Suppressing the Ion Migration in Halide Perovskite Wafers for Current-Drift Free X-ray Detectors

Metal halide perovskites have been demonstrated as potential X-ray detection materials due to their high defect tolerance, large diffusion length, and high attenuation efficiency. X-ray detectors based on hot-pressed perovskite wafers are investigated intensively recently because of the convenience of scalable fabrication. However, in spite of the large crystal size within wafers, the prepared detectors usually suffer from severe ion migration and current drift under both dark and bright states. In this work, ethylenediamine dihydroiodate (EDDI) was introduced as a strong surface passivation agent, which compensated for the surface iodide vacancy successfully. The ion migration in optimal MAPbI3@EDDI wafer is significantly suppressed, which is manifested by increased migration activation energy and stable current under high bias for 10 h. Moreover, the introduction of EDDI also reduced the dark current, contributing a high on-off ratio and a champion sensitivity of 8291.22 mu C Gyair -1 cm-2. A low detection limit of 340 nGyair s-1 is also obtained, which is much lower than that of commercial X-ray detectors. Besides, the as-fabricated X-ray detector can endure long-term operation with flat current under a high bias of 20 V. This work provides a route for the performance improvement of perovskite wafer-based X-ray detectors.

Automated summary

Metal halide perovskites have potential for X-ray detection due to their properties such as high defect tolerance, large diffusion length, and high attenuation efficiency. This study introduced ethylenediamine dihydroiodate (EDDI) as a surface passivation agent to improve the performance of perovskite wafer-based X-ray detectors. The introduction of EDDI greatly suppressed ion migration, reduced dark current, and resulted in a low detection limit and high on-off ratio.