Berlin 2005 – wissenschaftliches Programm
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SYOO: Organic Optoelectronics and Photonics
SYOO 2: Optoelectronic Properties
SYOO 2.2: Vortrag
Montag, 7. März 2005, 11:45–12:00, TU C130
A universal picture of chromophores in PI-conjugated polymers: the single molecule approach — •Florian Schindler1, John M. Lupton1, Jochen Feldmann1, and Ullrich Scherf2 — 1Photonics and Optoelectronics Group, Department of Physics, LMU Munich — 2FB Chemie, University of Wuppertal
Single molecule spectroscopy provides unique insight into the fundamental photophysics of electroactive conjugated polymers by overcoming disorder broadening [1]. We apply this technique to the ordered ladder-type poly(para-phenylene) and disordered poly(phenylene-vinylene) (PPV) at low temperatures. We observe identical spectroscopic features on the single chromophore level, such as similar fluorescence linewidths and spectral diffusion dynamics, which appear to be independent of the chemical structure [2]. However, interchromophoric coupling mechanisms differ strongly. In PPV, coherent coupling results in spectral broadening. Such behaviour is absent in ladder-type polymers, where the linewidth of the emissive species is identical for all molecules. By comparing a model ladder-type oligomer with the ladder-type polymer we can also clarify the effective conjugation length of the polymer and count the number of chromophores present on the chain. Our results demonstrate that structure-property relationships in conjugated polymers derive mainly from chain morphology rather than chromophoric properties and should be considered extrinsic in nature.
Müller et al., PRL 91, 267403 (2003)
Schindler et al., PNAS 101, 14695 (2004)