Alignment of One-Dimensional SnO2 Lines by Electrohydrodynamic Jet Printing

One-dimensional (1-D) SnO2 line as a representative semiconducting oxide were formed by electro- hydrodynamic jet-printing (EHD) of tin chloride pentahydrate and polyvinylpyrrolidone (PVP, 1,200 k, Aldrich) solution ink. The 1-D polymer lines including Sn precursors were created by controlling the viscosity, that is, polymer/tin precursor ratio, and adjusting printing conditions such as tip to substrate distance, applying voltage, flow rate of ink and velocity. The printed lines were dried at 200 degrees C to get rid of solvent and finally heat-treated at 600 degrees C to burn out PVP and form tin oxide line. We found out that the linearity and shape of the aligned 1-D SnO2 could be controlled by adjusting various parameters such as the viscosity of a precursor solution, the ratio of Sn to PVP polymer in the solution, the shape of a cone, the size of a droplet, the applied voltages, the working distance, the flow rate on the glass slides and the Si wafers with a SiPO2 layer, respectively. It is found out that the heat-treatment for the removal of polymers should be tailored to produce continuous 1-D SnO2 lines due to the drastic volume reduction (>90%) of the aligned fibers in the annealing process. The electrical properties of the 1-D SnO2 aligned on the Si wafers with Au electrode patterns were evaluated.