Recent progress in tuning charge transport in single-molecule junctions by substituents

Abstract

Molecular electronics is generally considered an alternative approach for the future fabrication of electronic devices. In the past few decades, benefiting from the impressive advancement in synthetic chemistry there emerged abundant molecular structures that are able to serve as conductive backbones for the electrons to transport through, as well as derivatives containing versatile substituents. Controlling the charge transport through a molecule lays the foundation for incorporating the molecule as a functional component in an active electronic device. In recent years the study on substituent-dependent conductance behavior attracted intensive research interest as it provides a feasible strategy to tune the electron transport in the molecule. In this review, we summarized the influence of substituents on single-molecule conductance and the mechanism of the influence into three aspects: the quantum interference effect, the electronic effect of substituents inducing changes in the energy levels of molecular orbitals, and the conformational restriction of the conductive backbone by the weak interaction between the substituents.