MUNICH, Germany The Dresden technical university and OLED vendor Novaled AG (Dresden, Germany) claim they have reached an efficiency of 90 lumen per watt. Now researchers have to overcome only lifetime issues to trigger the breakthrough to general lighting applications with OLEDs.
Hitherto, fluorescent tubes were the most efficient sources for white light in general lighting applications, offering efficiencies between 50 and 70 lumen per watt, if equipped with reflectors and similar efficiency-increasing measures. Now the team of Novaled and the Institute of Applied Photophysics (IAPP) of the Dresden technical university significantly surpassed this mark with 90 lm/W at a brightness of 1.000cd per square meter (as a comparison, an average computer screen offers a brightness of 300 cd per square meter). By applying systems to couple out the light, the efficiency can be increased to 124 lm/W. Even at a very high brightness of 5.000 cd per square meter the scientists could reach an efficiency of 74 lm/W.
The results were achieved with what the researchers called an "application relevant" component using Novaled's PIN doping technology.
The next issue for scientists will be the lifetime of the light sources. Novaled says it already has achieved devices with operating times of 100.000 hours and beyond albeit at lower efficiency. Another challenge will be the transfer to volume production. Novaled hopes the commercial production of OLED lamps could start in the 2009/2010 time frame. As opposed to other light sources, OLED lamps can be formed in just about any shape and typically will be implemented as large two-dimensional foils.
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