Conducive ultra-flexible graphene-based films for electronic applications

Abstract

One of the priority tasks for development of flexible printed electronics is creation of stable conductive 2D printing inks that can form highly flexible films. For instance, development of wearable electronic devices requires materials able to withstand strain at the level of human skin elastisity. The structure, flexibility, and electrical properties of thin films of a graphene-based composite with addition of the conductive polymer PEDOT:PSS and polyvinyl alcohol (PVA) were studied. The films were produced by 2D inkjet printing. The high conductivity of all the samples is provided by graphene because its content significantly exceeds the percolation threshold. It has been found that the addition of 5 wt.% or more of PVA results in retainment of the film structure under strain of up to 40% (bending radius of 0.13 mm). At the same time, the resistance change under such deformations declines significantly (~3 times) compared to that of films without PVA. This is due to the formation of a PVA flexible network inside the composite films. Moreover, owing to this network, when no more than 30 wt.% of PVA is added, the initial specific resistance stays within 20% from that of the original composite without PVA. Besides that, at the addition of PVA, the resistance remains low under repeated significant mechanical strains (ε≈17%). Thus, graphene-based composites with the addition of PVA are promising conductive materials for flexible and wearable electronics.