Enriching red emission of Y3Al5O12: Ce3+ by codoping Pr3+ and Cr3+ 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. (C) 2010 Optical Society of America