Over 16% Efficiency of Thick-Film Organic Photovoltaics with Symmetric and Asymmetric Non-Fullerene Materials as Alloyed Acceptor

High-performance organic photovoltaics (OPVs) with relatively thick active layers are essential for large-scale production. Herein, series of OPVs with different active layer thicknesses are fabricated using PM6 as the donor and BP4T-4F and BP3T-4F with symmetric and asymmetric structures as acceptors. With the active layer thickness increasing from 100 to 300 nm, the power conversion efficiency (PCE) of BP3T-4F-based binary OPVs is slightly decreased from 15.37% to 14.40%, while the PCEs of BP4T-4F-based binary OPVs are markedly decreased from 16.89% to 14.99%. The two kinds of binary OPVs exhibit distinct PCEs and thickness tolerance features, which may be recombined into ternary OPVs using compatible BP3T-4F and BP4T-4F as alloyed acceptors. The ternary OPVs exhibit a slightly decreased PCE from 16.91% to 16.03% along with active layer thickness from 100 to 300 nm, benefiting from the well-optimized phase separation in ternary active layers. It is worth highlighting that the fill factor (FF) of 71.47% is achieved in ternary thick-film OPVs. The PCE of 16.03% and FF of 71.47% should be among the highest values among OPVs with 300 nm thick active layers.