Wide bandgap small molecular acceptors for low energy loss organic solar cells

Non-fullerene organic solar cells (OSCs) have attracted great attention due to their advantages including tunable light absorption and low cost fabrication. Many important strategies have been used to achieve high performing OSCs including increasing the charge transport mobility and reducing the energy loss (Eloss). In this contribution, two wide bandgap small molecular acceptors (IDTzCR and IDTCR) were designed and synthesized for OSCs. Through replacing the thiophene moieties with thiazole ones, charge transport mobility was increased due to introducing S center dot center dot center dot N noncovalent conformational locks, resulting in a significant enhancement of photovoltaic performances. Furthermore, IDTCR based OSCs afforded a record low Eloss value for narrow bandgap donor: wide bandgap acceptor systems due to the small LUMO/LUMO energy offset. This contribution showed a novel method to achieve excellent wide bandgap acceptors for OSCs and sheds lights on understanding the relationship between the materials properties and device performances.