Spin-flip limited exciton dephasing in CdSe/ZnS colloidal quantum dots

Masia, Francesco ORCID: https://orcid.org/0000-0003-4958-410X, Accanto, Nicolo, Langbein, Wolfgang Werner ORCID: https://orcid.org/0000-0001-9786-1023 and Borri, Paola ORCID: https://orcid.org/0000-0002-7873-3314 2012. Spin-flip limited exciton dephasing in CdSe/ZnS colloidal quantum dots. Physical Review Letters 108 (8) , 087401. 10.1103/PhysRevLett.108.087401

Preview

PDF Download (201kB) | Preview

Abstract

The dephasing time of the lowest bright exciton in CdSe/ZnS wurtzite quantum dots is measured from 5 to 170 K and compared with density dynamics within the exciton fine structure using a sensitive three-beam four-wave-mixing technique unaffected by spectral diffusion. Pure dephasing via acoustic phonons dominates the initial dynamics, followed by an exponential zero-phonon line dephasing of 109 ps at 5 K, much faster than the ∼10  ns exciton radiative lifetime. The zero-phonon line dephasing is explained by phonon-assisted spin flip from the lowest bright state to dark-exciton states. This is confirmed by the temperature dependence of the exciton lifetime and by direct measurements of the bright-dark–exciton relaxation. Our results give an unambiguous evidence of the physical origin of the exciton dephasing in these nanocrystals.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences Physics and Astronomy
Subjects:	Q Science > Q Science (General) Q Science > QC Physics
Publisher:	American Physical Society
ISSN:	0031-9007
Funders:	EPSRC
Last Modified:	17 May 2023 21:12
URI:	https://orca.cardiff.ac.uk/id/eprint/33619

Citation Data

Cited 47 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item