Big Advance in OLED Lighting Might Signal Beginning of the End for the Bulbs

By Eliza Strickland | May 15, 2009 1:55 pm

OLEDsThe up-and-coming electronics technology known as organic light-emitting diodes (OLEDs) has spent the week in the, yes, spotlight. Earlier this week researchers announced that they had joined OLEDs to a rubbery conductor to make a computer display screen that could be bent, folded, and crumpled. Now, another team has tweaked OLEDs to make ultra-efficient panels that produce a white light similar to that produced by traditional incandescent light bulbs. Study coauthor Karl Leo says some big technical hurdles still need to be overcome, but adds: “I’m pretty convinced that in a few years OLEDs will be a standard in buildings” [BBC News].

Incandescent lighting is being phased out in some parts of the world because it isn’t energy efficient, and it’s being replaced by compact fluorescent bulbs or light-emitting diode (LED) fixtures. But with both fluorescent and LED lighting, the quality of white light produced has always left something to be desired. Fluorescent lighting can make people appear unhealthy because less red light is emitted, while most white LEDs on the market today have a bluish quality, making them appear cold [Technology Review]. In contrast, OLEDs, which are made from organic compounds that emit light when electricity is passed through them, can provide a nice white light, but efficiency problems have held the technology back.

As the researchers explain in a paper in Nature, their modifications boosted OLED’s efficiency past that of traditional lighting sources. Their improved device yielded 90 lumens (a measurement of brightness) per watt of electricity consumed…. This compared to 15 lumens for a conventional incandescent light bulb and between 50 and 70 lumens per watt for modern compact fluorescent light bulbs [AFP]. They produced the efficiency gain with a series of technical adjustments. One trick was to make the outer surfaces of the device from types of glass that have optical properties that more closely match those of the device substrate. Otherwise, much of the emitted light is reflected and either reabsorbed or lost through heat. “In conventional structures, about 80 percent of the light is lost,” [Technology Review], says study coauthor Sebastian Reineke.

But the technology still faces several large obstacles:. Just like previous white OLEDs, the devices degrade within an hour or two, because the polymers that produce the blue part of the light are unstable. However, Professor Leo said that promising first results on stable, phosphorescent blue polymers are starting to emerge. “I’m personally convinced that it may take a few years, but chemists will solve this problem and find materials which are stable enough,” he said [BBC News]. OLEDs are also expensive to produce, but researchers hope that the material can soon be produced in large sheets, making it commercially viable.

Related Content:
80beats: Rubbery Computer Screens Can Be Bent, Folded, and Even Crumpled
DISCOVER: Future Tech shows why the light bulb is becoming as quaint as a vacuum tube

Image: F. Erler / N. Seidler

CATEGORIZED UNDER: Technology
  • http://clubneko.net Nick

    Incandescent lights DO NOT produce white light. They produce warm yellow light unless the inside has been coated with phosphor to absorb the light and fluoresce white – basically the same way fluorescents produce white except it’s not a charged gas making the fluorescent, just the heat and light of the incandescent filament.

    And anyone can go out and buy a “daylight” spectrum compact fluorescent bulb and overcome the ‘dead person’ problem of fluorescents. 5500 kelvin in the spectrum they put out, same as the sun. I’ve been using them for years, and they’re amazingly better than any incandescent or inferior CFL – and even if they’re 4, 5, or 7 dollars each you STILL save money over incandescents.

    But hey, since OLEDs consume less energy than either of those two, I for one can’t wait to welcome our new OLED overlords.

  • Chris

    A few issues with this blog entry and Nick’s reply post:

    1 – Incandescent lights CAN produce white light. Halogen lamps (which are a subset of incandescents) do produce white light by operating at much higher temperatures.
    2 – Incandescent lamps that have a white interior coating DO NOT phosphoresce. The coating is merely to mask the appearance of the lamp filament, and does not actually convert energy into light
    3 – The fluorescent lamps of the 60s and 70s did give things a nasty blue/green pallor, but modern triphosphor lamps (available and widespread since the early 90s) have improved chemical recipes and are not lacking in the red portion of the visible spectrum.
    4 – white LEDs are now available with color temperatures in the 3000-3500K range (standard “warm white” in North America) with color rendering above 85, as good as the best conventional sources.

    Also, Nick, “daylight” spectrum lamps are a gigantic rip-off. They’re just high color temperature (read: blue-white) lamps that have been relabelled and marked up 300-500 percent.

  • http://www.oled-info.com/oled-light Ron Mertens

    Philips actually see color-tunable OLEDs within 3-5 years:

    http://www.oled-info.com/philips-sees-tunable-color-and-transparent-oleds-3-5-years-flexible-ones-5-8

    So you can choose the color of your light, anyway you want…

    Ron

  • http://www.sbizgroup.com Herb Rubenstein

    Check out pain reduction systems using OLED from http://www.biocaresystems.com. They are great people who developed the company and are now looking for a distributor/reseller/manufacturer. They have patents and FDA approval!!! Contact me at herb@sbizgroup.com if you have any sugggestions. Herb Rubenstein

  • Michael

    While this is great and all it’s hardly news… higher efficiency white OLEDs (102lm/W) have been demonstrated over a year ago by Universal Display Corporation. See here: http://www1.eere.energy.gov/buildings/ssl/highlights_udc08.html

  • http://www.arnoarts.blogspot.com Arnold L. Johnson

    Warning Will Robinson!! I am pumped about OLEDs but I have reservations because what we will do is tack a 120AC converter circuit onto them so that we can still use grid power, that is why LED bulbs are so expensive, I think (tell me it ain’t so!). The light socket has been with us since Edison, time to retire an icon.

    I would introduce a separate low power lighting circuit similar to what is in RVs to be put in regular homes, have a single power converter and the ability to run lights with solar/wind/batteries. Now OLEDs could really save money and maybe even get off grid without lowering the quality of life.

    Then we will fold, spindle and mutilate OLEDs until they take the form of the antique and retro standard lighting we are use to. That dining room chandelier in the 50-75 year old house does not go away. What about the table lamp with a shade? Perhaps we could just use an OLED in place of the shade, then the base can be anything!?! I hope we don’t see more junk jewellery for the room (but we will).

    What I want is bright clean light, without the flicker of fluorescents (makes my wife sick). And quit calling those twisty ice-cream sundae looking mercury laden fluorescent bulbs green just because they save energy.

    You can put OLEDs in every place of work in America, but you won’t get the high-five until it hits average home owners where they live. Still, it is great to see folks doing something about the user side of the energy equation.

  • Crossi

    Philips made a great job with his Lumiblades.
    Check http://www.oledgadgets.com/oled-lighting.html

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