Thermal rectification in restructured graphene with locally modulated temperature dependence of thermal conductivity

Abstract

We study thermal rectification (TR) in a selectively restructured graphene by performing deviational phonon Monte Carlo (MC) simulations with frequency-dependent phonon transport properties obtained from first principles. The restructuring is achieved by introducing vacancy defects in a portion of graphene. The defects significantly change phonon transport properties, which results in a modulation of temperature dependence of thermal conductivity. With this modulated temperature dependence, we predict TR ratio through an iterative scheme (IS), where heat flow through the system is analyzed by solving the Fourier's law of heat conduction with spatially varying temperature-dependent thermal conductivity. To identify structure parameters for maximal TR ratio, we investigate the influence of defect size, volume percentage of defects, and system (consisting of defective and non-defective regions) length through IS analysis. As results, we find that TR ratio is mainly a function of length of defective and non-defective regions, and volume percentage of defect, whereas it is mostly independent of defect size. A longer (of the order 10 μm) non-defective side, coupled to a shorter (of the order 100 nm) defective side, can lead to large TR ratios. Finally, MC simulation for the restructured graphene (full system) is performed to verify the predictions from IS analysis. The full system calculations give similar trends but with enhanced TR ratios up to 70% for the temperature range of 200-500 K.

Computational Study of the Thermal Rectification Properties of a Graphene-Based Nanostructure

“…Accuracy can be improved by introducing an energy-based formulation. 45 , 46 This formulation is effective in conserving energy in the relaxation time approximation. 47 , 48 The energy-based Boltzmann transport equation is given by wherein e is the energy distribution function in the phase space of the system, ∇ is the gradient operator, and e loc is the local energy equilibrium distribution function.…”

“…Accuracy can be improved by introducing an energy-based formulation. 45,46 This formulation is effective in conserving energy in the relaxation time approximation. 47,48 The energy-based Boltzmann transport equation is given by…”

Quantifying phonon particle and wave transport in silicon nanophononic metamaterial with cross junction

“…Figure 1 (a) shows the simulation cell of NCJ, consisting of wires that are connected by cross junction. Despite previous studies demonstrating that there is a strong wave effect in the junction part, [26][27][28] in order to probe the phonon transport from partible standpoint, we use MC method [35][36][37], which solves Boltzmann transport equation based on phonon particle transport. Therefore, the MC simulation will ignore the wave effect and hence, surely overestimate the thermal conductivity.…”

Radial thermal rectification in concentric silicon ring from ballistic to diffusive regime

“…It attributes to that the thermal conductivity decreases significantly as the characteristic length of the thermal system decreases from macro-to-nanoscale and the phonon boundary scattering increases. Arora et al [35] studies the thermal rectification in a selectively restructured graphene by introducing vacancy defects in a potion of graphene. As a result, they find that the thermal rectification is mainly a function of length of defective and nondefective regions and volume percentage of defect, and it is mostly independent of defect size.…”