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Title: Determining the exact number of dye molecules attached to colloidal CdSe/ZnS quantum dots in Förster resonant energy transfer assemblies

Semiconductor quantum dots functionalized with organic dye molecules are important tools for biological sensor applications. Energy transfer between the quantum dot and the attached dyes can be utilized for sensing. Though important, the determination of the real number of dye molecules attached per quantum dot is rather difficult. In this work, a method will be presented to determine the number of ATTO-590 dye molecules attached to CdSe/ZnS quantum dots based on time resolved spectral analysis. The energy transfer from the excited quantum dot to the attached ATTO-590 dye leads to a reduced lifetime of the quantum dot's excitons. The higher the concentration of dye molecules, the shorter the excitonic lifetime becomes. However, the number of dye molecules attached per quantum dot will vary. Therefore, for correctly explaining the decay of the luminescence upon photoexcitation of the quantum dot, it is necessary to take into account the distribution of the number of dyes attached per quantum dot. A Poisson distribution of the ATTO-590 dye molecules not only leads to excellent agreement between experimental and theoretical decay curves but also additionally yields the average number of dye molecules attached per quantum dot. In this way, the number of dyes per quantum dotmore » can be conveniently determined.« less
Authors:
; ; ; ; ; ;  [1]
  1. Department of Physics and Material Sciences Center, Philipps-University Marburg, Renthof 5, D-35032 Marburg (Germany)
Publication Date:
OSTI Identifier:
22412838
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; CADMIUM SELENIDES; CONCENTRATION RATIO; ENERGY TRANSFER; EXCITONS; LIFETIME; LUMINESCENCE; MOLECULES; QUANTUM DOTS; SEMICONDUCTOR MATERIALS; SENSORS; TIME RESOLUTION; ZINC SULFIDES