Simple and effective fabrication of Sb₂Te₃ films embedded with Ag₂Te nanoprecipitates for enhanced thermoelectric performance

The embedding of nanoprecipitates into a semiconducting matrix can lead to improved thermoelectric performances by enhancing the power factor or reducing the thermal conductivity of the system in which they are incorporated. Thus, we herein demonstrate the successive annealing of an electrodeposited amorphous Ag-Sb-Te film for the simple and effective fabrication of a nanocomposite consisting of highly dense (∼6 vol%) β-Ag₂Te nanoprecipitates in an Ag-doped Sb₂Te₃ matrix. During the annealing process, nanoscale (∼40 nm) β-Ag₂Te precipitates were generated spontaneously due to differences in the binding energies of the Ag-Te and Sb-Te bonds. As a result, the electron-transport properties of the p-type Sb₂Te₃ were significantly enhanced in the presence of the β-Ag₂Te nanoprecipitates owing to an energy-dependent carrier-filtering effect at the Ag-doped Sb₂Te₃/β-Ag₂Te interface. Furthermore, a high power factor of 1870 μW m^-1 K^-2 was obtained at 300 K due to the increased density of states effective mass (m∗ ∼1.8m₀) without any significant deterioration in the electrical conductivity being observed.