New cavity design boosts light output for OLED devices
August 7, 2009
Scientists at SRI International have found an innovative design for organic light-emitting diodes (OLED) that makes use of cavities to enhance their luminosity and energy efficiency. The device, called a COLED (where the 'c' stands for 'cavity') was designed by Dr. Yijian Shi and employs a regular pattern of cavities, implementing a structure that generates as much as five times the light output of a standard OLED per watt consumed depending on the color being displayed.
OLED displays make use of a thin organic film deposited on its surface with a simple printing process, and present several advantages compared to traditional LCD displays: most notably, they don't require a backlight to function, which allows for much thinner and power-saving displays.
Thanks to a combination of light-emitting polymers provided by the Japan-based SDK and the innovative COLED design, researchers were able to obtain an output of 30 lumens per watt for blue light — the most challenging to produce effectively with OLED technology — which was higher than any other result obtained with similar technology.
As for green light (pictured above), which is technically less challenging to produce with OLED devices, the COLED-polymer combination achieved a stunning 80 lumens per watt, about three times more than a typical OLED. The combination also proved a feasible, economic solution for the production of white light, which requires a mixture of red, green and blue light.
Finally, this new COLED device is also very promising from an environmental point of view: according to SRI, this technology could be as much as two times more energy-efficient than compact fluorescent lights, which also contain mercury and therefore present a disposal problem.
The researchers estimate that this technology could be available to consumers as soon as next year.
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