Enhancing anti-thermal quenching performance in a broadband blue-emitting Ba2ZnSi2O7: Bi3+ phosphor via increasing zinc vacancy concentration

A B S T R A C TDeveloping ultraviolet (UV) chip-pumped LED can suppress high-energy blue light emission from conventional blue-chip-based architectures substantially mitigating the risk of retinal photochemical damage.​However, the anti-thermal-quenching (anti-TQ) of phosphors is one of the significant challenges in developing high-quality blue light-emitting phosphor in w-LEDs. Here, we reported a broadband blue emitting Ba2ZnSi2O7: Bi3+ phosphor under 290 nm UV light excitation with low thermal quenching performance. The low thermal quenching is mainly attributed to the high structural rigidity of the Ba2ZnSi2O7 and the thermally induced emission compensation in the phosphor. Thermal-induced emission compensation is facilitated by zinc vacancy defects. Through DFT calculations, it has been confirmed that zinc vacancies are induced by the charge imbalance between Bi3+ and Ba2+ ions in Ba2ZnSi2O7: Bi3+ phosphor. To further improve their anti-thermal-quenching property, zinc vacancies were created by deliberately reducing the stoichiometric ratio of Zn in Ba2ZnSi2O7: Bi3+ phosphor. The integrated emission intensity of the 420 nm peak increased to 111%, 109% and 102% at 428 K, 453 K and 478 K of the original intensity at 303 K respectively. Moreover, the blue LED packaged with the prepared phosphor manifested outstanding stability under a current ranging from 200 to 1000 mA. Their spectra significantly overlap the absorption spectrum of chlorophyll, exhibiting the great potential applications in high-quality blue lighting and plant illumination.