Enhancement of red spectral emission intensity of Y3Al5O12:Ce3+ phosphor via Pr co-doping and Tb substitution for the application to white LEDs

We have enhanced color-rendering property of a blue light emitting diode (LED) pumped white LED with yellow emitting Y3Al5O12:Ce3+ (YAG:Ce) phosphor using addition of Pr and Tb as a co-activator and host lattice element, respectively. Pr3+ addition to YAG:Ce phosphor resulted in sharp emission peak at about 610 nm through 1D2→3H4 transition. And when Tb3+ substituted Y3+ sites, Ce3+ emission band shifted to a longer wavelength due to larger crystal field splitting. Y3Al5O12:Ce3+, Pr3+ and (Y1−xTbx)3Al5O12:Ce3+ phosphors were coated on blue LEDs to fabricate white LEDs, respectively, and their color-rendering indices (CRIs, Ra) were measured. As a consequence of the addition of Pr3+ or Tb3+, CRI of the white LEDs improved to be Ra=83 and 80, respectively. Especially, blue LED pumped (Y0.2Tb0.8)3Al5O12:Ce3+ white LED showed both strong luminescence and high color-rendering property.