Low-temperature, solution-based, scalable synthesis of Sb ₂Te₃ nanoparticles with an enhanced power factor

Nanostructured thermoelectric (TE) materials, for example Sb ₂Te₃, PbTe, and SiGe-based semiconductors, have excellent thermoelectric transport properties and are promising candidates for next-generation TE commercial application. However, it is a challenge to synthesize the corresponding pure nanocrystals with controlled size by low-temperature wet-chemical reaction. Herein, we report an alternative versatile solution-based method for synthesis of plate-like Sb ₂Te₃ nanoparticles in a flask using SbCl₃ and Te powders as raw materials, EDTA-Na₂ as complexing agent, and NaBH₄ as reducing agent in the solvent (distilled water). To investigate their thermoelectric transport properties, the obtained powders were cold compacted into cuboid prisms then annealed under a protective N ₂ atmosphere. The results showed that both the electrical conductivity (σ) and the power factor (S ² σ) can be enhanced by improving the purity of the products and by increasing the annealing temperature. The highest power factor was 2.04 μW cm^-1 K ^-2 at 140°C and electrical conductivity remained in the range 5-10 × 10³ S m^-1. This work provides a simple and economic approach to preparation of large quantities of nanostructured Sb ₂Te₃ with excellent TE performance, making it a fascinating candidate for commercialization of cooling devices.