Stretchable and transparent nanofiber-networked electrodes based on nanocomposites of polyurethane/reduced graphene oxide/silver nanoparticles with high dispersion and fused junctions

Creating stretchable and transparent conductive electrodes for stretchable and transparent electronics is very challenging due to difficulties in obtaining adequate optical and mechanical properties simultaneously. Here, we designed a stretchable and transparent nanofiber-networked electrode (STNNE) based on a networked structure of electrospun stretchable nanofibers made from a mixture of polyurethane (PU)/reduced graphene oxide (rGO)/silver nanoparticles (AgNPs). The STNNE showed a sheet resistance as small as 210 Ω sq^-1 at an optical transparency of ∼83%. In addition, the STNNE has up to 40% mechanical stretchability and relatively high electrical stability (i.e., a resistance change of 83% at 40% stretching). The good electrical conductance, mechanical stretchability, and electrical stability under static/dynamic stretching or after cyclic stretching are attributed to the high dispersion of AgNPs in the nanofibers, which creates more electrically conductive pathways and forms fused junctions at the intersections between nanofibers during electrospinning. As a demonstration, an STNNE with a simple selective-patterning process was employed to fabricate a stretchable capacitive touch sensor with a stretchable and transparent dielectric (PU) on a polydimethylsiloxane substrate. The signal output of the touch sensor upon touching under stretched conditions was nearly unchanged. This STNNE has great potential in stretchable and transparent electronics.