Heterointerface Design of Perovskite Single Crystals for High‐Performance X‐Ray Imaging

Abstract Metal halide perovskite single crystals (MHP‐SCs) are known for their facile fabrication into large sizes using inexpensive solution methods. Owing to their combination of large mobility‐lifetime products and strong X‐ray absorption, they are considered promising materials for efficient X‐ray detection. However, they suffer from large dark currents and severe ion migration, which limit their sensitivity and stability in critical X‐ray detection applications. Herein, a heterointerface design is proposed to reduce both the dark current and ion migration by forming a heterojunction. In addition, the carrier transport performance is significantly improved using heterointerface engineering by designing a gradient band structure in the SCs. The SC heterojunction detectors exhibit a high sensitivity of 3.98 × 10⁵ µC Gy_air⁻¹ cm⁻² with a low detection limit of 12.2 nGy_air s⁻¹ and a high spatial resolution of 10.2 lp mm⁻¹ during imaging. These values are among the highest reported for state‐of‐the‐art MHP X‐ray detectors. Moreover, the detectors show excellent stability under continuous X‐ray irradiation and maintainclear X‐ray imaging after 240 d. This study provides novel insights into the design and fabrication of X‐ray detectors with high detection efficiency and stability, which are beneficial for developing inexpensive, high‐resolution X‐ray imaging equipment.