Temperature dependent thermoelectric properties of freestanding few layer graphene/polyvinylidene fluoride composite thin films

Freestanding few layer graphene platelet/polyvinylidene fluoride composites have been synthesized, resulting in flexible, light weight, and durable electrically conducting films. These composites exhibit reasonable thermoelectric properties including a maximum electrical conductivity of 2005 S m−1, Seebeck coefficient of 18.3 μV K−1, and power factor of 0.52 μW m−1 K−2. The temperature dependent behavior of these properties is also investigated. The electrical conductivity of the composites exhibits thermal fluctuation-assisted tunneling behavior coupled with a high energy phonon scattering term, while the thermoelectric power is characterized by electron-phonon enhanced metallic diffusion thermopower plus a phonon drag term. This results in a characteristic change in majority charge carrier type from hole to electron as the temperature decreases below 60 K. These composites have the potential to be used in low power applications where sufficient waste heat is available.

► The temperature dependent thermoelectric properties of graphene/polymer composites was measured.
► The electrical conductivity behavior is described by thermal fluctuation-assisted tunneling.
► The thermoelectric power is characterized by electron-phonon enhanced metallic diffusion.
► These properties result in a maximum power factor of 0.52 μW m−1 K−2 for a 60 wt% graphene composite.