Flexible thermoelectric generators for wearable energy harvesting and applications

Thermoelectric materials are critical for high-efficiency energy utilization and carbon neutrality. With the booming development of wearable electronics, flexible sensor networks and smart textiles, flexible thermoelectric generators (f-TEGs) have garnered immense interest for self-powered health monitoring and personalized thermal management. Focusing on wearable feasibility, this review summarizes the fundamental thermoelectric physics and performance metrics. It also highlights recent advances in flexible materials - including inorganic (carbon nanomaterials, chalcogenides), organic [polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene) (PEDOT), and composites], and inorganic-organic hybrid systems - with an emphasis on structure-property relationships and wearable-adapted processing. At the device level, the review compares fiber/yarn, film/ribbon, and porous/textile-like architectures. It focuses on heat transfer, mechanical durability, and skin comfort, which are critical for on-skin applications. Key wearable-specific bottlenecks are outlined, such as stable n-type materials, scalable fabrication, and environmental/biological durability. Finally, it proposes opportunities for application-oriented f-TEG platforms, facilitating the development of next-generation wearable energy-harvesting systems through interdisciplinary collaboration.