A ligand-free direct heteroarylation approach for benzodithiophenedione-based simple small molecular acceptors toward high efficiency polymer solar cells

Simple fused-ring nonfullerene acceptor BDDEH with benzobithiophenedione as core unit is obtained through organostannane-free and ligand-free direct heteroarylation approach for the first time, which delivers a high efficiency of 12.59% in PSCs.