Significantly enhanced thermal conduction across multilayer graphene assembled by molecular bridges vs van der Waals interactions

Layered 3D van der Waals (vdW) structure, as a highly anticipated candidate for next-generation chip cooling solutions, shows extraordinary properties such as high-temperature resistance and high in-plane thermal conductivity (TC). However, the cross-plane TC is greatly limited by weak vdW interactions, making chip-level integration challenging. Here, a strategy of molecular bridge (MB) assembling 3D vdW structure is reported to significantly enhance cross-plane TC. An over 20-fold enhancement is realized through molecular dynamics simulation in multilayer graphene-based structure (MLG). Through phonon hybridization at the interface between MB and graphene, a novel continuous phonon transmission channel (around 50 THz) is triggered compared with the regular interrupted channel (below 5 THz) induced solely by vdW interactions. In addition, ballistic-diffusive phonon transport is observed with changing lengths of the MB connected to graphene layers. Our work presents an efficient strategy for designing 3D vdW structures with high thermal efficiency and tunable heat conduction through MB.