Martin Kühnel, Kasper Nørgaard
Nano-Science Center & Department of Chemistry, University of Copenhagen, Denmark
Reduced graphene oxide (rGO) is a promising electrode material in a wide variaty of applications, ranging from macro to micro-sized structures. In molecular electronics rGO has been demonstrated as a good electrode material, leading to high yield fabrication of molecular devices. In order to gain a more in-depth understanding of charge transport in molecular monolayers, electronic measurements at low temperatures (<50K) are needed. We have previously shown that upon cool down, the vertical resistance of a rGO thin film increases many orders of magnitude, hence devices become inoperational at low temperatures .
In this study we show that by optimizing the reaction conditions for the rGO synthesis, the charge transport properties can be greatly altered, both at room temperature and at lower temperatures. In addition to a nearly temperature independent conductance profile, we observe a change in the charge transport mechanism from a 2D Mott Variable Range Hopping (VRH) to Efros-Shklovskii-VRH.
As the main motivation was to develop an electrode material useable in low temperature measurements of molecular monolayers, devices with a monolayer of OPE3 (oligo phenyl ethynylene) and the optimized rGO was prepared and measured as a proof of functionality.
 J. R. Hauptmann, T. Li, S. Petersen, J. Nygard, P. Hedegard, T. Bjornholm, B. W. Laursen, K. Norgaard, Phys Chem Chem Phys 2012, 14, 14277-14281
Martin Kühnel is a PhD student at the University of Copenhagen, supervised by Kasper Nørgaard, working mainly with chemical derived graphene and molecular electronics. He received his M.Sc. degree in Nano Science from the University of Copehagen in 2013. His PhD project is part of the Danish Alliance of Graphene Application Technology and Engineering (DA-GATE).
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