Electron Transport Through Molecules: Gate Induced Polarization and Potential Shift

TL;DR

This paper investigates how gate-induced polarization and potential shifts influence molecular conductance, revealing that potential shifts significantly affect electron transport and could enable single-molecule transistor applications.

Contribution

It provides a detailed ab initio analysis of gate effects on molecular conductance, distinguishing the roles of polarization and potential shifts across various molecular systems.

Findings

Polarization effects are minimal due to screening.

Potential shifts have a substantial impact on conductance.

Results suggest a mechanism for single-molecule transistors.

Abstract

We analyze the effect of a gate on the conductance of molecules by separately evaluating the gate-induced polarization and the potential shift of the molecule relative to the leads. The calculations use ab initio density functional theory combined with a Green function method for electron transport. For a general view, we study several systems: (1) atomic chains of C or Al sandwiched between Al electrodes, (2) a benzene molecule between Au leads, and (3) (9,0) and (5,5) carbon nanotubes. We find that the polarization effect is small because of screening, while the effect of the potential shift is significant, providing a mechanism for single-molecule transistors.