Parametric Study of Nozzle-Jet Printing for Directly Drawn ZnO Field-Effect Transistors

A parametric study of nozzle-jet printing (NJP) has been performed on continuous, straight, uniform and smooth printed line patterns in terms of nozzle moving speed, air pressure, stage temperature, applied voltage, and working distance. With optimized parameters, as-formulated ZnO inks are directly printed on different substrates, and the obtained lines are well-defined without showing any cracking behavior and coffee ring effect. Interestingly, the surface smoothness of nozzle-jet printed ZnO patterns is much better than that of spin-coated films. Furthermore, we have obtained absolutely uniform ZnO printed line patterns with various widths and thicknesses with single-pass printing on indium tin oxide (ITO) substrates by controlling the parameters digitally. Such a printed feature indicates that the NJP technique has the potential to fabricate printed electronics and other multi-functional devices. The ZnO based field-effect transistors (FETs) fabricated by NJP show field-effect mobility of 1.42 cm(2)v(-1)s(-1) and an ON/OFF current ratio of 6 x 10(3).