Mechanical Effects on the Electronic Properties of a Biphenyl-Based Molecular Switch

Using a combination of density functional theory and nonequilibrium Greens function calculations, the effect of mechanically stretching a biphenyl-based molecular switch bonded to Au electrodes was studied. Thermodynamic and transport properties of the high- and low-conductance species were analyzed. A disulfide functionality bridging the aromatic rings was used to switch between the high- and low-conductance species. The potential of such a system as a molecular device has already been confirmed ( J. Phys. Chem. C 2013, 117, 25724). Mechanically stretching the molecular junction has major effects on both the thermodynamics of the switching reaction and the conductance ratio between the high- and low-conductance species involved in the molecular switch. It is also shown that the conductance of each individual species can be modulated by means of an external mechanical force, thus providing a dual switching mechanism for the proposed system.