Ion Migration in Metal Halide X‐Ray Detectors: Mechanism, Impact, and Suppression

ABSTRACT In recent years, metal halides (MHs) and their derivatives have emerged as promising candidates for x‐ray detection. These materials offer distinct advantages, including high x‐ray absorption efficiency, tunable bandgaps, low costs, and facile processing. While the performance of MHs‐based devices has improved rapidly, ion migration under high operating bias voltages remains a critical bottleneck. This phenomenon leads to severe degradation issues, such as elevated dark currents, electrode corrosion, baseline drift, and reduced carrier collection efficiency. Therefore, a systematic review of ion migration in MHs‐based x‐ray detectors is of crucial importance for breaking through the bottlenecks in their performance and stability, as well as advancing their practical applications. This review starts with the microscopic mechanisms of ion migration, detailing its origins, pathways, driving forces, and electrical characterization methods. Subsequently, based on energy band analysis, we elucidate the impact of ion migration on device performance. We then categorize existing suppression strategies into four main approaches: enhancing lattice interactions, minimizing migration channels, blocking transport pathways, and designing self‐powered detectors. Finally, the review discusses current challenges and outlines future development directions for stable MHs‐based x‐ray detectors.