CdSe/CdSe1-xTex core/crown heteronanoplatelets: tuning the excitonic properties without changing the thickness
Author
Kelestemur Y.
Guzelturk, B.
Erdem, O.
Olutas M.
Erdem, T.
Usanmaz, C. F.
Gungor K.
Demir, Hilmi Volkan
Date
2017Source Title
Journal of Physical Chemistry C
Print ISSN
1932-7447
Publisher
American Chemical Society
Volume
121
Issue
8
Pages
4650 - 4658
Language
English
Type
ArticleItem Usage Stats
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Abstract
Here we designed and synthesized CdSe/CdSe1-xTex core/crown nanoplatelets (NPLs) with controlled crown compositions by using the core-seeded-growth approach. We confirmed the uniform growth of the crown regions with well-defined shape and compositions by employing transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. By precisely tuning the composition of the CdSe1-xTex crown region from pure CdTe (x = 1.00) to almost pure CdSe doped with several Te atoms (x = 0.02), we achieved tunable excitonic properties without changing the thickness of the NPLs and demonstrated the evolution of type-II electronic structure. Upon increasing the Te concentration in the crown region, we obtained continuously tunable photoluminescence peaks within the range of ∼570 nm (for CdSe1-xTex crown with x = 0.02) and ∼660 nm (for CdSe1-xTex crown with x = 1.00). Furthermore, with the formation of the CdSe1-xTex crown region, we observed substantially improved photoluminescence quantum yields (up to ∼95%) owing to the suppression of nonradiative hole trap sites. Also, we found significantly increased fluorescence lifetimes from ∼49 up to ∼326 ns with increasing Te content in the crown, suggesting the transition from quasi-type-II to type-II electronic structure. With their tunable excitonic properties, this novel material presented here will find ubiquitous use in various efficient light-emitting and -harvesting applications.
Keywords
Electronic structureHigh resolution transmission electron microscopy
Light emission
Photoluminescence
Transmission electron microscopy
Tuning
X ray diffraction
Excitonic properties
Fluorescence lifetimes
Nano-platelets
Non-radiative
Novel materials
Photoluminescence peak
Photoluminescence quantum yields
Seeded growth
X ray photoelectron spectroscopy