BASF develops new semiconductor inks for printed electronics in LCD and OLED displays
Researchers at BASF SE, a globally active chemistry corporation based in Ludwigshafen, Germany, have succeeded in improving the composition of individual semiconductor ink components to double the mobility of the charge carriers in the printed circuits. This is expected to allow a further reduction of the structures in size and to produce high-resolution LCD or OLED screens on plastic substrates.
"Because of their technical properties, the semiconductor inks we have offered so far have already proved successful in our customers' applications," explains Dr Heike Pfistner, marketing organic electronics at BASF New Business GmbH. "We are continuously optimising the products from our portfolio and can now offer printable semiconductors with significantly better performance and with the usual good processability." The mobility of the charge carriers is an important criterion and is decisive for the use of the semiconductor inks in a range of applications. The printing inks are based on semiconducting polymers featuring good solubility allowing easy adjustment of viscosity. This property is important for the use in various coating and printing processes, such as large-area processing (e.g. slot die coating).
A digital photo and thus also a display consists of picture elements (pixels). To present an image or a film on a display, the pixels are controlled individually via the backplane. Today the backplane is produced by complex, energy-intensive processes at high temperatures under vacuum. This limits the choice of substrate materials to e.g. glass and high-temperature stable polymers.
The printable semiconductor inks and new process technologies open up a range of options in this respect. For example, new, flexible substrate materials can be used. The printing processes are typically operated in air and at low temperatures. The combination of printability and high mobility will enable all conventional display technologies (ePaper, LCD, OLED) to be equipped with printed backplanes. This makes flexible displays easier to manufacture. Further applications include circuits and memories for intelligent packaging through which the consumer can, for example, obtain additional information about the packaged products, as well as portable electronics (wearables) such as fitness wristbands or smartwatches.