PHYS 74 |
| Energy transfer (ET) processes are of major importance for the efficiency of π-conjugated polymer based organic solar cells. We use dye-endcapped conjugated polymers as model systems to study intrachain exciton migration by single molecule (SM) spectroscopy. While power-dependent measurements identify the exciton-blockade-effect causing ET interruption, polarization-dependent studies reveal the distribution of emissive subunits – chromophores – within a polymer chain. Furthermore, photoluminescence excitation spectra recorded on SMs hint at an unexpectedly broad continuum-like absorption. Consequently, the SMs' intrinsic properties may permit efficient harvesting of the broad sunlight spectrum without the need of disorder broadening. Finally, little influence of the primary excitation wavelength on the emission characteristics is expected. However, our excitation-energy-dependent studies on SMs show that the amount of dissipated energy on the absorbing chromophore influences the spectral features of the energetically and spatially remote emitting unit. Power-, polarization- and excitation-energy-dependent SM fluorescence spectroscopy turns out to be a powerful means to study the truly intrinsic absorption and ET characteristics of conjugated polymers usually masked in the ensemble. M.J. Walter et al., Nano Lett. 8, 3330 (2008). |
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New Developments in Energy Conversion and Light-Harvesting
1:30 PM-4:50 PM, Sunday, March 22, 2009 Salt Palace Convention Center -- 250 F, Oral
Division of Physical Chemistry |