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

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)₂CsPb₂Br₇, 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.