Rare‐Earth Enhanced Thermoelectric Performance of BiSbTe Alloys

The efficient Bi 2 Te 3 ‐based thermoelectric (TE) coolers are essential for thermal management in next‐generation electronics, but are hindered by the low TE performance of Bi 2 Te 3 ‐based alloys. Herein, using Yb metal and in situ Yb 2 O 3 as the rare‐earth functional elements (REFE), a series of x REFE/Bi 0.5 Sb 1.5 Te 3 (BST) composites ( x = 0–0.20 wt.%) were prepared to decouple entangled TE parameters. It has been demonstrated that REFE/BST heterointerfaces act as potent multi‐scale phonon scatterers, leading to a drastic reduction in lattice thermal conductivity, which serves as the primary contributor to the enhanced zT . In addition, metallic Yb moderately enhances electrical conductivity via Schottky‐barrier‐induced local electric fields and sustains a high Seebeck coefficient through energy‐dependent carrier scattering at interfaces, while the 4f‐s electron interaction between Yb and BST further modulates carrier transport. The optimal 0.10 wt.% REFE/BST achieves a maximum zT of 1.54 at 370 K and a remarkable average zT of 1.42 (300–500 K), enhanced by 38% and 35%, respectively. The maximum refrigeration temperature difference of the 17‐pair REFE/BST device reaches 65.0 K, increased by 2.05 times compared as that of the BST device. This rare‐earth strategy provides a general route to remarkably enhance the cooling performance of a Bi 2 Te 3 ‐based device.