Regensburg 2004 – wissenschaftliches Programm

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.8: Poster

Donnerstag, 11. März 2004, 18:00–21:00, B

Self-Organized Nanocomposites of CdSe Nanocrystals and Porphyrins — •Abey Issac¹, Thomas Blaudeck², Frank Cichos², Edward Zenkevich³, Alexander Shulga³, and Christian von Borczyskowski¹ — ¹Institut für Physik 122501, TU Chemnitz, 09107 Chemnitz — ²Institut für Physik 123705, TU Chemnitz, 09107 Chemnitz — ³Institute of Molecular and Atomic Physics and B.I. Stepanov Institute of Physics National Academy of Sciences, 70 F. Skaryna Avenue, 220072 Minsk, Belarus

Composites of semiconductor nanocrystals (NC) and organic compounds open a road to new functional units for optoelectronic applications. Such composites may be prepared by self-organization of functionalized organic chromophores on semiconductor NCs. We present results of spectroscopic studies, where we investigate composites of pyridyl containing porphyrin molecules and CdSe NCs in solution. The experiments show a strong quenching of the emission of CdSe NCs even at ratios of the porphyrin to NC concentration much smaller than one. This is ascribed to the self-organization of porphyrin molecules on the NC surface by ligation interactions. The close proximity of NC and porphyrin and their electronic interaction opens nonradiative channels, which we tentatively ascribe to an electron transfer process from the NC to the porphyrin. With increasing number of porphyrin molecules per NC the NC emission is quenched almost completely. This points to an electron transfer, that occurs on a much shorter timescale than the emission decay of the NC which is confirmed by time resolved measurements. The dependence of the observed emission quenching on the NC size will be discussed.