Vacancy-assisted dynamic phonon coupling between metal & graphene for improved out-of-plane thermal transport

Graphene is predicted to be a potential heat spreader due to its high thermal conductivity. However, the material has not been explored or demonstrated yet for heat spreading applications. Graphene in its pristine form despite having high in-plane thermal conductivity is ineffective in spreading heat due to weak out-of-plane phonon coupling or low thermal boundary conductance (TBC) between graphene and metal. To address this issue, in this work, defect-engineering was carried-out on graphene and tracked the nanosecond time evolution of generated hotspots at metal-graphene interface using Thermoreflectance characterization technique. Furthermore, in this study extensive density functional theory simulations were carried out to gain atomistic insights into the underlying mechanisms and provide a theoretical framework that corroborates the experimental results. It is observed that defect-engineering at the interface enhances atomic orbital overlaps and phonon transmission which improves the out-of-plane phonon coupling and TBC at graphene-metal interface. In contrast to prior studies focused on graphene’s in-plane heat conduction, our work highlights interface engineering as a pathway to achieve more efficient out-of-plane thermal transport. The proposed solution reduces the generated hotspots thereby setting a new benchmark in overcoming interfacial limitations and underscoring graphene’s promise as a practical material for advanced thermal management applications.