Crystallization‐Resistant Hybrid Scintillator Glass for High‐Resolution and Remote X‐Ray Imaging

ABSTRACT Organic‐inorganic hybrid materials glasses are increasingly recognized as a distinctive class within the broader field of glass science, because they extend the concept of glass formation from rigid atomic or polymeric networks to chemically programmable hybrid solids that integrate organic and inorganic building units. This emerging class of materials offers unusual opportunities for tuning optical, electronic, and structural properties, but its development is fundamentally limited by poor resistance to crystallization and devitrification. Here we report an A‐site cation engineering strategy to develop crystallization‐resistant zero‐dimensional antimony halide hybrid scintillator glasses. Replacing an allyl‐substituted triphenylphosphonium cation with a more conformationally flexible methoxymethyl analogue frustrates ordered packing, weakens directional intermolecular locking, and increases melt viscosity, thereby shifting the competition between crystallization and vitrification toward a persistent glassy state. The resulting transparent (MTPP) 2 SbCl 5 glass exhibits markedly enhanced resistance to thermally induced devitrification, together with efficient and stable luminescence and good irradiation tolerance. It enables centimeter‐scale scintillating monoliths for X‐ray imaging with a spatial resolution of 19.0 lp mm −1 at an MTF of 0.2, and can be further processed into active fibers for proof‐of‐concept remote X‐ray imaging.