One-pot synthesis of electron-acceptor composite enables efficient fullerene-free ternary organic solar cells

Abstract

An effective strategy of synthesizing an electron-acceptor composite (ZITI-m) by one-pot reaction to improve photovoltaic performance is proposed. The ZITI-m composite is synthesized by one-pot Knoevenagel reaction of ZIT-2CHO and a mixture of INCN-2F and I-a, from which asymmetrical ZITI-3F and symmetrical ZITI-4F are separated. J71:ZITI-m-based OSC shows the highest PCE of 13.65 +/- 0.13% with remarkable PCE of 13.85% than those based on J71:ZITI-3F (12.97 +/- 0.15%) and J71:ZITI-4F (13.02 +/- 0.13%) blends. The effect of acceptor ratio in the composite on OPV performance indicates that all PCEs of composite system are higher than those of the materials based on pure acceptors with a broad composition tolerance, which is ascribed to the synergistic effect of the ternary blend system.