Stretch-Induced Tunability of Electrical Transport in 3D Graphene Foam

3D graphene foam with fast electron transport and mechanical flexibility finds wide applications in stretchable electronics. This study investigates the electrical transport properties of graphene foam by analyzing its temperature-dependent electrical resistance (R(T)) under various pre-stretching levels. Experimental results show that R(T) changes as pre-stretching level increases, some even exhibiting a notable transition from insulating to metallic behavior. This indicates a stretch-induced modulation of the electrical transport properties of graphene foam. Considering the interconnected polycrystalline graphene domains in graphene foam, we propose a conduction network model that effectively explains R(T) of graphene foam by incorporating thermally activated conduction and phonon-limited conduction within each graphene domain, along with the fluctuation-induced tunneling conduction between neighbouring domains. By fitting experimentally obtained R(T) to the model, we probed the stretch-induced modulation of the electrical transport of graphene foam by discerning the alterations of the conduction mechanisms and the conduction networks. The deduced conduction network changes aligns with the optically observed breakage or reconnection of graphene foam network branches under increasing pre-stretching levels. These findings provide valuable insights into the modulation of electrical transport properties in graphene foam-based stretchable electronics, offering opportunities for further refinement.