Conductivity Control by Welding of Nanomembrane for Stretchable Electronics

Welding is a technology that enhances conductivity by forming junctions of metal nanomaterials within a nanocomposite. Conventional nanocomposites have difficulty forming percolation because conductive nanomaterials are mixed with insulating polymers. Conductivity can be improved only through welding with harsh conditions, making it a challenge to control conductivity through welding. Herein, we introduce welding control technology to enable control over the conductivity of nanomembranes on a wide scale under mild conditions. Welding control is a technique that regulates the interparticle junction diameter of the nanomembrane by controlling the reactivity of the reduction solution, which removes ligands attached to the surface of nanoparticles. Reduction solutions can directly act on the nanoparticles exposed in the form of a monolayer in the nanomembrane. The reactivity of the reduction solution is directly proportional to the degree to which ligands are removed, thus increasing the junction diameter. By adjusting the diameter of these junctions, resistance can be tuned from a few ohms to several thousand ohms. This technology is applicable to various metal nanoparticles, such as Au and Ag, and can simplify circuit design when used for patterning. Hence, it can be used as a universal strategy in stretchable devices.