16 April 2018
A team says it has discovered new inks for inkjet printers that allow organic displays and solar cells on film and glass to be printed.
The researchers at the Fraunhofer IAP explain that they turn light into electricity or vice versa and can be printed on solid substrates as well as on flexible foils. In effect, solar cells and organic displays can be produced fast and cost-effectively.
Together with research partners, the Fraunhofer scientists say they have developed methods to print organic photovoltaic elements for use in architecture and for the textile industry on film. With a solar module as façade element and a power-generating jacket, they present the potential of their work at the fair. Using specially developed inks from organic light sources and quantum dots, the researchers explain they can 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. “Until we can flexibly roll up our televisions, we still have a little research to do”, explains Dr. Armin Wedel of Fraunhofer. “Although there are already curved and even scrollable displays, they still have to be rolled up on rigid rolls with a defined diameter.”
New perspectives for the production of printed displays result from the use of electrostatic (ESJET) printing. Fraunhofer says it is working on this procedure with twelve other partners within a project called ‘Hi-Response’. The ESJET printing process is said to allow for 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, Fraunhofer says. The printed structures can be as small as 1micron. In the future, the printing of high-resolution, active-matrix-driven OLEDs should be possible.
The Fraunhofer scientists are also researching QLEDs based on indium phosphide quantum dots, which are free of conventionally used toxic cadmium. The results, so far, are “ground-breaking” for the industry. Indium phosphide-based QLEDs are gradually catching up on the performance advantage of cadmium-based systems in many areas. Regarding luminance, Fraunhofer says they are already outperforming cadmium-based QLEDs.