Regulation of both the crystal structure and carrier concentration leading to the improved thermoelectric performance of Cu3SbSe4-based chalcogenides

Abstract

In this work we regulate the crystal structure of Cu3SbSe4 through alloying Cu3SnS4, and decouple the contribution of the phonon scattering on the distorted crystal structure. This contribution, which was not paid much attention to in the Cu3SbSe4-based systems previously, leads to 44% (RT) and 22% (607 K) drop in the lattice part (κL). Therefore, it is of great importance to improve the thermoelectric performance. At the same time, we regulate the carrier concentration (nH) through co-alloying Cu3SnS4 and ZnSe and attain the optimal nH value (~1020 cm-3) at RT. As a result, the electrical property improves with the highest power factor (PF) of 12.63 μWcm-1K-2 for the solid solution (Cu3SbSe4)0.1(Cu3SnS4)0.9(ZnSe)0.02. Consequently, the thermoelectric performance improves remarkably with the peak ZT value of 0.65 at 700 K while that of the pristine Cu3SbSe4 is only 0.26 at 588 K.