Organic Phosphonium Side‐Chain Engineering in Metal Halide Glassy Scintillators for Enhanced X‐Ray Dynamic Imaging

Abstract X‐ray imaging utilizing organic–inorganic hybrid metal halide (OIHMH) glassy scintillators has garnered significant attention. But their inferior radioluminescence makes achieving rapid image acquisition difficult, posing a persistent challenge for dynamic imaging. Herein, organic phosphonium halide side‐chain engineering is proposed, introducing bulky aromatic rings at the alkyl chain ends, to improve the radioluminescence of OIHMHs. For Mn(II)‐based OIHMHs, the (BUP) 2 MnCl 4 (BUP = butyltriphenylphosphonium) powder has a low relative light yield (5400 photons MeV −1 ). After introducing a benzyl group, this value of (BnO‐MTP) 2 MnCl 4 (BnO‐MTP = (benzyloxy)methyl) triphenylphonium) powder boosts to 60 000 photons MeV −1 . The introduction of benzyl group can restrict molecular non‐radiative vibrations, increase exciton binding energy, enhance electron‐phonon coupling, and reduce self‐absorption, thus significantly improving exciton utilization and scintillation performance of (BnO‐MTP) 2 MnCl 4 . Besides, the transparent (BnO‐MTP) 2 MnCl 4 glass has a low melting point (167 °C) and high relative light yield (26 000 photons MeV −1 ). When applied to X‐ray imaging, it can achieve static imaging with a spatial‐resolution of up to 24.6 lp mm −1 and clear dynamic imaging under X‐ray irradiation. Furthermore, this strategy also applies to Sb(III)‐based OIHMHs with self‐trapped exciton emissions, where (BnO‐MTP) 2 SbCl 5 exhibits superior scintillation performance compared to (BUP) 2 SbCl 5 , demonstrating its broad applicability in constructing high‐performance OIHMH glassy scintillators.