Persistent Luminescence for Night‐Time Individual Identification Based on Quantum Tunneling

Abstract Night‐time individual identification requires recognizing a specific object from a bunch of homogeneous entities through night‐vision devices. It will facilitate more effective coordinated actions in night‐time disaster rescue or enforcement actions. In this work, the near infrared (NIR) persistent luminescent materials are proposed as the technology solution, which can emit the non‐visible photons continuously for hours without the external excitation. In a magnetoplumbite‐type structure, Cr ³⁺ ions are incorporated to realize NIR emissions. By co‐doping lanthanide ions and constitutional modulation, the afterglow signal can be clearly traced under the night‐vision device over 144 h. A series of spectral measurements are utilized to reveal the mechanism behind this prolonged afterglow duration, and quantum tunneling accounts for the carrier pumping from the deep traps. It avoids the quick exhaust of carriers stored in the shallow traps, and extends the afterglow duration. In a proof‐of‐concept demonstration, the synthesized powders are used to make a quick response pattern, which can be clearly visualized in a dark room by the night‐vision devices. This work is expected to promote the research and development of persistent luminescent materials within NIR region, and to accelerate the applications in night‐time monitoring and recognition.