Enhancing n-Type PbTe Thermoelectrics via Valley Shape Modulation and Core–Shell Precipitates

Achieving both a high power factor and low lattice thermal conductivity in thermoelectric (TE) materials has been a longstanding challenge. Herein, we report significant advancements in PbTe-based materials through a band-sharpening approach that incorporates valley modification alongside an innovative core-shell structural strategy. The n-type Ag<i>_<i>x</i></i>Pb_1-<i>y</i>Sn<i>_<i>y</i></i>Te-0%Ag₂Te compounds demonstrate substantial band sharpening, resulting in exceptional electronic performance due to enhanced carrier mobility, despite a low density of states effective mass and moderate Seebeck coefficients. Furthermore, core-shell defect engineering introduces pronounced lattice disorder and abundant nanostructures, effectively scattering heat-carrying phonons. This combined strategy yields an impressive TE performance with a peak <i>zT</i> of ∼1.4 at 773 K in Ag_0.03Pb_0.97Sn_0.03Te-0%Ag₂Te. This work not only offers valuable insights into band curvature modulation for single-conduction-band systems from a valleytronics perspective but also establishes a robust framework for defect engineering using core-shell structures.