A strong electron–hole exchange interaction (EI) in semiconductor nanocrystals (NCs) gives rise to a large (up to tens of meV) splitting between optically active ('bright') and optically passive ('dark') excitons. This dark–bright splitting has a significant effect on the optical properties of band-edge excitons and leads to a pronounced temperature and magnetic field dependence of radiative decay. Here we demonstrate a nanoengineering-based approach that provides control over EI while maintaining nearly constant emission energy. We show that the dark–bright splitting can be widely tuned by controlling the electron–hole spatial overlap in core–shell CdSe/CdS NCs with a variable shell width. In thick-shell samples, the EI energy reduces to <250 μeV, which yields a material that emits with a nearly constant rate over temperatures from 1.5 to 300 K and magnetic fields up to 7 T. The EI-manipulation strategies demonstrated here are general and can be applied to other nanostructures with variable electron–hole overlap

Brovelli, S., Schaller, R., Crooker, S., Garcia Santamaria, F., Chen, Y., Viswanatha, R., et al. (2011). Nano-engineered Electron-Hole Exchange Interaction Controls Exciton Dynamics in Core-Shell Semiconductor Nanocrystals. NATURE COMMUNICATIONS, 2(1), 280-1-280-8 [10.1038/ncomms1281].

Nano-engineered Electron-Hole Exchange Interaction Controls Exciton Dynamics in Core-Shell Semiconductor Nanocrystals

BROVELLI, SERGIO;
2011

Abstract

A strong electron–hole exchange interaction (EI) in semiconductor nanocrystals (NCs) gives rise to a large (up to tens of meV) splitting between optically active ('bright') and optically passive ('dark') excitons. This dark–bright splitting has a significant effect on the optical properties of band-edge excitons and leads to a pronounced temperature and magnetic field dependence of radiative decay. Here we demonstrate a nanoengineering-based approach that provides control over EI while maintaining nearly constant emission energy. We show that the dark–bright splitting can be widely tuned by controlling the electron–hole spatial overlap in core–shell CdSe/CdS NCs with a variable shell width. In thick-shell samples, the EI energy reduces to <250 μeV, which yields a material that emits with a nearly constant rate over temperatures from 1.5 to 300 K and magnetic fields up to 7 T. The EI-manipulation strategies demonstrated here are general and can be applied to other nanostructures with variable electron–hole overlap
Articolo in rivista - Articolo scientifico
Core-Shell Semiconductor Nanocrystals
English
2011
2
1
280-1
280-8
280
none
Brovelli, S., Schaller, R., Crooker, S., Garcia Santamaria, F., Chen, Y., Viswanatha, R., et al. (2011). Nano-engineered Electron-Hole Exchange Interaction Controls Exciton Dynamics in Core-Shell Semiconductor Nanocrystals. NATURE COMMUNICATIONS, 2(1), 280-1-280-8 [10.1038/ncomms1281].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/44084
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