Concentration-Driven Selectivity of Energy Transfer Channels and Color Tunability in Ba3La(PO4)3:Tb3+, Sm3+ for Warm White LEDs

Here, we report the large-scale emission color tunability in Ba3La(PO4)(3):Tb3+, Sm3+ (BLPO:TS) system based on the detailed discussion on the concentration-driven selectivity of energy transfer (ET) channels from Tb3+ to Sm3+. It is induced by the concentration-dependent D-5(3) and D-5(4) emissions of Tb3+ and the different interaction mechanisms of ET from Tb3+ to Sm3+ via D-5(3) and D-5(4) channels. In the diluted Tb3+ scenario, the red emission of Sm3+ is efficiently sensitized via the D-5(3) channel, while in the concentrated Tb3+ case, the contribution of D-5(4) channel is dominant. Therefore, by simply adjusting the doping concentrations of Tb3+ and Sm3+, the emission color of the phosphors can be tuned from green to red. In view of the phosphors with red emissions are critical to the warm white light-emitting diodes (WLEDs), an Orange-red Tb3+, Sm3+ coactivated phosphor Ba3La0.90Tb0.05Sm0.05(PO4)(3) (BLPO:5T5S) with good thermal and chromaticity stability internal quantum efficiency similar to 67% is developed in the System. Then, a near-UV WLED (CCT approximate to 4500 K, R-a approximate to 81) is fabricated using this phosphor. These findings not only indicate that the orange-red Phosphor BLPO:5T5S is available for near-UV warm white LEDs but also deliver new insights into the ET processes in Tb3+ and Sm3+ activated phosphors.