Advancements in diffusion barrier layers based on heterogeneous connection of electrode/thermoelectric materials

With the development of thermoelectric (TE) materials and devices, there has been an increasing demand for establishing a reliable connection at the interface of TE materials/electrodes. In particular, noticeable reactions and diffusion occur between them. This phenomenon may degrade the performance of the interface. Therefore, it is crucial to achieve regulation of the reaction extent at the interface. Consequently, diffusion barrier layers, which are capable of regulating these reactions, have been developed to meet this requirement. This article provides a comprehensive review of the recent research on diffusion barrier layers. And it summarizes nearly a hundred research results in recent years. First, it briefly introduces the application background of diffusion barrier layers. The principles of screening materials as diffusion barrier layers are fully illustrated. The influence of preparation parameters and methods on barrier layers is also discussed. Then, this review enumerates and outlines the research results on diffusion barrier layers from the perspective of metals, alloys, and composite diffusion barrier layers. This mainly includes diffusion and interfacial reaction, mechanical properties, and TE performance. Furthermore, the shortcomings of diffusion barrier layers in these studies are briefly outlined. Meanwhile, its development prospects are also pointed out. We believe that this review can provide theoretical basis and guidance for relevant research and applications in the field of TE devices.