Improved thermoelectric properties of n-type Bi2S3 via grain boundaries and in-situ nanoprecipitates

To improve the thermoelectric properties of n-type Bi2S3 materials, a certain amount of SbCl3 were added into Bi2S3 materials by a conventional melting method combined with plasma activated sintering (PAS) process. The Bi2S3-based materials evolve from the lamellar- to particle-like structures after SbCl(3 )doping. The phonon scattering has strong enhancement through the increased grain boundaries and in-situ Bi2S3 nanoprecipitates, resulting in the low lattice thermal conductivity. Meanwhile, the high power factor is achieved because of the marked increase in the electrical conductivity. Hence, the synergistic effect of antimony and chlorine substitutions not only contribute to reduce the thermal conductivity but also tune the electrical transport properties, yielding a peak ZT value of similar to 0.65 at 773 K for the Bi2S3-1%SbCl3 sample.