Single-Molecule Multi-Channel Conductance Assisted by Through-Space Conjugation

Abstract

Molecular electronics has emerged and evolved within the context of the miniaturization of silicon-based microchips, with the purpose to achieve conducting functions by integrating individual molecules into circuits through a “bottom-up” approach, but the exploration of intrinsic physical phenomena and operational principles is still in the infancy stage. One of the biggest challenges arises from the fundamental difference in charge transport modes between conventional macroscopic and molecular microscopic circuits. The former follows Ohm's law, while the latter operates via quantum transport. Undoubtedly, a deep understanding of the intrinsic physical mechanisms governing complex molecular circuits is essential for moving molecular-scale devices from the laboratory to large-scale production. Here, we review the fields from a molecular topology perspective and propose a straightforward definition to differentiate single-channel and multi-channel molecular circuits. We detail previously reported models and analyze their structure–property relationships. We also compare the conductance of molecules with multiple channels to those with single channels, giving special attention to the impact of noncovalent channels, such as through-space conjugation. Lastly, we discuss the opportunities and challenges for single-molecule systems with multiple channels, highlighting the advantages of through-space channels in molecular devices and envisioning their potential applications.

Keywords

charge transport / multi-channel systems / scanning tunneling microscope break junction / single-molecule conductance / through-space conjugation

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