Protocols for degradation assessment and stability enhancement in perovskite solar cells

Metal-halide perovskite solar cells (PeSCs) have shown extraordinary progress in power conversion efficiency, but their operational long-term stability is still far behind for successful industrialization. There are various environmental factors impacting the degradation of perovskite materials, which should be studied and understood within harsh measuring protocols. In addition, the relating degradation mechanisms under device operation must be correlated and comprehended. Here, we summarize and review various mechanisms of how perovskite degrades during measurement protocols that use combinations of illumination, ambient atmosphere, and thermal stress. We suggest effective strategies to improve long-term stability of perovskite materials based on crystallization modification, compositions, and surface engineering strategies. We believe that the proper utilization of the understanding on the degradation of perovskite crystals and methodologies that we review in this article to improve the operational stability of PeSCs may facilitate commercialization of PeSCs.