Strategies for boosting thermoelectric performance of PbSe: A review

• General physical properties of typical IV-VI compounds are summarized. • Phase diagram, crystal and electrical band structures of PbSe are presented. • Recent ways of adjusting charge and phonon transport processes in PbSe are updated. • Typical preparation methods for PbSe and their scalability are discussed. • Key challenges and future research directions of PbSe are discussed. Thermoelectric materials enable the direct conversion between waste heat and electric energy, playing an important role in alleviating energy crisis. Many excellent thermoelectrics developed so far contain expensive and scarce Te element, largely limiting their applications. Therefore, exploring Te-free compounds with extraordinary thermoelectric performance becomes a vital topic in thermoelectric community in recent years. PbSe is an ideal candidate that meets above criteria and has advanced rapidly in the last decade with reported peak ZT s close to 2.0. Herein we review the recent research progress of PbSe-based thermoelectric materials. This review article starts with a general introduction of the properties of IV-VI semiconductors as advanced thermoelectric materials by comparing their cost, crustal abundance, mechanical strength and chemical bonding. Following that, phase diagram, crystal and electronic band structures of PbSe are comprehensively summarized. Then we discuss how the frequently used dopants regulate its carrier concentrations. Subsequently, electronic band structure engineering (including resonant levels, band flattening, band convergence, band inversion, etc. ) and microstructural architecturing (including atomic arrangements, dislocation arrays, nanoscale precipitates, etc. ) approaches and their impacts on charge and phonon transport properties of PbSe are elaborated. Finally, we summarize the typical production processes of PbSe and comment on their scalability. The future directions for how to further improve the thermoelectric properties of PbSe and promote its applications are discussed at the end of this article.