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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Poster: Nanoparticles and Composite Materials

CPP 12.2: Poster

Monday, March 11, 2013, 17:30–19:30, Poster C

Electrochemical Approach to Control CdSe/ZnS Quantum Dot Fluorescence — •David Plotzki, Nicole Amecke, and Frank Cichos — Molecular Nanophotonics Group, University of Leipzig

The fluorescence behaviour of colloidal semiconductor nanocrystals can be tuned by adjusting the electric conditions of their close environment. We aim to electrochemically manipulate the charge concentration on the nanocrystal surfaces in order to alter the occupancy of trap states. Recent research indicates that such surface traps strongly influence nonradiative decay channels.

We investigate single colloidal CdSe/ZnS Quantum Dots on ZnO-coated ITO surfaces. Using a confocal microscope setup with the ability to study lifetimes and spectra, we explore the fluorescence behaviour under specific electrochemical potentials.

From ensemble as well as single QD measurements we find potential ranges where the nanocrystal fluorescence is either enhanced or suppressed, accompanied by a decrease or increase of the total nonradiative decay rate. Additionally, sudden potential changes cause a delayed fluorescence response. These results hint at a rearrangement of the occupancy of trap states.