Electron Transport in Molecular Wires

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概要

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• Numerical simulations have been performed to study the influence of $\pi$-orbital interactions and molecule–metal coupling strength ($\sigma_{1}=\sigma_{2}=\sigma_{i}$) on the electronic transport properties of molecular assembly system. The model involves 1,4-dithiolbenzene (DTB) molecules stacked in one dimension ordered structure. The results show that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap (HLG) is reduced when decreasing the intermolecular distance $d$ and increasing the number of DTB molecular units $N$. The influences of the geometric and coupling-strength parameters $d$, $N$, $\pi$-orbital, and $\sigma_{i}$ on the current–voltage ($I$–$V$) or the conductance–voltage ($G$–$V$) characteristics are investigated. It is found that the conductance gap depends on the HLG. The system in the regime of strong $\pi$-interactions shows shorter conductance gap. The conductance gap for a wire made of two DTB molecular units decreases by 2.4 V when $d$ changes from 6.9 to 3.3 Å, while it sharply decreases by 3.3 V when the molecular structure goes from a single molecule to a wire made of six molecular units. The results indicate also that $\sigma_{i}$ is an important factor in determining the current flow. The saturation current for a wire containing four molecular units increases by 150 μA when $\sigma_{i}$ changes from 0.2 to 0.4 eV. In fact, the main factors that determine the $I$–$V$ or $G$–$V$ characteristics are clearly related to the magnitude of the HLG, $\sigma_{i}$ and the position of the energy levels of the molecule relative to the Fermi energy contacts.

• 2008-06-25

著者

• Alizadeh Hossein

  Department of Electrical and Computer Engineering, University of Toronto, Ontario M5S 3G4, Canada

• Gougam Adel

  Department of Electrical and Computer Engineering, University of Toronto, Ontario M5S 3G4, Canada

• Boudjella Aissa

  Faculty of Engineering and Science, University of Tunku Abdul Rahman, Bandar Barat, 31900 Kampar, Malaysia

関連論文

• Room Temperature Photoluminescence from Erbium in Silica by Evaporation and Thermal Oxidation
• Electron Transport in Molecular Wires

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