Regensburg 2004 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 3: Magnetic Resonance
CPP 3.3: Vortrag
Montag, 8. März 2004, 10:30–10:45, H 38
Study of Spin Dependent Recombination Mechanisms in Conjugated Polymers and Oligomers — •Michael Pientka1, Eugene Frankevich2, Jürgen Parisi1, and Vladimir Dyakonov1 — 1Institute of Physics, University of Oldenburg, 26111 Oldenburg, Germany — 2Institute for Energy Problems of Chemical Physics, 117828 Moscow, Russia
Recombination mechanisms of photo- and electrically generated excitations in conjugated polymers is a matter of intense discussions as they are directly related to the quantum yield of the light emission. By utilising the spin sensitive techniques, such as optically detected magnetic resonance, we analyse the contribution of molecular triplet excitons as well as of Coulomb bound polaron pairs to recombination of singlet excitons in conjugated oligomers and polymers. Both, the triplet-triplet annihilation as well as the suppressed quenching of singlet excited states by triplet excitons and polaron pairs, can in principle lead to an enhancement of the photo- and electroluminescence, provided these processes are spin dependent. By varying the excitation intensity and the modulation frequency we were able to distinguish between these two mechanisms. Independent evidences for the triplet-triplet annihilation were obtained by the frequency modulation technique with recording the fluorescence intensity on the second harmonic.