Molecular electronics, an interdisciplinary frontier, aims to revolutionize miniaturized electronic devices with diverse functionalities. Since classical Kirchhoff’s laws no longer validate in the scale of a single molecule, the quantum effects at the molecular scale often defy these principles, leading to phenomena like "1 + 1 ≠ 2" in multi-channel architectures. Thus, a critical challenge lies in understanding how electron transport mechanisms—such as quantum interference and through-space effects—govern conductance in multi-channel molecular systems.

In a study published in Chemistry - An AsianJournal, Prof. ZHANG Qianchong from Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, and Prof. YANG Yang from Xiamen University unveiled groundbreaking insights into conductance modulation in multi-channel molecular devices. In this study, various laws based on quantum interference and nanoscale featured effects dramatically enhance or suppress conductance.

For conductance enhancement, the superposition law—a quantum-interference-driven principle—serves as the theoretical foundation, where parallel channels converging at a node amplify conductance beyond classical predictions.

This effect is further augmented by two auxiliary strategies: the self-gating effect, which leverages intramolecular charges to shift orbital energies and optimize electron transport, and through-space transport, where π-π stacking or non-covalent interactions create additional conductive pathways.

Conversely, conductance suppression is dominated not only by destructive quantum interference (DQI) in σ-systems but also by a novel electron selective transport feature. When channels converge on aromatic nodes (e.g., benzene rings), electrons preferentially "choose" either high- or low-conductance paths rather than following superposition principles. This results in a linear combination of single-channel conductance, deviating from traditional quantum interference effects.

Such selectivity, observed experimentally in Pt-coordinated and benzothiophene-based structures, highlights a unique quantum behavior where electron autonomy dictates transport outcomes.

This study redefines the principles of electron transport in molecular electronics, demonstrating that multi-channel architectures are not merely extensions of macroscopic circuits but platforms for exploiting quantum phenomena.

Laws and effects that regulate conductance in multi-channel structures include superposition law, self-gating effect, through space transport, DQI in σ-system, and electron selective transport.(Image by Prof. ZHANG)

Prof. ZHANG Qianchong

Fujian Institute of Research on the Structure of Matter

Chinese Academy of Sciences

Email: zhangqianchong@fjirsm.ac.cn