Attaining enhanced thermoelectric performance in p-type (SnSe)1–(SnS2) produced via sintering their solution-synthesized micro/nanostructures

Abstract

SnSe, possessing strong lattice anharmonicity and structural anisotropy, has attracted massive attention in thermoelectric conversion. Herein, we demonstrate that simultaneously optimized electrical and thermal transport properties are achieved in SnS2-alloyed SnSe polycrystalline materials, which were fabricated via sintering the mixture of solution-synthesized SnSe microplates and SnS2 nanoplates. Resulting from the increased carrier concentration, p-type (SnSe)1–x(SnS2)x (x = 0.5%, 1%) samples obtain much-improved power factor between 300 K and 373 K, e.g. 0.72 mW m–1 K–2 at 300 K for (SnSe)0.99(SnS2)0.01, which is enhanced by 53% compared to that of SnSe. Additionally, the existing point defects and planar defects effectively strengthen phonon scattering, thus reducing the lattice thermal conductivity, for example, 0.47 W m–1 K–1 at 773 K for the x = 0.02 sample. Eventually, a maximum zT of 0.80 at 823 K and an average zT of 0.52 over 300 – 823 K are obtained in the (SnSe)0.99(SnS2)0.01 sample, which are increased by 33% and 45% compared to those of SnSe, respectively. This study demonstrates a secondary phase alloying strategy to synergistically optimize the electrical and thermal properties of polycrystalline SnSe.