Effect of Silver Nanowire Alignment on Electrical Resistance and Mechanical Reliability.

Given the increasing demands for high portability and large screens, electronic devices are evolving toward flexible electronics. Since the flexible devices will be operated by a current generated by repeated mechanical deformations, high mechanical stability, electrical conductivity, and optical properties of transparent conductive electrodes (TCE) under mechanical deformations are required; hence silver nanowire (AgNW) electrodes are attracting much interest. However, the anisotropic shape of AgNW can result in different electrical properties and mechanical reliability depending on the AgNW alignment. In this study, two kinds of AgNW films were prepared by roll-to-roll screening printing. One film has an isotropic arrangement of AgNW, the other an anisotropic arrangement, along the roll-to-roll machine direction (MD). These samples were cut with different directions from the MD. Whereas the isotropic sample exhibited an identical electrical resistance regardless of sample direction, the anisotropically aligned samples showed low resistance when parallel to the MD and high resistance when perpendicular to the MD. The mechanical reliability during repeated bending fatigue according to the AgNW alignment direction was also evaluated. Depending on the direction of alignment of the AgNW, the fatigue lifetime differed because the mechanical stability at the AgNW junction was different.