Research promises cheaper and brighter LED displays

Professor Yang Yang and research graduate Jinsong Huang, of the UCLA Henry Samueli School of Engineering and Applied Science, claimed to have produced the highest lumens per watt ever recorded for a red phosphorescent LED.

The boffins used a new combination of plastic, or polymer, infused liquid, and claimed that the configuration cost half as much to build as conventional designs.

"That means your next LED flat panel TV could be less expensive," said Professor Yang.

"And the picture will be brighter and clearer than ever before. "

LEDs are generally measured in lumens per watt. Lumens, a measure of the perceived power of light, and watts, a standard measure of power, combine to define the optical efficiency of power.

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

"That is a significant difference. Visually, it means you get a higher quality display, and the product is also lighter and thinner," said Huang.

"And with our improvements, you also need less energy, but you get an all-around better product."

Huang explained that conventional 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.

LCD televisions, for example, require polarisation, colour 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.

Using Yang and Huang's new polymer light emitting diodes, the devices have a very simple single-layer structure generated by a much cheaper solution process.

The new LED uses a polymer powder and liquid mixture added to a previously top-secret material developed by Canon 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.

"It is a much simpler, lighter, thinner and more elegant answer to creating a better LED product," said Professor Yang.