Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 23: Transport: Nanoelectronics III - Molecular Electronics

TT 23.11: Talk

Wednesday, March 25, 2009, 12:15–12:30, HSZ 105

Control of the Conductance in Molecular Switch Junctions — •Daijiro Nozaki, Cormac Toher, Florian Pump, and Gianaurelio Cuniberti — Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology, Dresden, Germany

We explore the usability of molecules with bistable characteristics as reversibly tunable molecular switches driven by external stimulation such as light [1] or current-pulse [2]. We have modeled three molecular switch-junctions formed with silicon contacts and azobenzene derivatives which have bistable cis- and trans-conformations. Using the nonequilibrium Green’s function approach implemented with the density-functional-based tight-binding theory [3], we analyzed electron transmission, on/off ratios, potential energy surfaces along reaction coordinate from cis- to trans-conformation, and the stability of the molecular switches in ambient conditions along MD pathways.

The numerical results have shown that transmission spectra in cis-conformations are more conductive than trans-ones inside of the bias window in three models. I-V characteristics also lead to the same trends. Additionally, the transmission along MD pathways have shown that the cis-conformations are always more conductive than trans-ones at room temperature. Therefore, the azobenzene derivative-based molecular switches can be expected to work as robust switching components.

[1] M. del Valle et al., Nature Nanotech. 2, 176 (2007).

[2] H. Riel et al., Small, 2, 973 (2006).

[3] A. Pecchia et al., Rep. Prog. Phys. 67, 1497 (2004).