Author
Chris Williams
Other affiliations: University of Texas at Dallas, Commonwealth Scientific and Industrial Research Organisation
Bio: Chris Williams is an academic researcher from University of Texas System. The author has contributed to research in topics: Carbon nanotube & Nanotube. The author has an hindex of 7, co-authored 13 publications receiving 2480 citations. Previous affiliations of Chris Williams include University of Texas at Dallas & Commonwealth Scientific and Industrial Research Organisation.
Topics: Carbon nanotube, Nanotube, Ribbon, Nanofiber, Charge carrier
Papers
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TL;DR: Self-supporting nanotube sheets are initially formed as a highly anisotropic electronically conducting aerogel that can be densified into strong sheets that are as thin as 50 nanometers and the measured gravimetric strength of orthogonally oriented sheet arrays exceeds that of sheets of high-strength steel.
Abstract: Individual carbon nanotubes are like minute bits of string, and many trillions of these invisible strings must be assembled to make useful macroscopic articles. We demonstrated such assembly at rates above 7 meters per minute by cooperatively rotating carbon nanotubes in vertically oriented nanotube arrays (forests) and made 5-centimeter-wide, meter-long transparent sheets. These self-supporting nanotube sheets are initially formed as a highly anisotropic electronically conducting aerogel that can be densified into strong sheets that are as thin as 50 nanometers. The measured gravimetric strength of orthogonally oriented sheet arrays exceeds that of sheets of high-strength steel. These nanotube sheets have been used in laboratory demonstrations for the microwave bonding of plastics and for making transparent, highly elastomeric electrodes; planar sources of polarized broad-band radiation; conducting appliques; and flexible organic light-emitting diodes.
1,630 citations
07 Jul 2016
TL;DR: In this article, the authors describe the properties and properties of carbon nanotube yarns, ribbons, and sheets, including extreme toughness, resistance to failure at knots, high electrical and thermal conductivities, high absorption of energy that occurs reversibly, up to 13% strain-to-failure compared with other fibers with similar toughness, retention of strength even when heated in air at 450°C for one hour, and very high radiation and UV resistance, even when irradiated in air.
Abstract: The present invention is directed to nanofiber yarns, ribbons, and sheets; to methods of making said yarns, ribbons, and sheets; and to applications of said yarns, ribbons, and sheets. In some embodiments, the nanotube yarns, ribbons, and sheets comprise carbon nanotubes. Particularly, such carbon nanotube yarns of the present invention provide unique properties and property combinations such as extreme toughness, resistance to failure at knots, high electrical and thermal conductivities, high absorption of energy that occurs reversibly, up to 13% strain-to-failure compared with the few percent strain-to-failure of other fibers with similar toughness, very high resistance to creep, retention of strength even when heated in air at 450°C for one hour, and very high radiation and UV resistance, even when irradiated in air. Furthermore these nanotube yarns can be spun as one micron diameter yarns and plied at will to make two-fold, four-fold, and higher fold yarns. Additional embodiments provide for the spinning of nanofiber sheets having arbitrarily large widths. In still additional embodiments, the present invention is directed to applications and devices that utilize and/or comprise the nanofiber yarns, ribbons, and sheets of the present invention.
661 citations
TL;DR: In this article, a solid-state process for nanotube assembly is presented that promises to eliminate the requirement to use binders and capture the inherent properties of nanotubes.
Abstract: Carbon nanotubes (CNTs) have a range of useful properties, such as high strength and modulus, high electrical and thermal conductivities, are stable at relatively high and low temperatures, and because of a low density, the specific properties are even better. For these reasons, CNTs are of great technological interest, however, difficulties in assembling the trillions of nanotubes into macro-sized objects without the use of binders has retarded the growth of practical applications. The work presented outlines efforts to develop a solid-state process for nanotube assembly that promises to eliminate the requirement to use binders and capture the inherent properties of nanotubes. These processes include spinning CNT forests into yarns having toughness and high electrical conductivity, and drawing the forests to form webs with gravimetric strengths higher than high tensile steel plate. Both yarns and webs have high electrical conductivities and can be used for emission of light by incandescence.
144 citations
TL;DR: In this article, the authors used transparent carbon nanotube (CNT) sheets as the hole-injecting anode for organic light-emitting diode (LED) with a brightness of 4500cd/m2 and current efficiency near 2.5 cd/A.
Abstract: We have fabricated efficient organic light emitting diodes using strong, transparent carbon nanotube (CNT) sheets as the hole-injecting anode. These devices show a brightness of 4500 cd/m2 and current efficiency near 2.5 cd/A, which is close to the efficiency we achieve with a similar device, which uses indium tin oxide (ITO) as the anode. We demonstrate that proper planarization of the electrode using the water-soluble polymer poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) is necessary for achieving high efficiency and can be accomplished by spin casting multiple layers. We believe that increased conductivity of the sheets could lead to CNT-based devices with efficiencies exceeding those on ITO.
83 citations
TL;DR: In this article, the electronic dopants, like tetrafluorocyanoquinodimethane (F 4 -TCNQ) molecules, used for p-doping of hole transport layers in organic light-emitting diodes (OLEDs) are found to quench the electroluminescence (EL) if they diffuse into the emissive layer.
19 citations
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TL;DR: Transparent, conductive, and ultrathin graphene films, as an alternative to the ubiquitously employed metal oxides window electrodes for solid-state dye-sensitized solar cells, are demonstrated and show high chemical and thermal stabilities and an ultrasmooth surface with tunable wettability.
Abstract: Transparent, conductive, and ultrathin graphene films, as an alternative to the ubiquitously employed metal oxides window electrodes for solid-state dye-sensitized solar cells, are demonstrated. These graphene films are fabricated from exfoliated graphite oxide, followed by thermal reduction. The obtained films exhibit a high conductivity of 550 S/cm and a transparency of more than 70% over 1000−3000 nm. Furthermore, they show high chemical and thermal stabilities as well as an ultrasmooth surface with tunable wettability.
4,314 citations
TL;DR: In this article, a review of the progress to date in the field of mechanical reinforcement of polymers using nanotubes is presented, and the most promising processing methods for mechanical reinforcement are discussed.
3,770 citations
TL;DR: In this paper, the technology involved with exfoliated clay-based nanocomposites and also include other important areas including barrier properties, flammability resistance, biomedical applications, electrical/electronic/optoelectronic applications and fuel cell interests.
2,917 citations
TL;DR: This review will explore the materials properties of transparent conductors, covering traditional metal oxides and conductive polymers initially, but with a focus on current developments in nano-material coatings.
Abstract: Transparent electrodes are a necessary component in many modern devices such as touch screens, LCDs, OLEDs, and solar cells, all of which are growing in demand. Traditionally, this role has been well served by doped metal oxides, the most common of which is indium tin oxide, or ITO. Recently, advances in nano-materials research have opened the door for other transparent conductive materials, each with unique properties. These include CNTs, graphene, metal nanowires, and printable metal grids. This review will explore the materials properties of transparent conductors, covering traditional metal oxides and conductive polymers initially, but with a focus on current developments in nano-material coatings. Electronic, optical, and mechanical properties of each material will be discussed, as well as suitability for various applications.
1,947 citations
TL;DR: This dense carbon-nanotube material is advantageous for numerous applications, and here it is demonstrated its use as flexible heaters as well as supercapacitor electrodes for compact energy-storage devices.
Abstract: Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super-capacitor electrodes
1,851 citations