Side-chain engineering of nonfullerene small-molecule acceptors for organic solar cells

Abstract

Thanks to their broad absorption spectra, easily modifiable molecular energy levels and chemical structures, nonfullerene small-molecule acceptors (SMAs) have attracted significant attention in the recent decade. To date, SMAs and polymer donor-based organic solar cells (OSCs) have achieved power conversion efficiencies (PCEs) of over 19%. During this time period, side-chain engineering has emerged as an effective method for enhancing the photovoltaic efficiency of the corresponding OSCs due to its simplicity and effectiveness in optimizing the physicochemical properties of nonfullerene SMAs. In this article, side-chain engineering of nonfullerene SMAs, including A–(π)–D–(π)–A-type SMAs and A–DA₁D–A-type SMAs, is summarized. The general methods for modifying the side chains of SMAs and their pivotal structure–performance relationships are combined and highlighted. The future challenges and prospects for the further side-chain optimization of the SMAs are proposed.