Dispersion-Stable Carboxymethyl Cellulose/Single-Walled Carbon Nanotube Composite for Water-Processed Organic Thermoelectrics

Carbon nanotubes (CNTs) have drawn great attention as promising candidates for realizing next-generation printed thermoelectrics (TEs). However, the dispersion instability and resulting poor printability of CNTs have been major issues for their practical processing and device applications. In this work, we investigated the TE characteristics of water-processable carboxymethyl cellulose (CMC) and single-walled CNT (SWCNT) composite. The microscopic analyses indicated that the CMC-incorporated SWCNT dispersions produced uniform and smooth TE films, capable of ensuring reliable TE performance. The resulting composite films provided a low temperature power factor of 73 μW m−1 K−2 with a high electrical conductivity of ≈1600 S cm−1 and a Seebeck coefficient of ≈21 µV K−1. Moreover, the composite films possessed low thermal conductivity of ≈25 W m−1 K−1, significantly lower than that of pure SWCNTs, with a maximum figure of merit of 1.54 × 10−3 at 353.15 K. Finally, we successfully demonstrated water-processed organic TEGs using CMC/SWCNT films as a p-type component. This work could offer valuable insights to support the development of printable organic-based TE materials and devices.