Realizing a High Thermoelectric Conversion Efficiency in Zintl-phase NaCdSb via Suppressing the Intrinsic Carrier Excitation

Zintl-phase NaCdSb compound exhibits exceptional intrinsic thermoelectric performance. However, the low-temperature carrier concentration of NaCdSb significantly deviates from the ideal, which greatly limits its thermoelectric efficiency. Herein, a stepwise strategy is proposed to enhance the thermoelectric performance of the NaCdSb-based Zintl phase. This approach effectively improves the power factor while maintaining low lattice thermal conductivity. Consequently, the Na_0.99Cd_0.995Ag_0.005Sb achieves a zT value of 1.41 at 673 K, with an average zT of 0.81 over the temperature range of 300–673 K. Furthermore, the NaCdSb-based single-leg device demonstrates a respectable conversion efficiency of ≈7% at a temperature difference of 373 K. These findings highlight the potential of 1-1-1 type Zintl-phase NaCdSb as a high-performance thermoelectric material. This breakthrough encourages further research into Zintl-phase thermoelectric materials.