Realizing High Performance in Commercial Bi0.5Sb1.5Te₃ Thermoelectric Material via Balancing the Magnetic Doping and Interface Engineering

As the only commercial available thermoelectric material, Bi 2 Te 3 ‐based alloys offer exceptional near‐room temperature performance, while it is complicated to realize further improvement. Incorporating magnetic impurity is an effective strategy to decouple the relationship between thermal and electrical transport for improved TE performance, while the design of magnetic impurity with precisely tailored chemical components, size, distribution, and crystallinity remains a big challenge. Herein, the amorphous FeO x layers with weak ferromagnetism are introduced to the grain boundaries of commercial p‐type Bi 0.5 Sb 1.5 Te 3 materials to improve its TE performance. The special serrated shape and weak‐ferromagnetism of the FeO x layer promote high mobility and Seebeck coefficients of the ALD coated samples. The phonon scattering at the FeO x layer reduce lattice thermal conductivity by over 30%. Consequently, the optimized sample achieves the maximum and average ZT of 1.42 at 330 K and 1.1 within 300–525 K, respectively, marking increases of 43.7% and 37.5% compared to the matrix. This work delves into the role of thermo‐electro‐magnetic interactions in ameliorating TE performance and offers inspiration for the development of high‐efficiency TE modules.