Synergistic modulation of thermoelectric performance in SnTe via Ge alloying and Sb doping

Abstract

As an eco-friendly alternative to conventional PbTe, SnTe has attracted increasing attention for mid-temperature thermoelectric applications. However, its intrinsically high hole concentration, low Seebeck coefficient, and high thermal conductivity have fundamentally constrained its thermoelectric performance. To address these challenges, we herein propose and implement a synergistic Ge-alloying and Sb-doping strategy. A series of samples were prepared using vacuum melting followed by spark plasma sintering (SPS). Phase composition, microstructure, and thermoelectric properties of the samples were characterized and analyzed. Ge alloying, combined with point defects, precipitates, dislocations, and grain boundaries, leads to a significant decrease in lattice thermal conductivity. Simultaneously, Sb doping effectively modulates the carrier concentration, enhancing the Seebeck coefficient while suppressing the electronic thermal conductivity. Benefiting from this synergistic modulation, Ge-alloying and Sb-doping Sn0.75Ge0.2Sb0.08Te achieved the peak zT of 0.78 at 773 K and the average zTave of 0.29 over the temperature range of 300-773 K. This work proposes a novel synergistic strategy of Ge-alloying and Sb-doping to synergistically optimize the carrier transport and phonon scattering of SnTe, effectively boosting its thermoelectric performance.