A Benzo1,2-b:4,5-b′Difuran Based Donor Polymer Achieving High- Performance (17) Single-Junction Organic Solar Cells with a Fill Factor of 80.4

摘要

In the field of non-fullerene organic solar cells (OSCs), most of the promisingpolymer donors are based on benzo1,2-b:4,5-b′dithiophene (BDT) unitswhile benzo1,2-b:4,5-b′difuran (BDF)-based polymers have drawn less attentionsince the efficiencies of BDF polymer-based devices are generally lowerthan those of BDT polymer-based ones. In this contribution, the BDT unit ina polymer donor named D18 is replaced with a BDF unit, and a new polymernamed D18-Fu is synthesized. As a highly-crystalline molecule named Y6-1Ois chosen as the acceptor, the efficiency of binary devices based on D18-Fucan reach 16.38. Furthermore, when one of fullerene derivatives PC71BM isadded, the ternary devices based on D18-Fu achieve an efficiency of 17.07and a high fill factor (FF) of 80.4, both of which are the highest valuesamong those of BDF polymer-based devices. For comparison, D18-basedternary devices show an inferior efficiency of 15.61 mainly due to the lowerFF of 73.9. Subsequent characterization reveals that D18-Fu possesses amore coplanar molecular geometry, leading to better morphology and highercharge mobility for a promising FF. The high performance shown in this workdemonstrates the potential role of BDF units in the design of polymer donorsfor highly efficient OSCs.