Synthesis and photophysical properties of fluorine substituted end group for benzo[1, 2-b:4, 5-b'] diselenophene-based small molecule acceptor

A-D-A types non-fullerene small molecule acceptors (NF-SMAs) have achieved excellent progress in recent years, while the development of series of new materials. Herein, a new NF-SMA, named BDSe-4F, based on linear benzo[1, 2-b:4, 5-b'] diselenophene with the difluorinated 5, 6-difluoro-3(dicyanomethylene) indanone (IC-2F) was synthesized and investigated. Due to the introduction of IC-2F, the intramolecular charge transfer is enhanced. Furtherly, the BDSe-4F exhibits a wider absorption from 600-800 nm in solution. From solution to film, the absorption spectrum shows an obvious red-shifted in the range of 800-900 nm and the maximum absorption peak red-shifted at 31 nm, suggesting that much stronger intermolecular interactions caused by non-covalent bond of F....S,F.... Se, and S....O. The BDSe-4F possesses good spectral absorption range and excellent molecular stacking, which beneficial to achieve high JSC and electron mobility. These results illustrate that the synergistic strategy of using benzo[1, 2-b:4, 5-b'] diselenophene core unit and IC-2F end group is a promising strategy to enhance performance in organic solar cells.