Interfacial thermal resistance and thermal rectification between suspended and encased single layer graphene

Abstract

With molecular dynamics simulations, we systematically investigate interfacial thermal resistance between suspended and encased single layer graphene. Combining with lattice dynamics analysis, we demonstrate that induced by substrate coupling which serves as perturbation, the long wavelength flexural phonon mode in the encased graphene is significantly suppressed when compared with that in the suspended graphene. Therefore, at the interface between suspended and encased graphene, in-plane phonon modes can transmit well, whereas low frequency flexural phonon modes are reflected, leading to this nontrivial interfacial thermal resistance. The impacts of coupling strength, temperature, and size of the system on this type of interfacial thermal resistance are explored. More interesting, we find that thermal rectification can be realized in this inhomogeneous encased graphene structures with a thermal rectification efficiency of 40% at 50 K temperature difference. Our study provides insight to better understand thermal transport in two-dimensional materials and promising structures for practical thermal rectification devices.

Tunable thermal rectification in silicon-functionalized graphene nanoribbons by molecular dynamics simulation

“…Thus with the increase of system length, the difference between the two overlapped phonon energies is reduced, and the thermal rectification becomes weak in this system. According to the overlapped phonon energy at different conditions, it is observed that the difference in the overlap of the phonon spectra is the origin of the thermal rectification phenomena and our results conform with the previous studies [16,17,21,22].…”

“…For both Si/ C ratios, the increase in jDj results in the increase in the rectification factor akin to the characteristic in electric rectifier. With jDj ¼ 0.5 and Si/C ratio of 5%, the thermal rectification of asymmetric graphene structure is 145%, which overwhelms the carbon nanotube based thermal rectifiers like carbon nanocone [21] and carbon nanotube intramolecular junctions [22] and is comparable to other graphene based thermal rectifiers [13,16,17]. Our result demonstrates that such asymmetric graphene structures have an obvious advantage when applied in nanoelectronic devices.…”

“…Many researchers adopt match/mismatch of the phonon spectra between the two sides of a rectifier to explain the asymmetric thermal rectification [16,17,21,22]. There is larger overlap of the phonon spectra in the direction of high heat flux and big mismatch of the phonon spectra in the reverse direction.…”

“…Their simulations indicate that spatial asymmetry in geometry is a key factor to realize thermal rectification. Other proposed thermal rectifiers in graphene show that the thermal rectification can also be tuned greatly through inhomogeneous external perturbation [17] and strain engineering [18]. Therefore, graphene is a good candidate as a thermal rectifier.…”

MoS2-graphene in-plane contact for high interfacial thermal conduction

“…To understand the difference of interfacial thermal conductance at ZZ and ZZ57 interfaces, the phonon transmission process across the interfaces was investigated using the phonon wave packet method 45,46 . Phonon wave packets are formed from a linear combination of vibration eigenstates of the crystalline lattices.…”