Instability of colloidal lead halide perovskite nanocrystals: Causes, improvement, and evaluation

The instability of colloidal lead halide perovskite nanocrystals (NCs) presents a significant challenge for their application in optoelectronic devices. This review examines the primary causes of instability in these NCs and the proposed mechanisms of degradation. It also introduces the recently developed synthesis and surface passivation methods to address the instability issue of colloidal perovskite NCs. Specifically, we focus on the various types of ligands and precursors introduced during NC synthesis or post-treatment and how they impact the structural and optical properties of the perovskite NCs. This review also proposes a systematic approach to evaluating stability enhancement strategies by establishing key parameters and ranking them based on working and processing conditions. Finally, we discuss the issues that need to be addressed in future research to achieve practical application of lead halide perovskite NCs in advanced optoelectronic systems.