Embedded Ag-rich nanodots in PbTe: Enhancement of thermoelectric properties through energy filtering of the carriers

The concept of energy filtering of the carriers to control the thermoelectric properties of PbTe is experimentally applied in this present work. The energy barriers at the grain interfaces of the nanocomposites and the embedded Ag-rich nanodots within the grains are supposed to control the energy dependency of carrier scattering: that is what we mean by energy filtering of carriers. As a case study, vertical Bridgman grown bulk PbTe:undoped, PbTe:Ag crystals and nanocomposites of PbTe: Ag are used as samples. Thermoelectric properties of all the samples have been evaluated through temperature dependent electrical conductivity, Seebeck coefficient and room temperature Hall and thermal conductivity measurements. It is found that the PbTe: Ag nanocomposites has the highest power factor of 18.78 x 10(-4) W m(-1) K(-2) with a room temperature thermal conductivity of 1.69 W m(-1) K(-1). The crystal structures of these samples show the effective potential barrier at the grain boundaries and embedded nanodots within the grains to facilitate the energy filtering of the carriers. (C) 2010 American Institute of Physics. [doi:10.1063/1.3488621]