Gradient Inverse Temperature Crystallization for High-Quality MAPbBr3 Perovskite Single Crystals and Supreme-Sensitivity X-ray Detectors

Abstract

Density functional theory calculations were used to systematically investigate the intrinsic defect formation of MAPbBr₃ perovskite, revealing that bromine-rich and lead-poor growth conditions are effective in minimizing deep-level defect formation. A gradient inverse temperature crystallization (G-ITC) method, combined with a bromine-rich, lead-poor approach, was used to prepare high-quality perovskite single crystals (SCs) by precisely controlling the temperature gradient and crystallization rate. Compared with the traditional method, the thermal stress and internal strain during crystal growth can be effectively mitigated by the G-ITC method, with the defect density reduced to 4.735×10⁸ cm^-3. The extremely narrow full width at half maximum of the rocking curve and ultra-long photoluminescence lifetime have verified the excellent crystalline quality of the as-prepared SCs. X-ray detectors based on these perovskite SCs achieve a high detection sensitivity of 4.36×10⁵ μC Gy air ^-1 cm ^-2, which stands at the leading level among the reported values for perovskite X-ray detectors, with an ultralow detection limit of 38.5 nGy air s ^-1.