Phonon transport in single-layer $\mathrm{M}{\mathrm{o}}_{1-x}{\mathrm{W}}_x{\mathrm{S}}_2$ alloy embedded with $\mathrm{W}{\mathrm{S}}_2$ nanodomains

Two-dimensional (2D) transition metal dichalcogenides have shown numerous interesting physical and chemical properties, making them promising materials for electronic, optoelectronic, and energy applications. Tuning thermal conductivity of 2D materials could expand their applicability in many of these fields. In this paper, we propose a strategy of using alloying and nanodomains to suppress the thermal conductivity of 2D materials. To predict the thermal conductivity of a 2D alloy embedded with nanodomains, we employ the Green's function approach to assess the phonon scattering strength due to alloying and nanodomain embedding. Our first-principles-driven phonon Boltzmann transport equation calculations show that the thermal conductivity of single-layer $\mathrm{Mo}{\mathrm{S}}_2$ can be reduced to less than one-tenth of its intrinsic thermal conductivity after alloying with W and introducing nanodomains due to the strong scattering for both high- and low-frequency phonons. Strategies to further reduce thermal conductivity are also discussed.

Figure 1

The schematic of the simulation domain. The inset shows a typical atomic configuration for the $\mathrm{M}{\mathrm{o}}_{1-x}{\mathrm{W}}_x{\mathrm{S}}_2$ alloy embedded with triangular $\mathrm{W}{\mathrm{S}}_2$ nanodomains.

Figure 2

(a) Thermal conductivity of $\mathrm{M}{\mathrm{o}}_{1-x}{\mathrm{W}}_x{\mathrm{S}}_2$ at 300 K as a function of alloy composition $x$. (b) Thermal conductivity of $\mathrm{M}{\mathrm{o}}_{1-x}{\mathrm{W}}_x{\mathrm{S}}_2$ alloy embedded with W nanodomains as a function of the size of nanodomains.

Figure 3

The accumulative thermal conductivity of $\mathrm{M}{\mathrm{o}}_{0.5}{\mathrm{W}}_{0.5}{\mathrm{S}}_2$ with and without nanodomains embedded as a function phonon frequency. The thermal conductivity difference is mainly caused by low-frequency phonons.

Figure 4

(a) The phonon nanodomain scattering rates of longitudinal acoustic (LA) phonons from the $\mathrm{\Gamma }$ point to the $M$ point as a function of phonon frequency. (b) The phonon nanodomain scattering rates of long-wavelength LA phonons at 0.03(0, $\pi /a_0\sqrt{3}$) and short-wavelength LA phonons at 0.97(0, $\pi /a_0\sqrt{3}$). The scattering rates are normalized by the area fraction of the nanodomains.

Figure 5

Thermal conductivity of $\mathrm{M}{\mathrm{o}}_{1-x}{\mathrm{W}}_x{\mathrm{S}}_2$ alloy embedded with 10-unit-cell-large $\mathrm{W}{\mathrm{S}}_2$ nanodomains at $10\%$ area fraction at 300 K as a function alloy composition $x$.

Figure 6

(a) Phonon alloy scattering rates as a function of phonon frequency. (b) Phonon nanodomain scattering rates as a function of phonon frequency.