Realizing an enhanced Seebeck coefficient and extremely low thermal conductivity in anharmonic Sb-substituted SnSe nanostructures

Abstract

Tin selenide (SnSe), an important thermoelectric material in the IV-VI chalcogenide family, has attracted significant attention for Thermoelectric power generation in the mid to high temperature (600–900 K) region. Herein, we report extremely low thermal conductivity and improved thermoelectric performance of polycrystalline SnSe through Sb substitution. Polycrystalline Sn1−xSbxSe (x = 0.01–0.05) was synthesized through a hydrothermal method followed through cold pressing technique. The existence of lone pair electrons induced the high lattice anharmonicity in Sb substituted SnSe, which reduced the thermal conductivity from enhanced the phonon scattering. Increasing Sb concentration drastically decreases the thermal conductivity to 0.23 W/mK at 640 K. Moreover, Sb substitution simultaneously enhanced the Seebeck coefficient 400 µV/K and the electrical conductivity value of 660 S/m at 550 K for X = 0.05 sample. It is observed that the aliovalent Sb substitution in the polycrystalline SnSe matrix exhibits an extreme reduction in thermal conductivity, which leads to high thermoelectric performance.