PTB7-Th-Based Organic Photovoltaic Cells with a High of over 1.0 V Fluorination and Side Chain Engineering of Benzotriazole-Containing Nonfullerene Acceptors.

is considered one of the most classic donor polymers for organic photovoltaic (OPV) cells. However, the power conversion efficiency (PCE) of -based OPV is lagging behind that of other promising polymers mainly because of the relatively low open-circuit voltage (). To increase the and PCE of -based OPV, the development of nonfullerene acceptors (NFAs) and studies of structure-property-performance relationship are vital. Here, three A-A-D-A-A-type acceptors, namely , , and , were developed by fluorination on the benzotriazole (BTA) unit and regulating alkoxy or alkyl phenyl side chains. Compared with , light absorption and π-π packing can be simultaneously improved for the two fluorinated BTA acceptors, resulting in an increased and FF. Moreover, the -based blend film exhibits better phase separation morphology and electron transport than those of and , which contribute to a device efficiency of 10.36% with a of 1.03 V. In addition, the Δ values of the three blends are less than 0.15 eV, together with their moderate Δ, efficiently decreasing their energy loss. These results highlight the importance of fluorination and side chain engineering for NFAs to boost the and PCE for low-band gap photovoltaic polymers.