Lattice Planification and Synergistic Cu/Sn Co‐Doping to Enhance Thermoelectric Performance in Polycrystalline PbSe

Abstract Thermoelectric materials have attracted considerable interest due to their ability to convert waste heat into electricity, offering a sustainable solution for energy harvesting. Among them, PbSe stands out as a promising candidate owing to its advantageous electronic and thermal transport properties. However, the strong coupling between electrical and thermal transports poses challenges in optimizing its thermoelectric performance. Herein, a decoupling and regulation strategy is reported for PbSe through Cu/Sn co‐doping. By introducing extra Pb to compensate for intrinsic vacancies, carrier mobility is enhanced. Cu interstitial doping increases carrier concentration, while Sn substitution reduces lattice thermal conductivity. This synergistic approach significantly improves the thermoelectric performance of PbSe, achieving a peak ZT value of 1.5 at 800 K and a high average ZT of 1.0. The single‐leg device based on the optimized PbSe exhibits a maximum power generation efficiency of 7% under a temperature difference of 500 K.