Absorptive Behaviors and Photovoltaic Performance Enhancements of Alkoxy-Phenyl Modified Indacenodithieno[3,2-b]thiophene-Based Nonfullerene Acceptors

Nonfullerene (NF) small molecular acceptors are very attractive for further improving the power conversion efficiencies (PCEs) of polymer solar cells (PSCs) to overcome the limited absorptive region and fixed-energy-level drawbacks of fullerene-based electronic acceptors (PC61BM and PC71BM). The acceptor–donor–acceptor (A-D-A)-type oligomers (ITIC) containing an electron-rich core (four hexyl-phenyl-substituted indacenodithieno[3,2-b]thiophene) as a donor motif sealed with 2-(3-oxo-2,3-dihydroinden-1-ylidene)-malononitrile as an acceptor motif has been intensively investigated, because of its excellent absorptive and photovoltaic properties. Side-chain modifications have been proven to be an effective approach to modulate the energy levels and absorptive behaviors of conjugated polymers, as well as conjugated small molecules. Through the introduction of various side-chain and end groups, a series of promisingly modified ITIC-based small molecules have been synthesized and well-studied. Herein, we reported...