Solvent Induced Recrystallization Suppressing Grain Boundary Defect and Ion Migration in Perovskite Thick Films for X-ray Imaging

Abstract

Digital X-ray imaging plays an important role in medical diagnostics, nondestructive testing, and fundamental scientific research. Polycrystalline perovskite thick films have emerged as a promising material for large-area X-ray imaging; however, conventional fabrication techniques often introduce a high density of grain boundaries. These boundaries not only introduce numerous defect states but also act as pathways for ion migration, undermining device performance. Herein, we report a solvent-induced recrystallization (SIR) strategy to optimize the crystalline quality of spray-coated FACsPbI3 perovskite thick films. Our findings demonstrate that the SIR process induces a dissolution-recrystallization mechanism that significantly enlarges grain size and minimizes grain boundary density. Thus, the sensitivity of the SIR-treated devices increased from (8.34 ± 0.18) × 103 μC·Gy1–·cm–2 to (2.12 ± 0.12) × 104 μC·Gy1–·cm–2, while the limit of detection (LoD) was substantially reduced from 1.28 μGy·s–1 to 24.5 nGy·s–1. Furthermore, by integrating the optimized thick films with TFT arrays, we successfully demonstrated high contrast X-ray image acquisition, with the spatial resolution improving from 1.1 to 2.0 lp·mm–1. This study provides a facile and efficient approach for developing high-performance, large area perovskite X-ray detectors, underscoring their vast potential for next-generation low-dose medical imaging applications.