Anti‐Thermal‐Quenching Bi3+ Luminescence in a Cyan‐Emitting Ba2ZnGe2O7:Bi Phosphor Based on Zinc Vacancy

Thermal quenching (TQ) of phosphor is one of the biggest challenges to develop high‐quality white light‐emitting diodes (w‐LEDs). Herein, an anti‐thermal‐quenching (anti‐TQ) property in cyan‐emitting Ba2ZnGe2O7:Bi3+ phosphor is reported. At 150 °C, its emission intensity increases to 114% of the original intensity at 25 °C. Especially, the integrated emission intensity reaches 138%, 148%, and 134% at 150, 200, and 250 °C, respectively, by artificially creating zinc and oxygen vacancy defect. The anti‐TQ phenomenon is mainly attributed to high structure rigidity and strong ability to compensate emission loss during thermal generation process. Thermal‐induced emission compensation mainly stems from self‐oxidization behavior of Bi2+ in zinc vacancy and the presence of oxygen vacancy defect. Oxygen vacancy is induced by native zinc vacancy and charge imbalance between Bi3+ and Ba2+ ions. The strategy to create oxygen vacancy defect and design self‐oxidization process of Bi opens a new insight to exploit anti‐TQ phosphors for high‐quality w‐LEDs applications. Anti‐thermal‐quenching luminescence is realized in Bi3+‐activated melilite phosphors based on the coexistence of Bi2+ ions and zinc vacancy defects, which opens a new insight to exploit anti‐TQ phosphors for high‐quality w‐LEDs applications.