Synergistically Improving Flexibility and Thermoelectric Performance of Composite Yarn by Continuous Ultrathin PEDOT:PSS/DMSO/Ionic Liquid Coating.

ABSTRACT

Combining fabrics with a poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOTPSS) coating is the most promising method to fabricate wearable thermoelectric (TE) devices. However, the high modulus, low strain, and low TE performance of PEDOTPSS coating lead to poor flexibility and low power generation efficiency. In this study, dimethyl sulfoxide (DMSO) and ionic liquids (ILs) were selected as a modifier to enhance the flexibility and TE performance of PEDOTPSS. Different from the penetrating structure and coil conformation of pristine PEDOTPSS coating, a flexible continuous ultrathin layer of PEDOTPSS/DMSO/1-ethyl-3-methylimidazolium dicyanamide (P/D/ED) with a linear conformation forms on the surface of cotton yarn. The morphology and structure of PEDOTPSS and P/D/ED coating were characterized by FESEM, XPS, and Raman spectroscopy. Compared with the pristine PEDOTPSS film, the P/D/ED film shows significantly reduced modules and enhanced strain and bending stability. Moreover, the TE performance of P/D/ED-coated yarn is significantly enhanced with nearly half mass loading. Based on this, a large-area wearable TE fabric with enhanced flexibility and TE performance was prepared. The output power density is 136.1 mW/m2 at ΔT = 40.8 K, which is a typically high value compared with the former reported composite TE fabrics. This study provides a new way to synergistically enhance the flexibility and TE performance of composite yarn, and the prepared TE fabric has great potential as a wearable power source.