Dual Substrate Effect of Silicon Substrate on Thermal Transport Characteristic of (14,14,14)-Graphyne: Transformation from Conventional Suppressing Role to Abnormal Promoting Role

Herein, (14,14,14)-graphyne (GY) supported by silicon substrate is chosen to be the research object. The results demonstrate that the increasing distance between substrate and supported materials (dsub-sup) results in the enhancement of thermal conductivity (TC) of supported GY, and the TC of supported GY is even higher than that of free-standing GY when dsub-sup exceeds a certain value, which means substrate plays an abnormal promoting role in the thermal transport in supported materials (SM). This phenomenon breaks the traditional cognition that the increasing dsub-sup can only lead to the TC of SM approaching that of free-standing model. The related mechanism can be seen as the combined impact of weak interaction of long-dsub-sup substrate and tensile effect led by lattice mismatch between substrate and GY. Combining with phonon analysis, it can be observed that the influence of substrate shows a closer relationship with phonon scattering, i.e., the anharmonicity, especially the anharmonicity of out-of-plane direction. The anomalous promoting effect of long-dsub-sup can be also attributed to the weaker scattering of out-of-plane phonon, especially the reduced four-order phonon scattering. This research provides a new idea to suppress the negative effect of substrate on heat dissipation in electronic devices. With the increase of dsub-sup, the thermal conductivity (TC) of supported graphene (GR) gradually approaches that of free-standing GR, while the TC of supported graphyne (GY) exceeds that of free-standing GY.image (c) 2024 WILEY-VCH GmbH