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Exciplex−Exciplex Energy Transfer and Annihilation in Solid Films of Porphyrin−Fullerene Dyads

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journal contribution
posted on 20.12.2006, 00:00 by Heli Lehtivuori, Helge Lemmetyinen, Nikolai V. Tkachenko
Exciplex−exciplex annihilation was observed for the first time in porphyrin−fullerene molecular films. The films were prepared using Langmuir−Blodgett and drop casting methods. The exciplex−exciplex interactions were studied using femtosecond pump−probe method. The exciplex−exciplex annihilation can be seen as a fast (within few picoseconds) decay of the transient absorption at excitation densities higher than 0.4 mJ/cm2. Analysis of the excitation density dependences indicates that in average four dyads are involved in the exciplex−exciplex interaction, suggesting that an exciplex−exciplex energy transfer may precede the annihilation.