[11a-Z28-1~16] 17.1 Carbon nanotubes & other nanocarbon materials

▲ [11a-Z28-12] Optical and Thermoelectric Properties of Ultrahigh-Conductivity Double-Wall Carbon Nanotube Films and Fibers

〇(D)Natsumi Komatsu¹, Yota Ichinose², Oliver Dewey¹, Lauren Taylor¹, Mitchell Trafford¹, Yohei Yomogida², Matteo Pasquali¹, Kazuhiro Yanagi², Junichiro Kono¹ (1.Rice Univ., 2.Tokyo Metropolitan Univ.)

Keywords:Carbon nanotubes, Thermoelectric

Recently, it has been shown that macroscopically aligned metallic carbon nanotube films with an optimized Fermi energy (E_F) are promising for thermoelectric applications. They exhibited surprisingly high power factors (σS²), maintaining both high values of Seebeck coefficient (S) and electrical conductivity (σ) due to sharp features in the electronic density of states near the E_F. Here, we chemically changed the E_F of aligned double-wall carbon nanotube (DWCNT) films and fibers and studied their optical and thermoelectric properties. Absorbance spectra for chlorosulfonic acid (CSA) doped and annealed DWCNT films prepared by a facile blade coating technique showed that the E₁₁ and E₂₂ exciton peaks in outer-wall semiconducting CNTs (S^o₁₁ and S^o₂₂) were suppressed in the CSA-doped film due to Pauli blocking, allowing us to estimate E_F. Then we prepared aligned DWCNT fibers by a CSA solution spinning technique, chemically tuned E_F, and obtained a power factor value of 14±5 mWm^-1K^-2, which is the highest p-type power factor ever achieved at room temperature.