Non-halogenated solvent additive-mediated donor–acceptor phase segregation leads to efficient all-polymer solar cells

Abstract

With the emergence of polymer acceptors with BTP cores and their derivatives, remarkable progress in power conversion efficiencies (PCEs) of all-polymer solar cells (all-PSCs) has been achieved. However, compared with the performance of state-of-the-art PSCs, there is a lag in their performance due to the difficulty in controlling the intertwined polymer donor and acceptor chains. Herein, we focus on the donor–acceptor phase separation within all-polymer active layers comprising PBQx-TCl:PY-IT by introducing non-halogenated solvent additives. Specifically, a tiny amount of anisole (in volume) enables us to finely tune the miscibility between PBQx-TCl and PY-IT, optimizing the phase segregation between the polymer donor and acceptor. Due to the synergistic effect of the favorable phase separation and the desired donor–acceptor distribution, devices treated with anisole showed significant improvements in charge transport and collection, thus exhibiting an optimized PCE of 17.3%. Our results highlight the importance of non-halogenated solvent additives in altering the phase separation of polymer donor–acceptor pairs for the practical application in high-performance all-PSCs.