Exciton migration in conjugated dendrimers

A joint experimental and theoretical study

Muhammet E. Kcöse, Peter Graf, Nikos Kopidakis, Sean E. Shaheen, Kwiseon Kim, Gary Rumbles

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

We report a joint experimental and theoretical investigation of exciton diffusion in phenyl-cored thiophene dendrimers. Experimental exciton diffusion lengths of the dendrimers vary between 8 and 17 nm, increasing with the size of the dendrimer. A theoretical methodology is developed to estimate exciton diffusion lengths for conjugated small molecules in a simulated amorphous film. The theoretical approach exploits Fermi's Golden Rule to estimate the energy transfer rates for a large ensemble of bimolecular complexes in random relative orientations. Utilization of Poisson's equation in the evaluation of the Coulomb integral leads to very efficient calculation of excitonic couplings between the donor and the acceptor chromophores. Electronic coupling calculations with delocalized transition densities revealed efficient coupling pathways in the bulk of the material, but do not result in strong couplings between the chromophores which are calculated for more localized transition densities. The molecular structures of dendrimers seem to be playing a significant role in the magnitude of electronic coupling between chromophores. Simulated diffusion lengths correlate well with the experimental data. The chemical structure of the chromophore, the shape of the transition densities and the exciton lifetime are found to be the most important factors in determining the size of the exciton diffusion length in amorphous films of conjugated materials.

Original languageEnglish
Pages (from-to)3285-3294
Number of pages10
JournalChemPhysChem
Volume10
Issue number18
DOIs
Publication statusPublished - Dec 21 2009

Fingerprint

Dendrimers
dendrimers
Chromophores
diffusion length
chromophores
excitons
Amorphous films
Thiophenes
Poisson equation
estimates
thiophenes
electronics
Energy transfer
Molecular structure
molecular structure
energy transfer
LDS 751
methodology
life (durability)
Molecules

Keywords

  • Dendrimers
  • Density functional calculations
  • Diffusion
  • Electronic structure
  • Excitons

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Atomic and Molecular Physics, and Optics

Cite this

Exciton migration in conjugated dendrimers : A joint experimental and theoretical study. / Kcöse, Muhammet E.; Graf, Peter; Kopidakis, Nikos; Shaheen, Sean E.; Kim, Kwiseon; Rumbles, Gary.

In: ChemPhysChem, Vol. 10, No. 18, 21.12.2009, p. 3285-3294.

Research output: Contribution to journalArticle

Kcöse, Muhammet E. ; Graf, Peter ; Kopidakis, Nikos ; Shaheen, Sean E. ; Kim, Kwiseon ; Rumbles, Gary. / Exciton migration in conjugated dendrimers : A joint experimental and theoretical study. In: ChemPhysChem. 2009 ; Vol. 10, No. 18. pp. 3285-3294.
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