Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > CU researchers shed light on light-emitting nanodevice

Top view of the ruthenium tris-bipyridine light-emitting device created by Cornell researchers. The ruthenium metal complex is represented by red spheres, and counter ions are represented by green spheres. The material is sandwiched between two gold electrodes. Also visible is the probe of the electron force microscope used to measure the electric field of the device.
Top view of the ruthenium tris-bipyridine light-emitting device created by Cornell researchers. The ruthenium metal complex is represented by red spheres, and counter ions are represented by green spheres. The material is sandwiched between two gold electrodes. Also visible is the probe of the electron force microscope used to measure the electric field of the device.

Abstract:
An interdisciplinary team of Cornell nanotechnology researchers has unraveled some of the fundamental physics of a material that holds promise for light-emitting, flexible semiconductors.

CU researchers shed light on light-emitting nanodevice

Ithaca, NY | Posted on October 3rd, 2007

The discovery, which involved years of perfecting a technique for building a specific type of light-emitting device, is reported in the Sept. 30 online publication of the journal Nature Materials.

The interdisciplinary team had long studied the molecular semiconductor ruthenium tris-bipyridine. For many reasons, including its ability to allow electrons and holes (spaces where electrons were before they moved) to pass through it easily, the material has the potential to be used for flexible light-emitting devices. Sensing, microscopy and flat-panel displays are among its possible applications.

The researchers set out to understand the fundamental physics of the material -- that is, what happens when it encounters an electric field, both at the interfaces and inside the film. By fabricating a device out of the ruthenium metal complex that was spin-coated onto an insulating substrate with pre-patterned gold electrodes, the scientists were able to use electron force microscopy to measure directly the electric field of the device.

A long-standing question, according to George G. Malliaras, associate professor of materials science and engineering, director of the Cornell NanoScale Science and Technology Facility and one of the co-principal investigators, was whether an electric field, when applied to the material, is concentrated at the interfaces or in the bulk of the film.

The researchers discovered that it was at the interfaces -- two gold metal electrodes sandwiching the ruthenium complex film -- which was a huge step forward in knowing how to build and engineer future devices.

"So when you apply the electric field, ions in the material move about, and that creates the electric fields at the interfaces," Malliaras explained.

Essential to the effort was the ability to pattern the ruthenium complex using photolithography, a technique not normally used with such materials and one that took the researchers more than three years to perfect, using the knowledge of experts in nanofabrication, materials and chemistry.

The patterning worked by laying down a gold electrode and a polymer called parylene. By depositing the ruthenium complex on top of the parylene layer and filling in an etched gap between the gold electrodes, the researchers were then able to peel the parylene material off mechanically, leaving a perfect device.

Ruthenium tris-bipyridine has energy levels well suited for efficient light emission of about 600 nanometers, said Héctor D. Abruña, the E.M. Chamot Professor of Chemistry, and a principal co-investigator. The material, which has interested scientists for many years, is ideal for its stability in multiple states of oxidation, which, in turn, allows it to serve as a good electron and hole transporter. This means that a single-layer device can be made, simplifying the manufacturing process.

"It's not fabulous, but it has a reasonable emission efficiency," Abruña said. "One of the drawbacks is it has certain instabilities, but we have managed to mitigate most of them."

Among the other authors were co-principal investigators Harold G. Craighead, the C.W. Lake Jr. Professor of Engineering, and John A. Marohn, associate professor of chemistry and chemical biology.

####

For more information, please click here

Contacts:
Anne Ju
(607) 255-9735

Media Contact:
Press Relations Office
(607) 255-6074

Copyright © Cornell University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Chip Technology

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

Future flexible electronics based on carbon nanotubes: Study in Applied Physics Letters show how to improve nanotube transistor and circuit performance with fluoropolymers September 23rd, 2014

Twisted graphene chills out: When two sheets of graphene are stacked in a special way, it is possible to cool down the graphene with a laser instead of heating it up, University of Manchester researchers have shown September 22nd, 2014

SouthWest NanoTechnologies (SWeNT) Receives NIST Small Business Innovation Research (SBIR) Phase 1 Award to Produce Greater than 99% Semiconducting Single-Wall Carbon Nanotubes September 19th, 2014

Discoveries

UT Arlington researchers develop transparent nanoscintillators for radiation detection for medical safety and homeland security September 29th, 2014

Iranian Scientists Determine Grain Size, Minimize Time of Nanocomposite Synthesis September 29th, 2014

Nanoparticles Used to Improve Quality of Bone Cement September 29th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

Announcements

UT Arlington researchers develop transparent nanoscintillators for radiation detection for medical safety and homeland security September 29th, 2014

Iranian Scientists Determine Grain Size, Minimize Time of Nanocomposite Synthesis September 29th, 2014

Nanoparticles Used to Improve Quality of Bone Cement September 29th, 2014

'Pixel' engineered electronics have growth potential: Rice, Oak Ridge, Vanderbilt, Penn scientists lead creation of atom-scale semiconducting composites September 29th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE