Single-Channel Saturation at the Quantum Conductance Limit in Single-Molecule Junctions

doi:10.1021/jacs.5c18067

Single-Channel Saturation at the Quantum Conductance Limit in Single-Molecule Junctions

2026-02-07

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DOI：10.1021/jacs.5c18067

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Electron transport through a single quantum channel is fundamentally limited by the conductance quantum (G0 = 2e2/h ≈ 77.5 μS), achievable only in fully transparent systems without interfacial scattering. However, realizing this quantum limit in metal–molecule–metal junctions has long been hindered by intrinsic electronic mismatches at heterogeneous interfaces. Here, we report a carbon nanobelt single-molecule junction over 1 nm in length, whose conductance reaches G0, driven by the saturation of a single transport channel under ambient conditions. This unprecedented performance arises from electric-field-induced formation of covalent C–Au–C bonds at both contacts, creating atomically fused interfaces that seamlessly merge the nanobelt’s π system with Au d orbitals. The resulting d-π conjugation establishes a single, transparent electronic resonance aligned with the Fermi level, suppressing backscattering and enabling near ideal quantum transport. By eliminating heterogeneous interfacial resistance at the atomic scale, this strategy offers a general blueprint for engineering atomically precise, energy-efficient nanoelectronic and optoelectronic devices.

Keywords:

Quantum conductance limit

Single-molecule junction

Covalent C–Au–C bonds

d-π conjugation

Atomic-scale interfaces

Single-Channel Saturation at the Quantum Conductance Limit in Single-Molecule Junctions

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