Colloidal semiconductor quantum dots (QDs) have attracted significant attention for applications spanning from display, photovoltaics to biological imaging because of their extraordinary photo-physical properties. In this presentation, I will first describe using gel permeation chromatography (GPC) as a media to purify different types of QDs. GPC is further demonstrated as a reactor to perform solvent change and ligand exchange reactions with QDs. With the help of GPC purification technique, well-isolated and characterized QDs are prepared to perform the sequential chemistry studies of these materials. (1) I specifically study the effect of neutral ligands on the photo-physical properties of the QDs and their influence on the inorganic surface overcoating (shell growth) reaction. (2) The GPC purified QDs are used to perform surface modification reactions with a range of polymeric imidazole ligands for biological imaging applications.<br/><br/>In the second part, I will describe recent advances using semiconductor nanoparticles prepared in continuous flow systems. (1) Matrix-assisted laser desorption/ionization (MALDI) characterizes the growth transition between clusters and nanoparticles in the late-stage growth of InP QDs. MALDI and NMR studies yield a size/extinction coefficient calibration curve for InP QDs without any assumption on the particles’ density or shape. (2) Oscillatory flow reactor is used in automatically screening reaction conditions and studying the reaction mechanism of bi-phasic CdSe QD ligand exchange reactions. (3) Membrane-based in-line liquid-liquid extraction is efficient in removing impurities and excess precursors from nanomaterials as exemplified with continuous purification of CdSe QDs in octane.

Sequential chemistry study of well-isolated and characterized quantum dots using batch and continuous flow platforms

254th National Meeting (2017)

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