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Synthesis of anisotropic CdSe/CdS dot-in-giant-rod nanocrystals with persistent blue-shifted biexciton emission

(2018) ACS PHOTONICS. 5(11). p.4561-4568
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Abstract
Anisotropic single-phase wurtzite CdSe/CdS nanocrystals were synthesized by colloidal chemistry, introducing ZnCl2 to increase the shell growth in the radial direction. As a result, dot-in-giant-rod nanocrystals were obtained, with a core diameter that varied between 3.2 and 7.5 nm and an overall diameter between 15 and 22 nm, corresponding to a 14-26 ML CdS shell. In addition to an extended fluorescence lifetime, typical for CdSe/CdS heteronanocrystals, all samples also yielded a blue-shifted biexciton emission peak. This contrasts with existing data on CdSe/CdS dot-in-rod nanocrystals with a thin shell, which yield a type-I band offset and attractive biexciton interactions for CdSe/CdS with a core larger than about 2.8 nm. However, k.p calculations support the blue shift, with a significant electron delocalization into the CdS shell even for large core diameter. We assign this effect to the influence of strain at the CdSe/CdS interface and associated reduction of the conduction band offset, as well as the buildup of a piezoelectric field along the nanorod long axis. The strain-induced electron hole separation is particularly effective in large-core nanocrystals, providing a tool to engineer electron and hole wave functions that is complementary to quantum confinement.
Keywords
LUMINESCENT SOLAR CONCENTRATORS, QUANTUM DOTS, CATION-EXCHANGE, SEEDED, GROWTH, SHELL, NANOHETEROSTRUCTURES, HETEROSTRUCTURES, INTERFACE, NANORODS, quantum dots, photoluminescence, strain, band offset, piezoelectric, field, k.p calculations

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Citation

Please use this url to cite or link to this publication:

Chicago
Polovitsyn, Anatolii, Ali Hossain Khan, Ilaria Angeloni, Joel Q Grim, Josep Planelles, Juan I Climente, and Iwan Moreels. 2018. “Synthesis of Anisotropic CdSe/CdS Dot-in-giant-rod Nanocrystals with Persistent Blue-shifted Biexciton Emission.” Acs Photonics 5 (11): 4561–4568.
APA
Polovitsyn, A., Khan, A. H., Angeloni, I., Grim, J. Q., Planelles, J., Climente, J. I., & Moreels, I. (2018). Synthesis of anisotropic CdSe/CdS dot-in-giant-rod nanocrystals with persistent blue-shifted biexciton emission. ACS PHOTONICS, 5(11), 4561–4568.
Vancouver
1.
Polovitsyn A, Khan AH, Angeloni I, Grim JQ, Planelles J, Climente JI, et al. Synthesis of anisotropic CdSe/CdS dot-in-giant-rod nanocrystals with persistent blue-shifted biexciton emission. ACS PHOTONICS. 2018;5(11):4561–8.
MLA
Polovitsyn, Anatolii et al. “Synthesis of Anisotropic CdSe/CdS Dot-in-giant-rod Nanocrystals with Persistent Blue-shifted Biexciton Emission.” ACS PHOTONICS 5.11 (2018): 4561–4568. Print.
@article{8589966,
  abstract     = {Anisotropic single-phase wurtzite CdSe/CdS nanocrystals were synthesized by colloidal chemistry, introducing ZnCl2 to increase the shell growth in the radial direction. As a result, dot-in-giant-rod nanocrystals were obtained, with a core diameter that varied between 3.2 and 7.5 nm and an overall diameter between 15 and 22 nm, corresponding to a 14-26 ML CdS shell. In addition to an extended fluorescence lifetime, typical for CdSe/CdS heteronanocrystals, all samples also yielded a blue-shifted biexciton emission peak. This contrasts with existing data on CdSe/CdS dot-in-rod nanocrystals with a thin shell, which yield a type-I band offset and attractive biexciton interactions for CdSe/CdS with a core larger than about 2.8 nm. However, k.p calculations support the blue shift, with a significant electron delocalization into the CdS shell even for large core diameter. We assign this effect to the influence of strain at the CdSe/CdS interface and associated reduction of the conduction band offset, as well as the buildup of a piezoelectric field along the nanorod long axis. The strain-induced electron hole separation is particularly effective in large-core nanocrystals, providing a tool to engineer electron and hole wave functions that is complementary to quantum confinement.},
  author       = {Polovitsyn, Anatolii and Khan, Ali Hossain and Angeloni, Ilaria and Grim, Joel Q and Planelles, Josep and Climente, Juan I and Moreels, Iwan},
  issn         = {2330-4022},
  journal      = {ACS PHOTONICS},
  language     = {eng},
  number       = {11},
  pages        = {4561--4568},
  title        = {Synthesis of anisotropic CdSe/CdS dot-in-giant-rod nanocrystals with persistent blue-shifted biexciton emission},
  url          = {http://dx.doi.org/10.1021/acsphotonics.8b01028},
  volume       = {5},
  year         = {2018},
}

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