Ink formulation of functional nanowires with hyperbranched stabilizers for versatile printing of flexible electronics

Functional nanowire ink formulations require elaborate control over their composition, rheological properties, and fluidic properties to optimize their printing processes. They also require harsh post-fabrication treatments to maximize the performance of the resulting printed flexible devices, making it challenging to uniformly deposit nanowire-based architectures and ensure device reproducibility and scalability. Here, we propose a strategy for developing silver nanowire (AgNW) ink formulations, where hyperbranched molecules (HPMs) are employed as both dispersant and stabilizer for nanowires. The three-dimensional architecture with functional groups on the periphery of HPMs enables the preparation of thixotropic HPMs-AgNW inks with solid contents of up to 20 wt.% in both aqueous and organic solvents using a low amount of HPMs (AgNW and HPMs weight ratio = 1:0.001). The HPMs-AgNW inks can be printed into patterns with a resolution of 20 μm on various flexible substrates without needing harsh post-treatments. We obtain bar-coated transparent electrodes (sheet resistance of 17.1 Ω sq−1 at 94.7% transmittance), slot-die-coated flexible conductive patterns, screen-printed conductive lines (conductivity exceeding 6.2 × 104 S cm−1), and 3D printed stretchable wires. Importantly, this HPMs-stabilized formulation strategy is general for various functional nanowires, enabling the integration of a diverse set of nanowire-based wearable electronic systems. Depositing flexible electronics based on nanowires uniformly and reproducibly is a challenge. Here, the authors demonstrate the formulation of silver nanowire suspensions using hyperbranched molecules that enable scalable fabrication of electrodes with different printing technologies.