MUNICH, Germany A research group of the Dresden Technical University has achieved record energy efficiencies for OLEDs. The achievement brings the organic LED technology closer to industrial volume production.
The research team achieved an efficiency of 26, 22 and 3.1 percent for red, green and blue organic LEDs which combined form a white light source. The low efficiency for blue results of physical differences while red and green OELDs are phosphorescent light sources, their blue counterpart is a fluorescent one, resulting in lower light emission. The difference, however, can be compensated for by increasing the active size of the blue light emitter as well as sending a higher current through it, explained research group member Rico Meerheim.
In any case, the efficiency achieved is significantly higher than what was hitherto possible, in particular for the red light source. The OLED created by the Dresden team achieved a light intensity of 81, 101 and 4 lumen per watt.
The research was conducted in cooperation with Dresden-based OLED technology provider Novaled AG. A company spokesperson said the research results advances the OLED technology significantly. In comparison with silicon-based LEDs, Novaled claims OLEDs offer better displays with higher contrast, better color intensity, lower energy consumption, and an extreme viewing angle. In addition, OLEDs allow designers to build ultra-thin displays. Currently, only Japanese consumer electronics vendor Sony Corp. commercializes large OLED displays in a TV screen.
Besides computer and TV set displays, OLED are positioned for room lighting applications. The Novaled spokesperson declined to say to whom it licenses its technology. According to market researchers, the market for OLED materials will soon enter the boom phase.
The OLEDs in question are manufactured at Fraunhofer ITMS in prototype volumes, Meerheim said.