Thursday, 31 October 2013 12:07

Materials Day: Phosphorescent OLEDs

    Phosphorescent Organic LEDs (PHOLEDs) are leading a new generation of vivid color and depth perspective in televisions, according to Dr. Michael S. Weaver, director of PHOLED Applications Engineering and Development, for Ewing, N.J.-based Universal Display Corporation. Samsung uses organic LEDs in smart phone displays, and Samsung and LG have launched 55-inch OLED TVs. This year, OLEDs are a $10 billion industry and is forecast to rise $16 billion by 2014, Weaver said.

    M Weaver

    OLED television sales are also expected to grow to about 16 to 17 million units per year in about five years. Weaver spoke at the Materials Day Symposium, hosted by the Materials Processing Center, Oct. 23, 2013. The daylong symposium was held in Little Kresge Auditorium on the MIT campus.

    Phosphorescence incorporates a heavy metal atom into the organic LED material, which allows for from 100 percent light emitting efficiency compared to 25 percent for fluorescent devices. Making OLEDs with tight controls that keep out water and oxygen result in a significantly longer lifetime. “You don’t want impurities in your device whether they be from water, oxygen, impurities in organics; if you take all of those out of the system you will get significantly longer lifetime,” Weaver said. Current PHOLEDS have 400,000 to 1.5 million hours of operating lifetime.

    PHOLEDs can also be used in lighting applications, but with different cost structure than for TV. “You really need to use legislation to stop them (consumers) from buying incandescents,” Weaver said. Compared to other lighting technologies, OLEDs cover a much larger area, so one could imagine a future design in which the lampshade could be the bulb instead of a cover surrounding a bulb. In contrast to displays, where resolution is an issue, with solid-state lighting applications, the use of performance enhancing outcoupling can be used as blurring of the emitting surface isn’t an issue.

    The OLED display industry is well established, the challenge for the OLED lighting industry is to be cost effective as well., and Weaver suggested that is an area where academia and industry can join together from a performance metric and cost perspective. “We want to get to 120 lumens per watt,” Weaver said. Universal Display Corp. has received support for its work in solid-state lighting from the U.S. Department of Energy.

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    Last modified on Thursday, 31 October 2013 16:00