Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Screens set to go green

22.08.2011
Electronic screens based on new energy-efficient technology could become more affordable thanks to the substitution of expensive metal components with copper ones

Fitting the screens of electronic devices, such as televisions and smartphones, with a new display technology called ‘organic light-emitting diodes’ (OLEDs) will reduce their energy consumption, but such screens currently require rare and expensive metal components. Now, Masahisa Osawa and his colleagues at the RIKEN Innovation Center in Wako, along with researchers from electronics company Canon, have found a way to replace these costly metals with copper.


The molecular structure of the bulky organic ligand that turns copper (green) into an efficient light emitter (yellow, phosphorus; red, bromine). Copyright : © 2011 Masahisa Osawa

In addition to offering significant energy savings over conventional LCD-based displays, OLED screens improve picture quality by producing richer blacks; they also offer a wider viewing angle. In an LCD screen, each pixel is effectively a little filter, selectively blocking light produced by a large backlight. In an OLED screen, however, each pixel is a tiny light emitter such that no backlight is needed. This means that pixels in dark areas of the image consume no power, reducing energy use.

To maximize the energy-saving benefit, screen makers select OLED materials that most efficiently convert electrical current into light, a property known as high external quantum efficiency (EQE). Some of the best materials are phosphorescent metal complexes, but these are typically composed of rare and expensive metals such as iridium.

Copper complexes have long been known as potential alternatives, and would cost 1/2,000th that of iridium phosphors, according to Osawa. Until the work of Osawa and his colleagues, however, these copper complexes had a low EQE. Such complexes can be readily excited into a high-energy state, but they tend to physically distort, which dissipates their extra energy rather than emitting it as light.

The researchers resolved this problem by altering the molecular environment in which the copper sits. They wrapped each copper ion inside a newly designed bulky organic ligand. They then conducted X-ray diffraction studies, which revealed that the ligand had forced the copper to become three-coordinate—it had formed three bonds to the ligand, rather than the usual four (Fig. 1).

Osawa and colleagues also demonstrated that the EQE of their green-light-emitting copper complex increased dramatically and matched that of iridium complexes. “The three-coordinate structure is a crucial factor for high EQE, because it hardly distorts in the excited state,” Osawa explains.

The team’s next step will be to deploy the complex in a working device. Copper might not be limited to producing green light, Osawa adds. “Our goal is to make red-, green-, and blue-colored phosphorescent three-coordinate copper materials.”

The corresponding author for this highlight is based at the Luminescent Materials Laboratory, RIKEN Research Cluster for Innovation

Reference:
Hashimoto, M., Igawa, S., Yashima, M., Kawata, I., Hoshino, M. & Osawa, M. Highly efficient green organic light-emitting diodes containing luminescent three-coordinate copper(I) complexes. Journal of the American Chemical Society 133, 10348–10351 (2011).

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6675
http://www.researchsea.com

More articles from Life Sciences:

nachricht Navigational view of the brain thanks to powerful X-rays
18.10.2017 | Georgia Institute of Technology

nachricht Separating methane and CO2 will become more efficient
18.10.2017 | KU Leuven

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>