We have developed a process for chemical purification of carbon nanotubes for solution-processable thin-film transistors （TFTs） having high mobility. Films of the purified carbon nanotubes fabricated by simple drop ...We have developed a process for chemical purification of carbon nanotubes for solution-processable thin-film transistors （TFTs） having high mobility. Films of the purified carbon nanotubes fabricated by simple drop coating showed carrier mobilities as high as 164 cm2V-1s -1 normalized transconductances of 0.78 Sm-1 and on/off current ratios of 10^6. Such high performance requires the preparation of a suspension of micrometer-long and highly purified semiconducting single-walled carbon nanotubes （SWCNTs）. Our purification process includes length and electronic-type selective trapping of SWCNTs using recycling gel filtration with a mixture of surfactants. The results provide an important milestone toward printed high-speed and large-area electronics with roll-to-roll and ink-jet device fabrication.展开更多
Although the inter-layer coupling in layered materials has attracted considerable interest due to its importance in determining physical properties of two- dimensional systems, studies on the inter-layer coupling in o...Although the inter-layer coupling in layered materials has attracted considerable interest due to its importance in determining physical properties of two- dimensional systems, studies on the inter-layer coupling in one-dimensional systems have so far been limited. Double-wall carbon nanotubes （DWCNTs） are one of the most fundamental and ideal model systems to study the interqayer coupling in one-dimensional systems. In this work, Rayleigh scattering spectroscopy and transmission electron microscopy are used to characterize the electronic transition between inner-and outer-nanotubes of the exactly same individual DWCNT. We find that the interqayer coupling is strong, leading to downshifts in most of the optical transition energies （up to -0.2 eV） compared to isolated CNTs. We also find that the presence of metallic tubes lead to stronger shifts. The inter-layer screening of Coulomb interactions is one of the key factors in explaining the observed results.展开更多
Crystalline ErCl_(3) nanowires have been fabricated in single-walled carbon nanotubes(SWCNTs)with high yield(~90%),and the structural and magnetic properties of the resulting ErCl_(3) nanowires encapsulated in SWCNTs(...Crystalline ErCl_(3) nanowires have been fabricated in single-walled carbon nanotubes(SWCNTs)with high yield(~90%),and the structural and magnetic properties of the resulting ErCl_(3) nanowires encapsulated in SWCNTs(ErCl_(3)@SWCNTs)characterized.Encapsulation under high temperature and vacuum using high quality SWCNTs results in a high fi lling-ratio of ErCl_(3) nanowires in the SWCNTs.The high fi lling-ratio of ErCl_(3) nanowires and the use of highly pure SWCNTs with only a small amount of residual Fe catalyst nanoparticles enabled us to observe the magnetic properties of ErCl_(3)@SWCNTs.Structure determination based on simulated annealing calculations and high-resolution transmission electron microscope(HRTEM)image simulations revealed that the structure of the ErCl_(3) nanowires is unusual with respect to the coordination environment of the Eu3+ions.This work opens up new possibilities to fabricate various metal complex nanowires with high yield and may also be of more general importance in understanding and exploring magnetic properties in low-dimensional magnetic systems.展开更多
A fully flattened carbon nanotube （FNT）, a graphene nanoribbon （GNR） analogue, provides a hollow space at edges for endohedral doping. Due to the unique shape of the hollow space of FNTs, novel types of low-dimens...A fully flattened carbon nanotube （FNT）, a graphene nanoribbon （GNR） analogue, provides a hollow space at edges for endohedral doping. Due to the unique shape of the hollow space of FNTs, novel types of low-dimensional arrangements of atoms and molecules can be obtained through endohedral doping into FNTs, which provides a new type of nanopeapods. FNT-based nanopeapods have been synthesized through endohedral doping of C60, and their structural characterization with transmission electron microscopy （TEM） performed. The doping of C60 into the inner hollow space of FNTs has been carried out via the gas-phase filling method, where open-ended FNTs are sealed in a glass ampoule and heated at 723-773 K for two days. TEM observations show that most of the encapsulated C60 molecules align as single molecular chains along the edges of FNTs and that some of the C60 forms two-dimensional close-packed structures inside FNTs.展开更多
文摘We have developed a process for chemical purification of carbon nanotubes for solution-processable thin-film transistors （TFTs） having high mobility. Films of the purified carbon nanotubes fabricated by simple drop coating showed carrier mobilities as high as 164 cm2V-1s -1 normalized transconductances of 0.78 Sm-1 and on/off current ratios of 10^6. Such high performance requires the preparation of a suspension of micrometer-long and highly purified semiconducting single-walled carbon nanotubes （SWCNTs）. Our purification process includes length and electronic-type selective trapping of SWCNTs using recycling gel filtration with a mixture of surfactants. The results provide an important milestone toward printed high-speed and large-area electronics with roll-to-roll and ink-jet device fabrication.
文摘Although the inter-layer coupling in layered materials has attracted considerable interest due to its importance in determining physical properties of two- dimensional systems, studies on the inter-layer coupling in one-dimensional systems have so far been limited. Double-wall carbon nanotubes （DWCNTs） are one of the most fundamental and ideal model systems to study the interqayer coupling in one-dimensional systems. In this work, Rayleigh scattering spectroscopy and transmission electron microscopy are used to characterize the electronic transition between inner-and outer-nanotubes of the exactly same individual DWCNT. We find that the interqayer coupling is strong, leading to downshifts in most of the optical transition energies （up to -0.2 eV） compared to isolated CNTs. We also find that the presence of metallic tubes lead to stronger shifts. The inter-layer screening of Coulomb interactions is one of the key factors in explaining the observed results.
基金by the JST CREST Program for novel carbon nanotube materialsThe XAS experiments were performed at BL25SU in SPring-8 with the approval of JASRT(Proposal No.2007B1732).
文摘Crystalline ErCl_(3) nanowires have been fabricated in single-walled carbon nanotubes(SWCNTs)with high yield(~90%),and the structural and magnetic properties of the resulting ErCl_(3) nanowires encapsulated in SWCNTs(ErCl_(3)@SWCNTs)characterized.Encapsulation under high temperature and vacuum using high quality SWCNTs results in a high fi lling-ratio of ErCl_(3) nanowires in the SWCNTs.The high fi lling-ratio of ErCl_(3) nanowires and the use of highly pure SWCNTs with only a small amount of residual Fe catalyst nanoparticles enabled us to observe the magnetic properties of ErCl_(3)@SWCNTs.Structure determination based on simulated annealing calculations and high-resolution transmission electron microscope(HRTEM)image simulations revealed that the structure of the ErCl_(3) nanowires is unusual with respect to the coordination environment of the Eu3+ions.This work opens up new possibilities to fabricate various metal complex nanowires with high yield and may also be of more general importance in understanding and exploring magnetic properties in low-dimensional magnetic systems.
文摘A fully flattened carbon nanotube （FNT）, a graphene nanoribbon （GNR） analogue, provides a hollow space at edges for endohedral doping. Due to the unique shape of the hollow space of FNTs, novel types of low-dimensional arrangements of atoms and molecules can be obtained through endohedral doping into FNTs, which provides a new type of nanopeapods. FNT-based nanopeapods have been synthesized through endohedral doping of C60, and their structural characterization with transmission electron microscopy （TEM） performed. The doping of C60 into the inner hollow space of FNTs has been carried out via the gas-phase filling method, where open-ended FNTs are sealed in a glass ampoule and heated at 723-773 K for two days. TEM observations show that most of the encapsulated C60 molecules align as single molecular chains along the edges of FNTs and that some of the C60 forms two-dimensional close-packed structures inside FNTs.
