o‐electric energy conversion. Herein, atomic scale point defect engineering is introduced as a new strategy to simultaneously optimize the electrical properties and lattice thermal conductivity of thermoelectric materials, and (Bi,Sb) 2 (Te,Se) 3 thermoelectric solid solutions are selected as a paradigm to demonstrate the applicability of this new approach. Intrinsic point defects play an important role in enhancing the thermoelectric properties. Antisite defects and donor‐like effects are engineered in this system by tuning the formation energy of point defects and hot deformation. As a result, a record value of the figure of merit ZT of ≈1.2 at 445 K is obtained for n‐type polycrystalline Bi 2 Te 2.3 Se 0.7 alloys, and a high ZT value of ≈1.3 at 380 K is achieved for p‐type polycrystalline Bi 0.3 Sb 1.7 Te 3 alloys, both values being higher than those of commercial zone‐melted ingots. These results demonstrate the promise of point defect engineering as a new strategy to optimize thermoelectric properties.21:T427,Microstructure manipulation plays an important role in enhancing physical and mechanical properties of materials. Here a high figure of merit zT of 1.2 at 357 K for n‐type bismuth‐telluride‐based thermoelectric (TE) materials through directly hot deforming the commercial zone melted (ZM) ingots is reported. The high TE performance is attributed to a synergistic combination of reduced lattice thermal conductivity and maintained high power factor. The lattice thermal conductivity is substantially decreased by broad wavelength phonon scattering via tuning multiscale microstructures, which includes microscale grain size reduction and texture loss, nanoscale distorted regions, and atomic scale lattice distotions and point defects. The high power factor of ZM ingots is maintained by the offset between weak donor‐like effect and texture loss during the hot deformation. The resulted high zT highlights the role of multiscale microstructures in improving Bi 2 Te 3 ‐based materials and demonstrates the effective strategy in enhancing TE properties.22:T4f0,Defects and defect engineering are at the core of many regimes of material research, including the field of thermoelectric study. The 60-year history of V₂VI₃ thermoelectric materials is a prime example of how a class of semiconductor material, considered mature several times, can be rejuvenated by better understanding and manipulation of defects. This review aims to provide a systematic account of the underexplored intrinsic point defects in V₂VI₃ compounds, with regard to (i) their formation and control, and (ii) their interplay with other types of defects towards higher thermoelectric performance. We herein present a convincing case that intrinsic point defects can be actively controlled by extrinsic doping and also via compositional, mechanical, and thermal control at various stages of material synthesis. An up-to-date understanding of intrinsic point defects in V₂VI₃ compounds is summarized in a (χ, r)-model and applied to elucidating the donor-like effect. These new insights not only enable more innovative defect engineering in other thermoelectric materials but also, in a broad context, contribute to rational defect design in advanced functional materials at large.

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