Poly(benzodifurandione) Coated Silk Yarn for Thermoelectric Textiles.

Thermoelectric textile devices represent an intriguing avenue for powering wearable electronics. The lack of air‐stable n‐type polymers has, until now, prevented the development of n‐type multifilament yarns, which are needed for textile manufacturing. Here, the thermomechanical properties of the recently reported n‐type polymer poly(benzodifurandione) (PBFDO) are explored and its suitability as a yarn coating material is assessed. The outstanding robustness of the polymer facilitates the coating of silk yarn that, as a result, displays an effective bulk conductivity of 13 S cm−1, with a projected half‐life of 3.2 ± 0.7 years at ambient conditions. Moreover, the n‐type PBFDO coated silk yarn with a Young's modulus of E = 0.6 GPa and a strain at break of εbreak = 14% can be machine washed, with only a threefold decrease in conductivity after seven washing cycles. PBFDO and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coated silk yarns are used to fabricate two out‐of‐plane thermoelectric textile devices: a thermoelectric button and a larger thermopile with 16 legs. Excellent air stability is paired with an open‐circuit voltage of 17 mV and a maximum output power of 0.67 µW for a temperature difference of 70 K. Evidently, PBFDO coated multifilament silk yarn is a promising component for the realization of air stable thermoelectric textile devices. [ABSTRACT FROM AUTHOR]