Nanoscale Chemical and Electrical Stabilities of Graphene-covered Silver Nanowire Networks for Transparent Conducting Electrodes.

Seong Heon Kim,Dong-Jin Yun,Kwang Hee Kim,Dae Jin Yang,Sung Heo,Woon Ih Choi

doi:10.1038/srep33074

Abstract

The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs). However, these effects have been mainly observed via large-scale characterization, and precise analysis at the nanoscale level remains inadequate. Here, we present the nanoscale verification and visualization of the improved chemical and electrical stabilities of Gr-covered AgNW networks using conductive atomic force microscopy (C-AFM), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) combined with the gas cluster ion beam (GCIB) sputtering technique. Specifically by transferring island Gr on top of the AgNW network, we were able to create samples in which both covered and uncovered AgNWs are simultaneously accessible to various surface-characterization techniques. Furthermore, our ab initio molecular dynamics (AIMD) simulation elucidated the specific mechanistic pathway and a strong propensity for AgNW sulfidation, even in the presence of ambient oxidant gases.

Highlights

The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs)
The prepared island Gr (iGr)/AgNW samples were stored for several weeks in ambient conditions in the laboratory
It can be concluded that the bare AgNWs were considerably sulfidized and that the iGr-covered ones were protected by the iGr layer, as depicted in Fig. 1b, because the growth of Ag2S nanoparticles is characteristic on sulfidized AgNWs exposed to the atmosphere

Summary

Introduction

The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs). These effects have been mainly observed via large-scale characterization, and precise analysis at the nanoscale level remains inadequate. Various types of materials, such as conducting polymer composites, graphene (Gr), and carbon nanotubes (CNTs), have been examined as candidate TCE materials[4,5] Notwithstanding their outstanding merits of flexibility and solution processability at normal pressure, the sheet resistances (RS) and transparencies (T%) of these materials remain insufficient compared with those of existing TCO films (ITO: RS > 50 Ω/□at T%: 85%). We examined the performance of Gr as a gas barrier to protect AgNWs from corrosion, including sulfidation, and verified the chemical and electrical stabilities of Gr-covered AgNW network on the nanoscale. We introduced a hybrid structure of island Gr (iGr) and AgNWs to clearly compare the differences between Gr-covered and bare AgNWs

Methods

Results

Conclusion