Phosphors that meet the requirements of high-quality white LED lighting
The thermal quenching of phosphors is one of the biggest challenges facing the development of high-quality white light-emitting diodes. In response to this problem, researchers from China University of Geosciences and other units reported a Ba2ZnGe2O7:Bi3+ phosphor with cyan emission and high thermal stability. At 150℃, its emission intensity increased to 114% of its original intensity at 25℃. It is proved that the main reason for the phenomenon of thermal quenching resistance is the high structural rigidity, and it has opened up new ideas for the development of thermal quenching phosphors for high-quality WLED applications. Related papers were published in the journal Laser & Photonics Reviews with the title "Anti-Thermal-Quenching Bi3+ Luminescence in a Cyan-Emitting Ba2ZnGe2O7: Bi Phosphor Based on Zinc Vacancy".
The author reported a series of Bi3+-doped pyrite phosphors whose light-emitting color can be adjusted from blue to red. Due to the high structural rigidity, BMGO: Bi3+ phosphor has a very low TQ, and the emission intensity at 150°C reaches 87% of the initial intensity at 25°C. In addition, TQ characteristics can be further optimized through element replacement.
BZGO: Bi3+ phosphor has excellent anti-TQ performance, the fluorescence intensity at 150°C reaches 114% of the original intensity at 25°C. The anti-TQ performance of BZ0.95GO:Bi3+ is unprecedentedly improved. At 150℃, 200℃, 250℃, the luminous intensity increases to 138%, 148% and 134%, respectively, and its anti-TQ performance is significantly improved.
The main mechanism is the thermally induced self-oxidation of Bi2+ and oxygen vacancy defects. The concept of generating oxygen vacancy defects and realizing Bi2+ ion thermally induced self-oxidation provides new ideas for the development of anti-TQ phosphors. This concept contributes to the rapid development of lighting technology. In addition, W-led has a warm white light with high color rendering index (Ra=98.9) and lower corrected color temperature (CCT=4466k), which proves that the prepared cyan phosphor can well meet the requirements of high-quality W-led lighting.