January 30, 2006, Potsdam, Germany--Scientists at the Fraunhofer Institute for Applied Polymer Research IAP have succeeded in constructing transparent OLED displays using light-emitting polymers. They say the brightness, operating life time and efficiency are so high that the first commercial applications can be envisaged.
"We achieved this result by using a new type of metal electrode to supply the polymer film with electric current," said Armin Wedel of the IAP. "The clue of the transparency lies in its physical properties." Earlier metal oxide coatings were too thick to allow enough light to pass through. But making them thinner reduces their conductivity and hence the luminescence and operating life time of the display.
With the achieved degree of transparency, the Fraunhofer scientists say that OLED displays can now be combined with the meanwhile mature technology of TFT liquid crystal displays which are commonly found in a wide variety of products. They are considering integrating additional functions directly in displays, such as highlighted areas or flashing warning symbols. By combining the two types, it becomes possible to concentrate a higher density of information content within the same surface area. Project partner Optrex Europe GmbH (Frankfurt, Germany) has already produced demonstration models of the hybrid display.
Some new ideas are being investigated in collaboration with the University of Applied Sciences in Potsdam and the University of the Arts in Bremen. Transparent OLEDs allow conventional displays to be illuminated from the back or front. Once the manufacturing process even for larger surface areas has been mastered, it will be possible to incorporate the light-emitting polymers in laminated glass. The result would be, for instance, to transform car windshields or glazing elements in buildings into display panels that hardly interfere at all with their main function of letting in daylight or allowing a clear view out. Another novel idea are two-color transparent displays: The ability to mix colors permits the creation of entirely new effects and applications.
