Three-dimensional Printing of Heterogenous Nanowires via Visualization of Nanocapillary Tips

This contribution presents a method for producing serial junction heterogenous nanowires through three-dimensional(3D) printing of vertically freestanding nanostructures. Serial junction can be implemented by sequential printing of two different materials. One major issue is accurate positioning of the printing nozzle at the end of the pre-fabricated nanostructure for sequential printing of different material. Typically, nozzle-based direct printing method involves an optical microscope for positioning of the nozzle. However, optical microscopy often suffers from difficulties in identifying the position in the depth axis, distinguishing overlapped objects, resolving nanoscale features. In this study, we present a novel positioning method based on visualizing the nozzle tip with scattered light that is sensitive to contact. Direct 3D printing of PEDOT:PSS and P3HT serial junction heterogenous nanowire was demonstrated via precise positioning of the nanocapillary nozzle with the tip scattered light. Our direct printing method provides a simple route for producing heterogeneous junction nanowires in a position-selective manner, which can be used in light-emitting devices, image sensors, and solar cells.