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We compute the temperature dependent relaxation time (τ) of charge carriers in LiScX (X = C, Si, Ge) half-Heusler (hH) alloys using the deformation potential theory. This temperature dependent τ of charge carriers is used to investigate its effect on the thermoelectric properties of these hH alloys. It is shown that there is a significant effect of temperature dependent τ of charge carriers on the thermoelectric properties of these hH alloys.

Two dimensional materials based on chalcogenides are showing exciting thermoelectric efficiency. Recent experimental synthesisation of several Janus monolayers inspire investigation of novel materials. In this paper, we study the thermoelectric performance of the novel Janus Al2STe monolayer using Density Functional theory. We found that Janus Al2STe monolayer is an indirect band gap semiconductor with an energy gap of 1.17 eV and is dynamically stable. The transport coefficients such as Seebeck coefficient, electrical conductivity, power factor, and electronic thermal conductivity are evaluated using BoltzTraP2 code based on Boltzmann transport theory within constant relaxation time approximation. The dependence of relaxation time on temperature has been approximated with the deformation potential theory. Further, the lattice component of thermal conductivity has been obtained using ShengBTE code. The calculated value of ZT shows that both n-type and p-type Janus monolayer have outstanding thermoelectric performance. From the evaluated results, we conclude that Janus Al2STe monolayer can be used as a propitious candidate in the fabrication of thermoelectric devices.

In the present work, we investigated the effect of isotropic strain, both tensile (up to 9%) and compressive (up to − 9%) on the electronic structure and transport properties of LiScGe half-Heusler (hH) alloy. The electronic structure calculations using the density functional theory reveal that increase in tensile strain widens the energy band gap, whereas increase in compressive strain shortens it. The electronic thermal conductivity, κe = κ0-S2σT (where κ0 is the short-circuit electronic thermal conductivity) decreases under tensile strain whereas it increases under compressive strain with S2σT term playing a significant role in the determination of κe. The bipolar contribution to thermal conductivity (κbp) is found to decrease under tensile strain while it increases in case of compressive strain at strain values higher than − 3%. It is found that lattice thermal conductivity (κl) calculated using both the Slack ′ s equation and Callaway Model increases with increase in tensile strain in general whereas in case of compressive strain, κl decreases as strain is increased. Our results for transport properties show that increase in tensile strain leads to an overall increase in ZT values of n-type LiScGe and increase in compressive strain increases ZT of p-type LiScGe.