of competition between Ce3+→Cr3+ and Ce3+→Pr3+ transfers. White LEDs fabricated using the triply doped phosphor coated on blue LED chips show a color rendering index of 81.4 higher than that either using Ce3+ and Cr3+ doubly doped or Ce3+ singly doped phosphor