Improving thermal conductivity of graphene films with assistance of melamine

Abstract

Due to high degree of integration and high power-density, excessive heat accumulation significantly endangers the performance of electronics. Therefore, developing high-performance thermal interface materials has become particularly vital for ensuring regular operation of the electronics. Graphene-based materials attract great attention due to the intrinsic excellent thermal conductivity of graphene. However, the internal defects in graphene and lack of interlayer heat conduction pathway between graphene microsheets dramatically reduces the thermal conductivity of the graphene-based materials. Herein, melamine is used to improve thermal properties of graphene films prepared by thermal reduction of graphene oxides microsheets. With an addition of 3 wt% of melamine, the in-plane and through-plane thermal conductivities of the graphene films with a thickness of 35 μm reaches 1.32 × 103 and 5.09 W m-1 K-1, respectively. This is likely due to covalent connection of graphene microsheets through amide structure formed by chemical reaction between melamine and graphene oxides, and remedy of defects in graphene by nitrogen doping with assistance of high temperature annealing. The operation temperature of LED is greatly reduced, when the prepared graphene film is used as thermal interface material, compared to other commercial products. The results provide a promising way to improve thermal properties of graphene films, which is of great significance for various applications, such as thermal management for high power-density electronics.