Electrical resistance measurements of silver nanowire junctions using Conductive Atomic Force Microscopy

Abstract

Transparent conductive materials (TCMs) are in high demand for widespread applications, including organic light-emitting diode displays, touch panels, solar cells. TCMs have conventionally been made from indium tin oxide (ITO) as it offers high electrical conductivity and transparency. However, as a brittle ceramic, its usage in future applications in building flexible electronic devices has become limited. Networks of silver nanowires (AgNWs) are an alternative TCM material, displaying flexibility and high optical transmittance. However, their low sheet resistance relies on minimizing the contact resistance between individual silver nanowires, which remains a major challenge. We have used an Atomic Force Microscope (AFM) to measuring the electrical resistance of individual nanowire junctions and conducting pathways in networks deposited on glass substrates. It was found that mechanical pressing at room temperature improves the electrical conductivity of the AgNW networks, but considerable resistance remains. This is attributed to residual layer of organic contamination from the dispersants used in the films formation process. Possible treatments to reduce this are discussed.