Separation of Metallic from Semiconducting Single-Walled Carbon Nanotubes

Krupke, Ralph; Hennrich, Frank; Löhneysen, H. v.; Kappes, Manfred M.

doi:10.1126/science.1086534

Cited by 1,463 publications

(1,124 citation statements)

References 19 publications

Supporting

Mentioning

1,074

Contrasting

Unclassified

Order By: Relevance

“…[56] These electronic transition differences, however, make SWNT sample homogeneity a major issue. For example, even if a SWNT sample has been separated according to type (met-versus sem-) and d t , [64][65][66][67][68][69][70] different chirality and modality nanotubes will contribute significant heterogeneity as the nanotube diameter gets smaller than 1.5−2 nm. This is expected to play a significant role in the reproducibility of advanced nanotube devices as the community continues the refinement in coupling a variety of biological stimuli to SWNT electronic transitions.…”

Section: Carbon Nanotube Propertiesmentioning

confidence: 99%

Carbon Nanotubes for Electronic and Electrochemical Detection of Biomolecules

2007

View full text Add to dashboard Cite

The unique electronic and optical properties of carbon nanotubes, in conjunction with their size and mechanically robust nature, make these nanomaterials crucial to the development of next-generation biosensing platforms. In this Review, we present recent innovations in carbon nanotube-assisted biosensing technologies, such as DNA-hybridization, protein-binding, antibody-antigen and aptamers. Following a brief introduction on the diameter-and chirality-derived electronic characteristics of single-walled carbon nanotubes, the discussion is focused on the two major schemes for electronic biodetection, namely biotransistor-and electrochemistry-based sensors. Key fabrication methodologies are contrasted in light of device operation and performance, along with strategies for amplifying the signal while minimizing nonspecific binding. This Review is concluded with a perspective on future optimization based on array integration as well as exercising a better control in nanotube structure and biomolecular integration.

show abstract

Section: Carbon Nanotube Propertiesmentioning

confidence: 99%

Carbon Nanotubes for Electronic and Electrochemical Detection of Biomolecules

2007

View full text Add to dashboard Cite

show abstract

“…Recent work has also demonstrated that it is possible to achieve limited separation of exfoliated SWNTs according to (n,m) structure, 58,121,136 left-or right-handed chirality, 95 length, 137,138 and electronic character (i.e., metallic or semiconducting). [139][140][141][142][143][144][145] SWNT surfactants are classified in terms of their ionic character (i.e., anionic, cationic, or nonionic). Ionic surfactants have a positively or negatively charged head group that interacts with the solvent and a nonpolar tail that associates with the nanotube sidewall; SWNT aggregation is hindered by charge repulsion between the polar head groups that extend into the solvent.…”

Section: Motivationmentioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

View full text Add to dashboard Cite

Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

show abstract

“…As the electronic property of an SWCNT strongly depends on its chirality, the lack of synthetic control in chirality has long been recognized as a fundamental impediment in the science and application of SWCNTs. Previous efforts to address this issue have resulted in significant progress in separation of synthetic mixtures, yielding predominantly single-chirality nanotube species [11][12][13][14][15] . However, separation processes are limited by their small scale, high cost and short length (o500 nm) of the resulting chirality-pure nanotubes.…”

mentioning

confidence: 99%

“…Our strategy is to combine nanotube separation with synthesis to achieve controlled growth of nanotubes with preselected chirality. Tremendous progress has been made in recent years in SWCNT separation [11][12][13][14][15]25,26 . In particular, DNA-based chromatographic separation allows purification of both semiconducting and metallic single-chirality SWCNTs through the use of different DNA sequences 12,26 .…”

mentioning

confidence: 99%

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

et al. 2012

View full text Add to dashboard Cite

Chirality-controlled synthesis of single-wall carbon nanotubes with predefined chiralities has been an important but elusive goal for almost two decades. Here we demonstrate a general strategy for producing carbon nanotubes with predefined chiralities by using purified singlechirality nanotubes as seeds for subsequent metal catalyst free growth, resembling vapourphase epitaxy commonly used for semiconductor films. In particular, we have successfully synthesized (7, 6), (6, 5) and (7, 7) nanotubes, and used Raman spectroscopy to show unambiguously that the original chiralities of the nanotube seeds are preserved. Furthermore, we have performed electrical measurements on synthesized individual (7, 6) and (6, 5) nanotubes, confirming their semiconducting nature. The vapour-phase epitaxy approach is found to be highly robust and should enable a wide range of fundamental studies and technological developments.

show abstract

Separation of Metallic from Semiconducting Single-Walled Carbon Nanotubes

Cited by 1,463 publications

References 19 publications

Carbon Nanotubes for Electronic and Electrochemical Detection of Biomolecules

Carbon Nanotubes for Electronic and Electrochemical Detection of Biomolecules

Photophysics of Individual Single-Walled Carbon Nanotubes

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

Contact Info

Product

Resources

About