Dr. Armin Wedel from the research field "polymers and electronics" of the IAP answers questions about our research and development work in concerning OLEDs.
What is the focus of the Fraunhofer IAP OLED research?
"The focus of our research are polymerbased flexible OLEDs which will realise the
monitor of tomorrow, as thin as and as rollable as wallpaper."
Why do you prefer light-emitting polymers as the basic material?
"Polymers nowadays allow the production of passive matrix displays in a more easy
way and with less costs than using organic small molecules. At present, the small
molecules are still superior to polymers concerning color, efficiency and life time.
Red and green pixel already keep up for over 10.000 hours, only blue pixel still fade
more quickly. But polymers catch up considerably. "
What is your research goal?
"Our goal is to achieve a long-term stability for flexible OLEDs. We must find a
method to protect the OLED from oxygen and water vapour. The quality of the
encapsulation determines the lifetime of a display. At present, solid glass is used
for the front and rear side cover. Special adhesives are used for sealing the edges
and covering the electrical connectors. But for future applications we look for
flexible, transparents foils which allow us to hermetically encapsulate dyes into
plastics. If we are able to do that we are also able to unroll displays."
What barriers do you still have to conquer?
"Problems that still must be solved are increasing the lifetime of OLEDs, improving
the readability under insolation and the development of efficient materials which
guarantee a consistent glow without colour differences over the whole lifetime. Here,
the so-called doping, a selective soilage helps to decrease the operating voltage and
thus to increase the efficiency."
What do you expect from the new technology?
"The goal of our research are not only computer displays but also displays for
household appliances like refrigerator, vacuum cleaner or washing machine. As
illumination and symbol display OLEDs are superior to the present displays because as
surface radiator they can be read from every angle. Even displays as labels in clothing
and on food are possible because they will be so energy-efficient and cost effective."