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Ligands for nanocrystals (NCs) have been widely studied beyond its role as a capping agent to applications such as tuning self-assembled properties of nanocrystals. Recent studies show that functionalized ligands can introduce precise control over charge and energy transfer of semiconductor NCs, or quantum dots (QDs). This can be used in various applications in optoelectronic devices, such as solar cells and light emitting diodes, or even further photocatalysis, and biological imaging. Herein, this project describes the design and synthesis of a series of novel dendritic ligands containing active moiety with efficient synthetic route for developing dendron series to graft onto the surface of CdSe/CdS core shell QDs. For active site in the ligand, ferrocene (Fc) was used because of its chemical stability and the ease of the Fc/Fc+ redox couple. To characterize the series of ligands, Nuclear magnetic resonance (NMR) spectroscopy and mass spectroscopy studies were performed to analyze and confirm molecular structure of compounds. In addition, the synthesized ligands were grafted onto QDs and self-assembly of NCD. For characterization of this hybrid system, the changes of energy dynamics were studied by Ultraviolet-visible spectroscopy (UV-Vis) and Fluorescence spectrometer. As a result, the quenching effect was observed as placed Fc near QDs and degree of quenching also varies. This study reveals that active moiety Fc introduced optical dynamic changes in absorbance and fluorescence when anchored on QDs surfaces compared to QD-as synthesized. This project will be a capstone for enhancing mechanistic understanding of how charge transfers between active moiety and QDs. The series of samples of ligands and QD-Fc ligand hybrids were successfully made as a part of collaboration work with Prof. Baxter group at Drexel University, for ultrafast spectroscopic analysis which will enable ultimate understanding of direct charge and energy flow.
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Date Posted: 31 May 2019
This document has been peer reviewed.