Spectral Diffusion and Stokes’ Shift in Conjugated Polymers: From Hopping to Twist

Add to your list(s) Download to your calendar using vCal

• Wichard J.D. Beenken, Department of Theoretical Physics I, Technische Universität Ilmenau, Germany
• Tuesday 20 March 2007, 14:30-15:30
• Small Lecture Theatre, Cavendish Laboratory, Department of Physics.

If you have a question about this talk, please contact Chris McNeill.

In conjugated polymers, important organic substances for photo-electronic devices, spectral diffusion is usually described in the framework of excitation energy transfer (EET), i.e. Förster-type hopping transfer, among so-called spectroscopic units. These spectroscopic units consist of several connected monomers of the polymer chain with common optical transition frequency and dipole. The transfer rate between two spectroscopic units can be calculated as dipole-dipole interaction between the respective transition (point-dipole approximation). We will present more sophisticated concepts of the excitonic interaction e.g. the line-dipole approximation, which result in a qualitative and quantitative better agreement with the energy transfer dynamics measured by e.g. anisotropy decay. Beside the EET , which dynamics of are on a ps-timescale, we found that there may exist other mechanisms, which result in the observed spectral diffusion and Stokes’ shift as well. These are directly connected with the nuclear relaxation of the polymer structure in the excited states. On timescales just a little bit longer than those characteristic for EET , torsions around the single-bonds connecting the monomeric units of the polymer become crucial. On the other hand stretching modes may be able to explain sub-ps kinetics, which have been found in anisotropy decay measurements. We will illustrate these effects by means of quantum-chemical calculations (ZINDO-S and TD-DFT) we have performed on oligo-thiophenes.

This talk is part of the Optoelectronics Group series.

This talk is included in these lists:

• All Cavendish Laboratory Seminars
• All Talks (aka the CURE list)
• Centre for Health Leadership and Enterprise
• Featured lists
• ME Seminar
• Neurons, Fake News, DNA and your iPhone: The Mathematics of Information
• Optoelectronics Group
• School of Physical Sciences
• Small Lecture Theatre, Cavendish Laboratory, Department of Physics
• Thin Film Magnetic Talks
• few29

Note that ex-directory lists are not shown.