Ultrathin\nEpitaxial Cu@Au Core–Shell Nanowires\nfor Stable Transparent Conductors

Abstract

Copper nanowire networks are considered\na promising alternative\nto indium tin oxide as transparent conductors. The fast degradation\nof copper in ambient conditions, however, largely overshadows their\npractical applications. Here, we develop the synthesis of ultrathin\nCu@Au core–shell nanowires using trioctylphosphine as a strong\nbinding ligand to prevent galvanic replacement reactions. The epitaxial\novergrowth of a gold shell with a few atomic layers on the surface\nof copper nanowires can greatly enhance their resistance to heat (80\n°C), humidity (80%) and air for at least 700 h, while their optical\nand electrical performance remained similar to the original high-performance\ncopper (e.g., sheet resistance 35 Ω sq^–1 at\ntransmittance of ∼89% with a haze factor <3%). The precise\nengineering of core–shell nanostructures demonstrated in this\nstudy offers huge potential to further explore the applications of\ncopper nanowires in flexible and stretchable electronic and optoelectronic\ndevices.