Realizing high thermoelectric performance in non-nanostructured n-type PbTe

Nanostructure engineering has improved the performance of thermoelectric materials, but the deteriorated stability of the materials at high temperatures shortens the service life of thermoelectric modules. Here, we realized a high zT value of 1.7 at 750 K in S-doped n-type PbTe without introducing any nanoprecipitates. This is comparable to the state-of-the-art nanocomposites. Small S-doping can increase the formation energy of Pb vacancies by increasing the bonding energy between anionic and cationic atoms, thus resulting in the elimination of Pb vacancies and improvement in carrier mobility. Fabricated single and segmented thermoelectric modules based on optimized PbTe in this work show high conversion efficiencies of 9.3% and 12.2%, respectively. The output properties of the segmented module remain unchanged over a 10 h measurement period. This emphasizes the good stability of the materials. This work demonstrates the importance of manipulating vacancies in thermoelectric materials and illustrates the practical value of efficient and stable PbTe thermoelectric modules. A high zT of 1.7 without introducing any second phase in n-type PbTe was realized and a high energy conversion efficiency of 12.2% in an assembled generation module was achieved as well.