Good thermoelectric performance and stability in copper sulfide synthesized by hydrothermal method and densified by HP technique

We investigate the thermoelectric performance and the stability of polycrystalline p -type Cu 2− x S fabricated by hydrothermal method and hot-pressing technique. The relative pure copper sulfides are obtained via the sintering process and their crystal structures are dependence on the atomic ratio of Cu/S. The thermoelectric performance tests show a good figure of merit of ZT  = 0.78 at 550 °C. In addition, we repeated measured the thermoelectric parameters to confirm the stability of the samples. The electrical conductivity and the Seebeck coefficient have dramatically change between the different tests, which originate from the variation of carrier concentration and mobility. Nonetheless, the figure of merit ZT maintains unchanged, indicating that the samples synthesized in this work possess quite stable thermoelectric performance.