Dresden University (www.tu-dresden.de) and specialist OLED producer Novaled (Dresden / Germany; www.novaled.com) have developed organic light-emitting diodes (OLEDs) that offer higher energy efficiency than fluorescent tubes. So far, fluorescent tubes with a brightness of 50-70 lm/W (lumens/watt) have been regarded as the benchmark for use in reflectors and lamps. The new record-breaking OLED components produce up to 90 lm/W even with flat, scalable outcoupling – the efficiency at which photons are extracted from the component – and the research scientists in Dresden report efficacy of 124 lm/W with special 3D outcoupling concepts.

The developers say that it should be possible to manufacture the white OLEDs as ultra-thin, flexible, transparent or colour-tunable large-area lighting components in any size and shape. “Our approach combines a novel, very energy-efficient emission layer design with improved light outcoupling concepts,” said project manager Sebastian Reineke of the Institute of Applied Photophysics (IAPP) at Dresden University. “The potential of these devices is obvious when one considers that even at the very high brightness of 5,000 cd/m² (candelas/m²) a power efficiency of 74 Im/W is obtained,” says IAPP’s director Karl Leo.

The findings will now be used to develop white OLEDs with a commercially acceptable lifetime. Novaled’s CEO Gildas Sorin says that he is confident that the technology, which combines high efficiency with high brightness, represents a breakthrough in establishing OLEDs as mainstream lighting sources.