In Situ Multiscale Investigation of Capillary-Force-Induced Cold-Welding of Silver Nanowire Networks

Silver nanowire (AgNW) networks are in the spotlight as flexible transparent electrodes (TEs) thanks to their combination of high optical transmittance, low electrical resistance, and excellent flexibility. As such network is formed from a multitude of interwoven AgNW, a postdeposition treatment is needed to get the best electrical conductivity from each interconnect. Traditionally, thermal annealing above 200 °C enhances AgNW junction contacts but restricts compatibility with heat-sensitive substrates such as polymers and perovskites, common in flexible electronics and solar cells. The present study explores the potential of capillary-force-induced cold-welding, an already reported low-temperature alternative operating at or below 100 °C. Better insight into the morphological and electrical properties of cold-welded AgNWs is essential for their large-scale integration as flexible and stable TEs in devices. In this work, the effective welding of AgNW junctions is directly demonstrated by in situ and nanoscale transport measurements. The junction resistance is drastically reduced while preserving both optical transparency and nanowire morphology at significantly lower temperatures than those used with conventional treatments such as thermal annealing. These results strengthen cold welding as a promising approach for overcoming the challenges of AgNW network integration in flexible electronics.