Intrinsically Chemo- and Thermostable Electron Acceptors for Efficient Organic Solar Cells

The traditional preparation of non-fullerene acceptors (NFAs) via Knoevenagel condensation reaction (KCR) of aldehyde and active methylene leaves vulnerable and reversible exocyclic vinyl bonds in structures, which undermine the intrinsic chemo- and photostability of NFAs. In this work, we demonstrate a new access to acceptor-donor-acceptor (A-D-A) NFAs via Stille coupling between new electron deficient groups and classic donor core in over 90% yield, wherein the robust carbon-carbon bonds, replacing the exocyclic double bonds from traditional KCR, result in stable A-D-A acceptors, Q1-XF (X representing 0, 2 and 4 fluorine atoms, respectively). Among the three studied examples, Q1-4F exhibits improved optoelectronic and electron transport properties, leading to the best photovoltaic performance with optimal charge kinetics for Q1-4F based OSCs. Overall, this strategy can lead to a new way for developing stable photovoltaic materials.