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Charge separation in type II tunneling structures of close-packed CdTe and CdSe nanocrystals

Gross, Dieter and Susha, Andrei S. and Klar, Thomas A. and Da Como, Enrico and Rogach, Andrey L. and Feldmann, Jochen (2008) Charge separation in type II tunneling structures of close-packed CdTe and CdSe nanocrystals. NANO LETTERS, 8 (5). pp. 1482-1485.

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We report on charge separation between type II aligned CdTe and CdSe nanocrystals. Two types of electrostatically bound nanocrystal structures have been studied: first, clusters of nanocrystals hold together by Ca(II) ions in aqueous solution and, second, thin film structures of nanocrystals created with layer-by-layer deposition in combination with polyelectrolytes. In both types of structures, short interparticle distances of less than I nm have been achieved, whereby the isolating organic ligands on the nanocrystal surfaces and/or the polymer monolayers act as tunneling barriers between nanocrystals. We have observed an efficient quenching of photoluminescence and a reduced emission lifetime for CdTe nanocrystals in both types of type II heterostructures. This result is explained by a spatial charge separation of the photoexcited electron-hole pairs due to tunneling of charge carriers through the thin organic layer between CdTe and CdSe nanocrystals. Type II heterostructures demonstrated here may find future applications in photovoltaics.

Item Type:Article
Subjects:Physical Science > Nanophysics
Material Science > Nanostructured materials
Material Science > Nanochemistry
ID Code:1346
Deposited By:Anuj Seth
Deposited On:09 Dec 2008 14:09
Last Modified:02 Mar 2009 10:31

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