Oxygen- and photo-induced decay of perovskite solar cells: Mechanisms and strategies

Perovskite solar cells (PSCs) have emerged as a promising photovoltaic technology with their rapid improvement in power conversion efficiency from 3.8% to 26.7%. However, the unsatisfactory stability is still a major hurdle to the future commercialization of PSCs. Among various causes of instability, oxygen and photo-induced instability are indispensable aspects to be considered, especially there is a growing demand of manufacturing PSCs with low-cost environmental conditions. This review aims to provide a timely and comprehensive summary of the investigations related to the oxygen- and photo-induced decay (OP-decay) in perovskites. Key factors affecting the OP-decay pathways and decay rate have been discussed. Techniques for the analysis of oxygen and photo-induced decay processes are included. Strategies for improving photo-oxygen stability have been summarized, from the aspects of suppressing the generation yield of superoxide, protecting perovskites from the generated superoxide, and slowing down the oxygen penetration, respectively.