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Abstract Weak‐light imaging plays a pivotal role in various fields such as astronomical photography, military nighttime surveillance, and biomedical imaging. The capability of photodetectors (PDs) in detecting weak‐light relies heavily on minimizing their noise current. In this study, the weak‐light detection performances of PDs constructed from PEA 2 MA n‐1 Pb n I 3n+1 ( n = 1, 2, 3) 2D perovskite single crystals are presented. Among these, the n = 1 PD showcases incredibly low noise current that induces an ultra‐low detection limit of 14 pW cm −2 under 532 nm light illumination, and a high detectivity of 3.25 × 10 15 Jones. The n = 1 PD also meets imaging requirements even under black‐level illumination conditions of 75 pW cm −2 . The investigation reveals that decreasing n value corresponds to an increase in the PEA + ratios of cations, resulting in reduced defects and enhanced ion migration activation energy and exciton binding energy. These reduce noise current of devices from electron/hole, ion, and exciton dynamic behaviors. Notably, inhibiting ion migration can significantly improve the stability of the noise current baseline and facilitate the stable detection of weak signals. This study underscores the potential of 2D perovskites for advancing weak‐light imaging technologies, offering valuable insights for future development in this field.
Xi et al. (Sat,) studied this question.