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

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

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


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.

Original languageEnglish
Pages (from-to)2590-2597
Number of pages8
JournalJournal of Physical Chemistry Letters
Issue number13
Publication statusPublished - 17 Jun 2015

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.


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


Dive into the research topics of 'Controlling Charge Carrier Overlap in Type-II ZnSe/ZnS/CdS Core-Barrier-Shell Quantum Dots'. Together they form a unique fingerprint.

Cite this