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.