Significantly enhanced thermoelectric figure of merit of n-type Mg3Sb2-based Zintl phase compounds via co-doped of Mg and Sb site

N-type Mg 3 Sb 2 thermoelectric material has a complex crystal structure and electronic structure, which is a new thermoelectric material with excellent application prospects. The state density and band structure of Mg 24 Sb 16 and Bi/Se/Pr–Se/Nd–Se doped Mg 24 Sb 16 are first-principles calculated. Se/Pr–Se/Nd–Se doped increases the density of states around the Fermi level. Bi-doped does not impact the band structure because the electronic structure between Sb and Bi are similar. The band gap of Pr–Se/Nd–Se doped becomes narrower, which is more conducive to carrier transport and increases carrier concentration than that of single-doped Se. The experimental results show that Pr and Nd replace Mg to provide more electrons for the system. The carrier concentration of the co-doped sample increases significantly, thus improving the power factor and optimizing the samples' electrical properties. The highest ZT value of the Mg 3.2 Sb 1.5 Bi 0.49 Se 0.01 sample is 1.21. Pr–Se/Nd–Se co-doped ZT values are 1.67 and 1.74, respectively, 38% and 43% higher than the Mg 3.2 Sb 1.5 Bi 0.49 Se 0.01 sample. Multi-element doped is an effective strategy to improve the thermoelectric properties of materials .