Structural features and thermoelectric performance of Sb- and Bi-doped Cu2SnSe3 compounds

In this paper, a series of Sb-doped and Bi-doped Cu2Sn1-xMxSe3 samples (M = Sb, Bi) are prepared by vacuum melting combined with the spark plasma sintering process. The effects of different atomic doping amounts on their properties are discussed. Structural studies indicate that all obtained samples comprise a single Cu2SnSe3 phase. Sb and Bi atoms are experimentally demonstrated to be efficient cation dopants for increasing the transport performance. Compared with that doping on the cation site, Bi doping is much more efficient in increasing the electron concentration of the Cu2SnSe3 system. Ultimately, a high figure of merit of 0.36 is achieved in the Cu2Sn0.94Sb0.06Se3 sample at 773 K due to the enhanced power factor and lowered lattice thermal conductivity, which are 1.73 times higher than those of the pure sample. Our results provide an efficient approach to enhance thermoelectric performance via other doping atoms, which could also be applied to copper-based chalcogenide materials.