Point Defect Engineering Thermoelectrics: From Disorder to Order

The persistent coupling between lattice thermal conductivity (κ_L) and carrier mobility (µ) remains the central bottleneck in thermoelectric optimization: randomly distributed defects that scatter phonons inevitably degrade electron transport. This review establishes the disorder-to-order transition of crystallographic defects as a unifying design principle to overcome this trade-off. We systematically examine three defect families, including substitutional atoms, vacancies, interstitials and antisite defects demonstrate how their spatial reconfiguration from random distributions into ordered architectures fundamentally decouples phonon and electron transport. Representative examples include iso-size alloying and symmetry enhancement in substitutional systems, vacancy-derived dislocation networks and ordered vacancy layers, lattice planarization via targeted vacancy filling, and self-assembled interstitial clusters and climb dislocations. We further extend this paradigm into the mechanical domain, showing that ordered interstitials at twin boundaries simultaneously enhance mechanical strength and thermoelectric performance. A consistent conclusion emerges across all systems: performance gains arise from controlling defect spatial arrangement rather than introducing additional disorder, offering a coherent framework for the next generation of high-performance, mechanically robust thermoelectric materials.