Printed Materials

Our efforts on materials development deal with exploring novel functional materials for diverse printing procedures. Especially functional materials for ink-jet printed electronic devices are in the focus of interest. For successful application of materials for printing processes, an ink needs to be composed not only of the material itself. Other components like the solvent or additives to adjust the fluid dynamics of the ink to the respective printing process,  or helper substances to optimize the annealing or surface wetting of the substrate have to be considered including their influences on the final material film and device properties.

We are developing functional inks for a variety of applications, e.g. semiconductors, dielectrics, conductors, electrolytes, or energy storage. These inks are later utilized in the Devices and Circuits topic to assemble larger electronic logics and optimized using a constant feedback loop.

One of the core structure of the Materials group is the printed transistor. As basic building block of each electronic circuit, it is the ideal test struture to examine the capabilities of conducting, semiconducting and electrolytic inks on one substrate . We can print a variety of different field-effect transistor geometries, in-plane, top-gate but as well vertical field effect transistors are in our portfolio.

Different applications and substrates require adapted materials structures and morphologies, therefore we are establishing printing methods to print even non-trivial material appearances, like porous structures, or we adjust our inks, e.g. using a precursor-based solution that forms a functional film after heating or a self-jellifying ink forming ionic gels post-printing to achieve the desired properties. The Materials group is closely connected to other material science parts of the Nanostructured Materials Group. New functional material developments made there, are transferred in order to prepare devices and to test the performances of these materials. One example are the High-Entropy Materials, which are under investigation for a multitude of applications and constitute a highly interesting novel material class for printed electronics.

Side view of a printed FET using a composite solid polymer electrolyte (CSPE) for the gating. The conformal contact between semiconductor and electrolyte is clearly visible
Porous SnO2 prepared by a template method. The porous structure allows penetration by an electrolyte ink increasing the effectively active surface of a device.