We report a microwave-assisted wet chemical method for doping Zn into SnTe thermoelectric materials to in-situ induce rich ZnTe nanoprecipitates, nanopores, a large number of grain boundaries and other multi-dimensional defects. While ensuring competitive electrical transport performance, the introduced multi-dimensional defects induced phonon scattering across the entire scale, reducing the lattice thermal conductivity of SnTe to the amorphous limit and enhancing its thermoelectric performance.

Abstract

The creation of hierarchical nanostructures can effectively strengthen phonon scattering to reduce lattice thermal conductivity for improving thermoelectric properties in inorganic solids. Here, we use Zn doping to induce a remarkable reduction in the lattice thermal conductivity in SnTe, approaching the theoretical minimum limit. Microstructure analysis reveals that ZnTe nanoprecipitates can embed within SnTe grains beyond the solubility limit of Zn in the Zn alloyed SnTe. These nanoprecipitates result in a substantial decrease of the lattice thermal conductivity in SnTe, leading to an ultralow lattice thermal conductivity of 0.50 W m⁻¹ K⁻¹ at 773 K and a peak ZT of ~0.48 at 773 K, marking an approximately 45 % enhancement compared to pristine SnTe. This study underscores the effectiveness of incorporating ZnTe nanoprecipitates in boosting the thermoelectric performance of SnTe-based materials.