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Conformational effects in poly(p-phenylene vinylene)s revealed by low-temperature site-selective fluorescence

Titelangaben

Heun, S. ; Mahrt, R. F. ; Greiner, Andreas ; Lemmer, Ulrich ; Bässler, Heinz ; Halliday, D. A. ; Bradley, D. D. C. ; Burn, P. L. ; Holmes, Andrew B.:
Conformational effects in poly(p-phenylene vinylene)s revealed by low-temperature site-selective fluorescence.
In: Journal of Physics: Condensed Matter. Bd. 5 (1993) Heft 2 . - S. 247-260.
ISSN 1361-648X
DOI: https://doi.org/10.1088/0953-8984/5/2/012

Volltext

Link zum Volltext (externe URL): Volltext

Abstract

Low-temperature site-selective fluorescence (SSF) Spectroscopy is employed to study morphological effects on the conformation of poly(p-phenylene vinylene) (PPV) and its phenyl-substituted, soluble derivative poly(phenylphenylenevinylene) (PPPV). Samples of PPV prepared as spin-coated thin films and stretch-aligned free-standing films, and samples of PPPV prepared as cast films and as blends with poly(methylmethacrylate) and polycarbonate have been studied. The results that we present are consistent with the notion that each polymer sample consists of an army of ordered chain segments whose average length reflects the perfection of the local structure. The statistical distribution of the segment lengths is responsible for inhomogeneous broadening of the optical spectra (absorption and emission). The dominant electronic excitation created by photoexcitation across the pi-pi* energy gap is a singlet exciton that can execute a random walk among the chain segments. SSF spectroscopy allows us to distinguish the contributions to the apparent fluorescence Stokes shift that arise from energy relaxation through excitation migration (spectral diffusion) and from structural relaxation of the polymer chain (self-localization). The structural contribution to the Stokes shift approaches zero in well aligned PPV and reaches values of up to 500 cm-1 in highly disordered PPPV films. The SSP method also provides a means of assessing the extent of phase separation that occurs in PPPV blends.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Zusätzliche Informationen: ISI:A1993KH87300012
Keywords: CONJUGATED POLYMERS; VIBRATIONAL-SPECTRA; SINGLE-CRYSTALS; SPECTROSCOPY; MODEL; ABSORPTION; EXCITON; LIGHT; PPV
Institutionen der Universität: Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Lehrstuhl Makromolekulare Chemie II > Lehrstuhl Makromolekulare Chemie II - Univ.-Prof. Dr. Andreas Greiner
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Lehrstuhl Makromolekulare Chemie II
Titel an der UBT entstanden: Nein
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
Eingestellt am: 16 Apr 2015 10:39
Letzte Änderung: 12 Jul 2022 11:36
URI: https://eref.uni-bayreuth.de/id/eprint/10320