Regensburg 2002 – wissenschaftliches Programm

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SYOH: Organische Halbleiter

SYOH 7: Poster

SYOH 7.30: Poster

Montag, 11. März 2002, 18:00–21:00, C

Transport kinetics in polymers with polarons and bipolarons forming complexes with counter ions — •Gernot Paasch — IFW Dresden

Additional charges on chains of doped polymers do occur not only as polarons but also as bipolarons. In contrast to experimental evidence of bipolarons in doped polymers, properties of organic devices are usually dicussed by ignoring bipolarons in most cases. Among the exceptions is a scenario discussed by Kirova and Brazovskii [1]. They supposed the formation of different complexes of polarons and bipolarons with counterions and suggested that the kinetics of the formation processes will be responsible e.g. for observed hysteresis effects. Recently, the small signal ac transport description for polarons and counter ions has been extended to include steady-state effects and traps [2] and further to account for the direct polaron-bipolaron reaction [3]. In contrast to the direct polaron-bipolaron reaction in the full Kirova-Brazovskii scenario there do occur also complexes of polarons or bipolarons with counter ions which are neutral. The resulting small signal ac equations are presented and conditions are analyzed under which such complex formation processes can be important in devices.

[1] N. Kirova, S. Brazovskii, Synthetic Metals 76 (1996) 229

[2] G. Paasch, Electrochemistry Communications 2 (2000) 37

[3] G. Paasch, S. Scheinert, to be published