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High Quantum Efficiency (high + quantum_efficiency)

Distribution by Scientific Domains

Polymers and Materials Science	71%
Chemistry	28%

Selected Abstracts

Rapid Synthesis of Non-Aggregated Fine Chloroapatite Blue Phosphor Powders with High Quantum Efficiency,

ADVANCED MATERIALS, Issue 18 2008
Wei-Ning Wang
Sub-micrometer-sized chloroapatite blue phosphors are successfully synthesized from aqueous precursors using a spray pyrolysis method with a very short processing time and without any post-heat treatments. The as-prepared phosphors reveal high quantum efficiency in the long-UV range (around 80% under excitation at 400,nm), spherical morphology, high crystallinity, and high color purity, showing great promise for white LED applications. [source]

Facile Synthesis of New Full-Color-Emitting BCNO Phosphors with High Quantum Efficiency,

ADVANCED MATERIALS, Issue 17 2008
Takashi Ogi
A novel full-color-emitting phosphor composed of B, C, N, and O atoms is prepared by a one-step solution process from inexpensive precursors at ambient atmosphere and relatively low temperatures (below 900,°C). Emission from this novel phosphor can be tuned from the violet to the near-red, as illustrated in the figure, simply by varying the carbon content in the samples. [source]

Kinetic modeling of the photocatalytic degradation of air-borne pollutants

AICHE JOURNAL, Issue 5 2004
H. Ibrahim
Abstract The photocatalytic conversion of organic model pollutants (acetone, acetaldehyde, and isopropanol) in a novel Photo-CREC-Air unit is considered. This photocatalytic unit features: (1) external near-UV lamps placed in parabolic reflectors, (2) a basket supporting the irradiated glass mesh holding TiO2 loadings to achieve high photoconversion rates, and (3) a fluid flow pattern securing high gas velocities in the near-mesh region. Given the high quantum efficiencies observed in Photo-CREC-Air and, as a result, the high prospects for this novel design, rate equations and associated mechanistic formulations are investigated. With this goal, a Langmuir,Hinshelwood model, involving a one-site model pollutant mechanism, is considered. The associated kinetic parameters with the related statistical indicators are established, using least-square nonlinear regression. It is found that this model is adequate for describing the photodegradation of acetone on both Degussa P25 and Hombikat UV-100. It is also observed that the same type of reaction rate model is less adequate for the photodegradation of acetaldehyde and isopropanol, in particular, for predicting the formation of carbon dioxide. © 2004 American Institute of Chemical Engineers AIChE J 50: 1017,1027, 2004 [source]

A Series of Red-Light-Emitting Ionic Iridium Complexes: Structures, Excited State Properties, and Application in Electroluminescent Devices

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2008
Shu-Juan Liu
Abstract A series of ionic diiminoiridium complexes [Ir(piq-C,N)2(L-N,N)](PF6) were prepared, where piq-C,N is 1-phenylisoquinolinato and L-N,N are bidentate N-coordinating ligands: 2,2,-bipyridine (bpy), 4,4,-dimethyl-2,2,-bipyridine (mbpym), 5,5,-bis(thiopen-2-yl)-2,2,-bipyridine (tbpyt), and 5,5,-bis(9,9-dioctylfluoren-2-yl)-2,2,-bipyridine (FbpyF). X-ray diffraction studies of [Ir(piq)2(mbpym)](PF6) revealed that the iridium center adopts a distorted octahedral geometry. All complexes exhibited intense and long-lived emission at room temperature. The substituents on the 2,2,-bipyridine moieties influence the photophysical and electrochemical properties. The excited states were investigated through theoretical calculations together with photophysical and electrochemical properties. It was found that the excited state of the [Ir(piq)2(FbpyF)](PF6) complex can be assigned to a mixed character of 3LC (,N,N,,*N,N), 3MLCT, 3LLCT (,C,N,,*N,N), and 3LC (,C,N,,*C,N). In addition, the alkylfluorene-substituted complex, [Ir(piq)2(FbpyF)](PF6), hadrelatively high quantum efficiency and good film-forming ability, and it was expected to be a good candidate for lighting and display applications. A nondoped, single-layer device that incorporates this complex as a light-emitting layer was fabricated and red phosphorescence was obtained.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Phenylcarbazole-Based Phosphine Oxide Host Materials For High Efficiency In Deep Blue Phosphorescent Organic Light-Emitting Diodes

ADVANCED FUNCTIONAL MATERIALS, Issue 22 2009
Soon Ok Jeon
Abstract Highly efficient deep blue phosphorescent organic light-emitting diodes are developed using novel phenylcarbazole-based phosphine oxide host materials (PPO1 and PPO2). A deep blue phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine) iridium, is doped into PPO1 and PPO2 at a doping concentration of 15% and a high quantum efficiency of 18.4% is obtained with color coordinates of (0.14, 0.15). [source]

Multifunctional Deep-Blue Emitter Comprising an Anthracene Core and Terminal Triphenylphosphine Oxide Groups

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Chen-Han Chien
Abstract A highly efficient blue-light emitter, 2- tert -butyl-9,10-bis[4,-(diphenyl-phosphoryl)phenyl]anthracene (POAn) is synthesized, and comprises electron-deficient triphenylphosphine oxide side groups appended to the 9- and 10-positions of a 2- tert -butylanthracene core. This sophisticated anthracene compound possesses a non-coplanar configuration that results in a decreased tendency to crystallize and weaker intermolecular interactions in the solid state, leading to its pronounced morphological stability and high quantum efficiency. In addition to serving as an electron-transporting blue-light-emitting material, POAn also facilitates electron injection from the Al cathode to itself. Consequently, simple double-layer devices incorporating POAn as the emitting, electron-transporting, and -injecting material produce bright deep-blue lights having Commission Internationale de L'Eclairage coordinates of (0.15,0.07). The peak electroluminescence performance was 4.3% (2.9 cd A,1). For a device lacking an electron-transport layer or alkali fluoride, this device displays the best performance of any such the deep-blue organic light-emitting diodes reported to date. [source]