Using fullerene as the third component to boosting the photovoltaic performances of pyran acceptor

Ternary blend strategy has been proved to be an effective method to improve the photovoltaic performance for organic solar cells (OSCs). In this work, efficient ternary OSCs are fabricated with one donor PBDB-T and two acceptors Ph-DTDP-TIC and PC71BM. Ternary components can form a cascade energy level alignment when PC71BM as the third component to enhance charge transfer between the non-fullerene acceptor Ph-DTDP-TIC and PC71BM, achieving improved charge separation and collection in the ternary OSCs. Meanwhile, it demonstrated that PC71BM as the third component can also improve the morphology of the active layer and form suitable phase separation scale. As a results, two binary devices (PBDB-T:Ph-DTDP-TIC and PBDB-T:PC71BM) exhibit moderate power conversion efficiencies (PCEs) of 8.80% and 6.74%, respectively. While, the optimized PBDB-T:Ph-DTDPTIC:PC71BM ternary device can produce an enhanced PCE of 11.07% through adding 40 wt% PC71BM in acceptors, originating from simultaneously improved Jsc of 17.57 mA/cm2 and FF of 70.90%. Our work demonstrated the ternary strategy with PC71BM as the third component can promote charge transfer and transport to improve photovoltaic performance for OSCs.