Copper(I) Halide Complex Featuring Blue Thermally Activated Delayed Fluorescence and Aggregate Induced Emission for Efficient X‐ray Scintillation and Imaging

Abstract Developing solution‐processable and stable scintillators with high light yields, low detection limits and high imaging resolutions holds great significance for flexible X‐ray imaging. However, attaining an optimal equilibrium among X‐ray absorption capacity, exciton utilization efficiency, and decay lifetime of scintillators remains a substantial challenge. Here, a new Cu(I) halide complex was synthesized in a mild condition. It exhibits intense blue thermally activated delayed fluorescence (TADF), remarkable aggregation‐induced emission (AIE) characteristic, as well as good water‐oxygen stability and photochemical stability. Notably, the complex shows excellent radiation resistance and efficient radioluminescence (RL) with an ultra‐low detection limit of 42.5 nGy air s −1 . This superior scintillation performance can be attributed to the synergistic effect of effective X‐ray absorption by the heavy Cu 2 I 2 core, the high radiation‐induced exciton utilization rate in TADF process, and the remarkable suppression of non‐radiative transitions by the restriction of intramolecular motions in solid state. Furthermore, the favourable solution processability of the complex facilitates the successful fabrication of a flexible film, achieving high‐quality X‐ray imaging with a resolution of 17.3 lp mm −1 . This work highlights the potential of hybrid Cu(I) halides with AIE‐TADF effects for high‐energy radiation detection and imaging, opening up new avenues for the exploration of cost‐effective and high‐performance scintillators.