High-Performance SnTe Thermoelectric Materials Enabled by the Synergy of Band Convergence and Phonon Scattering

SnTe, an environmentally friendly thermoelectric material, has garnered widespread scholarly interest owing to its lead-free nature; however, its intrinsic thermoelectric performance is constrained by a relatively low Seebeck coefficient and an extremely high lattice thermal conductivity. In this investigation, we employ the alloying of Ge and AgSbTe₂ to enhance the <i>zT</i> value of SnTe. The study found that Ge, Ag, and Sb can effectively enhance the Seebeck coefficient and power factor of SnTe by utilizing band convergence. At the same time, a multitude of point defects induce phonon scattering, consequently decreasing the lattice thermal conductivity of SnTe. Collectively, these synergistic effects result in Sn_0.75Ge_0.25Te-15% AgSbTe₂ achieving its highest <i>zT</i> value of 1.28 at 823 K, with an average <i>zT</i> value of 0.77 between 400 and 823 K. Such high <i>zT</i> values of the SnTe-based thermoelectric material provide the potential for applications in high-performance solid-state thermoelectric devices.