Insight into structure defects in high-performance perovskite solar cells

In the last few decades, extraordinary achievements have been made in boosting the energy conversion efficiency of perovskite materials, and much effort has been put forth to determine the underlying physical and photophysical mechanisms of perovskite-based devices, especially perovskite solar cells (PSCs). Although the record power conversion efficiency (PCE) of PSCs is now comparable with that of well-established commercially applied devices, there are still intractable issues to be solved, of which the defect issue is the most important. Both photovoltaic performance and long-term stability can be largely improved by eliminating nonradiative recombination and active states originating from lattice defects. Hence, understanding the type and density of these defects and trap states via efficient experimental characterization methods is an essential step towards the development of high-performance PSCs. Herein, we systematically summarize defect determination techniques from the point of view of chemical and physical analysis, establishing a practical route of qualitative and quantitative characterizations on defects in PSCs, especially the electrochemical measurements and corresponding mechanisms to explain the defect healing strategies. This detailed and comprehensive account of multiscale defect characterizations may provide an experimental reference for exponentially improving passivation studies and further improving high-performance PSCs.