Silver Nanowire-Based Printable Electrothermochromic Ink for Flexible Touch-Display Applications

Flexible, lightweight, low-power, and low-cost displays are an active area of interest in the electronics community. In this work, we have developed a composite electrothermochromic material consisting of silver nanowires (Ag NWs) and thermochromic powders, which exhibits reversible color (phase) change during biasing due to Joule heating. A wide variety of color combinations are possible with suitable thermochromic material selection. We have formulated this composite material as a printable ink so that patterned deposition can be achieved in a single step. A low processing temperature of 100 °C makes the composite compatible with a wide range of flexible substrates such as paper and polyethylene terephthalate (PET). The material (encapsulated with polydimethylsiloxane (PDMS)) exhibits good flexibility and is observed to be functional after 10 000 bending cycles with <7% resistance change. We have fabricated a low-power seven-segment color display to show the material's suitability for practical display applications. We have also demonstrated that the same layer can function as a display and as a touch sensor because of its conducting and chromatic properties without additional active layers on top. The material is suitable for the fabrication of low-cost, flexible touch color displays for interactive electronic readers, digital posters, and flexible digital signboards.