The critical role of Ag nanowires in the improvement of conductivity and flexibility of circuits fabricated with hybrid Ag nanopaste

Research into printable ink or paste materials has led to continued improvements in the electrical and mechanical properties of electrodes and circuits fabricated by solution-based processes on flexible polymer substrates. We introduce a facile approach to the production of highly-conductive flexible circuits via a hybrid silver (Ag) nanopaste, employing Ag nanowires (NWs) within a Ag nanoparticle paste. The hybrid Ag nanopaste allows for a significantly lower electrical resistivity of 14.2 μΩ cm as compared to that of conventional Ag nanopaste after annealing for 30 min at 150 °C. The addition of Ag NWs also improves the fatigue stability of Ag nanoparticle-based circuits; the electrical resistance of the hybrid Ag nanopaste annealed at 150 °C was sustained at the smallest rate of increase, 12 %, during 10⁶ cycles of repetitive sliding deformation. Microstructural characterization reveals that Ag NWs in the mixture behave as conductive bridges to reduce contact resistance between Ag nanoparticles, and at the same time, as obstacles to suppress the propagation of cracks under cyclic mechanical deformation.