Synergistic Material‐Interface Engineering: Unlocking Superior Performance in PbSe Thermoelectric Modules

The scarcity of tellurium (Te) critically restricts the large‐scale deployment of advanced thermoelectric technologies. Here, Te‐free PbSe is demonstrated as a cost‐effective alternative for both power generation and solid‐state cooling through crystal growth, a two‐step compositional optimization, and multilayer interface engineering. Light Te alloying (<1%) effectively suppresses lattice thermal conductivity while preserving high carrier mobility, and subsequent trace Bi substitution (<0.2‰) optimizes carrier concentration without degrading carrier mobility, yielding a high power factor of ≈37.5 µW cm −1 K −2 and excellent thermoelectric performance ( ZT ≈0.6 at 300 K and a peak ZT ≈1.3 at 773 K). Furthermore, replacing conventional Ni contacts with MgNi+Cu multilayers reduces interfacial resistivity by more than twofold. Benefiting from these advances, a segmented leg with an average ZT above 1.0 over 300–773 K achieves a conversion efficiency of ≈9.5%, while a 7‐pair module delivers a maximum cooling temperature difference of ≈63.2 K. These results establish PbSe as a cost‐effective and competitive candidate for high‐performance thermoelectric power generation and solid‐state cooling across wide operating temperatures.