Achieving excellent thermoelectric performance in p-type Mg3Sb2-based Zintl materials via synergistic band engineering and entropy engineering

n-Type Mg₃Sb₂-based materials have attracted considerable attention as high-performance thermoelectrics. However, the dimensionless figure of merit (zT) of its p-type counterparts remains much lower, limiting its practical applications. Herein, a remarkable increase in the power factor of p-type Mg₃Sb₂ is realized by incorporating 50 % YbZn₂Sb₂, which is related to the effectively decreased crystal field splitting energy and increased carrier concentration and mobility. Through entropy engineering, the lattice thermal conductivity at 323 K of Cd-alloyed (Mg_3.1Sb₂)_0.5(YbZn₂Sb₂)_0.5 is decreased by 56 % and 23 % as compared to that of Mg_3.1Sb₂ and (Mg_3.1Sb₂)_0.5(YbZn₂Sb₂)_0.5, respectively. Further, the hole concentration is optimized by Ag doping, resulting in a high power factor of 1.03 mW m⁻¹ K⁻² at 773 K. Eventually, a maximum zT value of ∼1.34 at 773 K and an average zT of ∼0.77 between 323 K and 773 K are achieved in (Mg_3.07Ag_0.03Sb₂)_0.5(YbZn_1.2Cd_0.8Sb₂)_0.5, which are excellent zT values for p-type Mg₃Sb₂-based materials. The present study offers an effective strategy for designing high-performance p-type Mg₃Sb₂-based thermoelectric materials.