Development of high performance stretchable electrodes and their applications

Abstract

Metal nanowires are focused as an alternative material for indium tin oxide (ITO) due to its superior mechanical characteristics as well as excellent opto-electrical property. However, there still remain many issues to overcome for commercializing the metal nanowires in various applications. First, junctions of nanowires should be fully connected in order to lower the contact resistance for enhancing the electrical property. Second, environmental stability of the metal nanowires should be enhanced, because the metal nanowires are easily oxidized in air. Third, metal nanowires should be able to be formed on various substrates without damaging the substrates. Forth, metal nanowires should be able to endure the high strain under folding and stretching condition. Here, processes for solving such issues are suggested. First, chemical reduction process for post-treatment of metal nanowires is proposed. By reacting the metal nanowires with vaporized reducing agent, junctions of metal nanowires are fully fused resulting in enhanced opto-electrical property and environmental stability. The chemistry and principle of the proposed reduction process are studied. Second, optimal structure of AgNWs for the highest stretchability is studied. Blending the AgNWs with graphene oxides (GOs) various structures of hybrid electrode are fabricated and compared the mechanical characteristics each other. With the experiment and simulation, fabrication strategy for the highest stretchable AgNWs electrode is suggested. Third, dry transfer process for the metal nanowires network is proposed. Utilizing the chemical reduction process, silver nanowires (AgNWs) are exfoliated from the substrate as the reduced AgNWs sample is immersed into water. Using a hydrophobic substrate, AgNWs are scooped up and drily transferred onto various substrates including copy-paper without damaging the substrates. Finally, various applications such as solar cell, touch screen, heater, paper-based printed circuit board (PCB) and frequency selective surface (FSS) are developed using the fabrication process exhibiting the applicability of the proposed electrode.