The Thermoelectric Properties of Monolayer MAs2 (M = Ni, Pd and Pt) from First-Principles Calculations

Abstract

The thermoelectric property of the monolayer MAs2 (M = Ni, Pd and Pt) is predicted based on first principles calculations, while combining with the Boltzmann transport theory to confirm the influence of phonon and electricity transport property on the thermoelectric performance. More specifically, on the basis of stable geometry structure, the lower lattice thermal conductivity of the monolayer NiAs2, PdAs2 and PtAs2 is obtained corresponding to 5.9, 2.9 and 3.6 W/mK. Furthermore, the results indicate that the monolayer MAs2 have moderate direct bang-gap, in which the monolayer PdAs2 can reach 0.8 eV. The Seebeck coefficient, power factor and thermoelectric figure of merit (ZT) were calculated at 300, 500 and 700 K by performing the Boltzmann transport equation and the relaxation time approximation. Among them, we can affirm that the monolayer PdAs2 possesses the maximum ZT of about 2.1, which is derived from a very large power factor of 3.9 × 1011 W/K2ms and lower thermal conductivity of 1.4 W/mK at 700 K. The monolayer MAs2 can be a promising candidate for application at thermoelectric materials.

Low-cost pentagonal NiX2 (X = S, Se, and Te) monolayers with strong anisotropy as potential thermoelectric materials

“…The thermoelectric performance of p-type case is obviously better than that of n-type pentagonal NiX 2 (X = S, Se, and Te) monolayers. Such results are also much higher than the ZT s of pentagonal NiAs 2 monolayer 81 ( ZT = ∼0.58 at 700 K) and PdSTe monolayer 82 ( ZT = ∼0.59 at 600 K). However, the ZT values in the x direction are significantly higher than the y direction in the p-type pentagonal NiTe 2 monolayer, which are very different from the corresponding ZT values for NiS 2 and NiSe 2 monolayers.…”

First-Principles Investigation on the Significant Anisotropic Thermoelectric Transport Performance of a Hf2Cl4 Monolayer

“…For example, in 2020, the thermoelectric properties of monolayer MAs monolayer NiAs 2 , PdAs 2 , and PtAs 2 were calculated with values of 0.58 (p-type), 2.1 (n-type), and 0.64 (p-type) at 700 K, respectively. 16 Patel et al reported a Janus WSTe monolayer with low thermal conductivity and a high ZT value of 2.56 at higher temperatures. 17 In addition, Gao et al 18 found that an optimal figure of merit of 2.36 is achieved for p-type doped As 2 Te 3 at 600 K using ab initio calculations combined with semi-classical Boltzmann transport theory.…”

“…In comparison, the potential of two-dimensional (2D) materials as TE materials has begun to emerge. For example, in 2020, the thermoelectric properties of monolayer MAs 2 (M = Ni, Pd, and Pt) were studied, and the ZT values of monolayer NiAs 2 , PdAs 2 , and PtAs 2 were calculated with values of 0.58 (p-type), 2.1 (n-type), and 0.64 (p-type) at 700 K, respectively . Patel et al reported a Janus WSTe monolayer with low thermal conductivity and a high ZT value of 2.56 at higher temperatures .…”

Strain Tunable Thermoelectric Material: Janus ZrSSe Monolayer

“…At the low phonon frequency (0–2 THz) range, the fastest phonon group velocity of the unstrained Janus ZrSSe monolayer is about 4 km/s. Such a low value is lower than many famous 2D TE materials such as TiS 3 (∼6.5 km/s), ZrS 3 (6 km/s), PtAs 2 (6 km/s), and so forth. One can also see that as the tensile strain increases, the phonon group velocity of the Janus ZrSSe monolayer decreases, which will further cause a decrease in the phonon thermal conductivity.…”