Pairing 1D/2D-conjugation donors/acceptors towards high-performance organic solar cells

Abstract

Two polymer donors, FTAZ and J71, and two fused-ring electron acceptors, ITIC1 and ITIC2, are used to investigate the effects of conjugation dimension on the performance of organic solar cells (OSCs). FTAZ and J71, and ITIC1 and ITIC2 share the same molecular backbone, respectively, while J71 and ITIC2 possess conjugated thienyl side chains. The addition of conjugated side chains slightly red-shifts the absorption spectra and lowers the bandgap due to the extended 2D conjugation. Conjugated side chains on the acceptor induce the self-aggregation of the acceptors, while conjugated side chains on the donor increase the miscibility of the donors and acceptors, thus optimizing the morphology of the active layers. The blends based on mixed combinations, namely 1D donor/2D acceptor and 2D donor/1D acceptor, show better performance relative to 1D donor/1D acceptor and 2D donor/2D acceptor.