Amphiphilic Fullerenes Employed to Improve the Quality of Perovskite Films and the Stability of Perovskite Solar Cells

Fullerene end-capped polyethylene glycol (C60-PEG) was introduced via an antisolvent method to fabricate the perovskite films. C60-PEG could enlarge the perovskite crystal size and passivate the defects of perovskite films, facilitating the carrier transport and hindering the carrier recombination. In consequence, the superior optoelectronic properties were attained with an improved power conversion efficiency of 17.71% for the perovskite device with C60-PEG treatment. Meanwhile, amphiphilic C60-PEG enhanced the resistance of perovskite films to moisture. After 40 days, the C60-PEG-based devices without encapsulation remained 93 and 86% of the original power conversion efficiency value under nitrogen and ambient conditions (25 °C temperature, 60% humidity), respectively.