Rational Molecular Encapsulation of Europium Complex Enables Aggregation‐Free Scintillation Films for High‐Resolution and Curved‐Surface X‐Ray Imaging

Flexible X‐ray scintillators are crucial for next‐generation wearable and portable imaging systems; however, their development is hindered by the persistent trade‐off among optical transparency, X‐ray sensitivity, and spatial resolution. Here, we overcome this challenge through a rational molecular encapsulation strategy. A fully organically shielded europium(III) complex, Eu(TTA) 4 (TEMA) (TTA = 2‐thenoyltrifluoroacetone; TEMA = triethylmethylammonium), is designed to exhibit intense narrow‐band red emission with a photoluminescence quantum yield of 90.34%. As an X‐ray scintillator, it achieves an ultralow detectable dose rate of 10.8 nGy s − 1 and a light yield of 9558 photons MeV − 1 . Crucially, the tailored molecular structure enables complete dissolution and molecular‐level dispersion within a poly(methyl methacrylate) (PMMA) matrix via a precursor solution process, yielding large‐area, aggregation‐free flexible films with outstanding transparency (>89% at 470–750 nm). The resulting scintillator demonstrates a record‐high resolution of 25.3 lp mm − 1 (MTF = 0.2) among solution‐processed, flexible Eu 3 + ‐based scintillation films. Furthermore, its excellent flexibility enables curved‐surface X‐ray imaging, effectively eliminating pincushion distortion for non‐planar objects—a unique advantage over rigid counterparts. This work provides a generalizable material and processing paradigm that seamlessly links molecular design, solution processability, and device performance, paving the way toward energy‐efficient, wearable radiation detection and high‐resolution imaging technologies.