Organic Phosphonium Chloride Engineering in Sb(III)-Based Hybrid Halides for High-Spatial Resolution X-ray Imaging

Zero-dimensional (0D) lead-free hybrid halides have garnered significant attention in the X-ray imaging fields due to their unprecedented structural versatility and outstanding optical properties. However, the fine structural modulation of organic components for achieving efficient emission has been insufficiently elucidated. Herein, we propose introducing Cl atoms into the bulky aromatic rings of organic phosphonium to modulate the structures and luminescence behaviors of 0D Sb(III)-based hybrid halides. The three synthesized Sb(III)-based hybrid halides feature diverse Sb–Cl polyhedral configurations, tunable emissions, and a peak photoluminescence quantum yield of 97.67%. Moreover, they demonstrate exceptional X-ray scintillator performance, with a high light yield of 42 000 photons/MeV, a low detection limit of 20.9 nGy/s, and an ultrahigh spatial resolution of up to 13.1 lp/mm. This study significantly advances the outstanding structure–luminescence relationship in Sb(III)-based hybrid halides and facilitates the development of 0D lead-free hybrid halides for advanced X-ray imaging technologies.