The influence of vibronic coupling on the shape of transport characteristics in inelastic tunneling through molecules

TL;DR

This paper investigates how vibronic coupling influences nonlinear transport properties in molecular electronic devices, revealing that quantum coherent polaron transport can explain discrepancies between theory and experiment.

Contribution

It introduces a nonperturbative Green's function approach to model vibronic effects, providing new insights into transport phenomena in molecular electronics.

Findings

Vibronic coupling significantly affects current-voltage characteristics.

Quantum coherent polaron transport explains experimental-theoretical discrepancies.

The method offers a detailed understanding of electron-phonon interactions in molecules.

Abstract

Here we present theoretical studies of the effect of vibronic coupling on nonlinear transport characteristics (current-voltage and conductance-voltage) in molecular electronic devices. Considered device is composed of molecular quantum dot (with discrete energy levels) weakly connected to metallic electrodes (treated within the wide-band approximation), where molecular vibrations are modeled as dispersionless phonon excitations. Nonperturbative computational scheme, used in this work, is based on the Green's function theory within the framework of mapping technique (GFT-MT) which transforms the many-body electron-phonon interaction problem into a one-body multi-channel single-electron scattering problem. In particular, it is shown that quantum coherent transport of virtual polarons through the molecule can be a dominant factor justifying some well-known discrepancies between theoretical calculations and experimental results.