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Size-Dependent Janus-Ligand Shell Formation on PbS Quantum Dots
We studied the size-dependent Janus ligand shell formation on PbS QDs employing an X-type ligand exchange reaction between native oleate ligands and two substituted cinnamic acid ligands, trifluoromethyl- and dimethyl amino-cinnamic acid, representing electron donating and electron withdrawing ligands. The exchange reactions become significantly more favorable for both electron donating and withdrawing ligands (..delta..G becomes more negative) in the smaller QDs compared to the larger QDs likely because the ligand density is smaller on the larger QDs reducing the strength of the ligand-ligand interactions. We found that Janus-ligand shells form more readily on smaller QDs than on bigger QDs with electron donating ligands. We also observed a dependence on the QD concentration that should be considered when forming Janus-ligand shells. Two-dimensional solution nuclear magnetic resonance spectroscopy (2D-NMR) shows evidence of pronounced phase segregation between oleate and electron donating ligands on the smaller QDs consistent with the enhanced ligand-ligand interactions. This study broadens our understanding of how to construct Janus and patchy ligand shell morphologies on small QDs.
Decoupling and Coupling of the Host-Dopant Interaction by Manipulating Dopant Movement in Core/Shell Quantum Dots
Abstract not provided
Origin of Vibronic Coherences During Carrier Cooling in Colloidal Quantum Dots
Not provided.
Reversible Ligand Detachment from CdSe Quantum Dots Following Photoexcitation
Not provided.
Terahertz Field-Induced Reemergence of Quenched Photoluminescence in Quantum Dots
Not provided.
Monodisperse and Water-Soluble Quantum Dots for SWIR Imaging via Carboxylic Acid Copolymer Ligands
Not provided.