Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Poster: Nanoparticles and Composite Materials

CPP 8.27: Poster

Montag, 26. März 2012, 17:30–20:00, Poster A

Surface Charges on CdSe/ZnS Quantum Dots in Apolar Solvents — •Nicole Amecke and Frank Cichos — Molecular Nanophotonics Group, University of Leipzig

Despite intensive research, semiconductor quantum dots (QDs) show many peculiar fluorescence characterstics (blinking, flickering, spectral diffusion) that are not fully understood today. Many of those are expected to be strongly influenced by charges in the QD core or its close proximity. With a confocal microscope and an electrophoretic cell, charged QDs in solution can be detected and separated from neutral QDs while monitoring their fluorescence. Depending on solvent and electrode characteristics we find the percentage and polarity of detected fluorescent charges to differ, showing a manipulation of the charges at the electrode. This charging of QDs and their total percentage can also be detected by the current flowing through the device. Spectra and lifetimes from charged and neutral QDs are taken separately and compared. As only minor differences are found, the charge must be located at the surface not in the core.