No abstract

A fully sealed field-emission display 4.5 in. in size has been fabricated using single-wall carbon nanotube ͑CNT͒-organic binders. The fabricated displays were fully scalable at low temperature, below 415°C, and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1 V/m and field emission current of 1.5 mA at 3 V/m (J ϭ90 A/cm 2) were observed. Brightness of 1800 cd/m 2 at 3.7 V/m was observed on the entire area of a 4.5 in. panel from the green phosphor-indium-tin-oxide glass. The fluctuation of the current was found to be about 7% over a 4.5 in. cathode area.

We present a novel binder-free multiwall carbon nanotube (MWCNT) structure as an anode in Li ion batteries. The interface-controlled MWCNT structure, synthesized through a two-step process of catalyst deposition and chemical vapor deposition (CVD) and directly grown on a copper current collector, showed very high specific capacity, almost three times as that of graphite, excellent rate capability even at a charging/discharging rate of 3 C, and no capacity degradation up to 50 cycles. Significantly enhanced properties of this anode could be related to high Li ion intercalation on the carbon nanotube walls, strong bonding with the substrate, and excellent conductivity.

Graphene was grown directly on porous nickel films, followed by the growth of controlled lengths of vertical carbon nanotube (CNT) forests that seamlessly emanate from the graphene surface. The metal-graphene-CNT structure is used to directly fabricate field-emitter devices and double-layer capacitors. The three-dimensional nanostructured hybrid materials, with better interfacial contacts and volume utilization, can stimulate the development of several energy-efficient technologies.

We present the fabrication and electrical characterization of large graphene structure on polyethylene terephthalate (PET) flexible substrate. Graphene film was grown on Cu foil by thermal chemical vapor deposition and transferred to PET by using hot press lamination. The graphene/PET film shows high quality, flexible transparent conductive structure with unique electrical-mechanical properties; ∼88.80% light transmittance and ∼1.1742 kΩ/sq sheet resistance. We demonstrate application of graphene/PET film as flexible and transparent electrode for field emission displays. Our proposed techniques can be tailored for any flexible substrate and large scale production, which could open up exciting device applications in foldable electronics.

The fabrication and functionalization of large-area graphene and its electrocatalytic properties for iodine reduction in a dye-sensitized solar cell are reported. The graphene fi lm, grown by thermal chemical vapor deposition, contains three to fi ve layers of monolayer graphene, as confi rmed by Raman spectroscopy and high-resolution transmission electron microscopy. Further, the graphene fi lm is treated with CF 4 reactive-ion plasma and fl uorine ions are successfully doped into graphene as confi rmed by X-ray photoelectron spectroscopy and UV-photoemission spectroscopy. The fl uorinated graphene shows no structural deformations compared to the pristine graphene except an increase in surface roughness. Electrochemical characterization reveals that the catalytic activity of graphene for iodine reduction increases with increasing plasma treatment time, which is attributed to an increase in catalytic sites. Further, the fl uorinated graphene is characterized in use as a counter-electrode in a full dye-sensitized solar cell and shows ca. 2.56% photon to electron conversion effi ciency with ca. 11 mA cm − 2 current density. The shift in work function in F − doped graphene is attributed to the shift in graphene redox potential which results in graphene's electrocatalytic-activity enhancement.

A unique nanoelectronic platform, based on single-walled carbon nanotubes (SWNTs), has been fabricated for measuring electrical transport in single-molecule DNA. We have tested 80 base pairs of single- and double-stranded DNA (ssDNA and dsDNA, respectively) of complex base sequences. About a 25-40 pA current (at 1 V) was measured for the dsDNA molecule covalently attached to the SWNT electrode at its termini. In the absence of base pair stacking, a ssDNA carries a feeble current of approximately 1 pA or less. Gate-voltage-dependent I-V characteristics revealed that the bridging dsDNA molecule acts as a p-type channel between SWNT source and drain electrodes.

Monoclinic gallium oxide nanowires are prepared here by arc discharge of GaN powder in the presence of a small amount of transition metal catalyst. The nanowires are characterized by X‐ray diffraction, energy dispersive X‐ray spectroscopy, and Raman spectroscopy, and evidence as to the mechanism of their formation (shown in the Figure) is obtained by high‐resolution transmission electron microscopy.