Tunable Blue-Green Color Emission and Energy Transfer of Ca₂Al₃O₆F:Ce³⁺,Tb³⁺Phosphors for Near-UV White LEDs

A series of new luminescent emission-tunable phosphors Ca 2 Al 3 O 6 F:Ce 3+,Tb 3+ have been synthesized by a high temperature solid-state reaction. The UV–vis reflectance, photoluminescence emission and excitation spectra, the lifetime, and the effect of Tb 3+ concentration are investigated in detail. The intense green emission is realized in the Ca 2 Al 3 O 6 F:0.08Ce 3+,0.05Tb 3+ phosphors on the basis of the highly efficient energy transfer from Ce 3+ to Tb 3+ with an efficiency of over 90%. The energy transfer mechanism from Ce 3+ to Tb 3+ in the Ca 2 Al 3 O 6 F host was ascribed to the exchange interactions, and the formation of the Ce–Ce clusters and Ce–Tb clusters should be the reason for the high energy transfer efficiency. The critical distance of the energy transfer has also been calculated by the concentration-quenching method. These results indicate that the Ca 2 Al 3 O 6 F:Ce 3+,Tb 3+ phosphors have potential applications as a near UV-convertible phosphor for white light-emitting diodes because of its broad excitation in the near-ultraviolet range and the efficient green emission light.