High efficient nanostructured PbSe0.5Te0.5 exhibiting broad figure-ofmerit plateau

Abstract

To have a very good energy conversion efficiency, thermoelectric (TE) material should exhibit higher figure-of-merit (ZT) for broad range of temperatures. In that direction, n-type PbTe0.5Se0.5 material with enhanced and temperature insensitive figure-of-merit was developed through nanostructured approach. A temperature insensitive ZT of 0.7 was observed from 400 K to 600 K. The enhanced and stable ZT over a wide temperature range was ascribed to the presence of various types of nanostructures that facilitated scattering of mid and long wavelength phonons, keeping the thermal conductivity low in addition to scattering low energy charge carriers elevating the Seebeck coefficient (−380 μVK−1 at 600 K). Most thermoelectric n-type materials such as PbQ (Q = Te, Se) materials exhibits very low ZT at room temperature which hampers the overall conversation efficiency. However, the developed material exhibits highest ZT at room temperature among PbQ (Q = Te,Se) materials that enables this material to be used in wearable thermoelectric applications. In this study, newly introduced technique was adopted to calculate TE conversion efficiency, which addresses overestimations of conventional efficiency calculations. The developed material showed power generation efficiency higher than many state-of-the-art TE n-type materials in 300 K–600 K range making it a competitive material for waste heat recovery applications.