Synergistic enhancement of thermoelectric performance in SnTe via in-situ nanocompositing and band structure engineering

SnTe has attracted significant attention as a promising thermoelectric material due to its favorable band structure and low cost. However, its high intrinsic hole concentration and thermal conductivity still hinder further performance enhancement. In this study, a series of Sn 2.9-x W x Te 2.9 –(In 2 Te 3 ) 0.03 –(Cu 2 Te) 0.18 (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15) composites were synthesized by incorporating in-situ formed In 2 Te 3 and Cu 2 Te nanophases along with W doping. Structural and microstructural analyses confirmed the formation of uniformly distributed nanoinclusions (10–20 nm) and homogeneous elemental distribution. W doping effectively suppressed intrinsic Sn vacancies and induced valence band convergence, while the introduction of In created resonant states. These synergistic effects significantly enhanced the Seebeck coefficient. Moreover, multiscale phonon scattering arising from nanophases, dislocations, and lattice distortions greatly reduced the lattice thermal conductivity. The sample with x = 0.09 exhibited a maximum power factor of 25.98 μW·cm −1 ·K −2 , while the sample with x = 0.12 achieved a minimum lattice thermal conductivity of 0.406 W·m −1 ·K −1 . As a result, the optimized composition reached a peak ZT of 1.23 and an average ZT of 0.44 at 823 K, representing improvements of approximately 209 % and 215 % over pristine SnTe, respectively. These results place the material among the top-performing SnTe-based thermoelectric systems reported to date.