Modulating the charge transport in metal│molecule│metal junctions via electrochemical gating

Abstract

This review introduces the concept of electrochemical gating, in conjunction with its working principle, and demonstrates its applicability and prospects towards fabricating functional molecular devices. In this vein, various redox-active and -inactive molecular systems of relevance have been discussed. In terms of the electrochemical environment for gating, the significance of ionic liquids over aqueous electrolytes has been highlighted in multiple examples. As a means of investigating the electrochemically gated molecular junctions, experimental testbeds based on scanning probe microscopy and break junction techniques—in terms of their setups and advantages—have been described. The manifestation of quantum interference effects and the approach for tuning these via electrochemical gating have been stressed. The relevance of electrochemically gated charge transport in biological systems has also been covered. A few miscellaneous systems—deploying indirect approaches involving chemical and environmental gating—have been exemplified. The review finally concludes by outlining the future research directions of the field. In essence, this review is aimed towards conveying the status of the conceptual understanding of electrochemical gating—which would further the development of emerging molecular device technologies.