Effect of Mechanical Properties of Substrates on Flexibility of Ag Nanowire Electrodes under a Large Number of Bending Cycles

Ag nanowire electrodes have attracted considerable attention because of their potential applications in next-generation flexible electronics. However, there is a paucity of studies on the mechanical properties of Ag nanowire electrodes subjected to a large number of bending cycles. In this study, the effects of the substrate on the mechanical behavior of Ag nanowire electrodes were studied for a high bending frequency. The mechanical reliability of the Ag nanowire electrodes fabricated on a polyethylene terephthalate (PET) substrate was better than that for a polyimide (PI) substrate; the increase in the resistance of the PET-based Ag nanowire electrode was 1.07%, while that of the PI-based one was 1.23%. Nanoindentation tests showed that the elastic modulus of PI was larger than that of PET. This resulted in a lower bending strain on PET-based Ag nanowire electrodes compared to those on PI-based ones, because of the smaller distance from the neutral plane of the PET-based system. Our study showed that the mechanical properties of the substrate influenced the strain imposed on the thin layer on the substrates, which, in turn, determines the mechanical reliability of the thin-layer/substrate multilayer system.