Color tunable emission and energy transfer of Ce3+/Dy3+ codoped Ba3La2(BO3)4 phosphor for UV white LEDs.

Polycrystalline Ba3La2(BO3)4:Ce3+,Dy3+ 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 Ba3La2(BO3)4:Dy3+ phosphors emit white light with three intense emission bands centered at 483, 575, and 665 nm. The efficient energy transfer from Ce3+ to Dy3+ in Ba3La2(BO3)4 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 Ba3La2(BO3)4:Ce3+,Dy3+ phosphors. Owing to the broad UV excitation band, indicating that Ba3La2(BO3)4:Ce3+,Dy3+ phosphors can be considered as a potential candidate for ultraviolet-based white light-emitting diodes.