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

(2017) NANOSCALE. 9(14). p.4730-4738
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Abstract
We studied the oscillator strength f(gap) 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.
Keywords
QUASI-TYPE-II, LIGHT-EMITTING-DIODES, QUANTUM DOTS, OPTICAL-PROPERTIES, SEEDED-GROWTH, CDS NANORODS, SEMICONDUCTOR NANOCRYSTALS, EXTINCTION COEFFICIENTS, CROSS-SECTION, WAVE-FUNCTION

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Citation

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Chicago
Angeloni, I, W Raja, A Polovitsyn, F De Donato, R Proietti Zaccaria, and Iwan Moreels. 2017. “Band-edge Oscillator Strength of Colloidal CdSe/CdS Dot-in-rods : Comparison of Absorption and Time-resolved Fluorescence Spectroscopy.” Nanoscale 9 (14): 4730–4738.
APA
Angeloni, I, Raja, W., Polovitsyn, A., De Donato, F., Zaccaria, R. P., & Moreels, I. (2017). Band-edge oscillator strength of colloidal CdSe/CdS dot-in-rods : comparison of absorption and time-resolved fluorescence spectroscopy. NANOSCALE, 9(14), 4730–4738.
Vancouver
1.
Angeloni I, Raja W, Polovitsyn A, De Donato F, Zaccaria RP, Moreels I. Band-edge oscillator strength of colloidal CdSe/CdS dot-in-rods : comparison of absorption and time-resolved fluorescence spectroscopy. NANOSCALE. 2017;9(14):4730–8.
MLA
Angeloni, I, W Raja, A Polovitsyn, et al. “Band-edge Oscillator Strength of Colloidal CdSe/CdS Dot-in-rods : Comparison of Absorption and Time-resolved Fluorescence Spectroscopy.” NANOSCALE 9.14 (2017): 4730–4738. Print.
@article{8538227,
  abstract     = {We studied the oscillator strength f(gap) 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.},
  author       = {Angeloni, I and Raja, W and Polovitsyn, A and De Donato, F and Zaccaria, R Proietti and Moreels, Iwan},
  issn         = {2040-3364},
  journal      = {NANOSCALE},
  keyword      = {QUASI-TYPE-II,LIGHT-EMITTING-DIODES,QUANTUM DOTS,OPTICAL-PROPERTIES,SEEDED-GROWTH,CDS NANORODS,SEMICONDUCTOR NANOCRYSTALS,EXTINCTION COEFFICIENTS,CROSS-SECTION,WAVE-FUNCTION},
  language     = {eng},
  number       = {14},
  pages        = {4730--4738},
  title        = {Band-edge oscillator strength of colloidal CdSe/CdS dot-in-rods : comparison of absorption and time-resolved fluorescence spectroscopy},
  url          = {http://dx.doi.org/10.1039/c6nr09021d},
  volume       = {9},
  year         = {2017},
}

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