Rectification Mechanism in Di-Block Oligomer Molecular Diodes

TL;DR

This paper explains the rectification effect in di-block oligomer molecular diodes through a new Green's function theory, linking electron transfer resonance and wave function localization to observed I-V asymmetry.

Contribution

It introduces a novel Green's function approach to theoretically explain rectification in molecular diodes based on bound state spectra.

Findings

The theory aligns qualitatively with experimental I-V spectra.

Resonant electron transfer causes rectification asymmetry.

Bias polarity influences wave function localization and rectification.

Abstract

We investigated a mechanism of rectification in di-block oligomer diode molecules that have recently been synthesized and showed a pronounced asymmetry in the measured I-V spectrum. The observed rectification effect is due to the resonant nature of electron transfer in the system and localization properties of bound state wave functions of resonant states of the tunneling electron interacting with asymmetric molecule in an electric field. The asymmetry of the tunneling wave function is enhanced or weakened depending on the polarity of applied bias. The conceptually new theoretical approach, the Green's function theory of sub-barrier scattering, is able to provide a physically transparent explanation of this rectification effect based on the concept of the bound state spectrum of a tunneling electron. The theory predicts the characteristic features of the I-V spectrum in qualitative agreement with experiment.