Enhanced photovoltaic performance of PM6/Y6-based organic solar cells by a wide-bandgap small molecule acceptor

Considering rare researches on wide-bandgap nonfullerene acceptors for ternary organic solar cells (OSCs), we reported a small molecule acceptor ITCN as the second acceptor for constructing PM6/Y6/ITCN ternary devices with better photovoltaic performance in this work. ITCN exhibits a large bandgap of 2.19 eV and a higher LUMO (the lowest unoccupied molecular orbital) than Y6, resulting in complementary optical absorption in the short-wavelength region and increased open-circuit voltage ( V OC ). As the content of ITCN increases, the hole mobilities increase continuously and the electron mobilities increase to a maximum value. Moreover, the incorporation of ITCN improves the nanoscale morphology and charge transport property to some extent. From PM6/Y6-based binary device to PM6/Y6/ITCN-based ternary device, the power conversion efficiency is increased from 15.01 to 16.04% with simultaneously enhanced V OC , short-circuit current, and fill factor. These results indicate that the design of wide-bandgap acceptors for high-performance ternary OSCs is available.