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Titolo:
OPTOELECTRONIC PROPERTIES OF CONJUGATED POLYMERS
Autore:
BASSLER H;
Indirizzi:
UNIV MARBURG,INST PHYS CHEM,HANS MEERWEIN STR D-35032 MARBURG GERMANY
Titolo Testata:
Macromolecular symposia
, volume: 104, anno: 1996,
pagine: 269 - 284
SICI:
1022-1360(1996)104:<269:OPOCP>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
SITE-SELECTIVE FLUORESCENCE; PHOTOCONDUCTIVITY; LUMINESCENCE; ABSORPTION; RELAXATION; LIGHT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
41
Recensione:
Indirizzi per estratti:
Citazione:
H. Bassler, "OPTOELECTRONIC PROPERTIES OF CONJUGATED POLYMERS", Macromolecular symposia, 104, 1996, pp. 269-284

Abstract

There is growing evidence, both theoretical and experimental, that the primary optical excitations in conjugated polymers are of excitonic nature. They are formed instantaneously upon photoexcitation and migrate incoherently among chain segments differing in length and, concomitantly, in excitation energy. Migration is associated with spectral relaxation manifest in the occurrence of a dynamic Stokes shift. Time-resolved photoluminescence as well as energy transfer studies support this conceptual framework. In systems of the polyphenylenevinylene familythe exciton binding energy is estimated to be about 0.4 eV, comparable to that in polydiacetylenes. However, transfer of a charge from an excited chain segment to neighboring chain segments costs less energy. Taking into account that all energy levels are disorder broadened thisensures that a fraction of excitations will find it energetically more favorable to decompose into an electron-hole pair on adjacent chains(off-chain or indirect exciton) that acts as precursor for photoconduction. Exciton breaking can be stimulated by a strong electric field as documented by cw and time resolved spectroscopy. Recent fluorescenceas well as pump and probe measurements on a ladder type polymer (LPPP) with 150 fs time resolution will be reported which support the aboveconceptual framework and document the occurrence of stimulated emission.

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Documento generato il 01/12/20 alle ore 13:37:49