Current rectification by asymmetric molecules: An ab initio study

TL;DR

This study uses ab initio methods to analyze current rectification in asymmetric molecules, revealing how molecular structure and coupling influence rectification ratios and electronic behavior.

Contribution

It provides a detailed ab initio analysis of current rectification in asymmetric molecules, highlighting the impact of molecular structure and coupling on rectification performance.

Findings

Rectification ratio of ~38 at n=5

Exponential decrease in conductance with increasing n

Observation of negative differential resistance at positive bias

Abstract

We study current rectification effect in an asymmetric molecule HOOC-C$_6$H$_4$-(CH$_2$)$_n$ sandwiched between two Aluminum electrodes using an {\sl ab initio} nonequilibrium Green function method. The conductance of the system decreases exponentially with the increasing number $n$ of CH$_2$. The phenomenon of current rectification is observed such that a very small current appears at negative bias and a sharp negative differential resistance at a critical positive bias when $n\ge 2$. The rectification effect arises from the asymmetric structure of the molecule and the molecule-electrode couplings. A significant rectification ratio of $\sim$38 can be achieved when $n=5$.