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

Enhancing electron extraction with efficient charge carrier separation, hybrid interface layer composed of amorphous TiO2 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‐TiO2 plays a role about efficient electron selective contact with perovskite material, while PC60 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. Interface design for efficient electron extraction is significant impact on the efficiency and reliability of the perovskite photovoltaics. A hybrid electron extraction layer which has excellent electron extraction efficiency and hole‐blocking ability is developed by organic interface treatment on amorphous TiO2 at low temperature. The findings show the design principle of the electron extraction layer for flexible perovskite devices.