Gas Pump-Induced Crystallization of MAPbBr ₃ Perovskite Assisted by Ligands for Sensitive Detection Applications

Because of their excellent stability and photoelectric properties, perovskite single crystals have been widely applied in fields such as detection and photovoltaics. This study demonstrated a ligand-assisted gas pump method for perovskite crystallization, in which the influence of the pressure change rate on the morphology of perovskite crystals and the quality of ligand-assisted crystallization were investigated. CH₃NH₃PbBr₃ single crystals were obtained via the gas pump method assisted with 3-(decyldimethylazaniumyl)propanesulfonate (DPSI) as the ligand for crystallization. With varying rates of environmental pressure variation, the (100) crystal surface exhibited a step-like growth process, and the steps were "center-initiated, outward-expanding". When the pressure changes rapidly, the steps are wide and steep; as the pressure change rate gradually slows, the slope of the steps becomes gentler. When the growth rate reached 20 Pa/h, the crystal surface became flat, and the growth steps disappeared. The rate of pressure change enables control of the crystal step morphology. To further control crystal growth and quality, the DPSI ligand was employed during the crystal growth process under low-pressure conditions. The -SO₃^- group in DPSI anchors uncoordinated Pb²⁺, effectively suppressing solution nucleation. This interaction significantly enhances crystal quality, increases crystal stability, and effectively expands the size of MAPbBr₃ crystals. The optimized MAPbBr₃ detector achieved an outstanding X-ray sensitivity of up to 10798 μC Gy_air^-1 cm^-2 at a bias of 50 V, along with a minimum detectable dose rate of 0.19 μGy_air s^-1 for 40 kVp X-rays. These advancements have contributed to reducing radiation exposure for patients during medical X-ray diagnostics. The methodology employed in this study enables the fabrication of high-quality crystals through controlled growth rate modulation, demonstrating significant potential for detector applications.