Color tunable emission and energy transfer of Ce/Dy codoped BaLa(BO) phosphor for UV white LEDs.

Polycrystalline BaLa(BO):Ce,Dy sub-micrometer-sized phosphors were synthesized by solid-state reaction under a weak reductive atmosphere. The structure, static and time-resolved photoluminescence are investigated. Under the near-ultraviolet excitation, the BaLa(BO):Dy phosphors emit white light with three intense emission bands centered at 483, 575, and 665 nm. The efficient energy transfer from Ce to Dy in BaLa(BO) phosphor was found by excitation/emission spectra and decay time measurements, and the resonant type was demonstrated by a dipole-dipole mechanism. A tunable emission hue from blue (0.18, 0.20) to blue-white (0.26, 0.29) and eventually to white (0.32, 0.33) was obtained in BaLa(BO):Ce,Dy phosphors. Owing to the broad UV excitation band, indicating that BaLa(BO):Ce,Dy phosphors can be considered as a potential candidate for ultraviolet-based white light-emitting diodes.