Near‐Infrared Emitting Lead‐Free Perovskite Scintillators for X‐Ray Imaging with Suppressed Optical Crosstalk

ABSTRACT Portable X‐ray imaging is crucial for rapid security inspections and prompt diagnostics in outdoor settings. However, most high‐performance scintillators emit in the ultraviolet to visible range, which significantly overlaps with white light‐emitting diode (wLED) sources and sunlight, complicating the clear internal images under high‐light conditions. Here, we develop a lead‐free Cs 4 MnBi 2 Cl 12 :Tm/Ce scintillator with intense Mn 2+ visible and Tm 3+ near‐infrared (NIR) emissions. Incorporating NIR luminescence reduces optical crosstalk from external light signals, enabling high‐contrast imaging even under intense ambient illumination. Ce 3+ doping enhances energy transfer and suppresses nonradiative recombination, resulting in a high light yield of 49964 photons MeV −1 , a low detection limit of 57.2 nGy air s −1 , and a high spatial resolution up to 16 lp mm −1 . Moreover, flexible scintillator films fabricated via screen coating demonstrate stable, high‐contrast imaging under wLED or sunlight, eliminating the need for complex optics. This work offers a promising solution for realizing the next‐generation portable outdoor X‐ray detection.