Controlling Charge Carrier Overlap in Type-II ZnSe/ZnS/CdS Core-Barrier-Shell Quantum Dots

Boldt, Klaus; Ramanan, Charusheela; Chanaewa, Alina; Werheid, Matthias; Eychmüller, Alexander

Controlling Charge Carrier Overlap in Type-II ZnSe/ZnS/CdS Core-Barrier-Shell Quantum Dots

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Date

2015

Authors

Boldt, Klaus

Ramanan, Charusheela

Chanaewa, Alina

Werheid, Matthias

Eychmüller, Alexander

DOI (citable link)

10.1021/acs.jpclett.5b01144

Collections

Physik
Zukunftskolleg

Publication type

Journal article

Published in

The Journal of Physical Chemistry Letters ; 6 (2015), 13. - pp. 2590-2597. - ISSN 1948-7185. - eISSN 1948-7185

Abstract

We describe the synthesis and spectroscopic characterization of colloidal ZnSe/ZnS/CdS nanocrystals, which exhibit a type-II electronic structure and wave function overlap that is strongly dependent on the thickness of the ZnS barrier. Barrier thickness is controlled by both the amount of deposited material and the reaction and annealing temperature of CdS shell growth. The results show that a single monolayer of ZnS mitigates the overlap significantly, while four and more monolayers effectively suppress band edge absorption and emission. Transient absorption spectra reveal a broad distribution of excitons with mixed S and P symmetry, which become allowed due to alloy formation and contribute to charge carrier relaxation across the barrier. We present a model of the core/shell interface based on cation diffusion, which allows one to estimate the extent of the diffusion layer from optical spectra.

Subject (DDC)

530 Physics

Keywords

cation exchange, mixed states, overlap integral, potential barrier, transient absorption spectroscopy

Cite This

ISO 690

BOLDT, Klaus, Charusheela RAMANAN, Alina CHANAEWA, Matthias WERHEID, Alexander EYCHMÜLLER, 2015. Controlling Charge Carrier Overlap in Type-II ZnSe/ZnS/CdS Core-Barrier-Shell Quantum Dots. In: The Journal of Physical Chemistry Letters. 6(13), pp. 2590-2597. ISSN 1948-7185. eISSN 1948-7185. Available under: doi: 10.1021/acs.jpclett.5b01144

BibTex

@article{Boldt2015Contr-31895,
  year={2015},
  doi={10.1021/acs.jpclett.5b01144},
  title={Controlling Charge Carrier Overlap in Type-II ZnSe/ZnS/CdS Core-Barrier-Shell Quantum Dots},
  number={13},
  volume={6},
  issn={1948-7185},
  journal={The Journal of Physical Chemistry Letters},
  pages={2590--2597},
  author={Boldt, Klaus and Ramanan, Charusheela and Chanaewa, Alina and Werheid, Matthias and Eychmüller, Alexander}
}

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