Thermostability and photostability of Sr3SiO5:Eu2+ phosphors for white LED applications

• The photo-assisted thermal degradation was observed for the Sr3SiO5:Eu2+ phosphor.
• The phosphor showed a reversible intensity decrease under the blue light irradiation.
• An anomalous emission enhancement with increasing temperature was found.
• Ba2+ substitution could suppress the thermal quenching of Sr3SiO5:Eu2+.
• Mechanisms for photostability and thermostability were discussed.

Sr3SiO5:Eu2+ phosphors were synthesized by solid-state reactions, and their photoluminescence (PL) stability under the impact of heat or light was studied. The thermal degradation in air was observed for the Sr3SiO5:Eu2+ phosphor, furthermore, this drop in emission intensity could be accelerated by simultaneously illuminating the phosphor with a high-power blue LED during the heating process. This enhanced thermal degradation phenomenon in the blue light can be ascribed to the photo-assisted thermal oxidation of Eu2+ ions. A reversible decrease in emission intensity at room temperature was observed on illuminating the Sr3SiO5:Eu2+ phosphor alone by the blue light, which could be related to trapping centers in the phosphor. The existence of traps is also responsible for the anomalous increase of emission intensity with increasing temperature from 30 to 100 °C. Considering the influences of Ba2+ doping on temperature-dependent PL properties of the Sr3SiO5:Eu2+ phosphor, the thermal quenching origin may be ascribed to the thermally assisted photoionization process.

The photo-induced reversible decrease in emission intensity and the anomalous emission enhancement with increasing temperature are related to trapping centers in the phosphor.Figure optionsDownload as PowerPoint slide