Scalable Green Synthesis of Ultrastable Perovskite Nanocrystals in Metal‐Organic Frameworks for High‐Performance X‐Ray Imaging

Perovskite nanocrystals (NCs) have emerged as promising candidates for next‐generation X‐ray scintillators. Nevertheless, their practical implementation remains hindered by inherent material instability and challenges in scaling up. Herein, a strategy is proposed that guides heterostructural engineering by utilizing the metal‐organic frameworks (PbBTC) and a facile mechanochemical synthesis to tailor ultrastable perovskite composites on a large‐scale at room temperature. In the constructed CsPbBr 3 @Cs 4 PbBr 6 /PbBTC heterostructure, PbBTC acts as a structural template directing the in situ crystallization of CsPbBr 3 @Cs 4 PbBr 6 and serves as a protective matrix ensuring environmental resilience. This heterostructure enables synergistic effects between surface passivation from the Cs 4 PbBr 6 /PbBTC interface and quantum confinement induced by PbBTC, enhancing photoluminescence quantum yield and environmental stability. The developed scintillator demonstrates not only a low X‐ray detection limit (132 nGy air s −1 ) and high spatial resolution (18 lp mm −1 ), but more significantly, maintains exceptional operational stability under harsh environmental stressors—including sustained thermal aging at 85 °C, humidity exposure at 85% RH, and cumulative X‐ray irradiation up to 7,000 mGy air —conditions under which conventional CsPbBr 3 counterparts exhibit severe performance degradation. Such a strategy enables robust and scalable scintillators with superior performance, advancing their practical deployment in complex applications.