Luminescence of TbAlO phosphors co-doped with Ce/Gd for white light-emitting diodes.

Tb CeGdAlO phosphors were synthesized through solid-state reactions. The influence of Gd on the luminescence was investigated. Under the excitation at 460 nm, TbCeAlO shows the characteristic emission band of Ce with a peak wavelength at about 554 nm. After co-doping Gd into TbCeAlO, the peak wavelength of the Ce emission band shifts to longer wavelengths, which is induced by the increasing crystal field splitting. However, the Ce emission intensity also decreases because the substitution of Tb with Gd causes lattice deformation and generates numerous structural and chemical defects. By comparing the light parameters of white light-emitting diodes (WLEDs) containing YCeAlO, TbCeAlO and TbCeGdAlO phosphors, we can find that the WLED containing the TbCeGdAlO phosphor generates warmer light than the WLEDs containing YCeAlO and TbCeAlO phosphors. Moreover, the WLEDs fabricated by integrating a blue LED chip and Ce/Gd-co-doped TbAlO phosphors show outstanding colour stability when driven under different currents.