Optimizing thermoelectric performance of Cd-doped β-Zn4Sb3 through self-adjusting carrier concentration

► A simple melting-slow cooling technique was employed to prepare Zn4Sb3 ingots. ► The facile control of Zn realizes the effective self-adjustment of carrier density. ► A highest ZT of 1.23 at 660 K is obtained for the Zn3.91Cd0.04Sb3 sample. ► The high ZT mainly stems from the large m∗ by Cd-doping and very low κL.