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 K₂La₂B₂O₇:Ce³⁺,Tb³⁺ (KLBO:Ce³⁺,Tb³⁺) color-tunable phosphor that meets these requirements. KLBO:Ce³⁺ can be stimulated efficiently by the n-UV light and shows an intense blue emission centered at 437 nm. Notably, KLBO:0.04Ce³⁺ exhibits exceptional internal QE (IQE = 94%) and outstanding thermal stability (I_{423 K}/I_{303 K} = 88%). Optimization of doping compositions enables efficient Ce³⁺ → Tb³⁺ energy transfer, resulting in substantial enhancements in QE and thermal stability. Specifically, KLBO:0.04Ce³⁺,0.28Tb³⁺ 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.