Reducing Voltage Losses in the A-DA'D-A Acceptor-Based Organic Solar Cells

Power conversion efficiencies (PCEs) of solution-processed organic solar cells (OSCs) have recently reached 17.4% (certified) for single-junction devices. Crucial to this advancement is the development of non-fullerene acceptors (NFAs) since 2015. The recent A-DA'D-A NFAs have attracted widespread attention because of their ladder-type electron-deficient-core-based central fused ring with improved transport properties and optimum energy levels. With the synergistic effect of electron-deficient-core and specific molecular geometry, the A-DA'DA molecules could achieve low voltage losses and high current generation at the same time, reaching new regimes of device physics and photophysics. This perspective will discuss the voltage losses in state-of-the-art A-DA'D-A NFA-based OSCs and propose new molecular design strategies to achieve PCEs over 20% in OSCs based on these new acceptors by further decreasing their total voltage losses.