Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ultrathin Leds Create New Classes Of Lighting And Display Systems

21.08.2009
A new process for creating ultrathin, ultrasmall inorganic light-emitting diodes (LEDs) and assembling them into large arrays offers new classes of lighting and display systems with interesting properties, such as see-through construction and mechanical flexibility, that would be impossible to achieve with existing technologies.

Applications for the arrays, which can be printed onto flat or flexible substrates ranging from glass to plastic and rubber, include general illumination, high-resolution home theater displays, wearable health monitors, and biomedical imaging devices.

“Our goal is to marry some of the advantages of inorganic LED technology with the scalability, ease of processing and resolution of organic LEDs,” said John Rogers, the Flory-Founder Chair Professor of Materials Science and Engineering at the University of Illinois.

Rogers and collaborators at the U. of I., Northwestern University, the Institute of High Performance Computing in Singapore, and Tsinghua University in Beijing describe their work in the Aug. 21 issue of the journal Science.

Compared to organic LEDs, inorganic LEDs are brighter, more robust and longer-lived. Organic LEDs, however, are attractive because they can be formed on flexible substrates, in dense, interconnected arrays. The researchers’ new technology combines features of both.

“By printing large arrays of ultrathin, ultrasmall inorganic LEDs and interconnecting them using thin-film processing, we can create general lighting and high-resolution display systems that otherwise could not be built with the conventional ways that inorganic LEDs are made, manipulated and assembled,” Rogers said.

To overcome requirements on device size and thickness associated with conventional wafer dicing, packaging and wire bonding methods, the researchers developed epitaxial growth techniques for creating LEDs with sizes up to 100 times smaller than usual. They also developed printing processes for assembling these devices into arrays on stiff, flexible and stretchable substrates.

As part of the growth process, a sacrificial layer of material is embedded beneath the LEDs. When fabrication is complete, a wet chemical etchent removes this layer, leaving the LEDs undercut from the wafer, but still tethered at anchor points.

To create an array, a rubber stamp contacts the wafer surface at selected points, lifts off the LEDs at those points, and transfers them to the desired substrate.

“The stamping process provides a much faster alternative to the standard robotic ‘pick and place’ process that manipulates inorganic LEDs one at a time,” Rogers said. “The new approach can lift large numbers of small, thin LEDs from the wafer in one step, and then print them onto a substrate in another step.”

By shifting position and repeating the stamping process, LEDs can be transferred to other locations on the same substrate. In this fashion, large light panels and displays can be crafted from small LEDs made in dense arrays on a single, comparatively small wafer. And, because the LEDs can be placed far apart and still provide sufficient light output, the panels and displays can be nearly transparent. The thin device geometries allow the use of thin-film processing methods, rather than wire bonding, for interconnects.

In addition to solid-state lighting, instrument panels and display systems, flexible and even stretchable sheets of printed LEDs can be achieved, with potential use in the health-care industry.

“Wrapping a stretchable sheet of tiny LEDs around the human body offers interesting opportunities in biomedicine and biotechnology,” Rogers said, “including applications in health monitoring, diagnostics and imaging.”

Rogers is affiliated with the Beckman Institute, the department of mechanical science and engineering, the Frederick Seitz Materials Research Laboratory, and the Micro and Nanotechnology Laboratory.

Ford Motor Co., the National Science Foundation and the U. S. Department of Energy funded the work.

James E. Kloeppel | University of Illinois
Further information:
http://www.illinois.edu

More articles from Physics and Astronomy:

nachricht Subnano lead particles show peculiar decay behavior
25.04.2018 | Ernst-Moritz-Arndt-Universität Greifswald

nachricht Getting electrons to move in a semiconductor
25.04.2018 | American Institute of Physics

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Getting electrons to move in a semiconductor

25.04.2018 | Physics and Astronomy

Reconstructing what makes us tick

25.04.2018 | Physics and Astronomy

Cheap 3-D printer can produce self-folding materials

25.04.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>