Significantly enhanced photoluminescence and thermal stability of LaSiNO:Ce,Tb the Ce → Tb energy transfer: a blue-green phosphor for ultraviolet LEDs.

A series of Ce-, Tb- and Ce/Tb-doped LaSiNO phosphors were synthesized by gas-pressure sintering (GPS). The energy transfer between Ce and Tb occurred in the co-doped samples, leading to a tunable emission color from blue to green under the 360 nm excitation. The energy transfer mechanism was controlled by the dipole-dipole interaction. The Ce/Tb co-doped sample had an external quantum efficiency of 46.7%, about 5.6 times higher than the Tb-doped LaSiNO phosphor (8.3%). The thermal quenching of the Tb emission in LaSiNO:Tb,Ce was greatly reduced from 74 to 30% at 250 °C, owing to the energy transfer from Ce to Tb. The blue-green LaSiNO:0.01Ce,0.05Tb phosphor was testified to fabricate a warm white LED that showed a high color rendering index of 90.2 and a correlated color temperature of 3570 K. The results suggested that the co-doped LaSiNO:Ce,Tb phosphor could be a potential blue-green down-conversion luminescent material for use in UV-LED pumped wLEDs.