Enhanced thermoelectric performance of Bi_2-xCu_xS₃ by hydrothermal synthesis and spark plasma sintering

Bi2S3 has been considered as a promising medium temperature thermoelectric material due to its low thermal conductivity and cost-effective features. However, the intrinsically poor electrical conductivity of Bi2S3 still limits its further thermoelectric applications. In this work, we optimize the thermoelectric performance of Bi2S3 using Cu doping via a facile hydrothermal method combined with spark plasma sintering. A well-tuned carrier concentration of 1.2 x 10(19) cm(-3) and electrical conductivity of 47 S cm(-1) at 523 K was attained, which is attributed to the increased electrons by Cu doping. In addition, the appeared micro-nano pores in both Bi2S3 and Cu doped Bi2S3 samples after spark plasma sintering benefits the reduction of lattice thermal conductivity (kappa l). The Bi1.985Cu0.015S3 sample exhibited the lowest kappa l of 0.405 W m(-1) K-1 at 573 K, which is the lowest value as far as we know in the reported Cu doped Bi2S3 materials at the same temperature. Finally, A maximum ZT value of 0.3 at 573 K was achieved in Bi1.985Cu0.015S3 sample. This study provides a new strategy to achieve low kappa l and high ZT value in Bi2S3-based thermoelectric materials.