Liquid-like copper chalcogenide modulates electron donors in high-performance n-type PbTe thermoelectrics
Ping‐Yuan Deng, Kuang‐Kuo Wang, Hsin‐Ya Sung, Wen‐Wei Wu, Hsin‐Jay Wu
Abstract
Lead tellurides have been recognized as state-of-the-art thermoelectric generators (TEGs) for over 60 years. Recent efforts aim to lift the performance of n-type lead telluride (PbTe). Instead of doping elemental electron donors, we add the liquid-like Cu2S into a fully dense PbTe crystal, enabling a mixture of ionic and electronic conductors. The homogeneously distributed Cu2S nanoparticles act as active electron donors, dynamically pinning the solubility of Cu to an optimal value. Adding Cu2S also elicits hierarchical defects, constituting nanosized precipitates, nanoparticles, and intercalated Cu layers. Our n-type Cu2S-PbTe attains a high peak zT of 1.3 at 673 K with an average zTave of 0.98 within 300–673 K. Most importantly, it has a maximum conversion efficiency η of 4%, which, to the best of our knowledge, breaks the current record for an n-type PbTe-base single-leg device under a temperature difference ΔT of 300 K.