Update: we discussed this research with Professor Lee Jun Yeob, who's in charge of that research at DKU, and he explained his research further.
Researchers from Dankook University's Center for Photofunctional Energy Materials (DKU CPEM) developed what they claim is the world's most efficient blue OLED emitter (30.1% luminous efficiency). That's the highest efficiency OLEDs can reach in theory. The blue OLED is made from indolopyridines.
The team at DKU has been working on blue OLEDs since 2008. In 2009 they achieved an efficiency of 18.4%, and in 2011 they announced blue OLEDs with 25.4% efficiency. Now they announce this new breakthrough. Of course it remains to be seen whether this new material can be commercialized and what are its other features (mainly the lifetime).