Polaronic transport through molecular quantum dots: charging-induced NDR and rectifying behavior

TL;DR

This paper investigates how charging effects influence polaronic transport through molecular quantum dots, revealing phenomena like current suppression, negative differential resistance, and rectification using a nonperturbative Green's function approach.

Contribution

It introduces a self-consistent Green's function method to analyze charging effects in polaronic transport through quantum dots, highlighting new transport phenomena.

Findings

Charging causes current suppression at high voltages

Negative differential resistance (NDR) observed due to charging

Rectification behavior emerges in polaronic transport

Abstract

Here we study the polaronic transport through molecules weakly connected to metallic electrodes in the nonlinear response regime. Molecule itself is treated as a quantum dot with discrete energy levels, its connection to the electrodes is described within the wide-band approximation, while the charging is incorporated by means of the self-consistent potential. Nonperturbative computational scheme, used in this work, is based on the Green's function theory within the framework of mapping technique (GFT-MT). This method transforms the many-body electron-phonon interaction problem into a one-body multi-channel single-electron scattering problem with occupation of polaron levels calculated in the self-consistent way. In particular, three different phenomena as a result of charging in polaronic transport via discrete quantum states are discussed in detail: the suppression of the current at higher voltages, negative differential resistance (NDR effect), and rectification.