Ultrabroad White/Near‐Infrared Multiexciton Emission in Single Metal Halide Crystals with Near 100% Luminous Efficiency and Efficient X‐Ray Radioluminescence for Pixel‐Level X‐Ray to Near‐Infrared Image Fusion and 3D Imaging

Abstract Recently, lead‐free metal halides have received much attention due to their fascinating optoelectronic properties and non‐toxic characteristics. However, realizing highly efficient white emission, near‐infrared (NIR) emission, and X‐ray radioluminescence (RL) simultaneously in a single compound has not yet been reported. Herein, this study first synthesizes Sb 3+ ‐doped [(C 3 H 7 ) 4 N] 2 ZnCl 4 crystals by a “green solvent” of ethanol at room temperature, which shows ultrabroad multiexciton emission within 400–1000 nm. Particularly, the efficient white light and NIR emission in Sb 3+ ‐doped [(C 3 H 7 ) 4 N] 2 ZnCl 4 crystal can be obtained under 340 nm excitation, and the corresponding luminous efficiency is close to 100% (NIR region: 37.8%). Moreover, Sb 3+ ‐doped [(C 3 H 7 ) 4 N] 2 ZnCl 4 crystal also emits bright RL emission with a light yield of 45 000 photons/MeV under X‐ray irradiation. Based on large‐area Sb 3+ ‐doped [(C 3 H 7 ) 4 N] 2 ZnCl 4 /PDMS flexible film, its applications have been demonstrated in white light, NIR, and X‐ray imaging, all of which exhibit remarkable optoelectronic properties and excellent operational stability. Particularly, the pixel‐level white light, NIR, and X‐ray image fusion are realized without pixel mismatch and complex imaging processing, and the internal information of the capsule wrapped with centrifuge tube and spring is observed clearly. Finally, the 3D image of the capsule and its internal structure is reconstructed by combining with multi‐angle imaging.