Bi 0.33 (Bi 6 S 9 )Br compositing in Bi 2 S 3 bulk materials forwards high thermoelectric properties.

The hexagonal Bi 0.33 (Bi 6 S 9 )Br intermediate was incorporated to enhance the thermoelectric properties of Bi 2 S 3 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 Bi 2 S 3 + 5% Bi 0.33 (Bi 6 S 9 )Br. This study provides a strategy for achieving Br doping in the Bi 2 S 3 system by adding the Bi 0.33 (Bi 6 S 9 )Br intermediate alloy, while the nanostructure was maintained in the matrix, which may be also suitable for other thermoelectric materials to obtain higher performance.