Electronic transport in molecular wires

Weidong Tian, Purdue University

Abstract

In this work we describe a theoretical model that we have developed for describing electronic transport in organic molecules sandwiched between two metallic contacts. Such molecules have been synthesized recently, and have potential applications in molecular electronics. We will begin with equilibrium properties and describe how the location of the Fermi energy can be fixed relative to the molecular energy levels. Next we will discuss the factors affecting the low bias resistance. By combining the Landauer approach with the Friedel sum rule, we relate the low bias conductance of the molecule to the energy level broadening and the charge transferred into or out of the molecule. Possible methods for enhancing the molecular conductance will be discussed. Finally we will discuss the current-voltage characteristics obtained at large bias and show that a third parameter, the voltage division factor, plays an important role. We will show that the experimentally observed conductance spectrum (dI/dV versus V) for a series of different molecules can all be understood in terms of three parameters, namely, the energy level broadening, the equilibrium Fermi energy and the voltage division parameter.

Degree

Ph.D.

Advisors

Datta, Purdue University.

Subject Area

Electrical engineering|Electromagnetism|Condensation

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