Abstract
In this study we have strategically designed and convergently synthesized two novel, symmetrical, and linear A–D–A-type π-conjugated donor molecules (BABDT6T, RHBDT6T), each containing a planar electron-rich 2-octylthiene-2-yl–substituted benzodithiophene (TBDT) unit as the core, each containing TBDT as the central electron donor unit flanked by three octylthiophene units and end capped with RH or barbutaric acid (BA) acceptors. The nature of the acceptor end groups affects the intermolecular interactions of RHBDT6T and BABDT6T and, thereby, their bulk properties, including their optical, electrochemical, and photovoltaic properties. Among our tested systems, the best BHJ solar cell device incorporating a blend of BATBDT and PC70BM at a ratio of 1:0.5 delivered the highest PCE (3.20%) after addition of 0.75% of 1,8-diiodooctane.