Fluorine-induced self-doping and spatial conformation in alcohol-soluble interlayers for highly-efficient polymer solar cells

The molecular design strategy for high-performance photoelectric materials emphasizes the intrinsic charge transfer/transport as well as the role of the polymer chemical structure and chain conformation. Here, we report a new interface engineering strategy for non-fullerene polymer solar cells (PSCs) by employing highly conductive polyelectrolyte interface layers with a fluorinated conjugated backbone. The fluorine atom-induced strong n-type self-doping effect and optimized expanded conformation were observed to substantially improve their intrinsic charge mobility. An outstanding power conversion efficiency of 11.51% was obtained when applying the new polyelectrolyte interlayer in PSCs based on a PBDB-T:ITIC active layer.