Asymmetric chlorination of A 2 -A 1 -D-A 1 -A 2 type non-fullerene acceptors for high-voltage organic photovoltaics.

Herein, we synthesized an asymmetric A 2 -A 1 -D-A 1 -A 2 type small molecule nonfullerene acceptor (NFA), HCl-BTA3, by chlorination on one side of A 1 . The synergistic effect of the asymmetric structure and chlorination endows HCl-BTA3 with a large dipole moment, close molecular packing, and high-efficiency charge transfer and transport. After being blended with a carboxylate-based polymer donor, TTC-Cl, HCl-BTA3 achieved a high open-circuit voltage ( V OC ) of 1.20 V and a satisfactory power conversion efficiency (PCE) of 11.2%, which are among the highest values for high-voltage carboxylate-based polymers.