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Issue 14, 2017
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Band-edge oscillator strength of colloidal CdSe/CdS dot-in-rods: comparison of absorption and time-resolved fluorescence spectroscopy

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Abstract

We studied the oscillator strength fgap of the band gap transition in heteronanocrystals (hNCs) with a spherical CdSe core embedded in an elongated CdS shell. A comparison with fgap of core-only CdSe NCs confirmed a reduction of the electron–hole overlap in hNCs with a band gap larger than 2.05 eV or smaller than 1.98 eV. However, the decrease in fgap is limited to about 50% when compared to CdSe NCs, suggesting that residual confinement still localizes the electron near the core. We correlated fgap with the radiative lifetime obtained from multiexponential photoluminescence (PL) decay traces. The different components were attributed to radiative decay, or deep and shallow carrier trapping, respectively, using the PL quantum efficiency (QE) as a guideline. Our data highlight the challenges associated when extracting the radiative decay, and demonstrate the added value of absorption spectroscopy to obtain the band-edge oscillator strength and the associated radiative recombination rate in colloidal hNCs.

Graphical abstract: Band-edge oscillator strength of colloidal CdSe/CdS dot-in-rods: comparison of absorption and time-resolved fluorescence spectroscopy

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Publication details

The article was received on 19 Nov 2016, accepted on 03 Mar 2017 and first published on 06 Mar 2017


Article type: Paper
DOI: 10.1039/C6NR09021D
Citation: Nanoscale, 2017,9, 4730-4738
  • Open access: Creative Commons BY-NC license
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    Band-edge oscillator strength of colloidal CdSe/CdS dot-in-rods: comparison of absorption and time-resolved fluorescence spectroscopy

    I. Angeloni, W. Raja, A. Polovitsyn, F. De Donato, R. P. Zaccaria and I. Moreels, Nanoscale, 2017, 9, 4730
    DOI: 10.1039/C6NR09021D

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