Tuning Charge Transport in Aromatic‐Ring Single‐Molecule Junctions via Ionic‐Liquid Gating

Abstract

Achieving gate control with atomic precision, which is crucial to the transistor performance on the smallest scale, remains a challenge. Herein we report a new class of aromatic-ring molecular nanotransistors based on graphene-molecule-graphene single-molecule junctions by using an ionic-liquid gate. Experimental phenomena and theoretical calculations confirm that this ionic-liquid gate can effectively modulate the alignment between molecular frontier orbitals and the Fermi energy level of graphene electrodes, thus tuning the charge-transport properties of the junctions. In addition, with a small gate voltage (|V |≤1.5 V) ambipolar charge transport in electrochemically inactive molecular systems (E >3.5 eV) is realized. These results offer a useful way to build high-performance single-molecule transistors, thus promoting the prospects for molecularly engineered electronic devices.

Achieving Efficient Multichannel Conductance in Through‐Space Conjugated Single‐Molecule Parallel Circuits

“…Molecular electronics have achieved tremendous progress in the past decades [1] and are expected to play more important roles in next-generation integrated circuits. [2] As a basic research topic in molecular electronics, single-molecule wires are essential components for molecular devices and can provide a fundamental understanding for electron transport in single molecules or molecular assemblies, which can lead to advancements in chemistry, [3] biology [4] and materials science. [5] One challenging area in molecular electronics is the achievement of high and controllable conductance in singlemolecule wires.…”

Electrical and spin switches in single‐molecule junctions

“…The formed electrical double layer by applying a gate voltage can be extremely thin, usually a few angstroms, regardless of the position of the gate electrode, which can enable much more efficient electrostatic coupling. For those non‐redox active molecules, applying a gate voltage can change the molecular orbital energy levels relative to the electrode Fermi level, and thus the molecular conductance will be efficiently regulated . The effect of a gate voltage is not only to tune the energy levels of electrochemically active molecules, but also to reversibly oxidize and reduce the molecules at the redox potential, exhibiting conductance switching effects …”

“…By changing aqueous electrolytes into ionic liquids, Guo et al realized gate‐controllable charge transport of non‐redox molecules on the basis of the platform of graphene‐molecule‐graphene single‐molecule transistors . Ambipolar charge transport characteristics were observed for both triphenyl and hexaphenyl molecular junctions, arising from the change of dominant conducting orbital from HOMO to LUMO as the gate voltage changed from negative to positive.…”

“…The initially ultimate goal of molecular electronics is to build integrated circuits for the next generation of super‐fast computer and ultrahigh density information storage. Currently, many functional single‐molecule electronic components, including molecular wires, molecular switches, molecular rectifiers, molecular transistors, and sensors, have been realized. In addition, many novel physical phenomena, such as quantum interference, Coulomb blockade, and Kondo effect, were discovered in the process of investigating charge transport within molecular junctions.…”

Control of Unipolar/Ambipolar Transport in Single‐Molecule Transistors through Interface Engineering

“…3) The molecular length should be comparable to or larger than the thickness of gate dielectric so that the gate field can efficiently modulate the transport capability of carriers in the channel, potentially avoiding the short channel effect. [ 25–27 ] Until now, most discussions in these considerations are based on theoretical calculations and systematic experimental investigations are in great demand.…”