Cation and anion doping to enhance thermoelectric performance of Bi2S3

Bismuth sulfide (Bi2S3) is a promising non-tellurium candidate for thermoelectric application due to its low thermal conductivity and abundance of low-toxicity elements. In this work, Bi2S3-based materials are fabricated by combining mechanical alloying, high-pressure and high-temperature treatment, and spark plasma sintering (MA ​+ ​HPHT ​+ ​SPS). Cation and anion doping (copper and chlorine) are then employed to enhance the thermoelectric properties. While chlorine doping can effectively improve the electrical transport properties of Bi2S3, it results in a corresponding increase in thermal conductivity. Upon copper doping, the electrical properties show a moderate and steady improvement, which also plays a role in reducing thermal conductivity. Thus, the collaborative optimization of electrical and thermal properties is achieved, whereby a maximum zT value of 0.45 is finally obtained for the Bi2S3-0.25 ​mol% Cu sample at 573 ​K. [Display omitted] •The Bi2S3 materials were fabricated by a MA + HPHT + SPS route.•Chlorine doping can optimize carrier concentration, it results in a corresponding increase in thermal conductivity.•Copper doping significantly suppress lattice thermal conductivity.•A high zT value of 0.45 is achieved in Bi2S3-0.25 ​mol% Cu at 573 ​K.