Shamrock-shaped non-fullerene acceptors via side-chain and end-group engineering for high-efficiency and high-voltage organic photovoltaics

Abstract

Side-chain and terminal engineering are both simple and effective strategies to regulate the optoelectronic properties of non-fullerene acceptors (NFAs). The emerging shamrock-shaped NFAs represented by AQI4 demonstrate significant potential for high-V_OC and high-efficiency organic solar cells (OPVs) due to their unique advantages. However, how side-chain and end-group engineering jointly determine the device performance based on shamrock-shaped NFAs remains unclear. Herein, three novel shamrock-shaped NFAs (AQI81, AQI82, and AQI84) were synthesized by introducing lateral branched chains and adjusting the number of fluorine atoms on the end groups. The synergistic regulation of the side chain and terminal group controls the molecule's energy level and molecular packing. Finally, the PE4:AQI81, PE4:AQI82 and PE4:AQI84-based devices exhibited 1.020 V/14.12%, 0.963 V/16.37%, and 0.924 V/16.69% open-circuit voltage (V_OC)/power conversion efficiency (PCE). This study demonstrates that the introduction of lateral branched chains and the modification of the end groups play a critical role in advancing high-V_OC and high-efficiency AQI acceptor-based OPVs.