Constructing multiple microstructures in Sb2Te3-based thermoelectrics enables a high-performance segmented power generator

Abstract

Thermoelectric (TE) technology offers a promising route for harvesting low-grade waste heat (<650 K). Despite decades of research, commercial TE generators still rely predominantly on Bi₂Te₃-based alloys, with efficiencies typically below 7%. In this work, Sb₂Te₃ is modified through substantial In incorporation, which effectively suppresses antisite defect formation and reduces the intrinsically high hole concentration. Concurrently, moderate Zn doping enhances the density-of-states effective mass, leading to an 8% improvement in the power factor across the entire temperature range. Furthermore, a powder metallurgy approach promotes microstructural refinement characterized by dense nanotwins and dislocations, resulting in a 10.3% reduction in lattice thermal conductivity at 300 K. As a result, the Zn_0.04In_0.15Sb_1.81Te₃ sample delivers a peak ZT of 1.13 at 575 K and an average ZT of 0.82 between 300 and 650 K. Notably, a fully Bi–Sb–Te-based monolithic segmented generator achieves a high conversion efficiency of 9.25% under a 350 K temperature gradient. These results provide a compelling strategy for extending the operational temperature range of Bi₂Te₃-based materials, highlighting their strong potential for efficient low-grade heat recovery.