Current rectification by molecules with asymmetric tunneling barriers

TL;DR

This paper presents a simple, experimentally feasible molecular rectifier design based on asymmetric tunneling barriers, achieving high rectification ratios through spatial asymmetry and a single resonant level.

Contribution

It introduces a novel molecular rectification mechanism relying on spatial asymmetry and a single resonant level, supported by extensive numerical simulations.

Findings

Rectification ratios up to ~500 achieved

Optimal molecular structure with m=2 and n=10 identified

Rectification largely independent of electrode work function differences

Abstract

A simple experimentally accessible realization of current rectification by molecules (molecular films) bridging metal electrodes is described. It is based on the spatial asymmetry of the molecule and requires only one resonant conducting molecular level (pi-orbital). The rectification, which is due to asymmetric coupling of the level to the electrodes by tunnel barriers, is largely independent of the work function difference between the two electrodes. Results of extensive numerical studies of the family of suggested molecular rectifiers HS-(CH2)_m-C6H4-(CH2)_n-SH are presented. The highest rectification ratio ~500 is achieved at m = 2 and n = 10.