Powerful drying and doping strategies for enhancing the thermoelectric performance of tellurium nanostructures prepared via green hydrothermal synthesis

Abstract

Tellurium (Te), a well-known p-type semiconductor with a narrow bandgap, is used as a thermoelectric material in various polycrystalline forms such as Bi–Te, Pb–Te, and Sn–Te compounds. In particular, Te nanostructures have gained significant interest in various fields such as piezoelectrics, gas sensors, and energy conversion application; therefore, efforts have been made recently to enhance the thermoelectric performance of the Te family by using nanostructures engineered through various methods. This requires controlling the nanoscale properties of materials and suggesting effective doping strategies to enhance their electrical conductivity and Seebeck properties. Herein, we report an effective drying and solution-based doping approach to enhance the thermoelectric properties of Te nanostructures prepared via green hydrothermal synthesis. The freeze-drying process can form a three-dimensional porous structure of the Te nanostructured film, leading to an effective diffusion of the dopant solution and thereby improving the doping efficiency. Consequently, the effective doping of In under optimized conditions improves the electrical conductivity and power factor of Te nanostructures, demonstrating that the combination of freeze-drying and sequential solution-based doping is a promising approach for improving thermoelectric performance. This study contributes significantly to the development of solution-based doping of Te-based nanostructures for functional thermoelectric power applications.