Bi_0.33(Bi₆S₉)Br compositing in Bi₂S₃ bulk materials forwards high thermoelectric properties

The hexagonal Bi_0.33(Bi₆S₉)Br intermediate was incorporated to enhance the thermoelectric properties of Bi₂S₃ by a facile synthesis process. As a result of the increase of carrier concentration caused by Br diffusion doping and the enhancement of phonon scattering caused by pores, point defects, and secondary phase interfaces, a maximum ZT value of 0.64 was achieved at 773 K in Bi₂S₃ + 5% Bi_0.33(Bi₆S₉)Br. This study provides a strategy for achieving Br doping in the Bi₂S₃ system by adding the Bi_0.33(Bi₆S₉)Br intermediate alloy, while the nanostructure was maintained in the matrix, which may be also suitable for other thermoelectric materials to obtain higher performance.