Key points are not available for this paper at this time.
Metal halide perovskites, particularly those with narrow bandgaps and broadband response, have emerged as promising candidates for photodetectors due to their outstanding optoelectronic properties and cost-effectiveness. Among these, CsPbI 2 Br films are notable for relatively high stability; however, they often suffer from phase segregation and operational instability, primarily caused by a substantial number of defects at the surface and grain boundaries. In this work, we present a bulk and surface copassivation strategy to mitigate such defects in CsPbI 2 Br films. This strategy involves the introduction of a pseudohalide salt, NH 4 SCN, in both the crystallization and post-treatment processes. The SCN – anions can substitute for I – anions or occupy iodide vacancies through strong coordination with Pb 2+, thereby facilitating homogeneous crystal growth and reducing the defect density in the CsPbI 2 Br films by ∼60%. As a result, photodetectors fabricated from NH 4 SCN-passivated CsPbI 2 Br films exhibit a low dark current density of 1.30 × 10 –10 A cm –2 at −0.1 V and a high specific detectivity of 4.09 × 10 12 Jones at 10 Hz, outperforming most previously reported CsPbX 3 vertical photodetectors. Moreover, these devices demonstrate excellent operational and ambient stability. This work highlights that bulk and surface copassivation using pseudohalide salts represents a facile and effective approach for developing stable and high-performance perovskite optoelectronic devices.
Zhou et al. (Fri,) studied this question.