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Title: Origin of line broadening in the electronic absorption spectra of conjugated polymers: Three-pulse-echo studies of MEH-PPV in toluene

Abstract

Integrated three-pulse stimulated echo peak shift data are compared for N,N-bis-dimethylphenyl-2,4,6,8-perylenetetracarbonyl diamide and poly[2-(2{sup '}-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEH-PPV) in toluene solvent. These two molecules represent a model probe of solvation dynamics and a prototypical soluble, electroluminescent conjugated polymer, respectively. The results indicate that it is inappropriate to describe the linear absorption spectrum of MEH-PPV as being primarily inhomogeneously broadened. Conformational disorder along the polymer backbone gives rise to an ensemble of polyene electronic oscillators that are strongly coupled to each other. As a consequence, fluctuations in the electronic energy gap on a time-scale of 50-fs derive primarily from bath-mediated exciton scattering. The data reported here provide an explanation for the broad, structureless electronic absorption of MEH-PPV. This interpretation provides a valuable insight into the nature of the initial photoexcited state, and the efficient population of the emissive state. (c) 2000 The American Physical Society.

Authors:
 [1];  [2];  [1];  [1];  [3];  [4]
  1. Department of Chemistry, University of California, Berkeley, California 94720 (United States)
  2. (United States)
  3. Centre for Electronic Materials and Devices, Department of Chemistry, Imperial College of Science, Technology, and Medicine, Exhibition Road, London SW7 2AY, (United Kingdom)
  4. Dyson Perrins Laboratory, Oxford University, Oxford OX1 3QY, (United Kingdom)
Publication Date:
OSTI Identifier:
20216558
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 61; Journal Issue: 20; Other Information: PBD: 15 May 2000; Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; POLYMERS; ABSORPTION SPECTRA; SOLVATION; ELECTROLUMINESCENCE; ELECTRONIC STRUCTURE; ENERGY GAP; LINE BROADENING; EXCITONS; EXPERIMENTAL DATA

Citation Formats

Scholes, Gregory D., Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, Larsen, Delmar S., Fleming, Graham R., Rumbles, Garry, and Burn, Paul L. Origin of line broadening in the electronic absorption spectra of conjugated polymers: Three-pulse-echo studies of MEH-PPV in toluene. United States: N. p., 2000. Web. doi:10.1103/PhysRevB.61.13670.
Scholes, Gregory D., Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, Larsen, Delmar S., Fleming, Graham R., Rumbles, Garry, & Burn, Paul L. Origin of line broadening in the electronic absorption spectra of conjugated polymers: Three-pulse-echo studies of MEH-PPV in toluene. United States. doi:10.1103/PhysRevB.61.13670.
Scholes, Gregory D., Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, Larsen, Delmar S., Fleming, Graham R., Rumbles, Garry, and Burn, Paul L. Mon . "Origin of line broadening in the electronic absorption spectra of conjugated polymers: Three-pulse-echo studies of MEH-PPV in toluene". United States. doi:10.1103/PhysRevB.61.13670.
@article{osti_20216558,
title = {Origin of line broadening in the electronic absorption spectra of conjugated polymers: Three-pulse-echo studies of MEH-PPV in toluene},
author = {Scholes, Gregory D. and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460 and Larsen, Delmar S. and Fleming, Graham R. and Rumbles, Garry and Burn, Paul L.},
abstractNote = {Integrated three-pulse stimulated echo peak shift data are compared for N,N-bis-dimethylphenyl-2,4,6,8-perylenetetracarbonyl diamide and poly[2-(2{sup '}-ethylhexyloxy)-5-methoxy-1,4-phenylenevinylene] (MEH-PPV) in toluene solvent. These two molecules represent a model probe of solvation dynamics and a prototypical soluble, electroluminescent conjugated polymer, respectively. The results indicate that it is inappropriate to describe the linear absorption spectrum of MEH-PPV as being primarily inhomogeneously broadened. Conformational disorder along the polymer backbone gives rise to an ensemble of polyene electronic oscillators that are strongly coupled to each other. As a consequence, fluctuations in the electronic energy gap on a time-scale of 50-fs derive primarily from bath-mediated exciton scattering. The data reported here provide an explanation for the broad, structureless electronic absorption of MEH-PPV. This interpretation provides a valuable insight into the nature of the initial photoexcited state, and the efficient population of the emissive state. (c) 2000 The American Physical Society.},
doi = {10.1103/PhysRevB.61.13670},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 20,
volume = 61,
place = {United States},
year = {2000},
month = {5}
}