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-DAD-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-DADA 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-DAD-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. Funding Agencies|National Natural Science Foundation of China (NSFC)National Natural Science Foundation of China (NSFC) [21875286]; National Key Research & Development Projects of China [2017YFA0206600]; Science Fund for Distinguished Young Scholars of Hunan ProvinceNational Natural Science Foundation of China (NSFC)National Science Fund for Distinguished Young Scholars [2017JJ1029]; Swedish Research Council VRSwedish Research Council [2018-06048]; Swedish Energy Agency EnergimyndighetenSwedish Energy Agency [2016-010174]; Stiftelsen For Strategisk Forskning through a Future Research Leader program [FFL18-0322]; NSERCNatural Sciences and Engineering Research Council of Canada