September 5, 2006 4:00 AM PDT
Tripping the lights organic
The Ewing, N.J., company--along with General Electric, Osram Opto Semiconductors and others--is tinkering with the idea of transforming organic light-emitting diodes (OLEDs), thin sheets of plastic that emit light, into a source of room lighting.
Pioneer and Samsung Electronics already use OLEDs for screens on consumer electronics products. By increasing the size of the sheets and the brightness, researchers think the material could become an energy-efficient substitute for the hoary incandescent bulb. OLED lighting--organic because the films that emit light contain hydrogen and carbon atoms--could be incorporated into fabrics, furniture and other items.
"The dream is to get to the point where you can roll out OLEDs or stick them up like Post-it notes," said Janice Mahon, vice president of technical commercialization at Universal Display.
One of the more interesting ideas is the "transparent window." By day, it would function like a regular clear plastic window. Flick a switch and it becomes a light fixture. Besides the novelty factor, the transparent window could cut energy costs by switching dynamically when sunlight will suffice. (Other companies are examining ways to slightly modulate window tone to conserve on heating and air conditioning.)
The company so far has made transparent light sources and prototypes of transparent displays.
Rising energy prices, combined with fears about climate change, are breathing new life into markets and ideas that a few years ago seemed quaint and forgotten. The electric car and ethanol are now debated as credible alternatives to traditional gas-burning cars. Several companies have begun to tout new battery technologies. Solar power has gone from a commune favorite to become the darling of venture capitalists.
Room lights are no exception. Approximately 22 percent of the electricity consumed in the United States goes toward lighting, according to the U.S. Department of Energy. It's a $58-billion-a-year bill and growing. Through its solid-state lighting research program, the energy department hopes to develop commercially acceptable lights that will need 50 percent less electricity by 2025.
Fiberstars of Solon, Ohio, and Sunlight Direct, of Oak Ridge, Tenn., have come up with ways to deploy high-intensity light and sunlight, respectively, through plastic fiber-optic cables. Some semiconductor manufacturers, meanwhile, are touting light-emitting diodes for lighting up rooms and cars.
The problem with modern lighting, say Mahon and others, is the bulb itself. Incandescent bulbs generate about 10 to 15 lumens of light per watt. Most of the energy delivered to a lightbulb doesn't get translated into light: It turns into heat, a quality really only appreciated by buffet managers and Easy-Bake oven owners.
OLED lighting could drastically reduce that. Last month, Universal Display showed off experimental white OLEDs covering a 25-centimeter square panel that generated 31 lumens per watt. That bested the record held by rival Osram at 25 lumens per watt.
A major breakthrough for OLED lighting occurred a few years ago when researchers at Princeton, the University of Southern California and Universal Display published a paper demonstrating how, from the perspective of fundamental physics, nearly 100 percent of the energy in OLEDs could be converted into light.
"Previously, people thought only a quarter of the electricity could be converted. Now you can convert up to 100 percent of it," Mahon said.
So far, the company has shown prototypes that boost the conversion rate past 30 percent. It's working with USC and the University of Michigan on a prototype that will convert 50 percent of the energy.
Generating a shade of white light out of OLEDs that is tolerable to humans has also mostly been achieved. White gets produced by combining red, green and blue OLEDs. For years, the quality of the blue light was the limiting factor.
Unfortunately, OLEDs, because they are organic, degrade over time.
"The goal is to get to 20,000 hours with 800 to 1,000 nits," Mahon said. It's closer to 10,000 now. (A nit is a measure of how many light rays strike a square meter.)
Manufacturing costs will also have to come down. Simply put, OLEDs for mobile phone screens command far higher prices than ones for lightbulbs, though both are processed in similar ways. Thus, until manufacturing becomes more widespread, companies will concentrate on producing components.
Nonetheless, lighting and OLED manufacturers have begun to contemplate the sort of frame, mounting structure and electrical connections for OLED lighting systems. Prototypes of architectural OLED lights could emerge in two or three years.
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