Investigation of the mechanism for current induced network failure for spray deposited silver nanowires

Abstract

Silver nanowires are one of the prominent candidates for the replacement of the incumbent indium tin oxide in thin and flexible electronics applications. Their main drawback is their inferior electrical robustness. Here, the mechanism of the short duration direct current induced failure in large networks is investigated by current stress tests and by examining the morphology of failures. It is found that the failures are due to the heating of the film and they initiate at the nanowire junctions, indicating that the main failure mechanism is based on the Joule heating of the junctions. This failure mechanism is different than what has been seen in literature for single nanowires and sparse networks. In addition, finite element heating simulations are performed to support the findings. Finally, we suggest ways of improving these films, in order to make them more suitable for device applications.

Enhancement of Antibacterial Performance of Silver Nanowire Transparent Film by Post-Heat Treatment

“…Previous simulation- [37] and experiment-based [29,34,36] studies have also reported that AgNWs break into more discontinuous segments when increasing the heat-treatment temperature. Wang et al [36] investigated the effect of heating temperature on a AgNW film where AgNWs with diameters of 20-30 nm and lengths of 25-30 μm are on a polyethylene terephthalate film.…”

“…The AgNW film heated at 200 • C (not contained in this study) showed the thickening of the AgNWs rather than the fragmentation, while the AgNW film heated at 250 • C (not contained in this study) showed a similar morphology to the AgNW-280 • C. The fragmentation and thickening of AgNWs are guessed as being spontaneous processes to minimize the surface energy and hence the total system energy through self-coalescence. It is believed that the fragmentation is driven by the Rayleigh-Plateau instability in which a fluid spontaneously breaks up into smaller droplets with larger surface-to-volume ratios to reduce the total system energy [31,37,38]. In particular, nanostructured materials including AgNW are more likely to cause self-coalescence owing to the high specific surface area, high surface energy, and hence low thermodynamic stability [39].…”

“…In particular, nanostructured materials including AgNW are more likely to cause self-coalescence owing to the high specific surface area, high surface energy, and hence low thermodynamic stability [39]. High environmental temperatures (normally, above 200 °C) cause AgNWs to fuse, and concurrently provide an energy for the spontaneous self-coalescence by surface diffusion [29,30,[32][33][34]37,40]. The excessive self-coalescence causes the fragmentation of AgNWs.…”

Long-term electrically stable silver nanowire composite transparent electrode under high current density

“…For example, a current density of 150 mA cm -2 on the AgNW network lm turns out to an extremely high current density of 5×10 6 A cm -2 on individual nanowire [10]. Second, the Joule heating caused by current in cross-linked junctions between nanowires is quite strong due to the high contact resistance, which tends to melt the nanowires to droplets in junctions followed with capillary or Rayleigh instability [9][10][21][22]. Third, the deposition of AgNW networks in nanoscale is not homogeneous, and may cause the non-uniform current ow, resulting in local hotspots and local failures [22][23].…”

“…Second, the Joule heating caused by current in cross-linked junctions between nanowires is quite strong due to the high contact resistance, which tends to melt the nanowires to droplets in junctions followed with capillary or Rayleigh instability [9][10][21][22]. Third, the deposition of AgNW networks in nanoscale is not homogeneous, and may cause the non-uniform current ow, resulting in local hotspots and local failures [22][23]. Forth, the surface of pristine AgNW is prone to be corroded with sul des, oxygen, moisture or other chemicals in ambient environment [24][25][26].…”