Conductance of metal superatom-based molecular wires influenced by nanoscale effects.

Abstract

High-conductance molecular wires are critical for advancing molecular-scale electronics, yet their performance typically diminishes exponentially with length. Here, we reveal an unconventional phenomenon where nanoscale molecular wires constructed from metal superatoms demonstrate enhanced conductance as their length increases. Through first-principles calculations, we find that quasi-one-dimensional assemblies of W@Cu₁₂ superatoms, below 2.5 nanometers in length, exhibit a gradual conductance decay. Importantly, when organized into bundle-like configurations, their conductance transitions to an increasing trend, with the decay factor shifting from 1.25 nm^-1 to -0.95 nm^-1. This reverse phenomenon can be attributed to the energy alignment of the dominant electron transport orbitals with the Fermi level of the electrode-scattering region-electrode systems, effectively lowering the tunneling barrier. Our results demonstrate that negative decay factors in molecular-scale devices are not intrinsic but can be engineered through structural design. This study provides a theoretical foundation for optimizing molecular circuitry through structural control and highlights the potential of metal superatoms in next-generation electronic transport applications.