Flexible Single‐Crystalline Perovskite Ferroelectric Thin Film for Efficient Self‐Driven X‐ray Detection

Abstract Flexible X‐ray detectors with a direct‐conversion working mode have attracted tremendous attention in security checks, medical diagnostics, industrial inspection, and scientific research. As promising flexible X‐ray detection materials, organic‐inorganic hybrid perovskites (OIHPs) offer significant advantages, including efficient X‐ray absorption, excellent charge transport, and cost‐effective processing. However, reported flexible OIHP‐based X‐ray detectors are predominantly limited to polycrystalline materials, which suffer from unavoidable grain boundaries, high defect densities, and poor charge mobility. Herein, we successfully fabricate flexible single‐crystal ferroelectric thin films for efficient self‐powered X‐ray detection. Specifically, leveraging the weak van der Waals interactions within the 2D perovskite layers of (benzylamine) 2 CsPb 2 Br 7 , high‐quality, flexible single‐crystal films are manufactured by mechanical exfoliation. Capitalizing on the intrinsic spontaneous polarization of ferroelectric photovoltaics, our flexible device demonstrates exceptional X‐ray sensitivity (693 µC Gy −1 cm −2 ) under zero bias, along with stable output under 1000 bending cycles and different bending angles. As the first demonstration of non‐planar self‐powered X‐ray detection in flexible single‐crystal ferroelectric thin films, this work provides a foundation for future wearable X‐ray detection systems.