Highly Efficient and Water‐Resistant Copper–Iodide Emitters Toward Underwater X‐Ray Imaging

ABSTRACT Advanced scintillators with superior performance and environmental robustness are urgently needed for emerging x‐ray imaging applications, especially in challenging environments such as underwater scenarios. Copper(I) iodide cluster complexes are promising candidates for advanced x‐ray imaging applications due to their excellent optical properties and solution‐processable nature. Herein, we report two green‐emitting Cu 2 I 2 cluster‐based complexes achieved through a dual‐ligand strategy. The rigid P,N‐bridging ligand serves to construct the emissive Cu 2 I 2 core and improve exciton utilization, while the meta‐fluorinated ancillary ligand introduces multiple weak interactions, suppressing nonradiative decay and enhancing water stability. Together with the aggregation‐induced emission (AIE) characteristics, two complexes achieve high photoluminescence quantum yields (PLQYs) of 86.4% and 92.5% in the solid state, respectively. The optimal complex shows efficient radioluminescence (RL) with a low detection limit of 73.5 nGy air s −1 . The fabricated flexible screen exhibits stable x‐ray imaging performance with a spatial resolution up to 21.4 lp mm −1 . More importantly, the complex demonstrates exceptional structural integrity and emission stability in air and water. These attributes ultimately allow for high‐performance underwater x‐ray imaging. This work not only provides a ligand‐engineering strategy for the construction of high‐PLQY, water‐resistant copper‐cluster‐based scintillators, but also advances their practical application in emerging x‐ray imaging scenarios.