Unlocking High‐Performance Te‐Free p‐Type Thermoelectrics via Cu Doping in Entropy‐Engineered Cd 0.5 Zn 0.5 Sb Zintl

ABSTRACT Zintl phases are crucial for Te‐free power generation and electrical cooling modules, which are considered next‐generation thermoelectric (TE) technology. While n‐type Zintl materials, such as Mg 3 Sb 2 , have achieved remarkable performance, their p‐type counterparts are restricted by electron‐phonon coupling. This work demonstrates a cost‐effective p‐type CdSb‐based Zintl material with high TE performance. We find that applying entropy engineering can sharply enhance the solid solubility of Cu in CdSb. Cu doping in entropy‐engineered Cd 0.5 Zn 0.5 Sb raises carrier concentration. More importantly, Cu boosts carrier mobility to about 222 cm 2 V −1 s −1 by screening ionized impurity scattering and enhancing covalent bonding across the cleavage plane along the [1 0 0] direction. Additionally, Cu doping induces dislocation scattering and lattice softening, significantly reducing lattice thermal conductivity. As a result, the Cd 0.46 Cu 0.04 Zn 0.5 Sb material achieves a high ZT of 1.5 at 573 K. Its high performance is verified by integrated TE devices. This work validates Cd 1− x Zn x Sb Zintl phases as highly efficient p‐type TE materials for practical applications.