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 (similar to 6 vol%) beta-Ag2Te nanoprecipitates in an Ag-doped Sb2Te3 matrix. During the annealing process, nanoscale (similar to 40 nm) beta-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 beta-Ag2Te nanoprecipitates owing to an energy-dependent carrier-filtering effect at the Ag-doped Sb2Te3/beta-Ag2Te interface. Furthermore, a high power factor of 1870 mu W m(-1) K-2 was obtained at 300 K due to the increased density of states effective mass (m* similar to 1.8m(0)) without any significant deterioration in the electrical conductivity being observed.