In a collaboration of experts in organic materials and nanofabrication, researchers have created one of the smallest organic light-emitting devices to date, made up of synthetic fibers just 200 nanometers wide (1 nanometer is one-billionth of a meter). The potential applications are in flexible electronic products, which are being made increasingly smaller.
The fibers, made of a compound based on the metallic element ruthenium, are so small that they are less than the wavelength of the light they emit. Such a localized light source could prove beneficial in applications ranging from sensing to microscopy to flat-panel displays.
The work, published in the February issue of Nano Letters, was a collaboration of nine Cornell researchers, including first author José M. Moran-Mirabal, an applied physics Ph.D. student; Héctor Abruña, the E.M. Chamot Professor of Chemistry and Chemical Biology; George Malliaras, associate professor of materials science and engineering and director of the Cornell NanoScale Facility; and Harold Craighead, the C.W. Lake Jr. Professor of Engineering and director of the National Science Foundation-funded Nanobiotechnology Center.
Using a technique called electrospinning, the researchers spun the fibers from a mixture of the metal complex ruthenium tris-bipyridine and the polymer polyethylene oxide. They found that the fibers give off orange light when excited by low voltage through micro-patterned electrodes -- not unlike a tiny light bulb.
"Imagine you have a light bulb that is extremely small," said Malliaras, an organic materials expert. "Then you can use the bulb to illuminate objects that you wouldn't be able to see otherwise."
Craighead's research group, which focuses on nanostructures and devices, supplied the expertise on the electrospinning technique.
The technique, explained Moran-Mirabal, who works in Craighead's laboratory, can be compared with pouring syrup on a pancake on a rotating table. As the syrup is poured, it forms a spiraling pattern on the flat pancake, which in electrospinning is the substrate with micropatterned gold electrodes. The syrup would be the solution containing the metal complex-polymer mixture in solvent. A high voltage between a microfabricated tip and the substrate ejects the solution from the tip, Moran-Mirabal said, and forms a jet that is stretched and thinned. As the solvent evaporates, the fiber hardens, laying down a solid fiber on the substrate.
As scientists look for ways to innovate -- and shrink -- electronics, there is much interest in organic light-emitting devices because they hold promise for making panels that can emit light but are also flexible, said Moran-Mirabal.
"One application of organic light-emitting devices could be integration into flexible electronics," he said.
The research also shows that these tiny light-emission devices can be made with simple fabrication methods. Compared with traditional methods of high-resolution lithography, in which devices are etched onto pieces of silicon, electrospinning requires almost no fabrication and is simpler to do.
The durability of organic electronics is still under investigation, and this recently completed research is no exception, Craighead said.
"The current interest is in the ease with which this material can be made into very small light-emitting fibers," he said. "Its ultimate utility, I think, will depend on how well it stands up to subsequent processing and use."
Other co-authors on the work are graduate students Jason D. Slinker, John A. DeFranco, Scott S. Verbridge, Samuel Flores-Torres and CNF staff member Rob Ilic.
Blaine Friedlander | EurekAlert!
Tangled magnetic fields power cosmic particle accelerators
14.12.2018 | DOE/SLAC National Accelerator Laboratory
In search of missing worlds, Hubble finds a fast evaporating exoplanet
14.12.2018 | NASA/Goddard Space Flight Center
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Power and Electrical Engineering
14.12.2018 | Physics and Astronomy
14.12.2018 | Physics and Astronomy