New fluorescent OLEDs display greater efficiencies than believed possible

March 24, 2011, University of Michigan

(PhysOrg.com) -- University of Michigan engineering researchers have designed an exceptionally efficient fluorescent blue OLED, or organic light emitting diode.

OLEDs are the next generation display technology. They are already used in televisions, cell phones and computers, and they are candidates for a vast array of light sources from advertising billboards to indoor and outdoor illumination. Fluorescent OLEDs are typically less efficient at emitting light per unit area than their phosphorescent counterparts.

That may be changing, according to new findings by professor John Kieffer and graduate student Changgua Zhen of the Department of Materials Science and Engineering. They released findings in the journal that shattered previous records. Traditionally, the ceiling for the efficiency of fluorescent OLEDs was believed to be 5 percent. Now, Kieffer and his collaborators have produced fluorescent OLEDs with close to 10 percent efficiency.

"Our results clearly indicate that fluorescent material have a bright future for highly efficient and stable OLEDs for flat-panel display and lighting applications," Kieffer said.

This was accomplished by redesigning a material being utilized by U-M collaborators in Singapore using .

"With the material, they had some positive results," Kieffer said. "We took those molecules and started to reconfigure them in a , adding different in a systematic way. We identified the mechanisms that control the performance of OLEDs, and by applying the fundamental understanding so obtained we improved the materials characteristics. Our research demonstrated the importance of simulation-based predictive design."

Explore further: High-brightness breakthrough

More information: The paper is called: "Achieving Highly Efficient Fluorescent Blue Organic Light-Emitting Diodes Through Optimizing Molecular Structures and Device Configuration" onlinelibrary.wiley.com/doi/10 … /adfm.201002165/full

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4 comments

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Kingsix
not rated yet Mar 24, 2011
Just give those OLEDs a cup of coffee every morning. I find it makes me more efficient.

On a serious note, the efficiency of our technology sucks. I can't imagine how much energy our world would save if our lighting, heating, cooling etc could all reach even 50% efficiency.
kaasinees
not rated yet Mar 24, 2011
im pretty sure OLEDs can reach atleast 30%
PinkElephant
not rated yet Mar 25, 2011
im pretty sure OLEDs can reach atleast 30%
I don't think so. The highest current white LED efficiency is about 15%, and most are below that. And this is inorganic LEDs; OLEDs have much worse efficiencies. Theoretical max with current inorganic designs is somewhere around 44%:

http://en.wikiped...ficiency

Also, it turns out that it matters how much current is passing through an LED. The higher the current, the lower is the efficiency. I suspect the results reported above were achieved at very low currents (much lower than would be used for lighting applications, but adequate for cell phone displays and such.)
materialsdave
not rated yet Mar 30, 2011
If you're interested in the science behind the story, you can access the original paper for free via MaterialsViews.com: http://ow.ly/4ppgW

Dave Flanagan
Editor, Advanced Functional Materials

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