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Title: Effects of {pi}-conjugation attenuation on the photophysics and exciton dynamics of poly(p-phenylenevinylene) polymers incorporating 2,2{prime}-bipyridines

Abstract

The effect of {pi}-conjugation attenuation on the photophysics and exciton dynamics of two conjugated polymers 1 and 2 are examined in solution. The structures of polymers 1 and 2 have 2,2{prime}-bipyridyl-5-vinylene units that alternate with one and three 2,5-bis(n-decyloxy)-1,4-phenylenevinylene monomer units, respectively. The photophysics and exciton dynamics of polymers 1 and 2 were compared to those of the homopolymer, poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV). A series of changes in the photophysics of polymers 1 and 2 were found as a result of {pi}-conjugation attenuation. These changes include blue shifts in absorption and emission spectra, spectral diffusion in stimulated emission, enhancement in photoluminescence quantum yields and lifetimes, and increases in photoinduced absorption intensities and lifetimes. These changes are systematically more pronounced in polymer 1 than in polymer 2 and are correlated with {pi}-conjugation attenuation in the polymers due to twisting of the 2,2{prime}-bipyridine groups about the 2.2{prime} single bond. An exciton dynamics model involving an ensemble of initial exciton states localized on oligomeric segments within the polymer with different conjugation lengths is proposed to describe the observed differences between polymers 1 and 2 and BEH-PPV. When the electronic coupling between these segments is strong, the polymer displays characteristics that are close to those ofmore » a one-dimensional semiconductor. However, when these couplings are weakened by groups, such as the 2,2{prime}-bipyridine that attenuate {pi}-conjugation, the polymer displays properties of an ensemble of oligomers.« less

Authors:
; ;  [1];  [2]
  1. Argonne National Lab., IL (United States). Chemistry Div.
  2. Argonne National lab., IL (United States). Chemistry Div.
Publication Date:
Research Org.:
Argonne National Laboratory (ANL), Argonne, IL
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
351583
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory
Additional Journal Information:
Journal Volume: 103; Journal Issue: 22; Other Information: PBD: 3 Jun 1999
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; PHOTOLUMINESCENCE; BIPYRIDINES; POLYMERS; COUPLING; ABSORPTION SPECTROSCOPY; EXCITON MODEL; STIMULATED EMISSION

Citation Formats

Chen, L X, Jaeger, W J.H., Niemczyk, M P, Wasielewski, M R, and Northwestern Univ., Evanston, IL. Effects of {pi}-conjugation attenuation on the photophysics and exciton dynamics of poly(p-phenylenevinylene) polymers incorporating 2,2{prime}-bipyridines. United States: N. p., 1999. Web. doi:10.1021/jp990248e.
Chen, L X, Jaeger, W J.H., Niemczyk, M P, Wasielewski, M R, & Northwestern Univ., Evanston, IL. Effects of {pi}-conjugation attenuation on the photophysics and exciton dynamics of poly(p-phenylenevinylene) polymers incorporating 2,2{prime}-bipyridines. United States. doi:10.1021/jp990248e.
Chen, L X, Jaeger, W J.H., Niemczyk, M P, Wasielewski, M R, and Northwestern Univ., Evanston, IL. Thu . "Effects of {pi}-conjugation attenuation on the photophysics and exciton dynamics of poly(p-phenylenevinylene) polymers incorporating 2,2{prime}-bipyridines". United States. doi:10.1021/jp990248e.
@article{osti_351583,
title = {Effects of {pi}-conjugation attenuation on the photophysics and exciton dynamics of poly(p-phenylenevinylene) polymers incorporating 2,2{prime}-bipyridines},
author = {Chen, L X and Jaeger, W J.H. and Niemczyk, M P and Wasielewski, M R and Northwestern Univ., Evanston, IL},
abstractNote = {The effect of {pi}-conjugation attenuation on the photophysics and exciton dynamics of two conjugated polymers 1 and 2 are examined in solution. The structures of polymers 1 and 2 have 2,2{prime}-bipyridyl-5-vinylene units that alternate with one and three 2,5-bis(n-decyloxy)-1,4-phenylenevinylene monomer units, respectively. The photophysics and exciton dynamics of polymers 1 and 2 were compared to those of the homopolymer, poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV). A series of changes in the photophysics of polymers 1 and 2 were found as a result of {pi}-conjugation attenuation. These changes include blue shifts in absorption and emission spectra, spectral diffusion in stimulated emission, enhancement in photoluminescence quantum yields and lifetimes, and increases in photoinduced absorption intensities and lifetimes. These changes are systematically more pronounced in polymer 1 than in polymer 2 and are correlated with {pi}-conjugation attenuation in the polymers due to twisting of the 2,2{prime}-bipyridine groups about the 2.2{prime} single bond. An exciton dynamics model involving an ensemble of initial exciton states localized on oligomeric segments within the polymer with different conjugation lengths is proposed to describe the observed differences between polymers 1 and 2 and BEH-PPV. When the electronic coupling between these segments is strong, the polymer displays characteristics that are close to those of a one-dimensional semiconductor. However, when these couplings are weakened by groups, such as the 2,2{prime}-bipyridine that attenuate {pi}-conjugation, the polymer displays properties of an ensemble of oligomers.},
doi = {10.1021/jp990248e},
journal = {Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory},
number = 22,
volume = 103,
place = {United States},
year = {1999},
month = {6}
}