In-Situ Silver and Nickel Metal Growth on Polyimide Substrate for Flexible Thermoelectric Devices

Flexible thermoelectric devices are increasingly demanded in fields such as wearable electronics, soft robotics and other flexible electronics applications. In this study, in order to enhance the adhesion of thermoelectric materials to flexible substrates, in-situ metal growth on polyimide (PI) was proposed for fabricating flexible three-dimensional (3D) silver (Ag)/nickel (Ni) thin film thermopiles (TFTPs), and the fabrication processes for in-situ Ag and Ni films growth on PI substrates were optimized to improve film conductivity using an orthogonal experiment method. The influence of annealing on metal film structure was systematically investigated through Xray diffraction (XRD) and scanning electron microscopy (SEM). Results demonstrate that annealing process significantly enhances the crystallinity and, consequently, the electrical conductivity of the films. Based on the optimized in-situ growth processes and annealing conditions for Ag and Ni films on PI films, 3D Ag/Ni TFTPs were successfully fabricated. These resulting devices exhibit a maximum Seebeck coefficient of 76.1 μ V/K and excellent flexibility performance, demonstrating their potential applications in flexible temperature sensing, energy harvesting, etc.