Organic Cation Methylation Design of Hybrid Eu(II)‐based Halide Scintillators for Improved X‐Ray Detection and Imaging

Abstract Organic–inorganic hybrid scintillators (OIHSs) have emerged as promising candidates for X‐ray imaging. However, inhibiting the concentration quenching effect and reducing vacancy defects remain major challenges for high‐performance OIHSs. Herein, a modification strategy of organic cation methylation is introduced to prepare PDMIMEuX 3 (PDMIM‐X, PDMIM = 1‐Propyl‐2,3‐dimethylimidazolium, X = Br, I) upon PMIMEuX 3 (PMIM‐X, PMIM = 1‐Propyl‐3‐methylimidazolium). Benefiting from the increased Eu‐Eu chain spacing and structural rigidity by the steric effect of inserted cationic methylation, PDMIM‐X suppresses nonradiative recombination between luminescent centers and the halogen vacancy defects. Particularly, PDMIM‐Br designed via such a cation methylation exhibits high light output, which is 3.57 and 9.7 times higher than that of commercial Lu 3 Al 5 O 12 :Ce and original PMIM‐Br, respectively, and thus it also demonstrates a low detection limit of 42.61 nGy s −1 . Moreover, leveraging the capability of rapid in situ solution processing, a transparent and large‐area PDMIM‐Br@film is prepared with a spatial resolution of 21.1 lp mm −1 for X‐ray imaging. This study developed high‐performance OIHSs and further provided an effective strategy via materials design to improve the detection and imaging capabilities.