Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 52: Symposium Semiconducting Nanoparticles for Nano-Optics and Optoelectronics

HL 52.4: Hauptvortrag

Freitag, 29. Februar 2008, 12:00–12:30, ER 270

Charge carrier dynamics of surface modified semiconductor nanocrystals — •Alf Mews, Ma Xuedan, Jessica Völker, Maxime Tchaya, and Herbert Kneppe — Physical Chemistry, University of Siegen, 57068 Siegen, Germany

The optical and electronic properties of semiconductor nanostructures are strongly related to their inorganic and molecular surface modification. This is a direct consequence of surface passivation and/or the electronic interaction between the molecular surface ligands and the inorganic semiconductor cores. For example, photo induced charge transfer from the nanocrystals to the attached surface ligands will have a strong effect on both, the fluorescence intensity and the fluorescence lifetime of the nanocrystals.

Here we present a detailed study of different core/shell nanoparticels and several nanoparticle-ligand combinations, which are investigated by a combination of optical spectroscopy and cyclic voltametry (CV), respectively. This allows to measure the absolute energetic positions of the electronic NC- and ligand-levels by CV and compare them to the respective band-gaps and fluorescence intensities from the optical spectra. In addition we present different functional ligands, where the energetic levels are depending on the chemical environment. Finally we present results from single nanoparticle fluorescence spectroscopy to get a deeper insight into the fluorescence dynamics of individual surface modified nanocystals.