Pavonite Homologous CdAg_2.5Sb_6.5Se₁₂ as a Promising Thermoelectric Compound

Pavonite compounds with complex and disordered structures are promising thermoelectric materials due to their extremely low lattice thermal conductivity. Herein, we report the pavonite compound CdAg 2.5 Sb 6.5 Se 12 with an extremely low lattice thermal conductivity of 0.36 W m –1 K –1 at 773 K. Because of the poor electrical properties, we adjust the ratio of Ag and Cd to populate a large quantity of carriers, thus increasing the carrier concentration. Based on the single parabolic band model, the density of state effective mass increases from 0.3 m e in the pristine sample to 1.3 m e in the doped one ( m e is the electron mass) because of the increase in the valence band degeneracy. Ultimately, the extremely low thermal conductivity combined with the enhanced electrical performance results in enhanced ZT ∼ 0.35 at 672 K compared with the pristine sample of ∼0.02.