Improved electrical conductivity of graphene film using thermal expansion-assisted hot pressing method

Dongpyo Hong, Gun-Sik Park*
Journal of the Korean Physical Society, 1 (2024)
DOI: 10.1007/s40042-024-01184-7

Abstract

Achieving highly conductive graphene flms requires the elimination of pores formed during the thermal reduction of graphene oxide (GO). Conventional methods such as hydraulic pressing often struggle to remove these pores efectively, especially in sub-micron large area flms for uniform high pressure. In this study, we introduce a thermal expansion-assisted hot pressing (TEHP) technique that leverages the diferential thermal expansion between graphite and tungsten to achieve
pore-free, highly conductive graphene flms. Here we heat the GO flm sandwiched between graphite (high thermal expansion coefcient) and tungsten (low thermal expansion coefcient) to 1800 °C where pressures of 13–48 MPa are estimated.
The TEHP resulted in graphene flms with a smooth, metallic surface, free of macropores. Raman spectroscopy and electron microscopy analyses confrmed the enhanced crystallinity and compactness of the flms. The electrical conductivity of the hot-pressed graphene flms shows a threefold improvement over normally annealed flms. This scalable method ofers a viable pathway for producing high-performance graphene flms for advanced applications.