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

Abstract 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 0.99 Cd 0.995 Ag 0.005 Sb achieves a z T 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.