Intralayer Hydrogen Bonds from Coordinated Water and X-ray Detection Performance in a Large-Sized 2D Rare-Earth Hybrid Perovskite Single crystal

Abstract In this study, we successfully synthesized large-sized single crystals of a two-dimensional rare-earth double perovskite, (TEA)KNd(NO3)5(H2O) (1). Single-crystal diffraction confirms coordinated water molecules construct an intralayer hydrogen-bond network, lowering lattice symmetry, strengthening intermolecular interactions, inhibiting phase transitions and boosting in-plane charge transport to favor charge collection and low-bias X-ray response under low dose rates. UV–vis diffuse reflectance measurements and DFT calculations validate its wide-bandgap characteristic; band-edge states mainly originate from nitrate O-2p orbitals, and coordinated water indirectly tunes electronic properties via structural modulation. Notably, 1 exhibits outstanding X-ray detection capability. Under a dose rate range of 30–402 nGy·s–1 and a bias of 5 V, the device achieved a sensitivity of 533.409 μC·Gyair–1·cm–2 and a low detection limit of 1.353 nGy·s–1, alongside excellent operational stability. These results highlight the critical role of coordinated water molecules in suppressing phase transitions and achieving high-performance X-ray detection, providing insights for the development of environmentally friendly, high-performance X-ray detectors.