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Published on: August 10, 2017
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Phase transfer of 1- and 2-dimensional Cd-based nanocrystals
Torben Kodanek1, Hadeel M Banbela, Suraj Naskar
1Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3A, 30167 Hannover, Germany. dirk.dorfs@pci.uni-hannover.de.
Nanoscale
|November 5, 2015
Summary
Researchers transferred luminescent cadmium selenide/cadmium sulfide (CdSe@CdS) nanocrystals and nanoplatelets into water using thiol ligands. Ligand choice impacts luminescence, with short-chain ligands preserving over 50% quantum yield in CdSe@CdS nanorods.
Area of Science:
- Materials Science
- Nanotechnology
- Photochemistry
Background:
- Colloidal semiconductor nanocrystals (quantum dots, nanorods, nanoplatelets) exhibit unique optical properties.
- Transferring these hydrophobic nanomaterials into aqueous solutions is crucial for biological and environmental applications.
- Existing methods often result in significant photoluminescence quenching.
Purpose of the Study:
- To develop and optimize ligand exchange strategies for transferring various luminescent CdSe@CdS-based nanostructures into an aqueous phase.
- To investigate the impact of different thiol-based ligands on the photoluminescence properties of transferred nanomaterials.
- To understand the factors affecting luminescence preservation during the transfer process.
Main Methods:
- Ligand exchange reactions using bifunctional thiol ligands: mercaptoacetic acid (MAA), 3-mercaptopropionic acid (MPA), 11-mercaptoundecanoic acid (MUA), and 2-(dimethylamino)ethanthiol (DMAET).
- Photoluminescence quantum yield (PLQY) measurements.
- Photoluminescence decay measurements.
- Characterization of CdSe@CdS dot-in-rod nanocrystals, CdSe@CdS/ZnS nanorods, and CdSe-CdS core-crown nanoplatelets.
Main Results:
- Successful transfer of CdSe@CdS nanorods, CdSe@CdS/ZnS nanorods, and CdSe-CdS core-crown nanoplatelets into aqueous solution.
- Photoluminescence properties are influenced by hole traps from thiol ligands and environmental passivation.
- Short-chain ligands preserved >50% PLQY for CdSe@CdS nanorods.
- MUA yielded the highest quantum efficiency for CdSe@CdS/ZnS nanorods.
- Up to 12% quantum efficiency was achieved for transferred 2D CdSe-CdS core-crown nanoplatelets.
Conclusions:
- Ligand selection is critical for successful aqueous phase transfer of luminescent nanomaterials, with optimal ligand depending on the specific nanostructure and its inorganic passivation.
- Hole traps and surface passivation significantly affect luminescence, while nanorod tips have minimal impact.
- This work enables the aqueous transfer of 2D nanoplatelets while maintaining significant luminescence, opening avenues for their use in aqueous environments.
