With the development of diversity of non-fullerene acceptors, it is found that there is no clear boundary between electron donors and electron acceptors. Modulation of the electron donating and withdrawing properties of organic semiconductors is necessary for organic photovoltaics research. In this work, we designed and synthesized three A1-D-A2-D-A1-type (A represents acceptor unit and D represents donor unit) small molecules, named as M-0F, M-1F, and M-2F, respectively containing zero, one, and two fluorine atoms in the terminal acceptor segments (A1), respectively. Fluorination substitution was found to be able to downshift the HOMO and LUMO energy level, red-shift the absorption, and enhance the electron mobility. The M-0F exhibited the highest efficiency of 5.99% as a donor in fullerene-containing system and the lowest efficiency of 0.58% as an acceptor in fullerene-free system. While the M-2F performed the lowest efficiency of 0.97% as the donor and the highest efficiency of 2.65% as the acceptor. The electron-donating and electron-withdrawing property of M-1F are in-between that of M-0F and M-2F. Among the three molecules, the electron mobility is increased while the hole mobility is decreased with increasing fluorination. This work provides a typical example of tuning of the electron donating and withdrawing property without changes to the backbone of the conjugated molecules, which is important for further designing high performance solution processable small molecules.

Transfer of molecular chirality to supramolecular chirality at nanoscale and microscale by chemical self-assembly has been studied intensively for years. However, how such molecular chirality further transfers to the macroscale along the same path remains elusive. Here we reveal how the chirality from molecular level transfers to macroscopic level via self-assembly. We assemble a macrostripe using enantiomeric camphorsulfonic acid (CSA)-doped polyaniline with hierarchical order. The stripe can twist into a single-handed helical ribbon via helical self-motion. A multi-scale chemo-mechanical model is used to elucidate the mechanism underlying its chirality transfer and induction. The molecular origin of this macroscopic helical chirality is verified. Results provide a comprehensive understanding of hierarchical chirality transfer and helical motion in self-assembled materials and even their natural analogues. The stripe exhibits disparate actuation behaviour under stimuli of enantiomeric amines and integrating such chiral perception with helical self-motion may motivate chiral biomimetic studies of smart materials.