CdTe Nanocrystals (cdte + nanocrystal)

Distribution by Scientific Domains


Selected Abstracts


Inkjet Printing of Luminescent CdTe Nanocrystal,Polymer Composites,

ADVANCED FUNCTIONAL MATERIALS, Issue 1 2007
E. Tekin
Abstract Inkjet printing is used to produce well-defined patterns of dots (with diameters of ca.,120,,m) that are composed of luminescent CdTe nanocrystals (NCs) embedded within a poly(vinylalcohol) (PVA) matrix. Addition of ethylene glycol (1,2,vol,%) to the aqueous solution of CdTe NCs suppresses the well-known ring-formation effect in inkjet printing leading to exceptionally uniform dots. Atomic force microscopy characterization reveals that in the CdTe NC films the particle,particle interaction could be prevented using inert PVA as a matrix. Combinatorial libraries of CdTe NC,PVA composites with variable NC sizes and polymer/NC ratios are prepared using inkjet printing. These libraries are subsequently characterized using a UV/fluorescence plate reader to determine their luminescent properties. Energy transfer from green-light-emitting to red-light-emitting CdTe NCs in the composite containing green- (2.6,nm diameter) and red-emitting (3.5,nm diameter) NCs are demonstrated. [source]


Layer-by-Layer All-Inorganic Quantum-Dot-Based LEDs: A Simple Procedure with Robust Performance

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010
James S. Bendall
Abstract A novel all-inorganic electroluminescent device is demonstrated based on highly luminescent CdTe nanocrystals intercalated within a laminar hydrotalcite-like structure. The laminar scaffold acts to both support and distribute the CdTe nanocrystals. The device is synthesized using simple wet chemical processes at room temperature in ambient conditions. It has high thermal stability, operating continuously up to 90 °C, and a maximum efficiency at J = 0.12 A cm,2. The device is targeted at the automotive industry. [source]


Preparation-Condition Dependence of Hybrid SiO2 -Coated CdTe Nanocrystals with Intense and Tunable Photoluminescence

ADVANCED FUNCTIONAL MATERIALS, Issue 8 2010
Ping Yang
Abstract When aqueously prepared CdTe nanocrystals (NCs) are coated with a SiO2 shell containing Cd ions and a sulfur source, they show a drastic increase in photoluminescence (PL) efficiency with a significant red shift and spectral narrowing after reflux. This is ascribed to the creation of a hybrid structure characterized by the formation of CdS-like clusters in the vicinity of the NCs in the SiO2 shell. Since these clusters are close to the NCs, their effective size increases to reduce the quantum size effect. The dependences of the PL properties on the preparation conditions are systematically investigated. The PL efficiency increases from 28% to 80% in the best case with a red shift of 80,nm. The PL behaviors differ from those of normal CdTe NCs and include less temperature quenching and longer PL lifetime. The SiO2 coating enables bioconjugation with IgG without deterioration of PL efficiency, making hybrid NCs amenable for bioapplication. [source]


Inkjet Printing of Luminescent CdTe Nanocrystal,Polymer Composites,

ADVANCED FUNCTIONAL MATERIALS, Issue 1 2007
E. Tekin
Abstract Inkjet printing is used to produce well-defined patterns of dots (with diameters of ca.,120,,m) that are composed of luminescent CdTe nanocrystals (NCs) embedded within a poly(vinylalcohol) (PVA) matrix. Addition of ethylene glycol (1,2,vol,%) to the aqueous solution of CdTe NCs suppresses the well-known ring-formation effect in inkjet printing leading to exceptionally uniform dots. Atomic force microscopy characterization reveals that in the CdTe NC films the particle,particle interaction could be prevented using inert PVA as a matrix. Combinatorial libraries of CdTe NC,PVA composites with variable NC sizes and polymer/NC ratios are prepared using inkjet printing. These libraries are subsequently characterized using a UV/fluorescence plate reader to determine their luminescent properties. Energy transfer from green-light-emitting to red-light-emitting CdTe NCs in the composite containing green- (2.6,nm diameter) and red-emitting (3.5,nm diameter) NCs are demonstrated. [source]


Morphology- and Color-Tunable Bright Fibers with High Concentration of CdTe Nanocrystals Assembled through Sol,Gel Reaction

ADVANCED MATERIALS, Issue 40 2009
Ping Yang
Intensely luminescent fibers are prepared by the self-assembly of hybrid SiO2 -coated CdTe nanocrystals (NCs), SiO2 monomers, and a complex of Cd2+ and thioglycolic acid. These fibers exhibit tunable photoluminescent colors (yellow to red) and morphologies (tubal, solid, and belt-like) with an extremely high concentration of CdTe NCs by controlling the preparation parameters. [source]


Photoluminescence Quenching Control in Quantum Dot,Carbon Nanotube Composite Colloids Using a Silica-Shell Spacer,

ADVANCED MATERIALS, Issue 4 2006
M. Grzelczak
One-dimensional nanocomposite colloids are prepared by means of electrostatic self-assembly of CdTe nanocrystals on both carbon nanotubes (CNTs) and silica-coated CNTs (see Figure). The dense coverage of these linear nanoparticle assemblies minimizes the spacing between the nanocrystals, thereby facilitating efficient electronic and energy transfer along the nanotubes. [source]


Effects of the grafting on the fluorescence properties of CdTe nanocrystals

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2009
Fang Mei
Abstract In this paper, we systematically investigated the influence of graft reagents having an amino or a carboxyl terminus with different chain lengths on the fluorescence properties of water-soluble thioglycolic acid-stabilized CdTe nanocrystals (TGA,CdTe). Strong enhancement effects of the grafting on the fluorescence intensity of TGA,CdTe were observed. The experiment results demonstrated that short-chain-length grafting can increase the fluorescence intensity of CdTe nanocrystals (NCs) better than long-chain-length grafting, and the grafting did not influence the emission wavelength of the CdTe NCs. The fluorescence intensity of the carboxyl-grafted TGA,CdTe was more stable than that of the amino-grafted TGA,CdTe at wide pH ranges (pH 5.1,10.0). Copyright © 2009 John Wiley & Sons, Ltd. [source]


Physical and optical properties of size-selective CdTe nanocrystals

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2010
Alice Fok
Abstract Physical and optical properties of colloidal cadmium telluride nanocrystals (CdTe NCs) were investigated. The CdTe NCs were synthesized by reacting elemental tellurium dissolved in tributylphosphine with a mixture of cadmium oxide, octadecene, and oleic acid. These NCs, which were characterized by transmission electron microscopy (TEM) are spherical and ranged from 5 to 7 nm in diameter. The identity of the compound post-synthesis was confirmed by X-Ray diffraction (XRD) patterns. UV-Vis and photoluminescence (PL) properties as grown and pure CdTe samples were investigated. Bright excitonic photoluminescence emission was observed (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Radiation pressure induced splitting of resonant modes in a nanocrystal-coated microcavity

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006
M. Gerlach
Abstract Melamine formaldehyde microspheres were coated with a soft polyelectrolyte multilayer (PAH/PSS) and one monolayer of CdTe nanocrystals. A micro-PL setup was used to trap the sample within the tightly focused laser beam. The radiation pressure was used to deform the spherical shape of the polyelectrolyte multilayer which changes the optical properties of the resonance modes (whispering gallery modes) in the microcavity. Optically induced shifting and splitting of the resonances were observed with changing characteristics based on varying particular parameters such as laser intensity and focus position. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Spontaneous emission from semiconductor nanocrystals in coupled spherical microcavities

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2005
Yu. P. Rakovich
Abstract We report on the coherent coupling of whispering gallery modes (WGM) in a photonic molecule formed from two melamine-formaldehyde spherical microcavities coated with a thin shell of light-emitting CdTe nanocrystals (NCs). Utilizing different excitation conditions the splitting of the WGM resonances originating from bonding and anti-bonding branches of the photonic states is observed and fine structure consisting of very sharp peaks resulting from lifting of the WGM degeneracy has been detected. Time-resolved measurements showed a slight increase in the spontaneous emission rate of NCs in a photonic molecule when compared to the spontaneous emission rate for NCs coating a single microsphere. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Size-Tunable Highly Luminescent SiO2 Particles Impregnated with Number-Adjusted CdTe Nanocrystals

CHEMPHYSCHEM, Issue 4 2010
Ping Yang Dr.
Abstract Highly luminescent SiO2 particles impregnated with CdTe nanocrystals (NCs) are prepared by a sol,gel procedure. Partial ligand exchange from thioglycolic acid to 3-mercaptopropyltrimethoxysilane (MPS) on the NCs enables retention of the initial photoluminescence (PL) efficiency of the NCs in water, while the simultaneous addition of a poor solvent (ethanol) results in regulated assembly of the NCs through condensation of hydrolyzed MPS. The SiO2 particles thus prepared have, for example, a diameter of 16 nm and contain three NCs each. The PL efficiency of these particles is 40,%, while the initial efficiency is 46,% in a colloidal solution. The redshift and narrowed spectral width in PL observed after impregnation indicate that the concentration of NCs in these nearly reaches the ultimate value (on the order of 1021 particles per liter). The porosity of these particles is investigated by means of N2 adsorption,desorption isotherms. Due to the SiO2 shell, these particles have higher stability in phosphate-buffered saline buffer solution than the initial NCs. Their potential use for labeling in bio-applications is investigated by conjugating biotinylated immunoglobulin G to them by using streptavidin maleimide as linker. Successful conjugation is confirmed by electrophoresis in agarose gel. This preparation method is an important step towards fabricating intensely emitting biocompatible SiO2 particles impregnated with semiconductor NCs. [source]