Stable Anchoring Chemistry for Room Temperature Charge Transport through Graphite-Molecule Contacts

Science Advances 3, e1602297 (2017)

Stable Anchoring Chemistry for Room Temperature Charge Transport through Graphite-Molecule Contacts

Alexander V. Rudnev, Veerabhadrarao Kaliginedi, Andrea Droghetti, Hiroaki Ozawa, Akiyoshi Kuzume, Masa-aki Haga, Peter Broekmann, Ivan Rungger

An open challenge for single molecule electronics is to find stable contacts at room temperature with a well-defined conductance. While common coinage metal electrodes pose fabrication and operational problems due to the high mobility of the surface atoms, here we demonstrate how molecules covalently grafted onto mechanically robust graphite/graphene substrates overcome these limitations. We explore the effect of the anchoring group chemistry on the charge transport properties of graphite/molecule contacts by means of the scanning tunneling microscopy break-junction technique and ab initio simulations. Molecules adsorbed on graphite only via van der Waals interactions have a conductance that decreases exponentially upon stretching the junctions, while molecules bonded covalently to graphite have a single well defined conductance and yield contacts of unprecedented stability at room temperature. Combined with the prospect of new functionalities due to a strongly bias dependent conductance, such covalent contacts are ideal candidates for next generation molecular electronics devices.

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