We demonstrate that the conductance switching of benzo-bis(imidazole) molecules upon protonation depends on the lateral functional groups. The protonated H-substituted molecule shows a higher conductance than the neutral one (Gpro>Gneu), while the opposite (Gneu>Gpro) is observed for a molecule laterally functionalized by amino-phenyl groups. These results are demonstrated at various scale lengths : self-assembled monolayer, tiny nanodot-molecule junction and single molecules. From ab-initio theoretical calculations, we conclude that for the H-substituted molecule, the result Gpro>Gneu is correctly explained by a reduction of the LUMO-HOMO gap, while for the amino-phenyl functionnalized molecule, the result Gneu>Gpro is consistent with a shift of HOMO, which reduces the density of states at the Fermi energy.
Cite
@article{arxiv.2005.00080,
title = {Electrical molecular switch addressed by chemical stimuli},
author = {H. Audi and Y. Viero and N. Alwhaibi and Z. Chen and M. Iazykov and A. Heynderickx and F. Xiao and D. Guerin and C Krzeminski and I. M. Grace and C. J. Lambert and O. Siri and D. Vuillaume and S Lenfant and H. Klein},
journal= {arXiv preprint arXiv:2005.00080},
year = {2020}
}