Cheaper LEDs to light a green path?

Using plastic could help light-emitting diodes sell for less and compete with power-hungry traditional bulbs, company says.

Michael Kanellos Staff Writer, CNET News.com
Michael Kanellos is editor at large at CNET News.com, where he covers hardware, research and development, start-ups and the tech industry overseas.
Michael Kanellos
3 min read
The future of light is plastic, Cyberlux says.

The company, which specializes in light-emitting diodes, plans to reveal in about four months prototypes of a new style of white-light LEDs that would both cost substantially less to manufacture and provide more light than conventional LEDs.

Combined, the two advantages would enable light fixtures based on LEDs, which are now relatively expensive, to better compete with traditional lamps based on conventional glass bulbs and fluorescent lights, according to Cyberlux President Mark Schmidt.

"We estimate that the cost and efficiency could be better than fluorescent."
--Mark Schmidt, president, Cyberlux

Consumers currently have to pay more than $5 for a basic LED-lighting chip, he said. To be able to use it in a flashlight or lamp, they have to pay another $10 or so for connectors and other parts.

"We estimate that the cost and efficiency could be better than fluorescent," he said. Schmidt, an IBM computing veteran, likened the movement toward LEDs in the light industry to what happened with computers in the 1970s and 1980s.

The new style of LEDs is based on technology licensed from the University of California at Santa Barbara and Rensselaer Polytechnic Institute.

In conventional white-light LEDs, a semiconductor emits blue light. The blue light passes through the phosphor and becomes white light. The phosphor is thin film on a substrate; the substrate has to be placed in intricate proximity to the semiconductor. Positioning the phosphor is one of the more expensive steps in creating an LED, Schmidt said.

In the coming prototype, the conventional phosphor is replaced with a sheet of polymer, which sort of applies itself to the LED, almost like a layer of shrink wrap. The technology was invented by UC Santa Barbara's Steven DenBaars, who has been a big advocate of LED lighting as a way to increase energy efficiency and reduce greenhouse gases, and Nobel Prize winner Alan Heeger. Heeger also helped found solar-technology company Konarka Technologies.

The switch to a polymer does mean that other aspects of the LED must be changed. LEDs emit heat, which can melt plastic. Thus, the LEDs with polymer phosphors will have to be larger than conventional ones so the heat is dissipated over a wider range. Cyberlux's LEDs, however, will last 25,000 to 75,000 hours--fewer than many LEDs can live but more than conventional bulbs can.

Meanwhile, the prototype will have a greater efficiency than conventional LEDs because more photons will get through the phosphor and emerge as white light. Currently, many photons bounce off the phosphor because they hit it at weird angles. "You're basically losing photons in the diode," Schmidt said.

The scattered photon extraction technology from Rensselaer boosts the output of photons. Cyberlux has worldwide exclusive licenses from both Rensselaer and UC Santa Barbara for commercializing their respective inventions in this manner.

Cyberlux will likely license the design of its LEDs to chip manufacturers. The company will then buy LEDs from its licensees and make lighting elements, Schmidt said.

Approximately 22 percent of the electricity consumed in the United States goes toward lighting, according to the U.S. Department of Energy.

To make matters worse, traditional lightbulbs are incredibly inefficient. Only about 5 percent of the energy that goes into them turns into light. The majority gets dissipated as heat. Fluorescent bulbs are much more efficient but aren't as prevalent, particularly inside homes. LED advocates say their devices will beat fluorescent bulbs.

In a speech last year, DenBaars said that if 25 percent of the lightbulbs in the United States were converted to LEDs putting out 150 lumens per watt (higher than the current commercial standard), the country as a whole could save $115 billion in utility costs, cumulatively, by 2025. That would alleviate the need to build 133 new coal-burning power stations, he said.

In turn, carbon emissions in the atmosphere would go down by 258 million metric tons.