Luminescent Functional Metal–Organic Frameworks

Fluorescent carbon nanoparticles or carbon quantum dots (CQDs) are a new class of carbon nanomaterials that have emerged recently and have garnered much interest as potential competitors to conventional semiconductor quantum dots. In addition to their comparable optical properties, CQDs have the desired advantages of low toxicity, environmental friendliness low cost and simple synthetic routes. Moreover, surface passivation and functionalization of CQDs allow for the control of their physicochemical properties. Since their discovery, CQDs have found many applications in the fields of chemical sensing, biosensing, bioimaging, nanomedicine, photocatalysis and electrocatalysis. This article reviews the progress in the research and development of CQDs with an emphasis on their synthesis, functionalization and technical applications along with some discussion on challenges and perspectives in this exciting and promising field.

Carbon quantum dots and their applications

Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

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Lanthanide luminescence for functional materials and bio-sciences

Lanthanide-based luminescent hybrid materials.

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Remote Sensing of Explosive Materials Using Differential Reflection Spectroscopy

Synergistic temperature and electron irradiation effects on cathodoluminescent (CL) degradation of ZnS:Ag,Cl powder phosphor have been investigated. After continuous 2 keV electron beam exposure at 250°C for a 24 C/cm 2 dose, the CL intensity upon cooling to room temperature decreased to 40% of the original intensity which is less than room temperature degradation for the same experimental conditions. Reduced degradation at high temperatures is consistent with the electron stimulated surface chemical reaction model of degradation which predicts that elevated temperatures reduce the mean stay time of physisorbed gases, decreasing the rate of the surface reactions leading to CL degradation. In a water-dominated ambient, the electron beam stimulates the formation of nonluminescent ZnO dead layers, while dissociation and reaction of H 2 leads to volatilization of S and Zn. Vaporization of Zn is accelerated by electron beam heating of the phosphor. The amount of heating was calculated using a heat transfer model to be ∼200°C for a primary beam of 2 keV, 25 c/cm 2 . This is consistent with morphological erosion on the surface of ZnS particles degraded at elevated temperatures or high power densities in H 2 -rich ambients. It is speculated that at a temperatures of about 300°C, surface chemical reactions with H 2 in combination with heating leads to removal of S as H 2 S and evaporation of Zn. The consequences of beam heating on current saturation measurements is discussed.

Synergistic Temperature and Electron Irradiation Effects on the Degradation of Cathodoluminescent ZnS:Ag,Cl Powder Phosphors

PbS and ZnO nanoparticles prepared separately by a sol-gel process were incorporated in SiO2 by an ex situ method, resulting in a green emitting ZnO–SiO2:PbS powder phosphor. Particle morphology, structure, and chemical composition of the ZnO nanoparticles, PbS nanoparticles, and ZnO–SiO2:PbS composite were analyzed with transmission electron microscopy, x-ray diffraction, and energy dispersive spectroscopy (EDS), respectively. With or without ZnO nanoparticles, green photoluminescence with a peak at 540nm was observed from SiO2:PbS when excited with a 325nm He–Cd laser in air at room temperature. This peak was different from defect-related emission from ZnO nanoparticles at 580nm and red-orange emission from SiO2:Pb2+ with a broad peak at 600–750nm. Again, the 540nm peak was different from the band edge emission from pure PbS nanoparticles at 1200nm. Note that this emission (540nm) was enhanced considerably when ZnO nanoparticles were incorporated. Photoluminescence properties of ZnO–SiO2:PbS is discussed.

Synthesis, characterization, and luminescent properties of ZnO–SiO2:PbS

The effects of solution processing on the photovoltaic response of poly(n-vinyl carbazole) (PVK) films were investigated. PVK films were formed by spincasting onto glass coated with indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene) (PEDOT)–polystyrenesulfonate (PSS). Some of the PVK films were redissolved in chlorobenzene and redried in the absence or presence of an electric field. Illuminated current–voltage characteristics were measured for an ITO/PEDOT:PSS/PVK/Ca:Al device. Films spincast from a 50 mg/mL solution, redissolved, and dried in the absence of the electric field exhibited a 26% higher charge collection efficiency than films dried in the presence of the electric field. The increased charge collection efficiency was attributed to changes in the molecular configuration of the PVK films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Paul H. Holloway

Papers

Remote Sensing of Explosive Materials Using Differential Reflection Spectroscopy

Synergistic Temperature and Electron Irradiation Effects on the Degradation of Cathodoluminescent ZnS:Ag,Cl Powder Phosphors

Synthesis, characterization, and luminescent properties of ZnO–SiO2:PbS

Effects of solution processing on the photovoltaic response of poly(n-vinyl carbazole) films

48-1: Invited Paper: High Efficiency and Ultra-Wide Color Gamut Quantum Dot LEDs for Next Generation Displays