Emission from Storage Phosphors That Glow Even in Bright Ambient Light

Abstract

Light-emission phenomena of storage phosphors have received widespread attention, provoking the continuous developments of persistent luminescence, photostimulated luminescence, and mechanoluminescence. In the study and application of storage phosphors, as a matter of experience, it is always necessary to avoid or eliminate ambient light. It is the requirement for ambient darkness that is hindering the further development of storage phosphors under different ambient conditions. Here, we report an interesting glow phenomenon of storage phosphors in bright ambient light by introducing a concept termed ambient stimulated emission, in which the ambient temperature and ambient lighting can simultaneously release energy stored in the storage phosphors and lead to long-lasting emissions beyond the visible spectrum. As a proof of concept, we focus our discussion on an x-ray-charged ${\mathrm{La}\mathrm{Mg}\mathrm{Al}}_{11}{\mathrm{O}}_{19}:{\mathrm{Gd}}^{3+}$ phosphor, which exhibits ambient stimulated emission in the ultraviolet-B region, with increased initial light emission when the phosphor is exposed to ambient illumination instead of dark conditions. The ambient-stimulated-emission performances are found to depend on the illuminance and spectral distribution of ambient light. Moreover, our study indicates that the glow phenomenon in bright ambient light commonly appears in various storage phosphors, involving ultraviolet and infrared phosphors. The introduction of ambient stimulated emission brings different insights to luminescence research and offers approaches to further learn about and utilize storage phosphors.