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Proceedings Paper

Photoexcitations in disubstituted acetylene polymers
Author(s): Martin Liess; Ilarie I. Gontia; Toshio Masuda; Katsumi Yoshino; Z. Valy Vardeny
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Paper Abstract

We have used a variety of optical techniques to study the photoexcitation dynamics in several disubstituted acetylene polymer thin films. We found that although these polymers have a degenerate ground state, as determined by iodine doping and C60 photodoping, they show strong photoluminescence in the blue/green spectral range with high quantum efficiency in thin films. The cw photo modulation spectrum contains a single photoinduced absorption (PA) band at 1.7 eV with monomolecular recombination kinetics with a lifetime of 25 ms. PA detected magnetic resonance (PADMR) shows that this PA band is related to spin 1/2 excitations, which therefore identifies it as due to neutral soliton antisoliton pairs (So, So), similar to the 1.35 eV PA band in t-(CH)x. No triplet PADMR signal was observed and we therefore conclude that triplet excitations are unstable in disubstituted acetylene polymers, even though singlet excitons relatively stable. We consider therefore a possible So photogeneration mechanism via singlet to triplet intersystem crossing, followed by triplet exciton decomposition into So So pairs. Also we detected polarons in a degenerate ground state polymer for the first time.

Paper Details

Date Published: 1 December 1997
PDF: 11 pages
Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997); doi: 10.1117/12.295529
Show Author Affiliations
Martin Liess, Univ. of Utah (United States)
Ilarie I. Gontia, Univ. of Utah (United States)
Toshio Masuda, Kyoto Univ. (Japan)
Katsumi Yoshino, Osaka Univ. (Japan)
Z. Valy Vardeny, Univ. of Utah (United States)

Published in SPIE Proceedings Vol. 3145:
Optical Probes of Conjugated Polymers
Z. Valy Vardeny; Lewis J. Rothberg, Editor(s)

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