Near-Infrared Persistent Luminescence and Trap Reshuffling in Mn4+ Doped Alkali-Earth Metal Tungstates

Near-infrared persistent luminescent materials have great potential for in vivo bioimaging and night-vision surveillance due to their long-lasting autofluorescence-free emission through deep tissues and multicycle photostimulated luminescence by releasing energy from captured traps using high-intensity 808 or 980 nm lasers. However, phosphors combining both near-infrared persistent luminescence and photostimulated luminescence are found mostly in chromium doped gallates hosts, other emitters are rarely reported. Herein, a new material system with near-infrared persistent luminescence is achieved in tetravalent manganese doped double-perovskite alkali-earth metal tungstates via the aliovalent substitution of calcium ions with lanthanum ions. Persistent luminescence can be generated via X-ray irradiation, providing great promise in long-term deep-tissue ultrasensitive imaging, information storage, and X-ray detection. Photostimulated detrapping is successfully demonstrated using a common 420 nm light emitting diode instead of a high-intensity 808 or 980 nm laser. The traps distribution is proved to be reshuffled upon this laser-free visible light stimulation. Reshuffling of trap distributions upon visible light stimulation may be promising for optical information storage applications. This work is expected to broaden the range of near-infrared persistent material systems and provides new insights into manipulating photostimulated traps via laser-free light stimulation.