Hierarchical Architectures Boosting Thermoelectric Performance in GeTe With Sb ₂ Te ₃ Precipitates

The thermoelectric properties of eco‐friendly GeTe are limited by the relatively low Seebeck coefficient and high thermal conductivity, partially caused by the intrinsic high cation defects concentration. Herein, to targeted optimize the band structures, elemental In is introduced into the Ge 0.94 Sb 0.06 Te matrix, Surprisingly, a type of nanoscale Sb 2 Te 3 precipitate is found pioneeringly in our GeTe‐based recipe, constituting to the all‐scale hierarchical structure in GeTe. Based on the all‐round scattering of phonons, the lattice thermal conductivity is significant decreased over the whole temperature range, especially reaching a 60% reduction at the low temperature area. Eventually, the synergistic effect results in a peak ZT value of 2.2 at 773 K and ZT ave of 1.31 (323–773 K) in the Ge 0.93 Sb 0.06 In 0.01 Te sample. The conversion efficiency of corresponding single leg module reached ≈11.0%, implying the huge applying potential of high performance GeTe‐based materials in the power generation field.