The Verification of Thermoelectric Performance Obtained by High-Throughput Calculations: The Case of GeS2 Monolayer From First-Principles Calculations

Abstract

Electronic fitness function (EFF, achieved by the electrical transport properties) as a new quantity to estimate thermoelectric (TE) performance of semiconductor crystals is usually used for screening novel TE materials. In recent years, because of the high EFF values, an increasing number of two-dimensional materials have been predicted to have the potential for TE applications via high-throughput calculations. Among them, the GeS2 monolayer has many interesting physical properties and is being used for industrial applications. Hence, in this work, we systematically investigated the TE performance, including both electronic and thermal transport properties, of the GeS2 monolayer with first-principles calculations. The results show that the structure of the GeS2 monolayer at 700 K is thermally unstable, so we study its TE performance only at 300 and 500 K. As compared with other typical TE monolayers, the GeS2 monolayer exhibits excellent electronic transport properties but a relatively high lattice thermal conductivity of 5.71 W m−1 K−1 at 500 K, and thus an unsatisfactory ZT value of 0.23. Such a low ZT value indicates that it is necessary to consider not only the electron transport properties but also the thermal transport properties to screen the thermoelectric materials with excellent performance through high-throughput calculations.

Strain-Enhanced Thermoelectric Performance in GeS2 Monolayer

“…Moreover, the VBM is mainly contributed by the S- p orbital, while the CBM is occupied by both Ge- s and S- p orbitals. Our results are in accordance with the previous theoretical predicated [ 25 , 46 ], indicating that our calculation parameters are reasonable.…”

“…The side and top views of the GeS 2 monolayer are plotted in Figure 1 a,b, respectively. The relaxed lattice parameters are a = b = 3.44 Å, which agree with previous theoretical predictions [ 21 , 25 ]. Figure 1 c describes the atom orbitals project band structure of the GeS 2 monolayer.…”

“…Recently, the 1T-GeS 2 monolayer has been reported as a potential thermoelectric material due to its relatively high electronic fitness function (EFF) value from high-through computational screening [ 21 ]. Moreover, the high-power factor of the GeS 2 monolayer further reveals its great potential application in the field of thermoelectrics [ 25 ]. However, the ZT value of the 1T-GeS 2 monolayer is only 0.23 when the thermal transport property is considered [ 25 ], which significantly hinders its further application.…”

“…Moreover, the high-power factor of the GeS 2 monolayer further reveals its great potential application in the field of thermoelectrics [ 25 ]. However, the ZT value of the 1T-GeS 2 monolayer is only 0.23 when the thermal transport property is considered [ 25 ], which significantly hinders its further application. Therefore, it is of great significance to improve its thermoelectric performance by adjusting the thermal transport properties of GeS 2 monolayers.…”

First-Principles Investigation of Adsorption Behaviors and Electronic, Optical, and Gas-Sensing Properties of Pure and Pd-Decorated GeS2 Monolayers

“…This structure corresponds to a single slab of the high-pressure, layer-structured, tetragonal CdI 2 -type phase. , To determine the equilibrium lattice parameters of the GeS 2 monolayer, the total energy of the 4 × 4 × 1 supercell of the monolayer as a function of the lattice constant was calculated and is shown in Figure b. We found that the GeS 2 monolayer possesses a symmetry group of P 3̅ m 1 with the lattice constants of a = b = 3.416 Å, which is slightly smaller than previous reports (3.45 Å). − The Ge–S bond length in the GeS 2 monolayer is 2.44 Å, which is very different from that of the GeS monolayer in which two types of Ge–S bond lengths are found (2.37 and 2.47 Å). The electronic properties (band structure (BS) and partial density of states (PDOS)) of the GeS 2 monolayer in Figure c,d showed that it is a nonmagnetic semiconductor with a band-gap width of 0.93 eV, which is in good agreement with previous work. − It should be emphasized that although the PBE method we used underestimates the band gap width of the GeS 2 monolayer, which was reported to be 1.47 eV by using the HSE06 functional, in this work what we mainly focus on is the change of the band gap before and after molecular adsorption, which will determine the sensitivity of the gas sensor.…”