Navigation Links
Novel LEDs pave the way to cheaper displays
Date:11/8/2013

OLEDs are already used in the displays of smart phones or digital cameras today. They offer an especially bright image with high contrast, but come with a serious drawback: typically, only one quarter of the electrical energy invested in running the device is actually converted into light. This ratio can be raised by adding traces of noble metals such as platinum or iridium to the active material, but these elements are rare and very expensive. Making high-quality OLEDs is therefore a rather costly business.

This could change in the near future. The scientists from Bonn, Regensburg and the US have demonstrated a novel type of OLED, which shows potential for high conversion efficiencies without having to resort to noble metals. OLED displays could well get quite a bit cheaper soon.

OLEDs aren't really "organic"

OLEDs are called so because, ideally, they are made up of organic molecules, which consist solely of carbon and hydrogen. The operating principle of an OLED is rather simple: a thin film of the molecules is contacted by electrodes, which are connected to a battery so that an electrical current can flow. This current is made up of positive and negative charges. When the charges meet, they annihilate, destroying each other in a flash of light.

Since positive and negative charges attract each other, generating light from electricity should be a pretty efficient business. The problem lies in the intricate quantum-mechanical nature of charges, which also posses a magnetic moment scientists call this the "spin". Charges with like spin repel each other, much as the north poles of two bar magnets do. This repulsion outweighs the attraction between positive and negative charges, so that different charges with like spin cannot generate light. Instead, they convert electrical energy into heat a rather exotic and not overly useful way of electrical heating.

In conventional OLEDs this loss of energy occurs frequently: three quarters of all charges carry the same spin. Much like the needle of a compass, they point in the same direction but cannot touch each other, effectively lowering the yield of useful light. OLED manufacturers have come up with a clever trick to raise the yield: they twirl the compass needles around with an even stronger magnet, allowing the charges to generate light after all. To do this requires heavy metals such as platinum or iridium, which allow virtually all of the electrical energy to be converted into light. Strictly speaking, conventional materials in OLEDs are not organic compounds at all, but metal-organic substances. This distinction is more than semantic in nature, since noble metals are extremely expensive.

Useful spin flip flops

"We can also raise the efficiency using a different mechanism", Dr. John Lupton, Professor of Physics at the University of Regensburg, explains. "Charges can flip the orientation of their spins spontaneously you just have to wait for long enough for this to occur." In conventional OLEDs, however, there is not enough time to do this since the electrical energy is not stored for long enough in the molecular architecture. Instead, the molecules give up and simply convert the energy to heat.

"It appears that, in our OLEDs, the molecules can store electrical energy for significantly longer than is conventionally assumed", notes chemists Professor Sigurd Hger of the University of Bonn. "Our molecules can therefore exploit the spontaneous jumps in spin orientation in order to generate light." The new compounds therefore hold potential to minimize electrical generation of heat in OLEDs without having to resort to any "metal-organic tricks", thereby converting the electrical energy very effectively into light.


'/>"/>

Contact: Dr. Sigurd Höger
hoeger@uni-bonn.de
49-228-736-127
University of Bonn
Source:Eurekalert  

Related biology news :

1. Novel technique for suturing tissue-engineered collagen graft improves tendon repair
2. Novel mutations define 2 types of bone tumor
3. NIH funds development of novel robots to assist people with disabilities, aid doctors
4. Mutations in novel tumor suppressor gene associated with early onset breast cancer
5. IRICoR and Université de Montréal license a novel program for early-onset morbid obesity to Pfizer
6. Novelty of eco-friendly bamboo garments lures consumers -- if the price is right, Baylor study shows
7. Novel mechanism discovered in first line of immune defense
8. Novel avian influenza A virus has potential for both virulence and transmissibility in humans
9. Researchers develop novel polymer to help oral medications reach the bloodstream
10. Novel approach to gene regulation can activate multiple genes simultaneously
11. Cancer scientists discover novel way gene controls stem cell self-renewal
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Novel LEDs pave the way to cheaper displays
(Date:6/3/2016)... LONDON , June 3, 2016 /PRNewswire/ ... Transport Management) von Nepal ... ,Angebot und Lieferung hochsicherer geprägter Kennzeichen, einschließlich ... weltweit führend in der Produktion und Implementierung ... an der Ausschreibung im Januar teilgenommen, aber ...
(Date:6/1/2016)... YORK , June 1, 2016 ... Technology in Election Administration and Criminal Identification to Boost ... to a recently released TechSci Research report, " Global ... By Region, Competition Forecast and Opportunities, 2011 - 2021", ... 24.8 billion by 2021, on account of growing security ...
(Date:5/12/2016)... 12, 2016 WearablesResearch.com , a brand ... overview results from the Q1 wave of its quarterly ... was consumers, receptivity to a program where they would ... health insurance company. "We were surprised to ... Michael LaColla , CEO of Troubadour Research, "primarily ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... 27, 2016   Ginkgo Bioworks , a leading ... was today awarded as one of the World ... world,s most innovative companies. Ginkgo Bioworks is engineering ... real world in the nutrition, health and consumer ... with customers including Fortune 500 companies to design ...
(Date:6/24/2016)... ... ... Researchers at the Universita Politecnica delle Marche in Ancona combed medical journal ... Their findings are the subject of a new article on the Surviving Mesothelioma website. ... the blood, lung fluid or tissue of mesothelioma patients that can help point doctors ...
(Date:6/23/2016)... 23, 2016 /PRNewswire/ - FACIT has announced the ... biotechnology company, Propellon Therapeutics Inc. ("Propellon" or ... of a portfolio of first-in-class WDR5 inhibitors for ... as WDR5 represent an exciting class of therapies, ... medicine for cancer patients. Substantial advances have been ...
(Date:6/23/2016)... SANTA MONICA, Calif. , June 23, 2016  The Prostate Cancer ... to pioneer increasingly precise treatments and faster cures for prostate cancer. Members of ... 77 institutions across 15 countries. Read More About the ... ... ...
Breaking Biology Technology: