Ultra-flexible and Transparent AgNWs-based Electrodes for Joule Heating

Flexible and transparent electrodes have huge potential in wearable applications. Therefore, metal nanowires with high flexibility, high transmittance and low resistance have been extensively studied to replace traditional ITO conductive films. However, the further development of metal nanowires is hindered by their poor adhesion to the substrate, easy corrosion and rough surface. Here, we demonstrate an ultra-flexible and transparent heater based on a composite film of Ag nanowire (AgNW) networks and polymers. A commercial polymer, named polycarbon waterborne polyurethane resin (PUD 3039), was chosen to coat the AgNWs networks. The PUD polymer tightly wraps the nanowires due to its excellent permeability, forming a stable and tight interconnecting conductive network. The electrodes based on AgNWs/PUD composite exhibit excellent mechanical and chemical stability. The surface roughness of the composite films was greatly optimized because the nanowires were fully embedded into the PUD substrate. Lastly, a 5 x 5 cm(2) heater was fabricated and its heating performance was tested, showing a high saturation temperature of 141(degrees)C at a low voltage of 5 V, highly repeatable heating and long-term stability. In addition, under a 2 mm radius of curvature, the AgNWs/PUD heaters still have excellent heating performance after 10,000 bending cycles.