APPLICATIONS OF TECHNOLOGY:
- Displays for consumer electronics, digital video and medical imaging devices
- Displays for architectural and automobile windows and flexible plastics
- OLEDs for lighting
- Significantly improved OLED performance at reduced drive voltages due to
- enhanced charge injection efficiency and
- more balanced charge distribution
- Increased OLED device lifetime
- Capable of scale-up manufacturing–either “top-down” or “bottom-up” processing
- Enables the use of flexible substrates
Scientists at Berkeley Lab have modified the cathode-organic layer of an OLED device to significantly enhance electron injection efficiency and reduce the sensitivity of the cathode to environmental degradation by water and oxygen. Two approaches are used:
An ordered arrangement of nanostructures (top-down processing) or
A nanomaterial interfacial layer (bottom-up processing).
This technology represents a significant improvement over existing technology. Currently, the interface between an OLED device’s cathode and organic layer is a resistant barrier that inhibits the efficient flow of electrons. This barrier can also create heating that damages the OLED. Additionally, low work function metals used to reduce operating voltage and improve device yield are physically and chemically unstable and difficult to fabricate into a thin layer.
The Air-stable Nanostructured Electrodes promise to significantly reduce the drive voltage necessary to induce light emission inside organic materials and will thereby increase the energy conversion efficiency of the OLEDs. The ordered arrangements of nanostructures or nanomaterials to enhance charge injection efficiently overcome the large energy barrier at the cathode-organic layer interface. Charge balance between holes and electrons is improved, a steeper rise in current as a function of voltage is realized, and electrical-optical conversion efficiency is increased.
Using less reactive materials makes the cathode more resistant to degradation than conventional metal electrodes. This feature increases OLED device lifetime, simplifies packaging requirements and makes it amenable to scale-up manufacturing processes.
- Published US Patent Application 12/297,615 available at www.uspto.gov. Available for licensing or collaborative research.
To learn more about licensing a technology from LBNL see http://www.lbl.gov/Tech-Transfer/licensing/index.html.
FOR MORE INFORMATION:
Liu, Deang; Fina, Michael; Guo, Jinghua; Chen, Xiaobo; Liu, Gao; Johnson, Stephen G.; Mao, Samuel S.; “Organic Light-Emitting Diodes with Carbon Nanotube Cathode-Organic Interface Layer,” Applied Physics Letters, 94, 013110 (2009) .
REFERENCE NUMBER: IB-2231
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