2D Halide Perovskite Single Crystals Constructed by Aromatic Diammonium for High Sensitivity and Low Detection Limit X‐Ray Detectors

ABSTRACT 2D perovskites exhibit remarkable features such as strong X‐ray absorption, high resistivity, and low ion migration, endowing them with high competitiveness in X‐ray detection. Although numerous 2D perovskites (RP, DJ, and ACI phases) have drawn substantial attention, their widespread application is still restricted by excessively large interlayer spacing and limited structural stability. In this study, an aromatic diamine 2AMPY (2‐aminomethylpyridine) is designed to enhance structural rigidity and reduce interlayer spacing of the 2D perovskites by modulating the tailored hydrogen bonding interactions and the embedding depth of organic cations within the inorganic octahedral frameworks. Moreover, high quality centimeter‐sized 2D perovskites (2AMPY)PbX 4 (X = Cl, Br, I) single crystals (SCs) are successfully grown via a solution method. Among them, (2AMPY)PbBr 4 SCs display the shortest interlayer spacing and therefore the highest carrier mobility‐lifetime product. As a result, detectors fabricated using these SCs achieve high sensitivity (13306 µC Gy −1 cm −2 ), ultralow detection limit (1.69 nGy s −1 ), superior stability, and high‐resolution x‐ray imaging. These detectors exhibit superior performance among the reported 2D perovskite X‐ray detectors. In conclusion, this work establishes a new strategy for constructing novel 2D perovskite using aromatic diammonium cations, providing a promising solution for the development of X‐ray detection technology.