Hydrochloric Acid-Assisted Layered Perovskite CsMnCl₃ 2H₂O Single Crystals for Sensitive and Stable X-ray Detection with Anisotropic Response

Low-dimensional lead-free perovskite single crystals (SCs) have exhibited great potential in high-energy ionizing radiation detections owing to their outstanding sensitivity and charge transport properties. However, the preparation of chlorine-based SCs is more challenging due to their low solubility in organic solvents and acidic solutions. In this work, we report a universal growth strategy of hydrochloric acid-assisted temperature lowering for low-dimensional layered perovskite CsMnCl₃·2H₂O SCs. Compared with SCs prepared by solution evaporation crystallization, centimeter-sized SCs were achieved with ultrahigh crystal quality, showing a very small full width at half-maximum of 0.02° at the plane (002). Our layered perovskite CsMnCl₃ 2H₂O X-ray detector shows unique anisotropic X-ray detecting performance at parallel and perpendicular to the (002) crystal plane. An ultralow detection limit of 9.3 nGy_air s^-1 has been obtained, which is significantly lower than the 5.5 μGy_air s^-1 required for regular medical diagnostics. Furthermore, the device shows enhanced stability with a slight degradation of 8% after storage in air ambient for 6 months. Our work suggests a promising approach to fabricate high-quality SCs for sensitive and stable X-ray detection applications.