Epitaxial, ultra-thin Au coating as a barrier for oxidation damages for silver nanowires

Y. Zhu
University of California, Riverside,
United States

Keywords: epitaxial, ultra-thin, Au coating, silver nanowires, transparent electrode

Summary:

Silver nanowires (AgNWs) hold promise for applications such as transparent and flexible displays, solar cells, chemical/biological sensors, photonic circuits and scanning tunneling microscopies, but their susceptibility to damage from oxidation has limited their commercialization. Here, we develop a room-temperature chemical coating technique to deposit an ultra-thin, epitaxial layer of Au on the AgNWs surface, which shields the AgNWs from oxidation, and thus it could represent a key to realize their commercial potential. Our work has shown that the Ag@Au core-shell nanowires are stable in air for at least 183 days (>6 months) and in physiological buffer solution (PBS) for at least 21 days. The thin Au coating did not introduce significant Au fluorescence in the SERS spectrum, making them feasible for SERS and plasmonic sensing applications. The results also showed that the thin coating does not have adverse effects on the coupling of surface plasmon polariton in AgNW waveguides, and the device performance is stable for at least 21days. AgNW-AFM probes are low-cost alternatives of high-aspect-ratio, high-resolution AFM probes. It was demonstrated that the Ag@Au core-shell nanowires functions similarly to bare-AgNW, with a much longer shelf-life for at least 3 weeks in the air. The performance of transparent film based on Ag@Au nanowires with 6 nm Au can keep stable under heated, high-humidity environment (80℃ of temperature, 80% of humidity) for as long as 2016 hours (>84 days).