Fluoroalkyl-substituted fullerene/perovskite heterojunction for efficient and ambient stable perovskite solar cells

Fluoroalkyl-substituted fullerene/perovskite heterojunction (f-FPHJ) was developed in this study. The fluoroalkyl-substituted fullerene, DF-C60, not only can effectively passivate the defects/grain boundaries of perovskite but also increase its hydrophobicity. Consequently, a high power conversion efficiency (PCE) of 18.11% can be realized with respectable ambient stability. Interestingly, the f-FPHJ device can still deliver a decent PCE of 15.14% with small hysteresis even without employing a discrete PCBM electron-transporting layer (ETL), which might results from the preferential distribution of DF-C60 nearby the surface region of the f-FPHJ film to partially mimic the PCBM ETL to reduce the hysteresis.222