Room‐Temperature Nanosoldering of a Very Long Metal Nanowire Network by Conducting‐Polymer‐Assisted Joining for a Flexible Touch‐Panel Application

TLDR

The study develops a room‑temperature nanosoldering technique using a conducting polymer to join Ag nanowire percolation networks, aiming to produce highly flexible and stretchable transparent conductors as an alternative to brittle indium tin oxide. By drying the polymer on the nanowire network, capillary‑force‑assisted stiction bonds the wires and the substrate, improving conductivity, mechanical stability, and adhesion without high‑temperature annealing, and enabling large‑area (A4) transparent conductors and touch panels on non‑flat surfaces. The resulting Ag‑nanowire/polymer hybrid films exhibit low sheet resistance, high transmittance, and retain conductivity after 20 000 bends and 5–10 % stretching, demonstrating their suitability for flexible, wearable electronic devices.

Abstract

Abstract As an alternative to the brittle and expensive indium tin oxide (ITO) transparent conductor, a very simple, room‐temperature nanosoldering method of Ag nanowire percolation network is developed with conducting polymer to demonstrate highly flexible and even stretchable transparent conductors. The drying conducting polymer on Ag nanowire percolation network is used as a nanosoldering material inducing strong capillary‐force‐assisted stiction of the nanowires to other nanowires or to the substrate to enhance the electrical conductivity, mechanical stability, and adhesion to the substrate of the nanowire percolation network without the conventional high‐temperature annealing step. Highly bendable Ag nanowire/conducting polymer hybrid films with low sheet resistance and high transmittance are demonstrated on a plastic substrate. The fabricated flexible transparent electrode maintains its conductivity over 20 000 cyclic bends and 5 to 10% stretching. Finally, a large area (A4‐size) transparent conductor and a flexible touch panel on a non‐flat surface are fabricated to demonstrate the possibility of cost‐effective mass production as well as the applicability to the unconventional arbitrary soft surfaces. These results suggest that this is an important step toward producing intelligent and multifunctional soft electric devices as friendly human/electronics interface, and it may ultimately contribute to the applications in wearable computers.