Enhancing and Understanding the High Stretchability of Printable, Conductive Silver Nanowire Ink

A printable conductive ink that is both highly conductive and stretchable is desired for flexible and wearable electronics. This can be achieved by using silver nanowires as the conductive filler instead of the typically used silver flakes or nanoparticles. It is shown here that long, thin nanowires, lower metal fills and employing plasma sintering rather than thermal annealing leads to the best stretchability. The optimized silver nanowire ink with a 5% metal fill can have resistivity as low as 9.3 × 10−6 Ω cm, increases resistance by only 5× after 250 cycles of 30% strain, and remains conductive to at least 500% strain. It is significantly more stretchable and conductive than commercial stretchable inks, especially at the low sintering temperatures often used in flexible electronics. Moreover, this ink represents the best combination of stretchability and conductivity of all printable inks in the literature. It is found that the reason for the high stretchability of nanowire inks is both its low metal fill and high mechanical strength.Graphical Abstract