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      Type-II colloidal quantum wells: CdSe/CdTe core/crown heteronanoplatelets

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      Author(s)
      Keleştemur, Y.
      Olutas M.
      Delikanlı, S.
      Güzeltürk, B.
      Akgül, M. Z.
      Demir, Hilmi Volkan
      Date
      2015
      Source Title
      Journal of Physical Chemistry C
      Print ISSN
      1932-7447
      Publisher
      American Chemical Society
      Volume
      119
      Issue
      4
      Pages
      2177 - 2185
      Language
      English
      Type
      Article
      Item Usage Stats
      237
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      256
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      Abstract
      Solution-processed quantum wells, also known as colloidal nanoplatelets (NPLs), are emerging as promising materials for colloidal optoelectronics. In this work, we report the synthesis and characterization of CdSe/CdTe core/crown NPLs exhibiting a Type-II electronic structure and Type-II speci fic optical properties. Here, based on a core-seeded approach, the CdSe/CdTe core/crown NPLs were synthesized with well-controlled CdTe crown coatings. Uniform and epitaxial growth of CdTe crown region was verified by using structural characterization techniques including transmission electron microscopy (TEM) with quantitative EDX analysis and X-ray diffraction (XRD). Also the optical properties were systematically studied in these Type-II NPLs that reveal strongly red-shifted photoluminescence (up to ∼150 nm) along with 2 orders of magnitude longer fluorescence lifetimes (up to 190 ns) compared to the Type-I NPLs owing to spatially indirect excitons at the Type-II interface between the CdSe core and the CdTe crown regions. Photoluminescence excitation spectroscopy confirms that this strongly red-shifted emission actually arises from the CdSe/CdTe NPLs. In addition, temperature-dependent time-resolved fluorescence spectroscopy was performed to reveal the temperature-dependent fluorescence decay kinetics of the Type-II NPLs exhibiting interesting behavior. Also, water-soluble Type-II NPLs were achieved via ligand exchange of the CdSe/CdTe core/crown NPLs by using 3-mercaptopropionic acid (MPA), which allows for enhanced charge extraction efficiency owing to their shorter chain length and enables high quality film formation by layer-by-layer (LBL) assembly. With all of these appealing properties, the CdSe/CdTe core/crown heterostructures having Type-II electronic structure presented here are highly promising for light-harvesting applications. (Graph Presented). © 2015 American Chemical Society.
      Keywords
      Cadmium telluride
      Electronic structure
      Fluorescence
      Fluorescence spectroscopy
      Optical properties
      Photoluminescence
      Transmission electron microscopy
      X ray diffraction
      3 - mercaptopropionic acid
      Colloidal quantum wells
      Layer - by - layer assemblies
      Photoluminescence excitation spectroscopy
      Structural characterization
      Synthesis and characterizations
      Temperature dependent fluorescence
      Time - resolved fluorescence spectroscopy
      Semiconductor quantum wells
      Permalink
      http://hdl.handle.net/11693/23136
      Published Version (Please cite this version)
      http://dx.doi.org/10.1021/jp510466k
      Collections
      • Department of Electrical and Electronics Engineering 3863
      • Institute of Materials Science and Nanotechnology (UNAM) 2098
      • Nanotechnology Research Center (NANOTAM) 1125
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