UCLA engineers focus on LED TV

LOS ANGELES, CA-Two researchers at the UCLA Henry Samueli School of Engineering and Applied Science want to make sure future generations of plasma TV watchers will be able to enjoy the brightest, most beautiful color possible, and for a lot less money.

Jun 1st, 2007

LOS ANGELES, CA-Two researchers at the UCLA Henry Samueli School of Engineering and Applied Science want to make sure future generations of plasma TV watchers will be able to enjoy the brightest, most beautiful color possible, and for a lot less money. Materials science and engineering professor Yang Yang and his graduate researcher Jinsong Huang recently achieved the highest lumens per watt ever recorded for a red phosphorescent LED using a new combination of polymer-infused liquid -and they did it at half the current cost, according to a presentation at the recent SID meeting.

“That means your next LED flat panel TV could be less expensive,” Yang said. “And the picture will be brighter and clearer than ever before.”

Current red LEDs generally score around 12 lumens per W. Yang and Huang’s newest device rates a record-breaking 18 lumens per W.

“Visually, it means you get a higher quality display, and the product is also lighter and thinner,” Huang said. “And with our improvements, you also need less energy, but you get an all-around better product.”

Conventional organic LEDs are made from a variety of organic semiconductor materials and have a complicated multiple-layer structure formed by expensive thermal evaporation techniques constructed to control charge flow in the device. Liquid crystal display televisions, for example, require polarization, color filters and other components to make the resulting picture clear and bright. The more you build into a product, Yang said, the more energy it takes to run it, and the bigger it is.

Yang and Huang’s new polymer LEDs (PLEDs) have a very simple single-layer structure, generated by a much cheaper solution process. Their PLED uses a polymer powder and liquid mixture added to a previously top-secret material developed by the Canon company to create a paint-like product. The product is used to coat a layer of glass, and a charge is added. The end result is a slim single layer of glass with two electrodes.

Yang began his high-performance PLED research at UCLA Engineering in early 2003 with a then-graduate student named Qianfei Xu, who was part of the professor’s research group, and achieved a record-high efficiency for green PLEDs.

“Using our simple solution method, we already have successfully achieved several world records in device efficiency, including 20 lumens/watt white emission fluorescent PLEDs, 30 lumens/watt green emission fluorescent PLEDs and 18 lumens/watt red emission phosphorescent PLEDs,” Yang said.

The new technology, which already has been licensed by Canon, should be available in consumer products in about three years.

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