Triple Synergistic Modulation via Sn Doping in Tetrahedrites: Electronic Structure, DOS, and Scattering Engineering for a High Thermoelectric Performance

Achieving a high power factor and low lattice thermal conductivity is crucial for improving the thermoelectric performance. The eco-friendly Cu₁₂Sb₄S₁₃ tetrahedrite inherently exhibits a high power factor (∼10–14 μW cm^–1 K^–2) and low thermal conductivity (0.5–1.00 W m^–1 K^–1), but these properties also impose significant limitations for further performance enhancement. To overcome these challenges, researchers have explored strategies such as codoping/synergistic element doping and nanocomposites. In this work, we demonstrate that Sn doping at the Sb site in Cu₁₂Sb₄S₁₃ (without the use of nanocomposites) enables the synergistic modulation of both the electronic and thermal properties. The Sn doping increases the hole concentration and enhances the density of states (DOS), leading to a marked improvement in the power factor (at 750 K), 12 μW cm^–1 K^–2 for x = 0 to 16 μW cm^–1 K^–2 for x = 0.04. Simultaneously, Sn doping induces strong phonon scattering, which lowers thermal conductivity by ∼69% (at 750 K). This synergistic modulation of the electronic structure, DOS, and scattering mechanisms results in a significant enhancement in the thermoelectric performance. The optimized Cu₁₂Sb_3.96Sn_0.04S₁₃ sample exhibits an exceptional figure of merit (ZT) of 1.26 at 750 K, representing a 126% increase compared to pristine Cu₁₂Sb₄S₁₃. These findings demonstrate the effectiveness of Sn doping in simultaneously optimizing the electrical and thermal properties of Cu₁₂Sb₄S₁₃ through the synergistic modulation of the electronic structure, density of states, and phonon scattering mechanisms.