Optimizing electrical resistivity in flexible conductive films by way of silver nanowire doping

Silver nanowires (AgNWs) have attracted significant research interest due to their potential in conductive films, flexible electronics, electromagnetic interference shielding, sensors, energy storage, and integration into wearable devices. This study developed conductive inks with tailored viscosities for fabricating films with stable electrical resistance. The formulations were optimized for screen printing, inkjet printing, and direct writing by doping AgNWs into carbon paste dispersed in N,N-dimethylformamide. Flexible conductive circuits were printed on silk film substrates, and their electrical resistance was evaluated by varying AgNW concentration and the number of printed layers. Cyclic bending and energizing heating experiments were conducted to assess durability. The results demonstrated that doping with AgNWs significantly reduced film resistivity, with a concentration of 30 mg/ml being optimal for screen printing, inkjet, and direct printing. Screen-printed films exhibited the lowest resistivity, decreasing from 1.2 × 10⁻⁴ to 3.5 × 10⁻⁵ Ω·cm with increasing AgNWs concentration from 5 to 30 mg/ml. The resistivity of inkjet-printed and direct-written films at 30 mg/ml AgNWs was 5.8 × 10⁻⁵ and 7.2 × 10⁻⁵ Ω·cm, respectively. Increasing the number of printed layers from one to seven further reduced resistivity by 62% for screen printing, 58% for inkjet printing, and 55% for direct writing. Cyclic bending tests showed that after 1000 bending cycles, the resistance increased by 18% for screen-printed films, 25% for inkjet-printed films, and 30% for direct-written films. Screen-printed films exhibited the lowest resistivity and longest service life, highlighting their potential for diverse applications in flexible electronics and the broader electronics industry.