A novel borate phosphor Lu5Ba6B9O27:Ce3+ codoped with Sr2+/Tb3+ for NUV-white light emitting diode application.

Abstract

At present, there are still challenges in developing highly efficient and thermally stable phosphors for ultraviolet/near ultraviolet-white light emitting diodes (UV/NUV-WLEDs). Herein, we use traditional high-temperature solid-state reactions to prepare blue-emitting phosphors Lu5-xBa6B9O27:xCe3+ (0.1% ≤ x ≤ 3.0%) and Lu4.975Ba6-ySryB9O27:0.5%Ce3+ (0% ≤ y ≤ 20%), and green-emitting phosphors Lu4.975-zBa6B9O27:0.5%Ce3+,zTb3+ (0% ≤ z ≤ 16%), abbreviated as LBB:xCe3+, LBB:0.5%Ce3+,ySr2+ and LBB:0.5%Ce3+,zTb3+, respectively. Upon 340 nm excitation, LBB:Ce3+ exhibits an asymmetric blue emission ranging from 360 nm to 480 nm. Furthermore, the emission intensity of LBB:0.5%Ce3+ increased 4.8-fold without a spectral shift through the partial substitution of Sr2+ for Ba2+. Through constructing the Ce3+ → Tb3+ energy transfer in the LBB structure, the temperature-dependent integral emission intensity at 483 K improved from only 25% to 68% of the intensity at 303 K due to the existence of fast energy transfer from Ce3+ to Tb3+. The related results indicate that LBB:xCe3+, LBB:0.5%Ce3+,ySr2+ and LBB:0.5%Ce3+,zTb3+ phosphors can be used for UV/NUV-WLEDs.