Large n- and p-type thermoelectric power factors from doped semiconducting single-walled carbon nanotube thin films
Single-walled carbon nanotube, Thermoelectric generator
College of Natual Science and Mathematics, Chemistry and Biochemistry
Lightweight, robust, and flexible single-walled carbon nanotube (SWCNT) materials can be processed inexpensively using solution-based techniques, similar to other organic semiconductors. In contrast to many semiconducting polymers, semiconducting SWCNTs (s-SWCNTs) represent unique one-dimensional organic semiconductors with chemical and physical properties that facilitate equivalent transport of electrons and holes. These factors have driven increasing attention to employing s-SWCNTs for electronic and energy harvesting applications, including thermoelectric (TE) generators. Here we demonstrate a combination of ink chemistry, solid-state polymer removal, and charge-transfer doping strategies that enable unprecedented n-type and p-type TE power factors, in the range of 700 μW m−1 K−2 at 298 K for the same solution-processed highly enriched thin films containing 100% s-SWCNTs. We also demonstrate that the thermal conductivity appears to decrease with decreasing s-SWCNT diameter, leading to a peak material zT ≈ 0.12 for s-SWCNTs with diameters in the range of 1.0 nm. Our results indicate that the TE performance of s-SWCNT-only material systems is approaching that of traditional inorganic semiconductors, paving the way for these materials to be used as the primary components for efficient, all-organic TE generators.
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MacLeod, B. A., Stanton, N. J., Gould, I. E., Wesenberg, D., Ihly, R., Owczarczyk, Z. R., . . . Ferguson, A. J. (2017). Large n- and p-type thermoelectric power factors from doped semiconducting single-walled carbon nanotube thin films. Energy & Environmental Science, 10(10), 2168-2179. DOI: 10.1039/c7ee01130j.