A light with a bright future

Light bulbs have blazed for more than 125 years, and people still can't seem to get enough of them. Priced at less than a dollar apiece, and screwed into billions of sockets worldwide, these glowing little orbs have changed the way humanity works and plays, turning night into day. But as energy costs soar, the future of the traditional incandescent light bulb is beginning to dim.

Futuristic solid-state lighting has already crept into consumer goods, such as cellphone screens and desk lamps. Light-emitting diodes (LEDs) and their cousins, organic light-emitting diodes (OLEDs), are two developing light sources beginning to beam into homes and offices. LEDs are showing up in night lights, flashlights, outdoor pathway lights, and Christmas lights. OLEDs are not as prevalent, but cellphones, notebook computers, and TVs made with them are moving from prototypes into products.

Those involved in lighting research say these new technologies will revolutionize the way we use lighting over the next decade. Because they can be made into extremely thin, flexible glowing sheets, designers envision:

• Ultralight, wall-size TVs.

• Electronic newspapers that can be rolled up and constantly updated.

• Under-cabinet surfaces that glow to light up kitchen counters.

• Clothes with electronic displays woven into them.

• Windshields that display information for the driver.

• "Smart windows" that double as TVs or computer screens, or that let in light during the day and glow at night.

• Easily movable light-emitting panels or light walls for homes or offices. The white light could be turned to "cooler" or "warmer" shades of color as desired.

• "Smart" goggles or helmets with displays for soldiers, police, or scuba divers.

LEDs, an older technology, are about five to eight years ahead of OLEDs - which, unlike LEDs, use organic polymers, such as proteins and DNA, to create light, says Nadarajah Narendran, research director at the Lighting Research Center (LRC), Rensselaer Polytechnic Institute in Troy, N.Y.

"Some high-end homes are already using LED [lights] to improve aesthetics," he says. And OLEDs should rise from about 60 million units produced in 2005 to about 280 million in 2010, according to a forecast by semiconductor industry tracker iSuppli in El Segundo, Calif.

Both LEDs and OLEDs need to drastically lower their cost and increase their energy efficiency before they can threaten the light bulb. "Flat-panel displays [computer and TV screens] sell for a lot more than light bulbs," says Bill Feehery, business director of DuPont OLED Displays. That's why the new lighting technologies will be seen there first, he says. [Editor's note: The original version misidentified Mr. Feehery's title.]

Today's incandescent light bulb really should be called a heat lamp, since it gives off most of its energy as warmth. Incandescent bulbs emit 10 to 15 lumens of light per watt consumed. Fluorescent tubes are much more efficient, giving off 60 to 80 lumens per watt. OLEDs now produce 20 to 30 lumens per watt. The US Department of Energy has challenged the industry to produce OLEDs with 100 lumens per watt by early next decade.

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