Ambipolar transition voltage spectroscopy: analytical results and experimental agreement

TL;DR

This paper derives analytical formulas for transition voltages in molecular junctions to accurately determine energy offsets and bias asymmetry, validated by experimental data showing excellent agreement with measured I-V curves.

Contribution

It introduces new analytical formulas for transition voltages that improve the determination of molecular orbital energy offsets and bias asymmetry in molecular junctions.

Findings

Analytical formulas accurately estimate energy offset and bias asymmetry.

Experimental I-V curves are well reproduced using the derived formulas.

Validation against multiple experimental datasets confirms the method's reliability.

Abstract

This work emphasizes that the transition voltages $V_{t \pm}$ for both bias polarities ($V${\raisebox{1.2ex}{$_{\stackrel{>}{<}}$}0}) should be used to properly determine the energy offset $\varepsilon_{0}$ of the molecular orbital closest to electrodes' Fermi level and the bias asymmetry $\gamma$ in molecular junctions. Accurate analytical formulas are deduced to estimate $\varepsilon_{0}$ and $\gamma$ solely in terms of $V_{t \pm}$. These estimates are validated against experiments, by showing that full experimental $I$-$V$-curves measured by Beebe et al [\prl 97, 026801 (2006)] and Tan et al [Appl. Phsy. Lett. 96, 013110 (2010)] for both bias polarities can be excellently reproduced.