The thermally-triggered n-type doping of single-walled carbon nanotubes is demonstrated using 1,1'-bis(diphenylphosphino)ferrocene, a novel n-type dopant. Through a simple thermal vacuum process, the phosphine compounds are moderately encapsulated inside single-walled carbon nanotubes. The encapsulation into SWNTs is carefully characterized using Raman/X-ray spectroscopy and transmission electron microscopy. This easy-to-handle doping with air-stable precursors for n-type SWNTs enables the large-scale fabrication of thermoelectric materials showing an excellent power factor exceeding approximately 240 μW mK(-2) .

Atomic doping is the most fundamental approach to modulating the transport properties of carbon nanotubes. In this paper, we demonstrate the enhanced thermoelectric properties of boron-substituted single-walled carbon nanotube (B-SWCNT) films. The developed two-step synthesis of large quantities of B-SWCNTs readily enables the measurements of thermoelectricity of bulk B-SWCNT films. Complementary structural characterization implies the unique configuration of boron atoms at the doping sites of SWCNTs, successfully enabling carrier doping to SWCNTs. The developed boron substitution, in combination with chemical doping, is found to substantially improve the thermoelectric properties.

Heavy doping is inevitable for utilizing single‐walled carbon nanotubes for wiring. However, the electrical conductivity of their films is currently as low as one tenth of the films made from typical metal pastes. Herein we report on metal‐comparable electrical conductivity from single‐walled carbon nanotube network films. We use ionic liquids and crown ether complexes for p‐type and n‐type doping, respectively. The encapsulation of counterions into carbon nanotubes promotes the conductivities in the range of 7000 S cm−1, approximately ten times larger than those of undoped films.

The stability of n‐type nanocarbon materials in air has yet to be realized for practical applications in organic thermoelectrics. In this work, n‐type carbon nanotubes stabilized by the encapsulation of air‐stable, redox‐active compounds are developed. This development readily enables the large‐scale fabrication of thermoelectric materials showing an excellent power factor exceeding approximately 240 μW mK−2 at raised temperatures. More information can be found in the Full Paper by Yoshiyuki Nonoguchi, Tsuyoshi Kawai et al. on page 2423 in Issue 17, 2016 (DOI: 10.1002/asia.201600810).