Laminated structure design accommodates thermal expansion mismatch for mechanically and thermally dual-stable thermoelectric contacts

Abstract

The quality of the barrier layer (BL) directly determines the long-term stability of thermoelectric (TE) modules. Conventional BLs struggle to simultaneously achieve thermal expansion matching with TE materials and robust diffusion-blocking capability. Here we show a bimetallic multilayer BL strategy that ensures thermal expansion matching while constructing a controllable interfacial stress field to inhibit element diffusion. Taking skutterudite (SKD) as an example, we construct a BL with alternating Nb and Cu layers, in which Nb serves as the primary diffusion barrier, while Cu tailors the effective thermal expansion behavior and regulates the stress field at the SKD/Nb interface via Nb/Cu back stress, thereby achieving mechanical stability and a strong diffusion-blocking effect. After aging at 823 K for 60 days, the SKD/Nb-Cu interface remains intact and maintains a low contact resistivity ( < 1 μΩ·cm²). Furthermore, the strategy proves effective in Bi2Te3- and GeTe-based TE systems, demonstrating its universality. This work proposes a design strategy based on laminated metals, in which thermal expansion of the barrier layer is tailored to regulate interfacial stress–diffusion coupling, enabling mechanically and thermally dual-stable thermoelectric contacts.