Keywords:Carbon nanotubes, Thermoelectric
Recently, it has been shown that macroscopically aligned metallic carbon nanotube films with an optimized Fermi energy (EF) 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 EF. Here, we chemically changed the EF 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 (So11 and So22) were suppressed in the CSA-doped film due to Pauli blocking, allowing us to estimate EF. Then we prepared aligned DWCNT fibers by a CSA solution spinning technique, chemically tuned EF, 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.