Ferroelectric dipole-MAPbI₃ coupled x-ray detector

Blade coating offers a low-cost production method for fabricating perovskite thick-film x-ray detectors. However, due to the preferential nucleation at the gas–liquid interface of a perovskite solution, high-quality perovskite thick films are in such a dilemma, sacrificing either the density of the thick film by forming a porous structure or the thickness of the film through depositing a compact structure. The porous structure will lead to carrier recombination and ion migration while low thickness will cause insufficient x-ray absorption, which will increase the dark current or reduce the sensitivity of the corresponding x-ray detector. In the present work, a scalable ferroelectric dipole–methylamine lead iodide (MAPbI3) coupled x-ray detector is proposed, where the x-ray photoconductor in situ formed on indium tin oxide shows a dense fibrous mesoscopic structure oriented along the charge-carriers transport direction. It is demonstrated that ferroelectric dipoles promise not only strong coupling effects with MAPbI3, driving better crystallinity and denser assemblies, but also excellent passivation to MAPbI3 interfaces, decreasing trap-state densities, leading to improved direct x-ray detection performance. In addition, the enhanced operational stability of the corresponding device suggests a strategy of introducing the localized polarization field for stable perovskite direct x-ray detectors.