Facile surfactant-free microwave-assisted solvothermal synthesis of Cu2Te1−xSx with enhanced thermoelectric performance

Cu 2 Te-based compounds show promise for thermoelectric applications, but their synthesis typically involves ball milling or melting-annealing processes. Here, we present a surfactant-free microwave-assisted solvothermal method for the controlled synthesis of Cu 2 Te 1− x S x ( x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) nanostructures at 503 K within just 30 min. The substitution of sulfur promotes the formation of a hexagonal structure in Cu 2 Te 1− x S x with x of 0.2 – 0.5, and inhibits phase transitions during heating. Moreover, the alloying of sulfur contributes to a reduction in hole concentrations toward the optimal range, resulting in enhanced power factors ( e.g. , 910 μW m −1 K −2 at 825 K for Cu 2 Te 0.9 S 0.1 ) and reduced thermal conductivity ( e.g. , 0.53 W m −1 K −1 at 825 K for Cu 2 Te 0.5 S 0.5 ). Ultimately, Cu 2 Te 0.5 S 0.5 achieves a maximum dimensionless figure of merit of 0.80 at 825 K. This study offers a controllable solution-based strategy for synthesizing Cu 2 Te-based materials with tunable compositions and enhanced thermoelectric performance.