We demonstrate that a simple phenomenological approach can be used to simulate electronic conduction in molecular wires under thermal effects induced by the surrounding environment. This “Landauer-Büttiker’s probe technique” can properly replicate different transport mechanisms, phase coherent nonresonant tunneling, ballistic behavior, and hopping conduction. Specifically, our simulations with the probe method recover the following central characteristics of charge transfer in molecular wires: (i) the electrical conductance of short wires falls off exponentially with molecular length, a manifestation of the tunneling (superexchange) mechanism. Hopping dynamics overtakes superexchange in long wires demonstrating an ohmic-like behavior. (ii) In off-resonance situations, weak dephasing effects facilitate charge transfer, but under large dephasing, the electrical conductance is suppressed. (iii) At high enough temperatures, kBT/ϵB > 1/25, with ϵB as the molecular-barrier height, the current is enhanced by a thermal activation (Arrhenius) factor. However, this enhancement takes place for both coherent and incoherent electrons and it does not readily indicate on the underlying mechanism. (iv) At finite-bias, dephasing effects may impede conduction in resonant situations. We further show that memory (non-Markovian) effects can be implemented within the Landauer-Büttiker’s probe technique to model the interaction of electrons with a structured environment. Finally, we examine experimental results of electron transfer in conjugated molecular wires and show that our computational approach can reasonably reproduce reported values to provide mechanistic information.
Skip Nav Destination
Article navigation
14 July 2015
Research Article|
July 14 2015
Charge transport in molecular junctions: From tunneling to hopping with the probe technique
Michael Kilgour
;
Michael Kilgour
Chemical Physics Theory Group, Department of Chemistry,
University of Toronto
, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
Search for other works by this author on:
Dvira Segal
Dvira Segal
a)
Chemical Physics Theory Group, Department of Chemistry,
University of Toronto
, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
Search for other works by this author on:
a)
Electronic mail: dsegal@chem.utoronto.ca
J. Chem. Phys. 143, 024111 (2015)
Article history
Received:
May 02 2015
Accepted:
June 25 2015
Citation
Michael Kilgour, Dvira Segal; Charge transport in molecular junctions: From tunneling to hopping with the probe technique. J. Chem. Phys. 14 July 2015; 143 (2): 024111. https://doi.org/10.1063/1.4926395
Download citation file:
Pay-Per-View Access
$40.00
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Citing articles via
A theory of pitch for the hydrodynamic properties of molecules, helices, and achiral swimmers at low Reynolds number
Anderson D. S. Duraes, J. Daniel Gezelter
DeePMD-kit v2: A software package for deep potential models
Jinzhe Zeng, Duo Zhang, et al.