Enhancement in the Thermoelectric Performance of SnS Monolayer by Strain Engineering

Abstract

Nanostructuring is one of the well-known tools for improving the thermoelectric figure of merit, but it has limits when tuning the lattice thermal conductivity. The thermoelectric coefficients, including the lattice thermal conductivity in two-dimensional materials, can further be modified using strain engineering, which manipulates the interatomic forces and the energy levels in these systems. With this in mind, we investigate the thermoelectric properties of the SnS monolayer under uniaxial compressive and tensile strains using first-principles calculations and the Boltzmann transport equation. Analysis of the elastic constants and Poisson ratio points toward the applicability of strain only along the armchair or b direction. Systems with uniaxial compressible and tensile strains from −4% to 5% along the armchair direction are found to be dynamically stable. A high power factor of ∼1.1 W m–1 K–2, which is ∼1.8 times higher than the unstrained case, is predicted for the 1% strain case for p-type carriers. A ∼77% enhancement in the dimensionless figure of merit (ZT) for p-type carriers and ∼86% enhancement in the figure of merit for n-type carriers with respect to equilibrium is detected upon application of a minimal 1% tensile strain. An almost 3-fold increase in ZT can be achieved for 1% strain at 600 K. This enhancement in ZT renders the strained monolayer a much more promising candidate for thermoelectric applications.

Giant Thermoelectric Effect in Rare Earth Sulfoiodides

“…It has been reported that electrical conductivity can be enhanced and thermal conductivity can be reduced by additional phonon scattering through strain engineering. − For example, in the experiment, the selection of different substrate in the Mg 3 Sb 2 film was able to stretch stress or compression stress in the film middle class, which was the maximum amount of 8%, and the thermoelectric properties were greatly improved . Our theoretical calculation shows that both tensile strain and compressive strain not only increase the power factor but also significantly decrease the lattice thermal conductivity.…”

Effects of stresses on the thermoelectric properties of In4Se3

“…This value is calculated using the formula ZT = S 2 sT/(k L + k e ), where S, s, T, k L , and k e represent the Seebeck coefficient, electrical conductivity, absolute temperature, and lattice and electronic thermal conductivity, respectively. [5][6][7][8][9][10] In the medium temperature range, layered In 4 Se 3 emerges as a promising n-type thermoelectric material, showing a unique layered crystal structure. This structure instigates the development of charge density waves (CDWs) and Peierls lattice distortions within the layer planes.…”

Strong anisotropy of Sc2X2Se2 (X = Cl, Br, I) monolayers contributes to high thermoelectric performance

“…The TE conversion efficiency is determined by the figure of merit: ZT = S 2 σT / κ , which is related to the Seebeck coefficient ( S ), electrical conductivity ( σ ), absolute temperature ( T ), and thermal conductivity ( κ ). Notice that the thermal conductivity has two parts: 1 electronic thermal conductivity ( κ e ) and lattice thermal conductivity ( κ l ). Therefore, to test whether a material is an ideal TE material or not, one must examine whether it has the characteristic of a high ZT value.…”

“…In addition to using strategies such as band structure engineering 3,4,24 and strain engineering 1,5,25,26 to optimize the performance of existing TE materials, it is important to explore and develop new thermoelectric materials based on theoretical research and provide the theoretical basis for relevant experimental research. Sarikurt et al 27 reported that Sc 2 X 2 Se 2 (X = Cl, Br, I) monolayers have great potential for thermoelectric applications using high-throughput calculations, but a comprehensive exploration of the electronic, phonon, and thermoelectric transport properties of these materials has not been reported.…”