Low-bandgap small molecule acceptors with asymmetric side chains

Abstract

Two low-bandgap ADA small molecule acceptors A1 and A2 with asymmetric out-of-plane side chains were synthesized. Different from previous studies, the asymmetric side chains of A1 and A2 were installed at the two sp³ bridge-head carbons of the core unit, respectively. A1 and A2 show larger molecular dipole moments, stronger π–π interactions and higher electron mobilities than the symmetric counterpart S1, and exhibit higher miscibility with the donor L1-S. Higher power conversion efficiencies of 13.25% and 14.43% were achieved by L1-S:A1 and L1-S:A2 solar cells, respectively.