High-Performance Simple Nonfused Ring Electron Acceptors with Diphenylamino Flanking Groups.

Four simple nonfused ring electron acceptors (H-2F, CH3-2F, OCH3-2F, and SCH3-2F) were designed and synthesized. The use of diphenylamine derivatives as the flanking group for the construction of nonfused ring electron acceptors can improve solubility, avoid the formation of oversized aggregates, and enhance the intramolecular charge-transfer effect to extend absorption spectra. The substituent group at the diphenylamine unit has a great impact on the absorption and energy level of acceptors, electron mobility and morphology of blend films. Unlike the other three acceptors, CH3-2F can form ordered molecular stacking and a face-on orientation in the donor/acceptor blend film. A single-crystal analysis demonstrates that CH3-2F can form a two-dimensional electron transport network. Among these four acceptors, CH3-2F-based organic solar cells provide the highest PCE of 12.28%. Our work has demonstrated that triarylamine is a helpful construction unit for low-cost and high efficiency nonfused ring electron acceptors.