Integrated SnSSe bulk and monolayer as industrial waste heat thermoelectric materials

Abstract

New, nontoxic and earth‐abundant materials for heat‐energy interconversion are urgently required to mitigate the over‐reliance on finite fossil fuels supply. Herein, using ab initio quantum mechanical calculations and Boltzmann theory, optimization of thermoelectric performances instable, mechanically robustCm‐SnSSe and P3m1‐SnSeS phases was performed. These phases exhibit an intrinsically low thermal conductivity of ~1.00 W m−1 K−1 at room temperature. Beyond 400 K, both phases display satisfactory thermoelectric performances, namely figure of merit ZT > 0.7 and power factor PF > 3.0 mW K−2 m−1. Better performances were obtained through holes doping at 1020 cm−3 concentration, where their ZT values reach 0.9 at 500 K and fluctuate minimally over broad temperature plateau, retaining the high PF over 3.0 mWK−2 m−1. Evolution into layered structure is also possible, with the calculated p‐type doping of P3m1‐SnSSe monolayer displaying decent ZT ~ 0.7 and very high PF > 6.0 mWK−2 m−1 beyond 300 K. In bulk form, the study specimens display superior machinability and mechanical properties, as evidenced by the approximately 8‐fold increase in their Vickers hardness when compared to PbTe and Bi2Te3 materials, while maintaining their plasticity characteristic. The computed E2D of 55.50 N m−1 is relatively low, which means Sn‐S‐Se alloy remains ductile when progressing to 2D state. Biaxial strain‐induced results show enhanced anharmonicity phonon scattering and thermopower increment, enabling maximum ZT ~ 1.0 and PF > 7.0 mW m−1 K−2 to be achieved in the appealing industrial waste heat akin 373 ≤ T ≤ 773 K range under 10% tensile strain.