Regulation of Anti‐Thermal Quenching and Emission Color in Eu2+‐Activated Na‐Beta‐Alumina Phosphors for Full‐Spectrum Illumination

Abstract Broadband cyan‐emitting phosphors are crucial to close the cyan gap of phosphor‐converted white light‐emitting diodes (pc‐WLEDs) for full‐spectrum illumination. In this work, efficient cyan‐emitting Eu 2+ ‐activated phosphor is achieved through structural modulation, which exhibits anti‐thermal quenching behavior. Redshift from blue (469 nm) to cyan (500 nm) emission and enhancement of emission is achieved by codoping Mg 2+ and Ge 4+ into Eu 2+ ‐activated Na‐beta‐alumina phosphor. The introduction of Mg 2+ ions dominates the redshift, while Ge 4+ dominates the enhancement of emission. Furthermore, the introduction of Mg 2+ and Ge 4+ reduces the content of deep trap levels related to V Na defect, which decreases the degree of anti‐thermal quenching and results in better thermal stability. The prototype pc‐WLED by using the cyan‐emitting phosphor exhibits higher color‐rendering index and potential to close the cyan gap of pc‐WLEDs for full‐spectrum illumination. This work presents a paradigm for exploring phosphors with highly efficient and thermally stable emissions.