Recent development in flexible organic thermoelectric fibers for wearable devices

With the merits of light-weight, flexibility, breathability, and selfpowering characteristics, organic fiber-based thermoelectric generators (TEGs) have attracted significant interest due to increasing demand for wearable and miniaturized electronic devices. Recently, fiber and fabric-based organic TE devices have been developed with notable progress. In this review, we summarize the current stateofthe-art in the development of organic TE fibers in terms of fabrication strategies (wet-spinning approach, gelation process, and coating technique), materials (conductive polymers, carbon nanomaterials, semiconductors, and their composites), and device configurations. We illustrate the details of fabrication procedures, morphology manipulation, and TE performance of organic fibers, and underlying mechanisms in optimizing microstructure and TE properties of the fibers are emphatically discussed. The corresponding flexible TEGs with different configurations are also introduced. Finally, the challenges and outlook on the future development of highly efficient thermoelectrics are briefly presented to promote the applications of organic fibers in wearable electronics.