Synergistic optimization of thermoelectric performance in Ag₂Se through MoSe₂ decoration

Interface engineering can effectively reduce thermal conductivity in thermoelectric materials, resulting in enhanced thermoelectric performance. However, achieving synergistically optimized thermal and electrical transport properties remains challenging. In this study, MoSe₂ was decorated into Ag₂Se by a two-step solvothermal/hydrothermal process combined with spark plasma sintering. Spark plasma sintering enables interfacial ion exchange, resulting in reduced carrier concentration and increased Seebeck coefficient. Meanwhile the decorated MoSe₂ at the grain boundaries strongly scatters phonons, along with the reduced electrical conductivity, resulting in significantly reduced thermal conductivity. Consequently, the Ag₂Se/4mol% MoSe₂ composite achieves a notable maximum figure of merit of 1.07 at 390 K and a theoretical maximum conversion efficiency of 2% at a temperature difference of 45 K, indicating that MoSe₂ doping substantially improves the thermoelectric characteristics of n-type Ag₂Se. This nanostructured interface design approach may be useful for improving the performance of various thermoelectric materials.