Luminescent properties and energy transfer studies of color-tunable LuBO 3 : Ce 3+ /Tb 3+ /Eu 3+ phosphors

Abstract A series of LuBO3: Ce3+/Tb3+/Eu3+ phosphors were synthesized via solid state reaction. The Ce3+/Tb3+ co-doped and Ce3+/Tb3+/Eu3+ tri-doped phosphors absorb near UV light through 4f-5d transitions of Ce3+, followed by sensitized Tb3+ green and Eu3+ red emission. Decay curves investigations for samples with various Tb3+ and Eu3+ contents reveal the occurrence of Ce3+ → Tb3+ → Eu3+ energy transfer. It is found that due to relative low Tb3+ → Eu3+ energy transfer rate, a high Tb3+ content (>40%) is required for efficient Ce3+ → Tb3+ → Eu3+ energy transfer. Emission color of LuBO3: Ce3+, Tb3+, Eu3+ varies from blue through green to red with Ce3+/Tb3+/Eu3+ ratio. The quantum efficiency of LuBO3: Ce3+, Tb3+ green phosphor and LuBO3: Ce3+, Tb3+, Eu3+ red phosphor is 50% and 30%, respectively. Green and red LED prototypes were fabricated. The results show that the obtained phosphors are potential candidates as down-converted phosphors for NUV LEDs.