Decorated dislocations lead to dynamically optimized thermoelectric performance in N-type PbTe

Abstract

A high thermoelectric energy conversion efficiency requires a large power factor and a low thermal conductivity over a broad temperature range. Optimizing the temperature-dependent carrier concentration and introducing structural defects are effective methods to realize these goals. In this work, we demonstrate that Ag-decorated dislocations can facilitate the dissolution of dopants into the PbTe matrix at elevated temperatures to optimize the carrier concentration in conjunction with the static doping effect of Sb. These spatially aligned and chemically decorated dislocations strongly scatter medium-to low-frequency phonons even at a rather low number density on the order of 1010 cm−2. Moreover, these dislocations show little scattering effect on electrons, maintaining a high carrier mobility. As a consequence, a maximum thermoelectric figure-of-merit, zT, of 1.5 at 750 K and an excellent average zT value of 1.1 between 300 and 800 K are obtained in Sb and dilute Ag2Te co-doped n-type PbTe. This work demonstrates that decorated dislocation networks could optimize the electrical and thermal transport properties of thermoelectrics in a wide temperature window.