Soft Biaxial Molecular Ferroelectric Thin Films toward Self-Driven X-Ray Detection

2D multilayer molecular ferroelectrics have attracted extensive interest in radiation detection due to their strong spontaneous polarization, bulk radiation absorption, and long carrier transport distance. However, the vast relative studies are limited to the bulk crystals rather than thin films, which greatly restricts the application. Herein, we have successfully fabricated a flexible X-ray detector based on 2D molecular ferroelectric EA₄Pb₃Br₁₀ thin films (EA = ethylammonium). Specifically, piezoelectric force microscopy confirms the ferroelectricity of the EA₄Pb₃Br₁₀ thin film, thereby endowing it with the ability for self-driven detection. Especially, this flexible detector exhibits outstanding X-ray detection with an extremely low detectable limit (72.1 nGy_air s^-1) and a high sensitivity (1.93 μC Gy_air s^-1 cm^-2). Such a detection limit is 76-fold lower than conventional medical diagnostics and superior to most of the reported molecular ferroelectric bulk-based X-ray detectors. This study proposes a new strategy for constructing self-powered high-energy radiation devices and broadening the applications of molecular ferroelectrics in wearable systems.