Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
by Staff Writers
Rochester NY (SPX) Apr 28, 2014
Scientists are facing a number of barriers as they try to develop circuits that are microscopic in size, including how to reliably control the current that flows through a circuit that is the width of a single molecule.
Alexander Shestopalov, an assistant professor of chemical engineering at the University of Rochester, has done just that, thereby taking us one step closer to nanoscale circuitry.
"Until now, scientists have been unable to reliably direct a charge from one molecule to another," said Shestopalov. "But that's exactly what we need to do when working with electronic circuits that are one or two molecules thin."
Shestopalov worked with an OLED (organic light-emitting diode) powered by a microscopically small, simple circuit in which he connected a one-molecule thin sheet of organic material between positive and negative electrodes. Recent research publications have shown that it is difficult to control the current traveling through the circuit from one electrode to the other in such a thin circuit. As Shestopalov explains in a paper published in the journal Advanced Material Interfaces, the key was adding a second, inert layer of molecules.
The inert-or non-reactive-layer is made of a straight chain of organic molecules. On top a layer of aromatic-or ring-shaped-molecules acts like a wire conducting the electronic charge. The inert layer, in effect, acts like the plastic casing on electric wires by insulating and separating the live wires from the surrounding environment. Since the bottom layer is not capable of reacting with the overlapping layer, the electronic properties of the component are determined solely within the top layer.
The bi-layer arrangement also gave Shestopalov the ability to fine-tune his control of the charge transfer. By changing the functional groups-units of atoms that replace hydrogen in molecules and determine a molecule's characteristic chemical reactivity-he could more precisely affect the rate at which the current moved between the electrodes and the upper layer of organic molecules.
In molecular electronic devices, some functional groups accelerate the charge transfer, while others slow it down. By incorporating the inert layer of molecules, Shestopalov was able to reduce any interference with the top layer and, as a result, achieve the precise charge transfer needed in a device by changing the functional group.
For example, an OLED may need a faster charge transfer to maintain a specific luminescence, while a biomedical injection device may require a slower rate for delicate or variable procedures.
While Shestopalov overcame a significant obstacle, there remains a great deal of work to be done before bi-layer molecular electronic devices become practical. The next obstacle is durability.
"The system we developed degrades quickly at high temperatures," said Shestopalov. "What we need are devices that last for years, and that will take time to accomplish.
Shestopalov's research was funded by the National Science Foundation and University of Rochester ChemE Startup.
University of Rochester
Computer Chip Architecture, Technology and Manufacture
Nano Technology News From SpaceMart.com
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|