Browsing by Author "Dewey, Oliver S."

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    Macroscopic weavable fibers of carbon nanotubes with giant thermoelectric power factor
    (Springer Nature, 2021) Komatsu, Natsumi; Ichinose, Yota; Dewey, Oliver S.; Taylor, Lauren W.; Trafford, Mitchell A.; Yomogida, Yohei; Wehmeyer, Geoff; Pasquali, Matteo; Yanagi, Kazuhiro; Kono, Junichiro; Carbon Hub
    Low-dimensional materials have recently attracted much interest as thermoelectric materials because of their charge carrier confinement leading to thermoelectric performance enhancement. Carbon nanotubes are promising candidates because of their one-dimensionality in addition to their unique advantages such as flexibility and light weight. However, preserving the large power factor of individual carbon nanotubes in macroscopic assemblies has been challenging, primarily due to poor sample morphology and a lack of proper Fermi energy tuning. Here, we report an ultrahigh value of power factor (14 ± 5 mW m−1 K−2) for macroscopic weavable fibers of aligned carbon nanotubes with ultrahigh electrical and thermal conductivity. The observed giant power factor originates from the ultrahigh electrical conductivity achieved through excellent sample morphology, combined with an enhanced Seebeck coefficient through Fermi energy tuning. We fabricate a textile thermoelectric generator based on these carbon nanotube fibers, which demonstrates high thermoelectric performance, weavability, and scalability. The giant power factor we observe make these fibers strong candidates for the emerging field of thermoelectric active cooling, which requires a large thermoelectric power factor and a large thermal conductivity at the same time.
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    Versatile acid solvents for pristine carbon nanotube assembly
    (AAAS, 2022) Headrick, Robert J.; Williams, Steven M.; Owens, Crystal E.; Taylor, Lauren W.; Dewey, Oliver S.; Ginestra, Cedric J.; Liberman, Lucy; Ya’akobi, Asia Matatyaho; Talmon, Yeshayahu; Maruyama, Benji; McKinley, Gareth H.; Hart, A. John; Pasquali, Matteo; The Smalley Institute for Nanoscale Science and Technology; The Carbon Hub
    Chlorosulfonic acid and oleum are ideal solvents for enabling the transformation of disordered carbon nanotubes (CNTs) into precise and highly functional morphologies. Currently, processing these solvents using extrusion techniques presents complications due to chemical compatibility, which constrain equipment and substrate material options. Here, we present a novel acid solvent system based on methanesulfonic or p-toluenesulfonic acids with low corrosivity, which form true solutions of CNTs at concentrations as high as 10 g/liter (≈0.7 volume %). The versatility of this solvent system is demonstrated by drop-in application to conventional manufacturing processes such as slot die coating, solution spinning continuous fibers, and 3D printing aerogels. Through continuous slot coating, we achieve state-of-the-art optoelectronic performance (83.6 %T and 14 ohm/sq) at industrially relevant production speeds. This work establishes practical and efficient means for scalable processing of CNT into advanced materials with properties suitable for a wide range of applications.