Optimizing Silver Nanowire Synthesis for Direct Ink Writing Applications: A Parametric Study

This work presents a parametric study for optimizing the synthesis of silver nanowires (AgNWs) using a polyol method for conductive ink applications. The effects of various parameters, including reaction time, reaction temperature, and the type of metal halide employed during synthesis, on the properties of the AgNWs are systematically investigated. The kinetics of AgNW formation are analyzed by temporal UV-Vis spectroscopy and TEM. To elaborate on the complexity of the metal halide employed during the production of silver nanowires, we have conducted various sets of experiments revealing the role of the metal in classical polyol synthesis. We have demonstrated that even though the stoichiometric ratio of Ag+/Cl- is kept constant, the type of halide source is directly related to the formation of high-yield silver nanowires. The optimized synthesis conditions are found to result in AgNWs with high aspect ratios to prepare a conductive ink with desired viscoelastic properties for direct writing applications. The AgNW ink prepared with a 4 wt.% PEO mixture can automatically level itself at the specified frequency, while the 5 wt.% solution requires an external force to spread out. The frequency sweep experiments revealed that both mixtures have a crossover point where their behavior changes. The crossover point for the 4 wt.% mixture is approximately 12 rad/s, whereas for the 5 wt.% mixture, it is 2.5 rad/s. As a result, the 5 wt.% mixture takes longer to spread out than the 4 wt.% mixture.