Air‐tolerant Fabrication and Enhanced Thermoelectric Performance of n‐Type Single‐walled Carbon Nanotubes Encapsulating 1,1′‐Bis(diphenylphosphino)ferrocene

Abstract

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) .

Ionic Dopant‐Encapsulating Single‐Walled Carbon Nanotube Films with Metal‐Like Electrical Conductivity

“…In this process, additionally, we also elucidated a dramatic increase in conductivity at around 37 °C from 2440 S cm −1 to 3881 S cm −1 . This conductivity enhancement is analogous to the recent works, and the film conductivity close to 4000 S cm −1 is quite high compared to reported buckypapers, especially as the n‐type one.…”

“…Since the decrease in the dopant induced conductivity increase, finally, we concluded that encapsulation plays a major role in the enhanced doping. This concept is indeed corresponding to recent results on encapsulation‐induced conductivity enhancement …”

“…500 S cm −1 films . Along with this, recent studies suggested that the encapsulation of dopants into SWCNTs might enhance doping efficiency that afford enhanced conductivity …”

Thickness-dependent thermoelectric power factor of polymer-functionalized semiconducting carbon nanotube thin films

“…Considering its extraordinary electrochemical stability [13,28,29], AgTFSI, a typical one-electron oxidizer (hole dopant) [30], was used for a p-type dopant. The addition of AgTFSI gradually changed the spectra, achieving (1) the complete suppression of the S 11 band (0.6–0.9 eV), and (2) the significant evolution of one-dimensional plasmon resonance in the MIR region (< 0.6 eV).…”

Synergistic Impacts of Electrolyte Adsorption on the Thermoelectric Properties of Single‐Walled Carbon Nanotubes

“…The small chloride anions (Cl − ) should interact efficiently with the positive charges on the PDDA main chains. Considering the “hard and soft acids and bases” rule, large anions such as TFSI might effectively compensate delocalized positive charges in the conjugated SWNT backbone. Considering the fully conjugated, narrow‐gap π‐electron SWNT systems, even these minor ionic interactions are crucial for inducing the progression of oxidative p‐type doping and tuning the doping level under ambient conditions…”