Electron Cascade-Triggered Synergy in Organic–Inorganic Composite Film for High-Performance X-Ray Imaging

Organic scintillators offer compelling advantages, including easy production, flexibility, and high quantum yield, yet the low atomic number intrinsically limits X-ray absorbance, compromising radioluminescence intensity and detection sensitivity. To address this challenge, a composite scintillator is devised by integrating high-Z LiLuF₄:Tb nanocrystals with 9,10-diphenylanthracene (DPA) in a polystyrene matrix. This architecture yields a ninefold enhancement of DPA radioluminescence intensity, and make it retains the original ultrafast decay dynamics, which exceed the performance of current state-of-the-art thermally activated delayed fluorescence (TADF) and hot-exciton scintillators to a certain extent. The optimized composite film exhibits a remarkable light yield of 40 466 photons/MeV and an ultralow detection limit of 43.7 nGy_air/s, outperforming commercial inorganic benchmarks (BGO and LYSO:Ce). Furthermore, it enables high-resolution X-ray imaging with a spatial resolution exceeding 26 lp/mm. Mechanistic investigations reveal an electron cascade triggered by escaped fast electrons from the LiLuF₄:Tb nanocrystals, which synergistically amplifies the excitation of DPA molecules. It is worth noting that this strategy is applicable to diverse organic scintillators, such as anthracene, tetraarylethene, and TPE-4Br, as evidenced by a significant boost in their radioluminescence intensity. This work thus elucidates nanoscale energy conversion pathways of escaped electrons and establishes a transformative platform for high-sensitivity, low-dose radiation detection and imaging.