Individual molecules have been used to create electrical components like resistors, transistors and diodes, that mimic the properties of familiar semiconductors. But according to Nongjian (NJ) Tao, a researcher at the Biodesign Institute at Arizona State University, unique properties inherent in single molecules may also allow clever designers to produce novel devices whose behavior falls outside the performance observed in conventional electronics.
In research appearing in today's issue of Nature Nanotechnology, Tao describes a method for mechanically controlling the geometry of a single molecule, situated in a junction between a pair of gold electrodes that form a simple circuit. The manipulations produced over tenfold increase in conductivity.
The unusual, often non-intuitive characteristics of single molecules may eventually be introduced into a broad range of microelectronics, suitable for applications including biological and chemical sensing; electronic and mechanical devices.
Delicate molecular manipulations requiring patience and finesse are routine for Tao, whose research at Biodesign's Center for Bioelectronics and Biosensors has included work on molecular diodes, graphene behavior and molecular imaging techniques. Nevertheless, he was surprised at the outcome described in the current paper: "If you have a molecule attached to electrodes, it can stretch like a rubber band," he says. "If it gets longer, most people tend to think that the conductivity will decrease. A longer wire is less conductive than a shorter wire."
Indeed, diminishing conductivity through a molecule is commonly observed when the distance between the electrodes attached to its surface is increased and the molecule becomes elongated. But according to Tao, if you stretch the molecule enough, something unexpected happens: the conductance goes upby a huge amount. "We see at least 10 times greater conductivity, simply by pulling the molecul
|Contact: Joseph Caspermeyer|
Arizona State University