Mediating Point Defects Endows n‐Type Bi2Te3 with High Thermoelectric Performance and Superior Mechanical Robustness for Power Generation Application

Abstract Bi 2 Te 3 ‐related alloys dominate the commercial thermoelectric market, but the layered crystal structure leads to the dissociation and intrinsic brittle fracture, especially for single crystals that may worsen the practical efficiency. In this work, point defect configuration by S/Te/I defects engineering is engaged to boost thermoelectric and mechanical properties of n‐type Bi 2 Te 3 alloy, which, coupled with p‐type BiSbTe, shows a competitive conversion efficiency for the fabricated module. First, as S alloying suppresses the intrinsic antisite defects and forms a donor‐like effect, electronic transport properties are optimized, associated with the decreased thermal conductivity due to the point defect scattering. The periodide compound TeI 4 is afterward adopted to further tune carrier concentration for the realization of an optimal ZT . Finally, an advanced average ZT of 1.05 with ultra‐high compressive strength of 230 MPa is achieved for Bi 2 Te 2.9 S 0.1 (TeI 4 ) 0.0012 . Based on this optimum composition, a fabricated 17‐pair module demonstrates a maximum conversion efficiency of 5.37% under the temperature difference of 250 K, rivaling the current state‐of‐the‐art Bi 2 Te 3 modules. This work reveals the novel mechanism of point defect reconfiguration in synergistic enhancement of thermoelectric and mechanical properties for durably commercial application, which may be applicable to other thermoelectric systems.