Enhanced thermoelectric performance of hot-pressed n-type Ag2Se nanostructures by controlling the intrinsic lattice defects

Abstract

Ag₂Se is a promising thermoelectric (TE) material for room-temperature (RT) applications owing to its excellent TE properties. In this work, we prepared Ag-deficient Ag₂Se using a hydrothermal method, and a hot-press densification process. The effect of TE properties was scientifically investigated. The calculated density of states (DOS) effective mass (m*) increased on increasing the Ag content, which must also be a reason for the enhanced maximum zT of 0.43 at 393 K for Ag_1.99Se. Moreover, complex nanostructures, including grain boundaries, nanograins, and lattice distortions, were obtained in Ag_2−xSe. Thus, the nanostructures strengthened the phonon scattering that leads to reduction in the total thermal conductivity (κ) in the range of 0.9–1.1 W m⁻¹ K⁻¹ in Ag_2−xSe at 303 K. The aim of our work was to increase the TE performance of Ag_2−xSe as a promising candidate for room temperature (RT) thermoelectric applications.