Scientists sponsored by display technology developer Opsys have developed high efficiency bi-layered green organic light emitting diode (OLED) devices.
A maximum efficiency of 40 lm/W at 400 cd/m2 was recorded for the OLEDs, which contain a solution processed light emitting dendrimer layer. These results are the most efficient ever reported for such devices.
The work is a collaboration by Opsys sponsored teams led by Dr. Paul Burn and Dr. Oleg Salata at the University of Oxford, and by Professor Ifor Samuel, Royal Society Research Fellow at the University of St Andrews.
This latest result builds upon Opsys’ recent announcement of 6.9 lm/W at 1500 cd/m2 for a single-layered dendrimer device and brings dendrimer technology closer to commercial viability for efficient, low cost manufacturing of flat panel displays.
Currently, displays based on small molecule fluorescent materials are regarded as the most mature in the field of OLEDs. However, small molecule materials can only be deposited by evaporation techniques and it is believed that, in the future, solution processing will provide a lower cost approach to large area full colour displays.
The results were announced by Professor Ifor Samuel at the forthcoming ‘Society for Information Display 2002’ conference in Boston, MA, in the late news session, paper L8, Room 304, Hynes Convention Center, on Wednesday 22 May.
They will also be published in a paper entitled ‘A Green Phosphorescent Dendrimer for Light-emitting Diodes’ in Advanced Materials, on 4 July 2002.