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

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 Cu₂I₂ cluster-based complexes achieved through a dual-ligand strategy. The rigid P,N-bridging ligand serves to construct the emissive Cu₂I₂ 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.