Rheological characterization of liquid electrolytes for drop-on-demand inkjet printing

Abstract Physico-chemical properties of inkjet printing liquids significantly affect the quality of print-out, thus being the key parameter in the performance of printed electronic device (PEDs). Complex hydrodynamic interactions that inks are subjected to in an inkjet printing device has an influence on their rheological response, thus final drop formation, jetting, and drying kinetics. This paper provides a systematic comparison of three PED electrolytes based on different solvents i.e. Sulfolane, 3-Methoxypropionitrile and Acetonitrile that gave them different physico-chemical properties. Rheological properties of printed electrolytes were found to strongly influence the quality of print-outs, which is investigated both optically and morphologically. Best printing results were obtained with the sulfolane-based electrolyte that has the most uniform temperature and shear rate dependent rheological behavior as well as the lowest evaporation rate. By carefully controlling the printing temperature window, it is possible to subject PED electrolytes to higher shearing viscosity profiles while avoiding undesirable dilatant behavior which results in clogged printing nozzles and disrupted droplet trajectory.