Enhanced Acoustic Phonon Scattering via engineering the Interface in MoS₂/CuS Nanocomposites for Ultra-Low Thermal Conductivity

Significant advancements in power factor are widely realized in bulk thermoelectric materials through strategies such as doping, band engineering, and nanostructuring. We report the first demonstration of simultaneous enhancement of the Seebeck coefficient and electrical conductivity in p-type MoS₂/CuS nanocomposites through precise compositional tuning that activates a strong energy filtering effect. Leveraging the phonon liquid electron crystal (PLEC) nature of CuS, our approach delivers synergistic optimization of charge and phonon transport. The optimized 20 wt% CuS composite achieves a high electrical conductivity of 893 Scm^-1 and a power factor of 41 μWm^-1K^-2 at 653 K, attributed to increased Cu²⁺ ion concentration and a high density of states near the Fermi level (~0.2 eV) enabled by band structure modulation. At the same temperature, the material also exhibits an ultra-low thermal conductivity of 0.2 Wm^-1K^-1 due to intensified acoustic and interfacial phonon scattering. This synergistic control of electronic and thermal transport represents a novel strategy for mid-temperature thermoelectric materials design, positioning MoS₂/CuS nanocomposites as promising candidates for next-generation power generation systems.