Ultrasound‐Assisted Crystallization Enables Large‐Area Perovskite Quasi‐Monocrystalline Film for High‐Sensitive X‐ray Detection and Imaging

Abstract In recent years, halide perovskites have shown great application potential in X‐ray detection due to their superior optoelectronic properties and high X‐ray attenuation coefficient. However, large‐area perovskite fabrication for high performance X‐ray detectors remains extremely challenging. Herein, ultrasound‐assisted crystallization combined with the hot‐pressing method is proposed to prepare large‐area (10 cm × 10 cm) and high‐quality quasi‐monocrystalline thick film of a mixed‐cation perovskite MA_0.42FA_0.58PbI₃. The rapid ultrasound‐assisted crystallization provides more homogeneous nucleation, which is essential to the fabrication of large‐area and uniform perovskite microcrystalline film. Furthermore, the post hot‐pressing treatment is implemented to fuse the crystal boundaries, rearrange the crystal grains, and eliminate the voids between crystals, resulting in a quasi‐monocrystalline film. After the hot‐pressing treatment, the carrier mobility and the carrier mobility‐lifetime product increased about 13‐fold (from 1.8 to 23.5 cm² s⁻¹ V⁻¹) and 18 times (from 8.4 × 10⁻⁶ to 1.5 × 10⁻⁴ cm² V⁻¹), respectively. As a result, a high‐performance MA_0.42FA_0.58PbI₃ quasi‐monocrystalline X‐ray detector is achieved with an impressively high sensitivity (1.16 × 10⁶ µC Gy_air⁻¹ cm⁻²) and low detection limit (37.4 nGy_air s⁻¹), demonstrating the potential of the ultrasound‐assisted crystallization and hot‐pressing strategy from an industrial perspective.