Functionalization mediates heat transport in graphene nanoflakes
HX Han and Y Zhang and N Wang and MK Samani and YX Ni and ZY Mijbil and M Edwards and SY Xiong and K Saaskilahti and M Murugesan and YF Fu and LL Ye and H Sadeghi and S Bailey and YA Kosevich and CJ Lambert and J Liu and S Volz, NATURE COMMUNICATIONS, 7, 11281 (2016).
The high thermal conductivity of graphene and few-layer graphene undergoes severe degradations through contact with the substrate. Here we show experimentally that the thermal management of a micro heater is substantially improved by introducing alternative heat-escaping channels into a graphene-based film bonded to functionalized graphene oxide through amino-silane molecules. Using a resistance temperature probe for in situ monitoring we demonstrate that the hotspot temperature was lowered by similar to 28 degrees C for a chip operating at 1,300 Wcm(-2). Thermal resistance probed by pulsed photothermal reflectance measurements demonstrated an improved thermal coupling due to functionalization on the graphene-graphene oxide interface. Three functionalization molecules manifest distinct interfacial thermal transport behaviour, corroborating our atomistic calculations in unveiling the role of molecular chain length and functional groups. Molecular dynamics simulations reveal that the functionalization constrains the cross-plane phonon scattering, which in turn enhances in- plane heat conduction of the bonded graphene film by recovering the long flexural phonon lifetime.
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