Self-consistent theory of molecular switching

Journal article (2008)
Department
Kavli Institute of Nanoscience (AS) (TU Delft)
Copyright: © 2008 The Author(s) ; American Physical Society
Molecular electronics Tunnelling Switching Franck-Condon factors Microswitches Vibrational states
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Published Date

25-08-2008

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Source:

Physical Review B, 78 (8), 2008

ISSN:

0163-1829

Faculty

Applied Sciences

Department

Kavli Institute of Nanoscience

Abstract

We study the model of a molecular switch comprised of a molecule with a soft vibrational degree of freedom coupled to metallic leads. In the presence of strong electron-ion interaction, different charge states of the molecule correspond to substantially different ionic configurations, which can lead to very slow switching between energetically close configurations (Franck-Condon blockade). Application of transport voltage, however, can drive the molecule far out of thermal equilibrium and thus dramatically accelerate the switching. The tunneling electrons play the role of a heat bath with an effective temperature dependent on the applied transport voltage. Including the transport induced “heating” self-consistently, we determine the stationary currentvoltage characteristics of the device and the switching dynamics for symmetric and asymmetric devices. We also study the effects of an extra dissipative environment and demonstrate that it can lead to enhanced nonlinearities in the transport properties of the device and dramatically suppress the switching dynamics.

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