Optimization of the thermoelectric performance of PEDOT : PSS–tetrahedrite $\left (Cu_{12+x}Sb_4S_{13} \right )$ nanocomposites

The unique properties of conductive polymers, such as flexibility, ease of processing, and low toxicity, make them highly promising for thermoelectric applications. A key strategy to enhance their thermoelectric performance while preserving these advantages is the development of polymer-inorganic composites. In this study, we introduce an innovative approach to both material composition and processing by designing PEDOT:PSS-based composites incorporating $Cu_{12+x}Sb_{4}S_{13}$ tetrahedrite (TH) nanoparticles. The TH phase, synthesized via our recently developed solvothermal method using 1-(2-aminoethyl)piperazine as a solvent, exhibits ultra-low thermal conductivity (0.25 $W·m^{−1}·K^{−1}$ at 300 K) and a tunable Seebeck coefficient ($150–400 μV·K^{−1}$), depending on Cu content. The composites were fabricated with TH volume fractions ranging from 2 % to 98 %. Initially prepared as pastes, they were subsequently shaped and consolidated into pellets using pulsed electric current sintering (PECS) at 393 K. For comparison, thin films with a higher polymer content were produced via drop-coating onto glass substrates. The incorporation of TH nanoparticles led to a simultaneous increase in the Seebeck coefficient and a reduction in thermal conductivity. The highest ZT value of 0.12 was achieved at 473 K for a composite containing 85.7 % TH by volume. These results demonstrate the potential of PEDOT:PSS-tetrahedrite composites as non-brittle, mechanically robust thermoelectric materials with versatile processing options for specialized applications.