Quantum dots doped semiconductor nanocrystals

Mocatta, D. Cohen, G. Schattner, J. Millo, O. Rabani, E. Banin, U., Heavily doped semiconductor nanocrystal quantum dots. Science 2011,332,77-81. 

Silica particles have been exploited in virtually every assay or detection strategy that polymer particles have been used in for bioapplication purposes. Recently, fluorescent dye-doped silica nanoparticles have been developed by a number of groups that have similar fluorescence characteristics to quantum dot nanocrystals (Chapter 9, Section 10). Fluorescent silica nanoparticles can be synthesized less expensively than quantum dots due to the fact that the silica particles incorporate standard organic dyes (Ow et al., 2005 Wang et al., 2006) and are not dependent on making reproducible populations of semiconductor particles with precise diameters to tune emission wavelengths. 

Charge transport through an array of semiconductor nanocrystals is strongly affected by the electronic structure of nanocrystal surfaces. It is possible to control the type of conductivity and doping level of quantum dot crystals by adsorbing/desorbing molecular species at the nanocrystal surface. As an... 

Quantum dots represent three-dimensional confinement in semiconductor materials. The optical spectroscopy of lanthanides-doped III-V semiconductor QDs has been observed to be very different from the bulk or thick film. For example, carrier confinement in QDs can strongly enhance the radiative quantum efficiency of the lanthanide emission, which thus makes lanthanide-doped III-V semiconductor QDs very promising candidates for full-color LEDs. It is notoriously difficult to dope lanthanide into III-V semiconductor nanocrystals by wet chemical synthesis methods. To date, most of these samples were prepared either by MBE, ion implantation or magnetron co-sputtering. 

A variety of luminescent nanoparticles have been specifically devised for con-focal and multiphoton microscopy. These include nanomaterials, such as silica-based nanoparticles doped with two-photon-absorbing fluorophores, able to exhibit aggregation-enhanced fluorescence, gold nanoparticles, semiconductor nanocrystals (quantum dots/rods), and nanophosphors, viz., ceramic nanoparticles containing luminescent lanthanide ions. 

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