Boosting Thermoelectric Performance of Wet‐Spun PEDOT:PSS‐Based Organic/Inorganic Composite Fibers via a Dual‐Interfacial Engineering Approach

Abstract Organic/inorganic thermoelectric (TE) composite fibers are promising for wearable electronics due to their flexibility and energy conversion capabilities, yet their performance remains limited. Here, we have successfully developed novel dual‐interfacial structured poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate)/single‐walled carbon nanotube@ polyaniline (PEDOT:PSS/SWCNT@PANI) TE composite fibers via wet‐spinning PANI was introduced between SWCNTs and PEDOT:PSS as an interlayer, which not only improved the dispersibility of SWCNTs in aqueous PEDOT:PSS but also facilitated the formation of numerous highly uniform dual‐interfaces at PEDOT:PSS/PANI and PANI/SWCNT contacts.Therefore, the PEDOT:PSS/SWCNT@PANI composite fibers exhibited a high degree of structural alignment and more efficient energy filtering effect. Furthermore, introducing PANI interlayers between SWCNTs and PEDOT:PSS also provided a facile route for finely tuning the carrier concentration of the ternary composite system. With an ammonium hydroxide treatment performed on PANI before fiber spinning, the TE properties of the ternary composite fibers are further optimized. The PEDOT:PSS/SWCNT@PANI composite fibers eventually delivered electrical conductivity of 2472 ± 23.3 S cm −1 and a Seebeck coefficient of 43.5 ± 0.7 µV K −1 . The corresponding power factor reached 467.8 ± 10.5 µW m −1 K −2 , which is remarkably higher than that of other PEDOT:PSS‐based composite fibers. This work domonstrates interfacial engineering as a critical strategy for high‐performance TE fibers, advancing their potential in flexible electronics.