Rectification in single molecular dimers with strong polaron effect

TL;DR

This paper theoretically investigates how strong electron-vibron coupling and polaron formation in molecular dimers cause asymmetric current-voltage characteristics, relevant for C_140 molecule experiments.

Contribution

It introduces a model explaining asymmetric transport in molecular dimers due to polaron states and their coupling conditions.

Findings

Polaron states cause strong asymmetry in I-V characteristics.

Current blockade occurs when polaron coupling is weaker than lead coupling.

Relevance demonstrated for C_140 molecular experiments.

Abstract

We study theoretically the transport properties of a molecular two level system with large electron-vibron coupling in the Coulomb blockade regime. We show that when the electron-vibron coupling induces polaron states, the current-voltage characteristic becomes strongly asymmetric because, in one current direction, one of the polaron state blocks the current through the other. This situation occurs when the coupling between the polaron states is smaller than the coupling to the leads. We discuss the relevance of our calculation for experiments on C_140 molecules.