Continuous, Large-scale Manufacturing of Functionalized Silver Nanowire Transparent Conducting Films

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This research aims to discover a new technique for the economical manufacture of silver nanowire transparent conductive films for the Internet of Nano Things. The Internet of Nano Things promises to connect a new generation of sensors, transducers, data processors and communication devices for a smart and connected world. A vital component of all nanodevices is transparent conductive films, generally made of silver nanowires. Current manufacture of silver nanowires is costly as it involves multi-step batch production. This award investigates a new approach for large-scale manufacture of silver nanowires with direct coupling with a three-dimensional printing system for patterning of transparent conducting films. The reduced cost of transparent conducting films and print-on-demand silver nanowires hasten the adoption of devices for the Internet of Nano Things, which contributes to the U.S. economy and prosperity. This research combines aspects of manufacturing, material science, nanotechnology, chemistry, and engineering. Students actively participate in research thus achieving engineering expertise in advanced manufacturing, which is important to U.S. industry. Undergraduate and graduate students, particularly from under-represented groups, are encouraged to participate in research and training.This project studies the reaction conditions and mechanisms in a continuous reactor to produce silver nanowire (AgNW)-based conductive inks that can be continuously printed onto flexible substrates to create transparent conducting films (TCFs) for the Internet of Nano Things (IoNT). The current batch production of AgNWs involves the costly steps of selective separation and concentration of the desired AgNWs. In addition, AgNWs are prone to oxidation in harsh environments. This project studies a millifluidic system for the manufacture of monodispersed AgNWs with controllable length and aspect ratio and sufficient concentration for high performance TCFs. The millifluidic reactor is connected to a 3D printer for continuous manufacture and printing of AgNW-based TCFs with a reduction in cost while maintaining high print quality. In-situ monitoring of the millifluidic synthesis by X-ray absorption spectroscopy provides fundamental understanding of the reaction mechanisms. Mechanistic knowledge of the chemical reactions helps to achieve control over the aspect ratio and yield of the AgNWs. The AgNWs are modified using Pd nanoparticles via the galvanic replacement of Ag with Pd cations to achieve stability against oxidation. This research advances AgNW TCFs that are low cost, environmentally stable, with flexible/stretchable characteristics needed in applications such as IoNT devices with high potential for advancing the field of flexible electronics.This project is jointly funded by the Advanced Manufacturing Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.