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

Title data

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. Vol. 5 (January 1993) Issue 2 . - pp. 247-260.
ISSN 1361-648X
DOI: https://doi.org/10.1088/0953-8984/5/2/012

Official URL: Volltext

Abstract in another language

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.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: ISI:A1993KH87300012
Keywords: CONJUGATED POLYMERS; VIBRATIONAL-SPECTRA; SINGLE-CRYSTALS; SPECTROSCOPY; MODEL; ABSORPTION; EXCITON; LIGHT; PPV
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Macromolecular Chemistry II > Chair Macromolecular Chemistry II - Univ.-Prof. Dr. Andreas Greiner
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Macromolecular Chemistry II
Result of work at the UBT: No
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 16 Apr 2015 10:39
Last Modified: 09 Apr 2018 13:42
URI: https://eref.uni-bayreuth.de/id/eprint/10320