Hamburg 2001 – scientific programme

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HL: Halbleiterphysik

HL 31: Organische Halbleiter

HL 31.1: Talk

Thursday, March 29, 2001, 11:45–12:00, S16

Non-equilibrium description of organic devices with polarons and bipolarons as charge carriers — •Gernot Paasch — IFW Dresden

Additional electrons and holes do occur on polymer chains as polarons and bipolarons. But in analyzing devices (OLED, OFET) usually only polarons are taken into account. Only recently we presented the theoretical equilibrium description of space charge layers in such devices both for the non-degenerate limit [1] and the general case [2] which includes the limit of high concentration (as in accumulation layers) considering the formation of the bipolaron lattice. Here, at first for the non-degenerate case, a general formulation of the basic equations is developed for the non-equilibrium behaviour of devices based on such materials. In particular, it is taken into account that in the transient behaviour not only the space charge layer is changed as a whole but that there takes place a redistribution between polarons and bipolarons by the formation of a bipolaron from two polarons or by the decay of the bipolaron into polarons. Possibilities of the numerical realization are discussed and qualitative conclusions are drawn.

[1] G. Paasch, P.H. Nguyen, S.-L. Drechsler, Synth. Met. 97 (1998) 255

[2] G. Paasch, P.H. Nguyen, S.-L. Drechsler, J. Malek, Synth. Met. 104 (1999) 197