At Printed Electronics Europe in Berlin this week, Fraunhofer IAP demonstrated how inks can be printed on solid substrates as well as on flexible foils for solar cells and organic displays.
Together with research partners, researchers at Fraunhofer have developed methods to print organic photovoltaic elements for use in architecture and for the textile industry on film.
Using specially developed inks from organic light sources and quantum dots, the researchers print, for example, organic light-emitting diodes (OLEDs) and quantum dot-based LEDs (QLEDs).
The displays can also be printed on different materials. Printing on film makes them flexible to some degree.
Dr. Armin Wedel, head of the research division Functional Polymer Systems at the Fraunhofer IAP, writes:
“Until we can flexibly roll up our televisions, we still have a little research to do. Although there are already curved and even scrollable displays, they still have to be rolled up on rigid rolls with a defined diameter.”
Fraunhofer IAP is working on the development for electrostatic printing with twelve other partners within the project Hi-Response, which is funded by the European Union.
This printing process allows the use of a wider range of inks, as even very viscous inks can be processed. The drop-on-demand system also makes it possible to set the thickness of the printed layer very precisely.
The printed structures can be as small as 1 micron. In the future, the printing of high-resolution, active-matrix-driven OLEDs should be possible.
In addition to OLEDs, the IAP scientists are also researching QLEDs based on indium phosphide quantum dots. They are free of conventionally used toxic cadmium.
Indium phosphide-based QLEDs are gradually catching up on the performance advantage of cadmium-based systems in many areas.