Wide-range tuning of trap depths in double perovskite phosphors enabling tunable NIR persistent luminescence

Persistent Luminescence (PersL) materials, which use traps to store energy and emit photons over a long period, have found important applications in the fields of optical information storage, security labeling, and biological imaging. The trap depth is a crucial factor determining the performance of these materials; however, achieving the desired trap depth with high precision remains a great challenge. Here, we provide double perovskite phosphors (Cs 2 SnCl 6 -Cs 2 ZrCl 6 -Cs 2 HfCl 6 series) with highly compatible crystal structures, enabling continuous and precise tuning of trap depth over an ultra-wide range of 0.11 to 1.25 eV. By incorporating W 4+ as the luminescent centers, these phosphors exhibit outstanding near-infrared (NIR) PersL performance at approximately 900 nm and a lasting emission duration exceeding 10 h. The underlying mechanism of PersL is elucidated, and the wide-range tunability of trap depth is attributed to the universal applicability of band-gap engineering in the entire material system. Furthermore, we demonstrate the practical application of these materials by designing a flexible detector plate for X-ray imaging. The detector plate exhibits a storage time of more than 1 week, a detection limit of 0.83 μGy air ·s -1 in the near-infrared region, and real-time and delay-time imaging resolutions of 14.2 lp·mm -1 and 2.5 lp·mm -1 , respectively. These attributes demonstrate strong potential for X-ray luminescence extension imaging. W 4+ -doped near-infrared persistent luminescence materials are reported for the first time, and the trap depth of the materials can be accurately and continuously modulated in an ultra-wide range (0.11-1.25 eV) based on a bandgap engineering method.