Electrical transport and mechanical properties of thermoelectric tin selenide

Abstract

Motivated by the unprecedented thermoelectric performance of SnSe, we report its band structure calculations, based on density functional theory using the full potential linearized augmented plane wave. These calculations were further extended to evaluate the electrical transport properties using Boltzmann transport theory and the results were compared with the as-synthesized polycrystalline counterpart, which was synthesized employing conventional vacuum melting technique followed by consolidation employing spark plasma sintering. The as-synthesized SnSe was thoroughly characterized employing XRD, FESEM and TEM for phase purity, morphology and structure. The theoretically predicted band gap values and the temperature dependence of the electrical transport properties of SnSe were in reasonable agreement with the experimental results, within the approximations employed in our theoretical calculations. These theoretical calculations suggested that the optimum thermoelectric performance in SnSe is expected to occur at a hole doping concentration of ∼3 to 5 × 10²¹ cm⁻³. The measured fracture toughness and hardness of SnSe were found to be ∼0.76 ± 0.05 MPa √m and 0.27 ± 0.05 GPa, respectively, which are comparable with other state-of-the-art thermoelectric materials. The high value of thermal shock resistance ∼252 ± 9 W m⁻¹, coupled with its good mechanical properties suggests SnSe to be a potential material for thermoelectric device applications.