Over 16% efficiency all-polymer solar cells by sequential deposition

Abstract

All-polymer solar cells (all-PSCs) have received extensive attention due to their excellent mechanical robustness and performance stability. However, the power conversion efficiency (PCE) of all-PSCs still lags behind those of organic solar cells (OSCs) based on non-fullerene small molecule acceptors. Herein, we report highly efficient all-PSCs via sequential deposition (SD) with donor and acceptor layers coated sequentially to optimize the film microstructure. Compared with the bulk heterojunction (BHJ) all-PSCs, an optimized morphology with vertical component distribution was achieved for the SD-processed all-PSCs due to the synergistic effect of swelling of polymer films and using additive. Such strategy involves using chlorobenzene as the first layer processing-solvent for polymer donor, chloroform as the second processing-solvent for polymer acceptor with trace 1-chlor-onaphthalene, efficiently promoting exciton dissociation and charge extraction and reducing trap-assisted recombination. Consequently, over 16% all-PSCs fabricated via SD method was realized for the first time, which is much higher than that (15.2%) of its BHJ counterpart and also among the highest PCEs in all-PSCs. We have further demonstrated the generality of this approach in various all-polymer systems. This work indicates that the SD method can yield excellent all-PSCs and provides a facile approach to fabricating high-performance all-PSCs.