Ultra‐Thick Graphene Films with High Thermal Conductivity Through a Non‐Stacking Strategy

The growing heat flow density from the miniaturization trend of electronic devices seriously challenges the heat diffusion in electronic systems. Consequently, there is an increasing demand for thermal management materials with both thermal conductivity (K) and material thickness (d) to effectively transfer devices' heat flux. Graphene films (GFs) with high K have attracted significant attention, but achieving both high K and large d remains challenging due to graphene's intrinsic properties and fabrication limitations. Here, a novel non-stacking strategy is proposed for fabricating monolithic thick GFs. By utilizing the ultra-small-sized graphene oxide slurry, introducing multi-line shearing, and utilizing a specially designed frame, stable and highly oriented thick films are successfully produced. These thick films eliminate the interfacial defects and enable a monolithic GF with ultra-high K over 1600 W m^-1 K^-1 (improved by 17.03%) when d exceeds 300 µm compared to the conventional multi-layer stacking method. While the K × d value, which represents the film's heat transfer capability, increased by 21.34% to 0.544 W K^-1, the chip's operating temperature further decreased by 3.3 °C. The proposed strategy provides a promising solution to produce high-performance thick GFs and represents an effective route for heat dissipation of electronic systems.