Dynamic Defect Tolerance in Metal Halide Perovskites: From Phenomena to Mechanism

Metal halide perovskite-based devices can exhibit exceptional optoelectronic performance at relatively high defect densities, a phenomenon commonly referred to as defect tolerance, which is one of the most important features of metal halide perovskites (MHPs). Defect tolerance is previously thought to be a static property, determined solely by the composition and manufacturing process. However, recent studies have shown that the defect tolerance of MHPs is dynamic and can vary over time. For example, the power conversion efficiency of MHPs-based solar cells has been found to improve significantly under continuous illumination. Although this is a unique self-optimization behavior of MHPs, it can seriously affect the stability of power output of MHPs-based solar cells in real-world operating conditions. In view of this, extensive research has been conducted, but the physical mechanism of this photoinduced dynamic defect tolerance (DDT) has remained inconclusive, as both the mechanisms and experimental phenomena continue to be subjects of controversy. Therefore, a timely summarization on mechanisms related to DDT is urgently needed. In this review, a systematic overview is first provided of the experimental phenomena, characteristics, and influencing factors of the DDT. Following that, the proposed mechanisms for DDT are summarized, with a focus on carrier-defect and carrier-lattice interactions. Finally, the current challenges faced in DDT research are summarized and an outlook on the future developments is provided. This review aims to offer a comprehensive understanding of DDT in MHPs to enhance the performance and stability of MHPs-based solar cells, thereby facilitating the advancement and commercialization of these technologies.