Double-Sided Graphene Oxide Encapsulated Silver Nanowire Transparent Electrode with Improved Chemical and Electrical Stability

Abstract

Owing to their high conductivity, transparency, flexibility, and compatibility with solution processes, silver nanowire (AgNW) networks have been widely explored as a promising alternative to indium tin oxide (ITO). However, their susceptibility to corrosion and thermal instability still remain limiting factors for widespread adoption in a range of devices including solar cells, transparent heaters, and light-emitting diodes. In this study, we report a scalable and economically viable process involving electrophoretic deposition (EPD) to fabricate a highly stable hybrid transparent electrode with a sandwich-like structure, where a AgNW network is covered by graphene oxide (GO) films on both sides. The newly developed all solution process allows the conductive transparent film to be transferred to an arbitrary surface after deposition and demonstrates excellent sheet resistance (15 Ω/sq) and tunable transmittance (70–87% at 550 nm). Unlike bare AgNW networks, the hybrid electrode retains its original conductivity under long-term storage at up to 80% relative humidity. This chemical resilience is explained by the absence of silver corrosion products for the AgNW encapsulated by GO as indicated by X-ray photoelectron spectroscopy. In situ voltage ramping and resistance measurements up to 20 V indicate a novel stabilization mechanism enabled by the presence of GO which delays the failure onset and prevents abrupt divergence of the resistance to the megaohm range experienced by bare AgNW networks. The double-sided nature of the GO coating offers combined stability and performance to the AgNW network, which adds unique versatility of our electrodes to be used toward applications that require a wide range of thermal and chemical stabilities.

Failing Forward: Stability of Transparent Electrodes Based on Metal Nanowire Networks

“…Regardless of such discrepancies, there is no question that the sulfidation of AgNW is a serious problem, particularly for TFHs with relatively high operating temperatures. [ 86–88 ]…”

“…A number of studies have demonstrated the incorporation of GO and rGO to MNW‐based transparent electrodes. Thus far, GO/AgNW, [ 38,45–48 ] rGO/AgNW, [ 42–44 ] rGO/CuNW [ 39,40 ] have all been synthesized using various solution‐processing techniques including, but not limited to, spin‐coating, [ 42 ] dip‐treatment, [ 38,40 ] layer‐by‐layer (LbL) coating, [ 48 ] rod‐coating, [ 145 ] electrophoretic deposition (EPD), [ 87 ] and spray‐coating. [ 39,43,45 ] It is interesting to note that both conductive rGO and insulating GO have been used with MNW networks to fabricate TE, with significant improvement of conductivity over bare MNW networks.…”

“…For instance, Chae et al. [ 87 ] showed that the resistance of a GO/AgNW/EPD‐GO (electrophoretically deposited) showed a delayed failure voltage, preventing the ultimate failure of the network ( Figure a). They also demonstrated that covering AgNW with a GO film suppresses AgNW sulfidation, which in turn preserves its conductivity even in high humidity conditions (Figure 13b).…”

In situ mechanical characterization of silver nanowire/graphene hybrids films for flexible electronics

“…Through a filtration method, the fabricated AgNW/graphene hybrid paper shows excellent flexibility with only <5% electrical conductivity loss over 500 times mechanical bending [30]. Single-layer graphene and AgNWs networks and mesh are also utilized for the fabrication of flexible transparent conductive films for electrical, optical, and thermal applications with improved mechanical stability [31][32][33][34][35][36][37][38][39][40][41]. However, the microstructure evolution and mechanical deformation process of the AgNW/graphene hybrid film have not been investigated, which is fundamental for the understanding of the mechanism for electromechanical performance enhancement for real applications.…”

Polyhedral oligomeric silsesquioxane polyimide nanocomposites for color filters and flexible conductive films

“…However, the carbon nanotube/POSS polyimide film is not transparent. Sliver nanowire (AgNW) films are synthesized by a solution‐based process and transferred onto different substrates such as glass and flexible polymer film, where the transparency and conductivity are intrinsically related to the mass of AgNW, showing a typically high transparency up to 70% in visible range 400–800 nm with a sheet resistance less than 10 Ohm square −1 , with optical and electrical parameters in Table S2 42–45 . Thus, a combination of AgNW conductive film and transparent POSS polyimide with reliable interface contact is promising for transparent and flexible electrodes in space application, while there are few reports yet.…”