Regensburg 2004 – wissenschaftliches Programm

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SYOH: Organic and Hybrid Systems for Future Electronics

SYOH 5: Poster

SYOH 5.86: Poster

Donnerstag, 11. März 2004, 18:00–21:00, B

Towards polymer spintronics: Manipulating the triplet state in conjugated polymers — •M. Reufer1, J. M. Lupton1, J. Feldmann1, and U. Scherf21Photonics and Optoelectronics Group, Physics Department, University of Munich, Germany — 2Fachbereich Chemie, Universität Wuppertal, Gauss-Str. 20, 42097 Wuppertal, Germany

Organic semiconductors are characterised by strong exchange interactions, which typically lead to a large energetic splitting of the singlet and triplet states. The presence of both of these levels is crucial to the photophysics of molecular semiconductors and particularly relevant to the operation of light-emitting diodes. Lupton et al. recently presented a novel technique to visualise triplet excitations in conjugated polymers using a new class of materials exhibiting strong room temperature phosphorescence due to trace amounts of metallic impurities [1]. Here we demonstrate that we can manipulate the triplet state by applying external perturbations in the form of electrical or optical fields. We can directly monitor and time resolve triplet creation and annihilation due to electric field induced carrier dissociation and recombination. As the conjugated polymers used exhibit strong optical gain, we are also able to use stimulated emission to deplete the singlet state before intersystem crossing to the triplet state occurs. This allows us to image and time resolve the process of spin-forbidden intersystem crossing and the associated spin flip in organic semiconductors directly.

[1] Lupton et al., Phys. Rev. Lett. 89, 167401 (2002)

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