Thermoelectric properties of orthorhombic group IV–VI monolayers from the first-principles calculations

Abstract

Two-dimensional (2D) materials may have potential applications in thermoelectric devices. In this work, we systematically investigate the thermoelectric properties of orthorhombic group IV-VI monolayers AB (A=Ge and Sn; B=S and Se) by the first-principles calculations and semiclassical Boltzmann transport theory. The spin-orbit coupling (SOC) is included to investigate their electronic transport, which produces observable effects on power factor, especially for n-type doping. According to calculated ZT , the four monolayers exhibit diverse anisotropic thermoelectric properties, although they have similar hinge-like crystal structure. The GeS along zigzag and armchair directions shows the strongest anisotropy, while SnS and SnSe show mostly isotropic efficiency of thermoelectric conversion, which can be understood by the strength of anisotropy of their respective power factor, electronic and lattice thermal conductivities. Calculated results show that ZT for different carriers of n-and p-type has little difference for GeS, SnS and SnSe. It is found that GeSe, SnS and SnSe show better thermoelectric performance compared to GeS in n-type doping, and SnS and SnSe exhibit higher efficiency of thermoelectric conversion in p-type doping. Compared to a lot of 2D materials, orthorhombic group IV-VI monolayers AB (A=Ge and Sn; B=S and Se) may possess better thermoelectric performance due to higher power factor and lower thermal conductivity. Our work would be beneficial to further experimental study.

First-Principles Calculations of Thermoelectric Properties of IV–VI Chalcogenides 2D Materials

“…From theoretical reports, the number of studies has been consistently increasing in the last decade, and several studies of 2D materials related to this field and presented in this work have been recently reported. For both experimental and theoretical studies, we found a fairly reasonable agreement of electrical properties with our reported values (Kumar and Schwingenschlögl, 2015;Sun et al, 2015;Morales Ferreiro et al, 2016;Tyagi et al, 2016;Ding et al, 2017;Guo and Wang, 2017;Li et al, 2017;Shafique and Shin, 2017).…”

“…Since SOC has been reported to have the possibility of influencing the electronic transport in TEs (Guan et al, 2015;Guo and Wang, 2017), we computed the electronic structures for GeS, GeSe, SnS, SnSe, SnS2, and SnSe2 without and with SOC. The band structures are shown in Figure 3.…”

“…The TE properties are plotted at a temperature range from 300 to 800 K. The electronic properties of TE materials are influenced by SOC, resulting in some cases with better TE properties such as Seebeck coefficient and electrical conductivity (Guo, 2016;Guo and Zhang, 2016;Guo and Wang, 2017). Figure 4 shows the calculated Seebeck coefficient without and with SOC at different doping levels.…”

“…These include SnSe, GeSe, SnS, GeS, SnS2, and SnS2. We evaluate the importance of the spin orbit coupling (SOC) due its potential relevance in the electronic transport in TEs (Guan et al, 2015;Guo and Wang, 2017). To compute TE properties, we solve the semi-empirical Boltzmann transport model, through the BoltzTraP software (Madsen and Singh, 2006), and for thermal properties, we used first-principles lattice dynamics combined with the iterative solution of phonon Boltzmann transport equations (BTEs) using the ShengBTE software (Li et al, 2014b This paper is organized as follows: Section "Computational Details" includes a description of the computational details with emphasis in simulation processes used for different types of calculations.…”

Ferroelectricity and piezoelectricity in monolayers and nanoplatelets of SnS

“…Tin sulfide SnS, which in the bulk form is a semiconductor with a layered structure, can be split into monolayers and nanoplatelets by chemical methods. [5][6][7] The interest to SnS quasi-2D structures is stimulated by their thermoelectric, electric, and optical properties [8][9][10][11][12][13][14][15][16][17] and the predicted ferroelectricity in SnS monolayers. 18,19 The latter suggests a possible application of piezoelectric properties of these structures.…”