Anomalous length dependent conductance of quasi-one-dimensional molecular wires assembled from metal superatoms

TL;DR

This study reveals that the electrical conductance of quasi-one-dimensional molecular wires made from metal superatoms can increase with length when assembled into bundle-like structures, challenging the typical decay trend.

Contribution

It demonstrates that conductance decay can be reversed through structural modulation of superatomic assemblies, a novel insight for molecular electronics.

Findings

Conductance of superatomic assemblies exhibits slow decay with length.

Extending assemblies into bundles increases conductivity and reverses decay.

Fermi level shifts reduce tunneling barriers, enhancing conductance.

Abstract

Molecular wires with high electrical conductance are desirable components for future molecular-scale circuitry. However, their conductance typically decays exponentially with increasing length. Here, we report a novel discovery that the conductivity of a nanoscale molecular wire assembled from metal superatoms increases with length. Specifically, high-precision first-principles calculations show that, while the conductance of quasi-one-dimensional superatomic assemblies formed with individual W@Cu12 superatoms as units exhibits a slow decay with increasing length, by extending the quasi-one-dimensional superatomic assemblies into bundle-like structures, their electrical conductivity increases with length, accompanied by a change in the corresponding decay factor from 1.25 nm-1 to -0.95 nm-1. This significant change in the decay factor originates from that the Fermi level of the superatomic assemblies shifts closer to the Fermi level of the electrodes, thereby reducing the tunneling barrier. Our findings highlight that molecular-scale devices exhibiting a negative decay factor are not an inherent characteristic, but rather can be regulated through structural modulation. This work not only provides theoretical references for modulating the performance of molecular-scale circuitry, but also opens up the application prospect of metal superatoms in electrical transport field.