Investigation of thermoelectric properties of novel cubic phase SnSe: A promising material for thermoelectric applications

The novel cubic structured SnSe (π-SnSe), with narrow band-gap and substantial phonon restraining effect, is considered a perspective energy storage material for futuristic applications. In this study, we explore the thermoelectric properties of π-SnSe in the framework of density functional theory and is therefore believed to be the first report of its kind. As a prerequisite for the calculations of thermoelectric properties, the electronic structure of π-SnSe was determined at the level of modified Becke-Johnson potential. The calculated bandgap of magnitude 0.97 eV is found to be in good agreement with recently reported experimental results of energy band-gap. Our calculations for electrical conductivity (σ/τ) show that the highest values occur at modest doping level magnitude to 3.6 × 10¹⁹/Ωms for p-type doping and 1.54 × 10²⁰/Ωms for n-type doping and was found to be decreasing linearly with increasing temperature. Similarly, it is found that π-SnSe exhibit high Seebeck coefficient at low temperature, observing a drastic degradation in the span of 2292 μK/V to 444.3 μK/V with increasing temperature ranging from 200 to 900 K, respectively. In consequence, a notable reduction in the values of thermoelectric power factor (PF) and figure of merit (ZT) has also been observed with increase in temperature. The maximum value of PF was documented to be 8.77 × 10¹⁰ W/mK²s at 200 K. An exceptionally high and record ZT value of ∼1 was obtained at 200 K which is superior to orthorhombic structure SnSe (polycrystalline and bulk). Thus our study point to cubic phase SnSe as an avenue for the next generation thermoelectric materials for a wide range of operational temperature devices.