Using ternary blend as a strategy to improve the driving force for charge transfer and facilitate electron transport in polymer solar cells

Abstract The recently emerged non-fullerene small molecular acceptors can enhance the light absorption and increase the open-circuit voltage in polymer solar cells (PSCs); however, sometimes a decrease in the driving force for charge transfer from donor to acceptor is accompanied. Here, we reported a ternary blend strategy by utilizing fullerene derivative (PC 71 BM) as a third component to improve the driving force for charge transfer, the charge transport, and the film morphology. Accordingly, the ternary blend PSCs demonstrate a much enhanced power conversion efficiency (PCE) with an optimized value of 9.18% and a good fill factor (FF) of 63%. In comparison, the non-fullerene PSCs without the third component only show a PCE of 6.90% and an FF value of 56%.