High-efficiency and thermal-stable tunable blue-green-emitting Ca3Lu(AlO)3(BO3)4:Ce3+,Tb3+ phosphors for near-UV-excited white LEDs

Abstract

In this paper, a series of blue-green color tunable Ca3Lu(AlO)3(BO3)4:Ce3+,Tb3+ phosphors were successfully prepared by a conventional solid state method. X-ray diffraction, luminescence properties, decay curves, thermal stability, and internal quantum efficiency were investigated in detail. The energy transfer from Ce3+ to Tb3+ ions in Ca3Lu(AlO)3(BO3)4 host was demonstrated to be dipole-quadrupole interaction and the energy transfer efficiency was reached up to 96%. With the increasing of the Tb3+ doping concentration in Ca3Lu(AlO)3(BO3)4:0.02Ce3+,xTb3+, the emission colors of the obtained phosphors can be tuned appropriately from deep blue (0.1691, 0.0476) to green (0.3663, 0.5388). When the value of x reached 0.5, the green emission intensity was the strongest. Moreover, the maximum internal quantum efficiency of the Ca3Lu(AlO)3(BO3)4:Ce3+,Tb3+ phosphors was measured to be 69.3%. Besides, Ca3Lu(AlO)3(BO3)4:Ce3+,Tb3+ phosphors possessed reasonable thermal stability and the emission intensity at 423 K was about 57.1% of that at 303 K. Finally, a prototype white light-emitting diode (LED) lamp exhibiting bright white light was fabricated by using a 365 nm near-ultraviolet-emitting LED chip combined with BaMgAl10O17:Eu2+ blue phosphors, CaAlSiN3:Eu2+ red phosphors, and Ca3Lu(AlO)3(BO3)4:0.02Ce3+,0.5Tb3+ green phosphors. Its correlated color temperature, color rendering index, and CIE chromaticity coordinates were measured to be 3128 K, 81, and (0.4279, 0.4004), respectively. Therefore, these results indicated that the as-prepared green-emitting Ca3Lu(AlO)3(BO3)4:0.02Ce3+,0.5Tb3+ phosphors have potential applications for white LEDs.