Ultrahigh Resolution X‐Ray Imaging With Thin‐Film Scintillators Based on Aggregation‐Induced Delayed Fluorescence Luminogens

ABSTRACT Flexible thin‐film scintillators based on organic semiconductors offer transformative potential for X‐ray imaging, enabling conformity to nonplanar objects and compatibility with complex structural applications. However, challenges in synergizing high solid‐state luminescence, X‐ray absorption, and efficient exciton utilization have become the bottleneck limiting their application in high‐resolution imaging. Herein, we make the breakthrough by using halogenated aggregate‐induced delayed fluorescence luminogens for flexible thin‐film scintillators, fulfilling key criteria such as high photoluminescence quantum yield, efficient exciton utilization, large Stokes shift, and rapid radiative decay kinetics. Our investigations demonstrate that the heavy atom effect and molecular aggregation enhance reverse intersystem crossing (RISC) and radiative transitions, leading to superior radioluminescence performance characterized by high light yield, low detection limits, and an unprecedented resolution of 29.2 lp/mm, surpassing the capabilities of currently reported scintillators. This work underscores the transformative potential of aggregate‐induced delayed fluorescence (AIDF) molecules in achieving high‐performance, easily prepared, and high‐resolution X‐ray scintillation and imaging technologies.