Highly enhanced thermoelectric properties of Bi2S3 via (Se, Cl)-co doping in hydrothermal synthesis process

Bi 2 S 3 -based materials with low thermal conductivity and high Seebeck coefficient has been regarded as promising thermoelectric materials for years. To optimize the thermoelectric properties of Bi 2 S 3 materials, (Se, Cl)-co-doped nanostructured Bi 2 S 3 bulks were prepared by hydrothermal method combined with spark plasma sintering . The doping contents of Se and Cl in Bi 2 S 3 depend on the reaction time of the hydrothermal process. A high power factor of 450 μWm −1 K −2 was achieved for Bi 2 S 3 sample with the reaction time of 24 h owing to the substitution of S by Se and Cl. Meanwhile, a low thermal conductivity of 0.35 Wm −1 K −1 is obtained for the Bi 2 S 3 sample with the reaction time of 18 h, owing to the strong phonon scattering caused by the high density of grain boundaries, pores and point defect . Therefore, benefiting from the improved electrical transport properties and reduced thermal conductivity, a peak ZT value of ~ 0.57 was obtained at 673 K for the Bi 2 S 3 sample with the reaction time of 24 h.