Influence of quantum dot concentration on Förster resonant energy transfer in monodispersed nanocrystal quantum dot monolayers

Manuela Lunz, A. Louise Bradley, Wei-Yu Chen, Valerie A. Gerard, Stephen J. Byrne, Yurii K. Gun’ko, Vladimir Lesnyak, and Nikolai Gaponik
Phys. Rev. B 81, 205316 – Published 20 May 2010

Abstract

The quantum dot (QD) concentration dependence of the optical properties of QD monolayers is shown to be dominated by Förster resonant energy transfer (FRET) from smaller to larger QDs in the ensemble. With increasing QD concentration a redshift of the peak emission wavelength, a shortening of the photoluminescence lifetime of the QDs on the high-energy side of the ensemble emission spectrum as well as increased difference in the lifetimes on the high- and low-energy sides are observed in the layer-by-layer deposited QD monolayers. There is also evidence of an increased rise time in the time-resolved photoluminescence decays on the low-energy side of the QD emission for two of the three samples presented in most detail. A theory of FRET in two dimensions is applied to explain the lifetime decrease on the high-energy side of the ensemble emission and confirms that the impact of the QD concentration on the optical properties is primarily due to FRET from the smaller to larger QDs in the ensemble. The concentration effects are stronger in QD samples which have a broader emission peak compared to the Stokes shift. Based on good agreement with FRET theory, the QD concentration and the overlap of the QD emission and absorption peaks can both be used to control the efficiency of the FRET process in monodispersed QD layers.

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  • Received 18 February 2010

DOI:https://doi.org/10.1103/PhysRevB.81.205316

©2010 American Physical Society

Authors & Affiliations

Manuela Lunz and A. Louise Bradley*

  • Semiconductor Photonics Group, School of Physics, Trinity College Dublin, Dublin 2, Ireland

Wei-Yu Chen, Valerie A. Gerard, Stephen J. Byrne, and Yurii K. Gun’ko

  • School of Chemistry, Trinity College Dublin, Dublin 2, Ireland

Vladimir Lesnyak and Nikolai Gaponik

  • Physical Chemistry, TU Dresden, Bergstraße 66b, 01062 Dresden, Germany

  • *Author to whom correspondence should be addressed; bradlel@tcd.ie

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Issue

Vol. 81, Iss. 20 — 15 May 2010

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