Energietransport und optische Linienformen in Dendrimeren

• Antragsteller: Professor Dr. Peter Reineker (†)
• Fachliche Zuordnung: Physik der kondensierten Materie
• Förderung: Förderung von 1999 bis 2008
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 5197150

• Erstellungsjahr: 2007

Zusammenfassung der Projektergebnisse

We have used a stochastic model to describe exciton transport and optical absorption under the influence of exciton-phonon interaction. For the parameters used in our calculation the time dependence of all occupation probabilities is oscillatory with a damping that depends on the strength of exciton-phonon interaction. For short times the exciton transport occurs in a wavelike, coherent manner. In the stationary state (for long times) the exciton is equally distributed over all molecular sites. The inclusion of an additional sink changes the features of exciton transport drastically, as the total occupation probability is no longer conserved any more. With respect to optical absorption, we found that for compact dendrimers with symmetrical branching our calculated spectra show all essential features of the experimental data. For compact dendrimers with unsymmetrical branching we also find a good analogy between our calculated spectra and experimental curves, but we cannot explain all spectral features that have been found experimentally. Furthermore we have investigated the optical absorption spectra for extended dendrimers using two different models. For the BPA model we did not find any remarkable redshift of the lowest absorption energy with growing dendrimer size. In our second model (ASA) for extended dendrimers, we have also allowed optical transitions within the linear chain sections. Here we find a redshift of the lowest absorption peak with growing dendrimer size. In magnitude it is comparable to the one which we found for compact dendrimers. In this case we cannot reproduce the essential features of the spectra found experimentally. Furthermore we have performed preliminary calculations of the influence of disorder, of the interaction between different dendrimer branches and of the quantum mechanical description of the vibrational degrees of freedom.

Projektbezogene Publikationen (Auswahl)

• Energietransport und optische Absorption von Dendrimeren. Dissertation, Universität Ulm (2000)
  A. Engelmann
  
• Energy Transfer and Optical Excitations in Dendrimers. Proceedings of the International School of Physics Enrico Fermi, Course CXLIX, Varenna, Villa Monastero, 31 July - 10 August 2001, edited by V. M. Agranovich and G. C. La Rocca, p. 507, IOS Press, Amsterdam 2002
  P. Reineker, A. Engelmann, V. I. Yudson
  
• Excitons in Dendrimers: Optical Absorption and Energy Transport. J. Lumin. 94 & 95, 203 (2001)
  P. Reineker, A. Engelmann, V. I. Yudson
  
• Energy Transfer and Optical Properties of Dendrimers. J. Nonlinear Optics 29, 671 (2002)
  P. Reineker, A. Engelmann, V. I. Yudson
  
• Excited States of Dendrimers: Energy Transfer and Optical Excitations. Bulletin of the Stefan University 14, No. 11, P. 73 (2002)
  P. Reineker, A. Engelmann, and V. I. Yudson
  
• Optical Properties and Energy Transfer in Dendrimers. Organic Nanophotonics, Ed. F. Charra, Kluwer Academic Publisher, 17 (2003)
  P. Reineker, A. Engelmann, V. I. Yudson
  
• Excited States of Dendrimers: Energy Transfer and Optical Excitations. In: Selected Topics in Luminescent Materials, Stefan University Press Series on Frontiers in Science and Technology, San Diego, 2004
  P. Reineker, A. Engelmann, and V. I. Yudson
  
• Optical Absorption and Energy Transfer Processes in Dendrimers. J. Lumin. 108, 333 (2004)
  P. Reineker, A. Engelmann, V. I. Yudson
  
• Optical Absorption in Dendrimers. J. Lumin. 110, 271 (2004)
  C. Supritz, A. Engelmann and P. Reineker
  
• Proceedings of the 325 the Wilhelm ans Else Heraeus Seminar on Organic Molecular Solids: Excited Electronic States and Optical Properties. J. Lumin 110, 165-427 (2004)
  P. Reineker, M. Hoffmann and K. Leo
  
• Selected Topics in Luminescent Materials. University Press Series on Frontiers in Science and Technology, San Diego (2004)
  P. Reineker, A. Vitukhnovsky, V. Stefan
  
• Optical Absorption in Compact and Extended Dendrimers. J. Lumin. Ill, 367 (2005)
  C. Supritz, A. Engelmann and P. Reineker
  
• Special Issue on Dendrimers. J. Lumin 111 (2005)
  P. Reineker and T. Basche
  
• Energy Transport in Dendrimers. J. Lumin. 119-120, 337 (2006)
  C. Supritz, A. Engelmann and P. Reineker
  
• Energietransport und optische Absorption in Nanostrukturen. Dissertation, Universität Ulm (2007)
  C. Supritz
  
• Optical Absorption in Dendrimers. J. Lumin. 122, 759 (2007)
  C. Supritz, A. Engelmann and P. Reineker
  
• Optical Absorption and Energy Transport in Compact Dendrimers with Unsymmetrical Branching. J. Lumin.
  C. Supritz, V. Gounaris and P. Reineker