Colloidal nanoplatelets with two-dimensional electronic structure

Semiconductor nanocrystals have for many years attracted attention for their optical properties and their potential use as superior fluorescence emitters. It is now shown that nanoplatelets can be controllably synthesized and have even more attractive properties. The syntheses of strongly anisotropi...

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Bibliographic Details
Published in:Nature materials 2011-12, Vol.10 (12), p.936-941
Main Authors: Ithurria, S., Tessier, M. D., Mahler, B., Lobo, R. P. S. M., Dubertret, B., Efros, Al. L.
Format: Article
Language:English
Subjects:
639/301/357/354
639/301/357/995
Absorption
Anisotropy
Biomaterials
Blood platelets
Cadmium selenides
Chemistry and Materials Science
Colloids
Condensed Matter Physics
Emissions
Fluorescence
Intermetallics
letter
Materials Science
Mathematical models
Nanocomposites
Nanocrystals
Nanomaterials
Nanostructure
Nanotechnology
Optical and Electronic Materials
Optical properties
Two dimensional
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Summary:Semiconductor nanocrystals have for many years attracted attention for their optical properties and their potential use as superior fluorescence emitters. It is now shown that nanoplatelets can be controllably synthesized and have even more attractive properties. The syntheses of strongly anisotropic nanocrystals with one dimension much smaller than the two others, such as nanoplatelets, are still greatly underdeveloped. Here, we demonstrate the formation of atomically flat quasi-two-dimensional colloidal CdSe, CdS and CdTe nanoplatelets with well-defined thicknesses ranging from 4 to 11 monolayers. These nanoplatelets have the electronic properties of two-dimensional quantum wells formed by molecular beam epitaxy, and their thickness-dependent absorption and emissionspectra are described very well within an eight-band Pidgeon–Brown model. They present an extremely narrow emission spectrum with full-width at half-maximum less than 40 meV at room temperature. The radiative fluorescent lifetime measured in CdSe nanoplatelets decreases with temperature, reaching 1 ns at 6 K, two orders of magnitude less than for spherical CdSe nanoparticles. This makes the nanoplatelets the fastest colloidal fluorescent emitters and strongly suggests that they show a giant oscillator strength transition.
ISSN:1476-1122
1476-4660
DOI:10.1038/nmat3145