A theoretical model of the thermoelectric properties of SnSxSe1−x and how to further enhance its thermoelectric performance

Abstract

Tin-based chalcogenides have a lot of potential as thermoelectric materials due to their ultralow thermal conductivity. Therefore, most reports on doped SnS focus on its power factor as the other condition for a high thermoelectric figure of merit (ZT). Here, we use the Boltzmann transport formalism to calculate both the power factor and the thermal conductivity for SnS, SnSe, and SnSxSe1−x and compare it with experimental measurements. Our theoretical model, based on a relaxation-time formalism, is in very good agreement with the reported values. We conclude that, while impurity scattering plays a major role in electron transport and, therefore, largely determines the power factor, alloy scattering is crucial for phonon transport. Specifically, alloying reduces the thermal conductivity of SnSe0.70S0.30 by a factor of ∼1.3 compared to SnSe and by a factor of ∼2 compared to SnS. This leads to ∼65% and ∼33% enhancements of ZT for p-type and n-type doping, respectively, at 800 K with respect to SnSe.

The Effect of Janus Asymmetry on Thermal Transport in SnSSe

“…We also approximate the thermal conductivity using a model by Madsen et al 40 that operates within the relaxation-time approximation. The relaxation time is approximated by the contribution from umklapp anharmonic scattering processes parameterized as 4 , 28 …”

“…To be able to perform this comparison, we also calculate the phonon contribution to thermal transport in these compounds. We start with ab initio calculations but also employ a simpler predictive model developed by some of us 4,32 to enable a more direct comparison of the key ingredients for thermal transport between the three structures. We find that along with its structure, the Janus SnSSe monolayer also inherits the main features of its phonon dispersion from its parent compounds.…”

“…Thermoelectric (TE) materials are reckoned to play a significant role in catering to the present global thrust for green and sustainable energy by enabling the conversion of waste heat into electricity. , Continued research in the field of thermoelectrics over the last decade has led to the discovery of several highly efficient bulk TE materials. − Theory shows that the key to optimizing the performance of TE materials lies in enhancing their TE figure of merit ( zT ), which is mainly achieved through alloying, doping, or nanostructuring …”

Temperature Dependent Excitonic Transition Energy and Enhanced Electron-Phonon Coupling in Layered Ternary SnS2-xSex Semiconductors with Fully Tunable Stoichiometry

“…The ternary alloys of the compounds have the tunable band gap that is critical for optical device applications. Thus far, only the basic properties of the ternary SnS 2-x Se x were reported [ 23 , 24 ]. Further investigations of SnS 2-x Se x as flexible sensors [ 25 ] and phototransistors [ 26 ] were also reported.…”

B-Site Stoichiometry Control of the Magnetotransport Properties of Epitaxial Sr2FeMoO6 Thin Film

“…The electrical transport properties for all the three above-mentioned stoichiometries of SFMO were calculated by using Boltzmann transport equation as implemented in BoltzTraP2 considering rigid band approximation. ,− The total relaxation time was calculated based on scattering mechanism given in ref . In the relaxation time approximation, the generalized transport coefficients are calculated from the transport distribution function as In the above equation, v k is the component of the group velocity of each carrier in the transport direction, E k is the energy of that electronic state, and τ k is its total relaxation time.…”