(Invited) Wearable Electronics Using Low-Dimensional Nanomaterials

Transparent conductive electrodes (TCEs), which have transparency and conductivity, are of increasing significance and demand for diverse application areas such as information (displays, touch screen), energy (solar cell, architectural), and environment (sensors). Nowadays, indium tin oxide (ITO) deposited by sputtering process is used as the main TCE material. Although the ITO presents low sheet resistance (~ 30 Ohm/sq) and high transparency (~ 90 %), its fragility limits many potential applications in flexible and stretchable electronics. For these reason, many types of alternative materials such as conducting polymers, carbon nanotubes, graphene, and metal nanowires, have been studied as candidates of the flexible and stretchable TCEs. Although many of these candidates exhibit good mechanical flexibility and stretchability, none shows significantly higher conductivity and transparency together, compared to ITO. Here, we present a simple fabrication process of high-performance, stretchable TCEs based on the metal nanofibers which have long and continuous web geometries, hybrid with 2D material graphene. These TCEs show superb electric conductivity (~ 1 Ohm/sq) with high transparency (~ 91 %) as well as substantial flexibility and stretchability. We believe these TCEs based on the nanostructures present a promising strategy toward flexible and wearable electronics, and indicate the promise of future electronics beyond the limits of conventional ITO.