Enhanced thermoelectric performance of Bi2-xCuxS3 by hydrothermal synthesis and spark plasma sintering

Abstract

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 × 1019 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 (κl). The Bi1.985Cu0.015S3 sample exhibited the lowest κl 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 κl and high ZT value in Bi2S3-based thermoelectric materials.