Self-aligned printing is a recently developed bottom-up printing technique which utilizes the unique droplet motion on heterogeneous surfaces to define sub- critical features and surpasses the resolution which can commonly be achieved by direct printing by two orders of magnitude. Here we extend this method, which was originally implemented with conductive polymer inks, to fabrication of functional conductive nanostructures with gold nanoparticle ink. We also designed a configuration where the ink was printed between two lithographically defined patterns to facilitate the study of the channel formation. Channel lengths from down to were achieved by controlling the surface tension and drying time of the ink. A fluid dynamical model is presented to explain the mechanism by which the channel forms in the self-aligned printing technique. Field-effect transistors fabricated using gold self-aligned printed source-drain electrodes exhibit significantly improved output currents than those using conducting polymers. Unambiguous evidence for the submicrometer channel dimension is obtained by imaging the potential drop along the channel using scanning Kelvin probe microscopy.
REFERENCES
We note that the surface tension of the ink is expected to decrease slightly at high temperature, which may reduce somewhat the contrast between the contact angles on hydrophobic and hydrophilic surfaces for the higher CHB concentrations.
