Keywords: copper nanowires, silver nanowires, conductive filament
Summary:The relatively high temperatures (>200 °C) required to sinter silver nanoparticle inks has limited the development of printed electronic devices on low-cost, heat-sensitive paper and plastic substrates. By studying the effect of nanostructure shape on the resistivity of nanostructure films, we found that films of long silver nanowires are 4000 times more conductive than films made from silver nanoparticles after drying at 70 °C. In fact, films of long silver nanowires dried at 70 °C are more conductive than films of silver nanoparticles sintered at 300 °C. This result indicates the resistivity of metal nanostructure films is dominated by the contact resistance between particles. However, the high cost of silver nanowires remains a significant barrier to their practical use. Therefore, we have developed a large-scale synthesis of silver-coated copper nanowires. Silver-coated copper nanowires can be made highly conductive and resistant to oxidation with as little as 5 mol% silver. We have incorporated these silver-coated copper nanowires into a 3D printing filament to achieve conductivities 100 times greater than commercially available carbon-based conductive filaments.