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Unformatted text preview: CREDIT:J.KIDO/YAMAGATA UNIVERSITY 16 DECEMBER 2005 VOL 310 SCIENCE www.sciencemag.org 1762 B OSTON If you want to save the world, you might start by getting rid of the light bulb. In the United States alone, lighting sucks up more than 6 quadrillion BTUs of energy every year, 17% of all the energy used in buildings. Incandescent bulbs turn about 90% of that energy into not light but heat. Fluorescents do better, converting 70% of the energy they use into light. But researchers have spent decades working to create novel semiconductor-based light-emitting diodes (LEDs) that do even better. Red LEDs and other colors made from inorganic com- pounds are already in widespread use in traffic lights, car taillights, and other niche applications. Inorganic white LEDs are also on the market. But so far, all of them remain too costly for general lighting use. Now a new competitor is coming on strong. At a recent meeting of the Materials Research Society * here, researchers from Japan, Germany, and the United States reported steady progress in turning thin organic films into high-efficiency lights. Because such films are likely to be made with inexpensive organic starting materi- als, they are potentially very cheap to man- ufacture, even in large panels. That day isnt here yet, but with prototype products already in development, the first white organic light-emitting diodes (OLEDs) for general lighting are expected to hit the market in 2007. The efficiency of these new OLEDs is moving up quite fast, says Stephen Forrest, an OLEDs researcher at Princeton University. That pace of improvement has recently caught the attention of numerous lighting companies, which are also pushing the tech- nology forward. No one cared about [white OLEDs] until a few years ago, says Anil Duggal, an OLED researcher at General Electric in Niskayuna, New York. Duggal says most of the interest in OLEDs until now has been for making flat-panel displays for everything from cell phones to wall-sized televisions. Thats partly because the display market, which brings in about $100 billion a year worldwide, is twice the size of the light- ing market. For displays, OLEDs also had the advantage of being ultrathin, a feature many experts believe will command a pre- mium on the market and compensate for the fact that the early devices had relatively poor efficiency. But to compete in the lighting market, where their sleek appearance isnt as critical, OLEDs had to become both better and cheaper. You need higher efficiency and brightness for lights, in order for OLEDs to carve out a niche in the market, Duggal says. Now, there is impressive progress on both fronts....
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This note was uploaded on 07/17/2011 for the course EMA 4666c taught by Professor Brennan during the Spring '08 term at University of Florida.
- Spring '08