Theoretical Studies of Electron Transport in Thiophene Dimer: Effects of Substituent Group and Heteroatom

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• 作者：Shundong Yuan ; Chunlei Dai ; Jiena Weng ; Qunbo Mei ; Qidan Ling ; Lianhui Wang ; Wei Huang
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：May 5, 2011
• 年：2011
• 卷：115
• 期：17
• 页码：4535-4546
• 全文大小：1597K
• 年卷期：v.115,no.17(May 5, 2011)
• ISSN：1520-5215

文摘

The electron-transport properties of various substituted molecules based on the thiol-ended thiophene dimer (2Th1DT) are investigated through density functional theory (DFT) combined with nonequilibrium Green鈥檚 function (NEGF) method. The current鈭抳oltage (I鈭?i>V) curves of all the Au/2Th1DT/Au systems in this work display similar steplike features, while their equilibrium conductances show a large difference and some of these I鈭?i>V curves are asymmetric distinctly. The results reveal the dependence of conductance on the energy level of the substituted 2Th1DT molecules. Rectification ratios are computed to examine the asymmetric properties of the I鈭?i>V curves. The rectifying behavior in the 2Th1DT molecule containing the amino group close to the molecular end is more prominent than that in the other molecules. The rectifying behavior is analyzed through transmission spectra and molecular projected self-consistent Hamiltonian (MPSH) states. Slight negative differential resistance (NDR) can be observed in some of the systems. The electron-transport properties of 2Th1DT molecules containing different heteroatoms are also investigated. The results indicate that the current in heteroatom-containing molecules is larger than that in their pristine analogues, and lighter heteroatoms are more favorable than heavier heteroatoms for electron transport of the thiophene dimer.