Quantum Dots
“A quantum dot is a semiconductor whose excitons are confined in all three spatial dimensions. Consequently, such materials have electronic properties intermediate between those of bulk semiconductors and those of discrete molecules. They were discovered at the beginning of the 1980s by Alexei Ekimov in a glass matrix and by Louis E. Brus in colloidal solutions. The term ‘quantum dot’ was coined by Mark Reed.
“There are colloidal methods to produce many different semiconductors. Typical dots are made of binary alloys such as cadmium selenide, cadmium sulfide, indium arsenide, and indium phosphide. [However], dots may also be made from ternary alloys such as cadmium selenide sulfide. These quantum dots can contain as few as 100 to 100,000 atoms within the quantum dot volume, with a diameter of 10 to 50 atoms. This corresponds to about 2 to 10 nanometers, and at 10 nm in diameter, nearly 3 million quantum dots could be lined up end to end and fit within the width of a human thumb.”
(Wikipedia, Quantum Dots, 11/9/2010)
Cell Imaging
Coated Quantum Dots
Compounding
Funtionalized Quantum Dots
Photoluminescent Quantum Dots
Quantum Dot Applications
Quantum Dot Cancer Drugs
Quantum Dot Drug Delivery
Quantum Dot Electronic Structure
Quantum Dots in Nanofibers
Quantum Dot Preparation
Quantum Dot Sensors
Semiconductors
Recent US Patents
2/15/2011
7,887,720
Polymer-nanocrystal quantum dot composites and optoelectronic devices
Drndic, Zivanovic and Qi of Louisana Tech University, Louisana, have developed composite materials composed of a semiconducting polymer, such as poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] ("MEH-PPV"), and PbSe nanocrystal quantum dots for optoelectronic devices. (RDC 8/26/2011)
10/12/2010
7,811,479
Polymer-nanocrystal quantum dot composites and optoelectronic devices
Drndic et al of the University of Pennsylvania has developed a semiconducting polymer, such as poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] ("MEH-PPV"), and PbSe nanocrystal quantum dots. These composite materials are useful in preparing optoelectronic devices, such as light emitting diodes, photovoltaic cells, lasers and photodetectors. (RDC 1/7/2011)
Recent Journal Articles
X-ray Nanodiffraction on a Single SiGe Quantum Dot inside a Functioning Field-Effect Transistor
(2875–2880) Nano Letters 11 #7 (2011)
Hrauda et al , Austria, France, Netherlands and Germany, showed that X-ray nanodiffraction represents an excellent tool to investigate the internal structure of such devices in a nondestructive way by using a focused synchotron X-ray beam with a diameter of 400 nm. We show results on the strain fields in and around a single SiGe island, which serves as stressor for the Si-channel in a fully functioning Si–metal–oxide semiconductor field-effect transistor. (RDC 7/20/2011)
Immobilization of quantum dots of cadmium selenide on the matrix of a graft liquid-crystalline polymer
(521-526) Polymer Science: Series A 53 #6 (2011)
Vasiletset al, Russia, developed a new luminescent composite based on quantum dots of CdSe immobilized on the polymer LC matrix prepared through the graft polymerization of the monomer of 4-(ω-acryloyloxyhexyloxy)benzoic acid on a fluorocarbon support after its preliminary irradiation with vacuum ultraviolet light. The CdSe particles are shown to interact with the carboxyl groups of mesogenic fragments of the LC polymer, and this interaction leads to the integration of quantum dots into the ordered LC structure of the composite. As a result of immobilization, the luminescence peak of the quantum dots is shifted toward lower wavelengths owing to the interaction between the nanoparticles and the polymer LC matrix. (RDC 6/24/2011)
Reversible and Multisensitive Quantum Dot Gels
(4306–4312) Macromolecules 44 #11 (2011)
Yan et al of the University of Science and Technology of China, China, and the University of California, California, have developed a hyperbranched macromolecule that can not only act as an excellent ligand to stabilize quantum dots but also act as a good gelator that can gel QD solution to form a reversible and multiresponsive fluorescent gel. This hyperbranched macromolecule-capped QD is stable, and the sol–gel switching can be easily realized via heating and ultrasonicating. Most important, the formed QD gel shows stronger fluorescence than that of the corresponding solution. (RDC 621/2011)
1/21/2011
Metal ion (silver, cadmium and zinc ions) modified CdS quantum dots for ultrasensitive copper ion sensing
(# 095503) Nanotechnology 22 #8 (2010)
Wang, Dong and Li of Jiangnan University, China synthesized metal ion (Ag+ , Cd2 + , Zn2 + ) modified CdS quantum dots (QDs) for Cu2 + sensing. Modification by these metal ions could enhance the PL intensity of CdS QDs with the extent of the PL enhancement being related to the concentration of the metal ions. Different metal ion (Ag+ , Cd2 + , Zn2 + ) modified CdS QDs also showed different analytical characteristics for Cu2 + sensing. In particular, Ag+ modified CdS QDs showed greatly enhanced sensitivity for Cu2 + determination than did the unmodified CdS QDs. This study demonstrates the important role of surface state of QDs in fluorescence sensing. (RDC 1/21/2011)
1/7/2011
Organic light-emitting devices fabricated utilizing core/shell CdSe/ZnS quantum dots embedded in a polyvinylcarbazole
(1239-1243) Journal of Materials Science 46 #5 (2011)
Lee et al of South Korea showed an abrupt increase in the current density above an applied voltage for the emitting device containing the quantum dots. (RDC 1/12/2011)
11/12/2010
Extraction of Electrochemiluminescent Oxidized Carbon Quantum Dots from Activated Carbon
(5895–5899) Chemistry of Materials 22 #21 (2010)
Dong et al of Fuzhou University, China have developed a method to extract oxidized carbon quantum dots directly from activated carbon by chemical oxidation. These quantum dots are 3 to 4 nm in diameter with surface carboxyl groups resulting in a strong electroluminescent activity. (RDC 11/9/2010)