Interface Design of Hybrid Electron Extraction Layer for Relieving Hysteresis and Retarding Charge Recombination in Perovskite Solar Cells

Abstract Enhancing electron extraction with efficient charge carrier separation, hybrid interface layer composed of amorphous TiO 2 and [6,6]‐Phenyl C61 butyric acid methyl ester (PCBM) is adopted to conventional n‐i‐p perovskite solar cells. In hybrid double layer, a‐TiO 2 plays a role about efficient electron selective contact with perovskite material, while PC 60 BM help electrons to rapidly extract from perovskite layers. From this new concept of configuration, it is possible to achieve not only high power conversion efficiencies but also low hysteretic behaviors in terms of current–voltage sweep direction. These enhanced characteristics are verified with photoluminescence and electrochemical impedance spectroscopic measurements. With such high efficiency and nonhysteretic perovskite solar cells, it is able to fabricate extremely high‐efficiency flexible perovskite solar cells which can be compared with the world's highest‐efficiency flexible perovskite devices.