SEMICONDUCTOR LEDS (light emitting diodes) have been used for years as bubble lights for electronics in computers, cars and toys. One of the biggest new LED applications is Christmas lighting.

It was a gloomy Sunday afternoon.

“I can’t believe how dark it is,” I told my daughter Bonnie, who was loading up her car to head back to Iowa City after Thanksgiving break.

It was only about 2:30 p.m., but my outdoor yard light that comes on at dusk kept flickering on and off.

Like the light, my plans to start getting ready for the holiday had to be changed because of the weather.

“I had wanted to put the Christmas lights up today,” I told Bonnie. I followed her as she quickly hurried in and out of the house in the light rain, loading her car’s trunk.

I looked up at the eaves of my house, wondering if I should buy some new lights or go with the old ones buried somewhere in the basement.

I had heard LED lighting was catching on this year. And I thought it might go along with my efforts to cut our electric bill.

Lighting up with LEDs

During the last few months, my wife and I had made a pact – with it finally being just the two of us at home, we would try to cut back on our utilities, including the light bill.

And it was working. We’d managed to trim it in half since Bonnie and Julie left for college in August. It was probably just a matter of turning on only the lights we needed in the main rooms.

But I also imagined that without the girls at home, there were a lot fewer appliances running, including fans, curling irons, hair dryers and TVs.

Still, I wondered what we could do with more efficient lights. So I had been using more fluorescent bulbs around the house. And I had been checking up on LEDs, which are supposed to eventually replace traditional incandescent lighting.

Semiconductor LEDs (light-emitting diodes) have been used for years as red or green indicator bubble lights for electronics in computers, cars and toys.

MAC HAY, of Lawrence, makes use of an unseasonably warm November day to put up his holiday lights display in this 2005 file photo.

One of the biggest new LED applications is Christmas lighting.

‘A coming phenomenon’

Although LED Christmas lights were out last year, they’ve become more popular this year, according to two local hardware store managers.

A.R. Wells, manager of the Ace Westlake Hardware store at 601 Kasold Drive, said this was his first year selling them.

“They’re a pretty popular item because of the energy savings and the fact that they’ll last you so much longer than regular Christmas lights,” Wells said.

Both Wells and Paul Groundwater, manager of the Westlake Ace Hardware store at 711 W. 23rd St., said their stores have displays featuring the new LED lights.

“There’s been quite a bit of interest in them,” Groundwater told me, over the phone. “I would say I’m still selling more of the traditional C-9 bulb over the LED, but they’re a coming phenomenon.”

LEDs don’t generate the amount of heat that the traditional bulbs put out, Groundwater said, and they’re not as easy to break.

“But the color isn’t quite as bright,” he said. “In the darkness they look real good. Using them in a lighted area as accent, they don’t stand out so much. … Free standing, out in the light, they kind of look pale.”

He said they look better up against a dark background, such as a tree.

How much do they cost? Groundwater went to check it out and put me on hold. After I heard a verse of the “The Christmas Song,” he returned with the verdict.

“They’re like $13 compared to $6.50 (for a 25-light package),” he said. “So, about double.”

But many people don’t mind the cost because they use 80 percent less electricity than standard C-9 Christmas light bulbs, he said. And the LED bulbs are expected to last for up to 20 years.

Also, because they’re not made out of glass, you don’t have to worry about breaking them.

“With all new technology, there’s always a year or two of higher prices, then they start to come down fairly quickly,” Groundwater said. “So I expect we’ll see the prices come closer in line to what the C-9 sets are in the future.”

Connecting the dots

I wondered, besides Christmas lights, when LEDs would replace my overhead light bulbs.

I learned from a Kansas University professor and researcher that scientists are getting closer to replacing the standard light bulb with LEDs thanks to minuscule particles known as “quantum dots” that make LEDs shine more brightly.

Until 1993, LEDs could produce only red, green and yellow light. Then Nichia Chemical of Japan figured out how to produce blue LEDs, according to Shih-I Chu, Watkins Distinguished Professor of Chemistry at KU.

By combining blue LEDs with red and green LEDs – or adding a yellow phosphor to blue LEDs – manufacturers were able create white light.

“However, these LEDs tend to produce white light with a cool, bluish tinge,” Chu said.

That’s where quantum dots enter the picture.

Quantum dots are nanoparticles approximately one billionth of a meter in size, containing anywhere from 100 to 1,000 electrons.

“They’re easily excited bundles of energy, and the smaller they are, the more excited they get,” he said. “When you shine a light on quantum dots or apply electricity to them, they react by producing their own light, normally a bright, vibrant color.

“Take an LED (light-emitting diode) that produces intense blue light. Coat it with a thin layer of quantum dots. The resulting hybrid LED gives off a warm white light with a slightly yellow cast, similar to that of the incandescent lamp.”

Accidental discovery

Chu told me the first solid-state white LED using quantum dots was created in 2003 by several laboratories, including the U.S. Department of Energy.

“I think, at this time, the quantum dots-LED is still in the developing stage,” Chu said.

Vanderbilt University chemists recently discovered – by accident – a way to make quantum dots spontaneously produce white light in a broad spectrum, Shu said.

The accidental discovery was reported in an online publication, “White-light Emission from Magic-Sized Cadmium Selenide Nanocrystals” Oct. 18 by the Journal of the American Chemical Society.

Chu said these newly discovered white-light quantum dot-LEDs create a slightly warmer, yellow tint.

The quantum dot-LED light looks more like sunlight than a fluorescent bulb. And they also give off less heat, he said.

Painting with light

I asked Chu what the future holds for these LEDs enhanced with quantum dots.

He said they can produce double the light of a regular 60-watt light bulb and last more than 50,000 hours.

“The Department of Energy estimates LED lighting could reduce U.S. energy consumption for lighting by 29 percent by 2025,” he said. “LEDs don’t emit much heat, so they’re also more energy efficient. And they’re much harder to break.”

Back at home

“Did I forget anything?” Bonnie said, sitting down in our living room after she finished packing.

She had been home for more than a week. But it seemed like only a day or two. Still, I couldn’t help but wonder if her being home would short-circuit my efforts to cut the electric bill.

It’s always sad when she has to leave.

But to lighten things up, I told her about looking at some LED bulbs and steered the conversation toward the holidays.

“Do you want me to wait until you get back to go get the Christmas tree?” I asked.

“No,” she said. “I think it would be fun to come back and see everything all Christmassy.”