Trifluoromethylation Enables a 3D Interpenetrated Low-Band-Gap Acceptor for Efficient Organic Solar Cells

摘要： Herein, tri?uoromethylation has proven to be an effective strategy for ultra-narrow band-gap NFAs. A PCE of 15.59% is achieved from BTIC-CF3-g-based devices, which is the highest value in reported ultra-narrow band-gap acceptors. A ternary device with 16.50% ef?ciency is also obtained, resulting from its red-shifted absorption. Meanwhile, the single-crystal structure of BTIC-CF3-g has been successfully presented, which gives a deep understanding of the solid-state molecular packings in these highly ef?cient acceptors.