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Tuning of fluorescence in films and nanoparticles of oligo-phenylenevinylenes

Tuning of fluorescence in films and nanoparticles of oligo-phenylenevinylenes Oligo-phenylenevinylenes (OPV) with a series of distance controlling, electron donating, and/or electron withdrawing substituents are deposited from vapor phase and solution as ultrathin films or nanoparticles with diameters of 20 - 200 nm. In some cases the systems are doped at levels of 10 -5 - 10 -3 with energy accepting OPV's of longer chainlengths. Absorption and fluorescence spectra, steady-state and time-resolved anisotropies, radiative and nonradiative deactivation rates of these systems are investigated and compared to the corresponding properties in dilute solutions. Fluorescence yields of the parent oligomers and their alkyl or oxyalkyl derivatives are high in solution with an `infinite' chain limit of (Phi) F approximately equals 0.5 and an upper radiative rate constant limit of k r (infinity ) equals (1 +/- 0.3) (DOT) 10 9 s -1 . Yields and k r decrease strongly in films and nanoparticles because of H-aggregate formation. However, doping with fluorescent acceptors can increase the yields up to (Phi) F yields 0.7. Introduction of electron withdrawing -CN and -SO 2 CF 3 substituents reduces (Phi) F in low viscous dilute solutions almost to zero. High viscosities and condensation to solid phases will rise the yields up to (Phi) F yields 0.6 because of suppression of nonradiative torsional deactivation and formation of J- aggregates with high k r . http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Proceedings of SPIE SPIE

Tuning of fluorescence in films and nanoparticles of oligo-phenylenevinylenes

Oelkrug, Dieter
Proceedings of SPIE , Volume 3145 (1) – Dec 1, 1997
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Publisher
SPIE
Copyright
Copyright © 2004 COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
ISSN
0277-786X
eISSN
1996-756X
DOI
10.1117/12.284148
Publisher site
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Abstract

Oligo-phenylenevinylenes (OPV) with a series of distance controlling, electron donating, and/or electron withdrawing substituents are deposited from vapor phase and solution as ultrathin films or nanoparticles with diameters of 20 - 200 nm. In some cases the systems are doped at levels of 10 -5 - 10 -3 with energy accepting OPV's of longer chainlengths. Absorption and fluorescence spectra, steady-state and time-resolved anisotropies, radiative and nonradiative deactivation rates of these systems are investigated and compared to the corresponding properties in dilute solutions. Fluorescence yields of the parent oligomers and their alkyl or oxyalkyl derivatives are high in solution with an `infinite' chain limit of (Phi) F approximately equals 0.5 and an upper radiative rate constant limit of k r (infinity ) equals (1 +/- 0.3) (DOT) 10 9 s -1 . Yields and k r decrease strongly in films and nanoparticles because of H-aggregate formation. However, doping with fluorescent acceptors can increase the yields up to (Phi) F yields 0.7. Introduction of electron withdrawing -CN and -SO 2 CF 3 substituents reduces (Phi) F in low viscous dilute solutions almost to zero. High viscosities and condensation to solid phases will rise the yields up to (Phi) F yields 0.6 because of suppression of nonradiative torsional deactivation and formation of J- aggregates with high k r .

Journal

Proceedings of SPIE – SPIE

Published: Dec 1, 1997

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