Temporal evolution of white light emission from CdSe quantum dots.

A study of white light emission from magic sized CdSe quantum dots is reported. Quantum dots were synthesized using a hot solution method and exhibited strong white light with a quantum yield in the range of 10-30%. The emission of white light was attributed to photoluminescence (PL) from both excitons and surface states. The wavelength and intensity of the PL from both excitons and surface states were found to depend upon the particle size, reaction time, reaction temperature and precursor ratio.

White light emission from single layer poly (n-vinylcarbazole) polymeric light-emitting devices by mixing singlet and triplet excimer emissions.

White light electroluminescence (EL) was obtained by mixing emission from singlet and triplet excimers from a single poly (n-vinylcarbazole) (PVK) spin cast layer after irradiation of the solution with UV light. With increased UV light irradiation, the intensity from the triplet excimer (red-630 nm) of PVK increased compared with that of the singlet excimer (blue-460 nm) due to an increased population of both adjacent benzene rings being aligned with one another (fully overlapping) versus only one of the adjacent benzene rings being aligned (partially overlapping). The emission color changed from blue to white with increased UV irradiation time while the EL brightness and current density decreased and the turn-on voltage increased.

Defect studies on as-synthesized and purified carbon nanostructures produced by arc-discharge in solution process.

Carbon nanostructures are synthesized using a novel arc-discharge in solution process. A multitude of defects on nanotubes and nanostructures is found. Evidence of these defects in as-synthesized carbon nanostructures is explored using high-resolution transmission electron microscopy (HRTEM). Tri-, tetra-, penta-, hexa-, heptagonal, toroidal, oval, and spherical nanoshells are found in HRTEM investigation along with carbon nanotubes, carbon nanohorns, carbon rods, nanoporous carbon, dislodged graphene sheets, and amorphous carbon. Purifications are carried out through two oxidation methods to eliminate the amorphous carbon. Several different defects caused by oxidations are also found in purified samples.

A parametric study on the synthesis of carbon nanotubes through arc-discharge in water.

A parametric study was carried out on a novel carbon nanotube (CNT) synthesis using 'arc-discharge in solution' (ADS). The carbon nanostructure yield as a function of time, the rate of erosion of the anode, and the rate of deposition of carbonaceous materials on the cathode electrode were investigated. Amperage dependent normalized kinetic parameters were evaluated. The production rate of carbon nanostructures including CNTs at 75 A is as high as 5.89 ± 0.28 g min(-1). Thermogravimetric analysis and x-ray diffraction studies reveal high purity of the carbon nanostructures collected from water and have a very good agreement with electron microscopy analyses. Very high surface area of the pristine multiwalled CNTs and nanostructures (84 ± 3.5 m(2) g(-1)) was measured using BET. The dynamic light scattering (DLS) analysis shows further agreement with the amperage dependent studies.