Elimination of negative differential conductance in an asymmetric molecular transistor by an ac-voltage

TL;DR

This paper investigates how applying an ac voltage to an asymmetric molecular transistor can suppress negative differential conductance caused by hot phonons, using a Tien-Gordon-type model to analyze photon-assisted tunneling.

Contribution

It demonstrates that ac driving can eliminate negative differential conductance in asymmetric molecular transistors by suppressing hot phonons, a novel insight into controlling molecular electronic transport.

Findings

Photon-assisted satellites appear in current-voltage characteristics.

Increasing ac amplitude suppresses hot-phonon-induced negative differential conductance.

Asymmetry enables ac-induced phonon suppression.

Abstract

We analyze resonant tunneling subject to a non-adiabatic time-dependent bias-voltage through an asymmetric single molecular quantum dot with coupling between the electronic and vibrational degrees of freedom using a {\em Tien-Gordon-type} rate equation. Our results clearly exhibit the appearance of photon-assisted satellites in the current-voltage characteristics and the elimination of hot-phonon-induced negative differential conductance with increasing ac driving amplitude for an asymmetric system. This can be ascribed to an {\em ac-induced suppression} of unequilibrated (hot) phonons in an asymmetric system.