Alloying and Embedding of Cu-Core/Ag-Shell Nanowires for Ultrastable Stretchable and Transparent Electrodes

Abstract

In this paper, transparent electrodes with dense Cu@Ag alloy nanowires embedded in the stretchable substrates are successfully fabricated by a high-intensity pulsed light (HIPL) technique within one step. The intense light energy not only induces rapid mutual dissolution between the Cu core and the Ag shell to form dense Cu@Ag alloy nanowires but also embeds the newly formed alloy nanowires into the stretchable substrates. The combination of alloy nanowires and embedded structures greatly improve the thermal stability of the transparent electrodes that maintain a high conductivity unchanged in both high temperature (140 °C) and high humidity (85 °C, 85% RH) for at least 500 h, which is much better than previous reports. The transparent electrodes also exhibit high electromechanical stability due to the strong adhesion between alloy nanowires and substrates, which remain stable after 1000 stretching–relaxation cycles at 30% strain. Stretchable and transparent heaters based on the alloyed and embedded electrodes have a wide outputting temperature range (up to 130 °C) and show excellent thermal stability and stretchability (up to 60% strain) due to the alloy nanowires and embedded structures. To sum up, this study proposes the combination of alloying and embedding structures to greatly improve the stability of Cu nanowire-based stretchable transparent electrodes, showing a huge application prospect in the field of stretchable and wearable electronics.

Recent Progress in Transparent Conductors Based on Nanomaterials: Advancements and Challenges

“…In contrast, Zhang et al demonstrated TSCs with Ag acting as the shell overtop of Cu‐core nanowires and depositing it via spray coating onto a polyurethane (PU) substrate 73. High‐intensity pulsed light (HIPL) both embedded the alloyed nanowires into the PU surface and made them smoother and denser (Figure 3d).…”

“…d) Schematic illustration of synthesis process of Cu@Ag core–shell nanowire based nanocomposite. Reproduced with permission 73. Copyright 2019, American Chemical Society.…”

“…Since particles in the spray are very small and evaporation during spraying occurs almost simultaneously, results of the coating are not commonly affected by fluidic effects such as Marangoni flow. In fabrication of TSCs, this method typically is used to coat 1D nanomaterials like CNT69 and MeNWs 64,66,69,73…”

“…Annealing processes including thermal annealing47,64 and photonic nanowelding (sintering)11,46,66,73 of metal nanomaterials effective approach to enhance mechanical and electrical properties. These processes enhance the conductivity and mechanical stability of conductors by directly connecting junctions between nanomaterials (Figure 6a–c) and also promote adhesion of nanomaterials by embedding nanomaterials in substrates 11,64,73. Since transparency and conductivity generally have negative relationship,58–60 annealing processes could be a good approach to fulfilling higher transparency with same conductivity.…”

“…In contrast, Zhang et al demonstrated TSCs with Ag acting as the shell overtop of Cu-core nanowires and depositing it via spray coating onto a polyurethane (PU) substrate. [73] Highintensity pulsed light (HIPL) both embedded the alloyed nanowires into the PU surface and made them smoother and denser ( Figure 3d). In addition to its electrical stability during 1000 strain cycles at 30%, the conductor exhibited excellent longterm stability when exposed to both high temperature (140 °C) and high humidity (85 °C, 85% relative humidity).…”