Regensburg 2002 – wissenschaftliches Programm
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SYOH: Organische Halbleiter
SYOH 7: Poster
SYOH 7.48: Poster
Montag, 11. März 2002, 18:00–21:00, C
Fluorescence dynamics and Charge Carrier Photogeneration of Phenylene substituted Polyphenylenevinylene - Trinitrofluorenone blend systems — •C. Im1, E. V. Emelianova1, P. Schouwink2, J. Lupton2, and H. Bässler1 — 1Institute of Physical, Macromolecular, and Nuclear Chemistry and Material Science Center, Philipps-University, Hans Meerwein Strasse, D-35032 Marburg, Germany — 2Max-Planck-Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
In order to investigate doping effects in a conjugated polymer, blend systems with phenylene-substituted polyphenylenevinylene (PhPPV) - trinitrofluorenone (TNF) were used. Steady state and time resolved fluorescence of PhPPV, both in solution and in form of spin coated films has been measured. In solution the fluorescence decays exponentially with a life time of 700 ps, whereas in film the 1/e decay is 400 ps. Doping the film by various amounts of TNF shortens the decay time without changing the form the Kohlrausch-William-Watts-decay law. This is a signature of exciton dissociation by transferring an electron to TNF in a random polymer matrix. Spectral, field, and temperature dependences of steady-state photoconductivity were also studied in thin films. The films were sandwiched between ITO and aluminium as well as between two aluminium contacts. Surface extrinsic carrier photogeneration was observed in ITO/PhPPV/Al samples with positively biased ITO and bulk extrinsic photogeneration in Al/PhPPV/Al samples sensitized by TNF while the intrinsic photoconductivity dominated in Al/PhPPV/Al samples and ITO/PhPPV/Al sandwiches with negatively biased ITO.