Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Nanotech OLED electrode liberates 20% more light, could slash display power consumption: A five-nanometer-thick layer of silver and copper outperforms conventional indium tin oxide without adding cost

Abstract:
A new electrode that could free up 20% more light from organic light-emitting diodes has been developed at the University of Michigan. It could help extend the battery life of smartphones and laptops, or make next-gen televisions and displays much more energy efficient.

Nanotech OLED electrode liberates 20% more light, could slash display power consumption: A five-nanometer-thick layer of silver and copper outperforms conventional indium tin oxide without adding cost

Ann Arbor, MI | Posted on June 29th, 2021

The approach prevents light from being trapped in the light-emitting part of an OLED, enabling OLEDs to maintain brightness while using less power. In addition, the electrode is easy to fit into existing processes for making OLED displays and light fixtures.

"With our approach, you can do it all in the same vacuum chamber," said L. Jay Guo, U-M professor of electrical and computer engineering and corresponding author of the study.

Unless engineers take action, about 80% of the light produced by an OLED gets trapped inside the device. It does this due to an effect known as waveguiding. Essentially, the light rays that don't come out of the device at an angle close to perpendicular get reflected back and guided sideways through the device. They end up lost inside the OLED.

A good portion of the lost light is simply trapped between the two electrodes on either side of the light-emitter. One of the biggest offenders is the transparent electrode that stands between the light-emitting material and the glass, typically made of indium tin oxide (ITO). In a lab device, you can see trapped light shooting out the sides rather than traveling through to the viewer.

"Untreated, it is the strongest waveguiding layer in the OLED," Guo said. "We want to address the root cause of the problem."

By swapping out the ITO for a layer of silver just five nanometers thick, deposited on a seed layer of copper, Guo's team maintained the electrode function while eliminating the waveguiding problem in the OLED layers altogether.

"Industry may be able to liberate more than 40% of the light, in part by trading the conventional indium tin oxide electrodes for our nanoscale layer of transparent silver," said Changyeong Jeong, first author and a Ph.D. candidate in electrical and computer engineering.

This benefit is tricky to see, though, in a relatively simple lab device. Even though light is no longer guided in the OLED stack, that freed-up light can still be reflected from the glass. In industry, engineers have ways of reducing that reflection--creating bumps on the glass surface, or adding grid patterns or particles that will scatter the light throughout the glass.

"Some researchers were able to free up about 34% of the light by using unconventional materials with special emission directions or patterning structures," Jeong said.

In order to prove that they had eliminated the waveguiding in the light-emitter, Guo's team had to stop the light trapping by the glass, too. They did this with an experimental set-up using a liquid that had the same index of refraction as glass, so-called index-matching fluid--an oil in this case. That "index-matching" prevents the reflection that happens at the boundary between high-index glass and low-index air.

Once they'd done this, they could look at their experimental set-up from the side and see whether any light was coming sideways. They found that the edge of the light-emitting layer was almost completely dark. In turn, the light coming through the glass was about 20% brighter.

The finding is described in the journal Science Advances, in a paper titled, "Tackling light trapping in organic light-emitting diodes by complete elimination of waveguide modes."

This research was funded by Zenithnano Technology, a company that Guo co-founded to commercialize his lab's inventions of transparent, flexible metal electrodes for displays and touchscreens.

The University of Michigan has filed for patent protection.

The device was built in the Lurie Nanofabrication Facility.

####

For more information, please click here

Contacts:
Katherine McAlpine


@umich

Copyright © University of Michigan

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 Links

Guo group

Related News Press

News and information

Getting to the root of tooth replantation challenges: Researchers from Tokyo Medical and Dental University (TMDU) report a delivery system that promotes healing in tooth replantation in rats September 17th, 2021

Researchers reveal multi-path mechanism in electrochemical CO2 reduction September 17th, 2021

Scientists demonstrate pathway to forerunner of nanotubes that could lead to widespread industrial fabrication September 17th, 2021

Silver nanoparticles boost performance of microbial fuel cells September 17th, 2021

Display technology/LEDs/SS Lighting/OLEDs

New substance classes for nanomaterials: Nano spheres and diamond slivers made of silicon and germanium: Potential applications as nano semiconductor materials September 10th, 2021

Controlling chaos in liquid crystals, gaining precision in autonomous technologies August 6th, 2021

Graphene nanotubes revolutionize touch screen use for prosthetic hands August 3rd, 2021

Removing the lead hazard from perovskite solar cells July 16th, 2021

Possible Futures

New nano particles suppress resistance to cancer immunotherapy September 17th, 2021

New physics research reveals fresh complexities about electron behavior in materials September 17th, 2021

Scientists demonstrate pathway to forerunner of nanotubes that could lead to widespread industrial fabrication September 17th, 2021

Silver nanoparticles boost performance of microbial fuel cells September 17th, 2021

Discoveries

Ultrasound at the nanometre scale reveals the nature of force September 17th, 2021

A simple way to get complex semiconductors to assemble themselves: Much like crystallizing rock candy from sugar syrup, the new method grows 2D perovskites precisely layered with other 2D materials to produce crystals with a wide range of electronic properties September 17th, 2021

Getting to the root of tooth replantation challenges: Researchers from Tokyo Medical and Dental University (TMDU) report a delivery system that promotes healing in tooth replantation in rats September 17th, 2021

Researchers reveal multi-path mechanism in electrochemical CO2 reduction September 17th, 2021

Announcements

Getting to the root of tooth replantation challenges: Researchers from Tokyo Medical and Dental University (TMDU) report a delivery system that promotes healing in tooth replantation in rats September 17th, 2021

Researchers reveal multi-path mechanism in electrochemical CO2 reduction September 17th, 2021

Scientists demonstrate pathway to forerunner of nanotubes that could lead to widespread industrial fabrication September 17th, 2021

Silver nanoparticles boost performance of microbial fuel cells September 17th, 2021

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

New nano particles suppress resistance to cancer immunotherapy September 17th, 2021

New physics research reveals fresh complexities about electron behavior in materials September 17th, 2021

Good for groundwater – bad for crops? Plastic particles release pollutants in upper soil layers: The environmental geoscientists at the Centre for Microbiology and Environmental Systems Science (CMESS) focused on a variety of parameters that contribute to plastic pollution in far September 17th, 2021

Ultrasound at the nanometre scale reveals the nature of force September 17th, 2021

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Lehigh University to lead ‘integrative partnerships’ for multi-university research collaboration in advanced optoelectronic material development: 5-year, $25 million NSF investment in IMOD, a revolutionary center for optoelectronic, quantum technologies September 10th, 2021

Leibniz Prize winner Professor Dr. Oliver G. Schmidt moves to Chemnitz University of Technology: President Professor Dr. Gerd Strohmeier refers to an 'absolute top transfer' September 10th, 2021

New molecular device has unprecedented reconfigurability reminiscent of brain plasticity: Device can be reconfigured multiple times simply by changing applied voltage September 3rd, 2021

Rice physicists find 'magnon' origins in 2D magnet: Topological feature could prove useful for encoding information in electron spins September 3rd, 2021

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project