Abstract:

Fiber-based thermoelectric materials and devices have garnered significant attention in the field of self-powered wearable electronics due to their excellent weavability and superior conformability to human skin. However, conventional fabrication strategies for inorganic thermoelectric fibers are often limited by high manufacturing costs and stringent temperature requirements. Herein, a facile approach to fabricate Ag₂Se thermoelectric fibers via dopamine surface modification combined with in-situ chemical deposition is reported. Specifically, a polydopamine adhesive layer was formed on the surface of polyimide fibers through self-polymerization. Subsequently, a dense silver layer was deposited onto the adhesive layer via a silver mirror reaction, followed by a selenization process to convert the silver into Ag₂Se. The effects of dopamine functionalization and Ag precursor concentration on the fiber microstructure and thermoelectric performance were systematically investigated. The results indicated that the dopamine-functionalized fibers facilitated a more compact and continuous Ag₂Se deposition, increasing the power factor from 16.74 μW·m^-1·K^-2 to 40.14 μW·m^-1·K^-2 compared to untreated fibers. Further investigating the effect of Ag precursor concentration, it was found that the thermoelectric Ag₂Se fibers with an AgNO₃ concentration of 0.015 g·mL^-1 exhibited optimal performance, achieving a power factor of 42.9 μW·m^-1·K^-2 at room temperature. Furthermore, the fibers demonstrated excellent service stability, with a maximum relative resistance change of only 11.5% after 500 bending cycles and a stable Seebeck coefficient after 10 repeated washing cycles. Notably, an assembled two-leg device delivered an open-circuit voltage of 7.84 mV at a temperature difference of 38.0 K. This study provides a novel strategy for the low-cost fabrication of flexible Ag₂Se thermoelectric materials and devices.

Key words: selenization, thermoelectric fiber, Ag₂Se, dopamine