Interface-driven energy filtering effect and enhanced thermoelectric performance of Ag₂Se/SnS composites: An...

This study examined the thermoelectric (TE) and mechanical properties of n-type Ag₂Se/SnS nanocomposites synthesized via hydrothermal methods and hot-press densification. The incorporation of SnS nanosheets into the Ag₂Se matrix enhanced the thermoelectric performance, achieving a maximum figure of merit (zT) value of 0.91 at 393 K for the sample with 2.5 wt% SnS, representing a 13 % improvement over that of Ag₂Se. This enhancement is attributed to an increased power factor (∼2704 μWm^-1 K^-2 at 393 K) resulting from band convergence and a reduced thermal conductivity (κ ∼ 0.744 Wm^-1 K^-1 at 303 K) owing to interfacial phonon scattering. Furthermore, the nanocomposites exhibited enhanced mechanical properties, with Vickers hardness increasing by up to 28 % compared to that of Ag₂Se. Density functional theory (DFT) calculations were employed to assess the structural and electronic properties of Ag₂Se and Ag₂Se/SnS nanocomposites. The computed bandgap confirmed improved electrical conductivity, whereas the binding energy and electron density difference analyses elucidated the interaction strength and charge transfer in the nanocomposite. These findings elucidate the potential of Ag₂Se/SnS nanocomposites as promising thermoelectric materials for room-temperature applications and demonstrate the efficacy of nanostructuring in enhancing thermoelectric and mechanical properties.