Conformational Disorder and Ultrafast Exciton Relaxation in PPV-family Conjugated Polymers

Tieneke E. Dykstra, Emmanuelle Hennebicq, David Beljonne, Johannes Gierschner, Gil Claudio, Eric R. Bittner, Jasper Knoester, Gregory D. Scholes*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

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Abstract

We report combined experimental and theoretical studies of excitation relaxation in poly[2-methoxy,5-(2'ethyl-hexoxy)-1,4-phenylenevinylene] (MEH-PPV), oligophenylenevinylene (OPV) molecules of varying length, and model PPV chains. We build on the paradigm that the basic characteristics of conjugated polymers are decided by conformational subunits defined by conjugation breaks caused by torsional disorder along the chain. The calculations reported here indicate that for conjugated polymers like those in the PPV family, these conformational subunits electronically couple to neighboring subunits, forming subtly delocalized collective states of nanoscale excitons that determine the polymer optical properties. We find that relaxation among these exciton states can lead to a decay of anisotropy on ultrafast time scales. Unlike in Forster energy transfer, the exciton does not necessarily translate over a large distance. Nonetheless, the disorder in the polymer chain means that even small changes in the exciton size or location has a significant effect on the relaxation pathway and therefore the anisotropy decay.

Original languageEnglish
Pages (from-to)656-667
Number of pages12
JournalJournal of Physical Chemistry B
Volume113
Issue number3
DOIs
Publication statusPublished - 22-Jan-2009

Keywords

  • 3-DIMENSIONAL ROTATIONAL AVERAGES
  • SITE-SELECTIVE FLUORESCENCE
  • PHOTOSYNTHETIC PURPLE BACTERIA
  • LONG POLYENE CHAINS
  • ENERGY-TRANSFER
  • MEH-PPV
  • POLY(P-PHENYLENE VINYLENE)
  • TRANS-STILBENE
  • POLY(PARA-PHENYLENE VINYLENE)
  • INTERCHAIN INTERACTIONS

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