Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Organic light-emitting diodes

08.11.2011
Research highlights energy efficient solutions for display and lighting applications

The search for innovative, cost-effective and energy-efficient solutions for display and lighting applications are the focus of ongoing intense worldwide photonics research and development activities.

Organic light-emitting diodes (OLEDs)—lightweight, potentially flexible, cheap-to-fabricate and highly energy-efficient lighting and display devices—offer one solution in alternative energy lighting and display applications. To highlight breakthroughs in this area, the Optical Society (OSA (http://www.osa.org)) today published a special Focus Issue on OLEDs (http://www.opticsinfobase.org/oe/issue.cfm?volume=19&issue=106) in Energy Express (http://www.opticsinfobase.org/ee), a bi-monthly supplement to its open access journal Optics Express (http://www.opticsinfobase.org/oe/home.cfm). The issue is organized and edited by Guest Editors Emil J.W. List of the NanoTecCenter Weiz GmbH and Graz University of Technology in Austria, and Norbert Koch of the Institute of Physics, Humbolt University in Germany.

"OLEDs are amongst the most promising candidates for alternative display and lighting solutions," said List. "The exciting findings presented in this focus issue will ultimately translate into real-world applications, providing consumers with cost-effective technology while reducing electricity consumption."

More than 20 percent of the world's total electricity consumption is used for lighting applications. That number increases to an estimated 25 percent when including display and TV applications. OLEDs, along with inorganic solid-state lighting technologies, are considered to be on the forefront of 21st century display and lighting technologies. The widespread use of this technology could save hundreds of gigawatt hours (GWh) of power or millions of tons of coal per year.

"OLEDs can be found in a variety of everyday products such as television screens, computer monitors and smartphones," said Koch. "As use of these products becomes more widespread, the need for research and development also grows. The latest advances reflected in this focus issue are truly exceptional and will prove to be invaluable to advancements in lighting and display technology."

Key Findings and Select Papers

The following papers are some of the highlights of the Energy Express Focus Issue on OLEDs. All are included in Volume 19, issue S6 and can be accessed online at http://www.opticsinfobase.org/ee.

The outcoupling of light from an OLED may be tackled by different means, including optical feedback structures in the active layer, by high index-media in top-emitting OLED, by lens or microlens-like arrays, or by using microcavity effects in the active device. As reviewed and discussed by Simone Hofmann, Karl Leo and their colleagues from the Institute for Applied for Photophysics, TU Dresden in Germany, in particular top-emitting OLEDs seem to be beneficial for lighting and display applications. Here, non-transparent substrates are used. The authors review and discuss different optical effects of the microcavity structure and identify important loss mechanisms due to waveguiding and surface plasmons, and show that further improvement in light extraction is required to reach the targeted high outcoupling efficiencies.

Paper: "Top-Emitting Organic Light-Emitting Diodes (http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-19-106-A1250)," Optics Express, Vol. 19, Issue S6, pp. A1250-A1264 (2011).

A very practical approach to improve the outcoupling efficiency in OLEDs up to 60 percent is demonstrated by Ruth Shinar and Joseph Shinar from the U.S. Department of Energy's Ames Laboratory and Iowa State University, and coworkers, using index-matching microporous phase-separated films of polymer blends acting as random microlens-like arrays. They demonstrate that the use of such blended thin films provides an economical method independent of the OLED fabrication technique, for improving outcoupling.

Paper: "Microporous phase-separated films of polymer blends for enhanced outcoupling of light from OLEDs (http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-19-106-A1272)," Optics Express, Vol. 19, Issue S6, pp. A1272-A1280 (2011).

To overcome the losses at the organic layer/cathode interface and to optimize the optical path in the devices, Lian Duan, Yong Qiu and their colleagues from the Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, and the R&D Center, Visionox Tech. Ltd, Beijing, introduce an approach by using a novel, rather thick, n-doped layer. Using a combination of a low-temperature-evaporable n-dopant KBH4 and a high charge carrier mobility electron transport material they show excellent performance of their devices due to reduced losses at the organic layer/cathode interface.

Paper: "Improving the performance of OLEDs by using a low-temperature-evaporable n-dopant and a high-mobility electron transport host (http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-19-106-A1265)," Optics Express, Vol. 19, Issue S6, pp. A1265-A1271 (2011).

About Energy Express

As a special bi-monthly supplement to Optics Express, Energy Express is dedicated to rapidly communicating new developments in optics for sustainable energy. Energy Express will have original research side-by-side with review articles written by the world's leading experts in the science and engineering of light and its impact on sustainable energy development, the environment, and green technologies. For more information, see: http://www.OpticsInfoBase.org/EE.

About Optics Express

Optics Express reports on new developments in all fields of optical science and technology every two weeks. The journal provides rapid publication of original, peer-reviewed papers. It is published by the Optical Society and edited by C. Martijn de Sterke of the University of Sydney. Optics Express is an open-access journal and is available at no cost to readers online at http://www.OpticsInfoBase.org/OE.

About OSA

Uniting more than 130,000 professionals from 175 countries, the Optical Society (OSA) brings together the global optics community through its programs and initiatives. Since 1916 OSA has worked to advance the common interests of the field, providing educational resources to the scientists, engineers and business leaders who work in the field by promoting the science of light and the advanced technologies made possible by optics and photonics. OSA publications, events, technical groups and programs foster optics knowledge and scientific collaboration among all those with an interest in optics and photonics.

Angela Stark | EurekAlert!
Further information:
http://www.osa.org

More articles from Power and Electrical Engineering:

nachricht Anode material for safe batteries with a long cycle life
06.08.2020 | Karlsruher Institut für Technologie (KIT)

nachricht ETRI develops eco-friendly color thin-film solar cells
31.07.2020 | National Research Council of Science & Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: ScanCut project completed: laser cutting enables more intricate plug connector designs

Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.

Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...

Im Focus: New Strategy Against Osteoporosis

An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.

Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...

Im Focus: AI & single-cell genomics

New software predicts cell fate

Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...

Im Focus: TU Graz Researchers synthesize nanoparticles tailored for special applications

“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.

Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...

Im Focus: Tailored light inspired by nature

An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.

Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“Conference on Laser Polishing – LaP 2020”: The final touches for surfaces

23.07.2020 | Event News

Conference radar for cybersecurity

21.07.2020 | Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

 
Latest News

Rare Earth Elements in Norwegian Fjords?

06.08.2020 | Earth Sciences

Anode material for safe batteries with a long cycle life

06.08.2020 | Power and Electrical Engineering

Turning carbon dioxide into liquid fuel

06.08.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>