In situ formed nano-interlayer enables robust interface bonding in efficient Bi2Te3-based thermoelectric modules

Interfacial robustness at thermoelectric–electrode junctions, characterized by exceptional elevated-temperature chemical stability and mechanical integrity, emerges as a critical determinant for the operational longevity of devices. Despite the proven efficacy of barrier layers in mitigating interfacial chemical reaction/diffusion, large-scale fabrication of strongly bonded thermoelectric–barrier–electrode interfaces remains a formidable challenge. In this study, we demonstrate a controllable and reproducible fabrication of Ni electrodes and Ti barrier layers on Bi₂Te₃-based thermoelectric materials via an industrially scalable magnetron sputtering process. Impressively, an in situ formed nano-interlayer creates atomic bonding at all heterojunctions, achieving an outstanding bonding strength of ∼23 MPa with a competitively low contact resistivity of ∼21 μΩ cm² at the junctions. These eventually enable one-pair thermoelectric modules to achieve a ∼53 K cooling effect at the hot-side temperature of ∼298 K and a sustained ∼4.8% conversion efficiency at a temperature gradient of ∼180 K. This work demonstrates a universal fabrication route for constructing robust interfaces across multiple functional layers in thermoelectric devices.