Intensive Widmannstätten Nanoprecipitates Catalyze SnTe With State‐of‐the‐Art Thermoelectric Performance

Nanoprecipitates play a vital role in designing high‐performance thermoelectric materials, particularly for those with short phonon mean‐free paths. However, their effectiveness in reducing lattice thermal conductivity is hindered by the uncontrollable intensity, poor interfacial coherence, and suboptimal morphology. To address these limitations, AgPbSbTe 3 is used to alloy SnTe to form intensive Ag 2 Te Widmannstätten nanoprecipitates for obtaining state‐of‐the‐art thermoelectric performance. Advanced microscopy characterizations reveal the crystallographic orientation relationships between SnTe and Ag 2 Te to guide the lath‐shaped morphology of Ag 2 Te, leading to the formation of the high‐intensity Widmannstätten nanoprecipitates, which effectively scatter phonons to reduce the lattice thermal conductivity. Togethering the optimized electrical properties through carrier concentration adjustment, band convergence, and the energy filtering effect, a maximum figure of merit ZT of 1.5 at 723 K and an average ZT of 1.1 between 423 and 823 K is achieved in (SnTe) 0.80 (Ag 1.05 PbSb 0.95 Te 3 ) 0.20 , enabling a single‐leg device and two‐pair module with energy‐conversion efficiency of 7.22% and 4.26% under a temperature difference of 450 K, respectively. The findings highlight the potential of intensive Widmannstätten nanoprecipitates as effective phonon scattering centers, providing a new pathway to enhance the thermoelectric performance of chalcogenides.