Efficient Energy Transfer for Near-Perfect Quantum Efficiency and Thermal Stability.

The pursuit of high-quality phosphors exhibiting swift response to near-ultraviolet (n-UV) excitation, elevated quantum efficiency (QE), superior thermal stability, and impeccable light quality has been a focal point of investigation. In this research, we synthesized a novel K 2 La 2 B 2 O 7 :Ce 3+ ,Tb 3+ (KLBO:Ce 3+ ,Tb 3+ ) color-tunable phosphor that meets these requirements. KLBO:Ce 3+ can be stimulated efficiently by the n-UV light and shows an intense blue emission centered at 437 nm. Notably, KLBO:0.04Ce 3+ exhibits exceptional internal QE (IQE = 94%) and outstanding thermal stability ( I 423 K / I 303 K = 88%). Optimization of doping compositions enables efficient Ce 3+ → Tb 3+ energy transfer, resulting in substantial enhancements in QE and thermal stability. Specifically, KLBO:0.04Ce 3+ ,0.28Tb 3+ achieves an IQE of 98% and a thermal stability of 97%, higher than those of most phosphors of the same type. White light-emitting diodes fabricated using phosphor samples emit warm white light characterized by high R a ( R a = 96.6 and 93.4) and low CCT (CCT = 4886 and 4400 K). This study underscores the feasibility of enhancing phosphor QE and thermal stability through energy transfer mechanisms.