Band structure engineering via piezoelectric fields in strained anisotropic CdSe/CdS nanocrystals

Strain in colloidal heteronanocrystals with non-centrosymmetric lattices presents a unique opportunity for controlling optoelectronic properties and adds a new degree of freedom to existing wavefunction engineering and doping paradigms. We synthesized wurtzite CdSe nanorods embedded in a thick CdS s...

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Bibliographic Details
Published in:Nature communications 2015-07, Vol.6 (1), p.7905-7905, Article 7905
Main Authors: Christodoulou, Sotirios, Rajadell, Fernando, Casu, Alberto, Vaccaro, Gianfranco, Grim, Joel Q, Genovese, Alessandro, Manna, Liberato, Climente, Juan I, Meinardi, Francesco, Rainò, Gabriele, Stöferle, Thilo, Mahrt, Rainer F, Planelles, Josep, Brovelli, Sergio, Moreels, Iwan
Format: Article
Language:English
Subjects:
Nanocrystals
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Summary:Strain in colloidal heteronanocrystals with non-centrosymmetric lattices presents a unique opportunity for controlling optoelectronic properties and adds a new degree of freedom to existing wavefunction engineering and doping paradigms. We synthesized wurtzite CdSe nanorods embedded in a thick CdS shell, hereby exploiting the large lattice mismatch between the two domains to generate a compressive strain of the CdSe core and a strong piezoelectric potential along its c-axis. Efficient charge separation results in an indirect ground-state transition with a lifetime of several microseconds, almost one order of magnitude longer than any other CdSe/CdS nanocrystal. Higher excited states recombine radiatively in the nanosecond time range, due to increasingly overlapping excited-state orbitals. k˙p calculations confirm the importance of the anisotropic shape and crystal structure in the buildup of the piezoelectric potential. Strain engineering thus presents an efficient approach to highly tunable single- and multiexciton interactions, driven by a dedicated core/shell nanocrystal design.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms8905