Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Poster: Structural Ordering and Electronic Transport (joint focus with HL)

CPP 6.26: Poster

Montag, 26. März 2012, 17:30–19:30, Poster A

Modelling charge carrier dynamics in disordered semiconducting materials — •Jens Lorrmann¹, Julien Gorenflot¹, Vladimir Dyakonov^1,2, and Carsten Deibel¹ — ¹Experimental Physics VI, Julius Maximilian University of Würzburg, D-97074 Würzburg — ²Bavarian Center for Applied Energy Research e.V. (ZAE Bayern e.V.), Würzburg

Organic semiconductors are promising candidates for low cost electronic applications, i.e. organic solar cells or organic light emitting diodes. Their performance is now approaching market maturity. But still there is little known about the impact of energetic and spatial disorder present in these materials, on the charge carrier dynamics and thus on the performance. To gain further insight, we developed a time dependent multiple trapping and release model to track the fate of electrons and holes hopping in a gaussian or exponential density of sates (DOS). The tail states of the DOS act as trap-states, where as the charge carriers move freely above the transport energy with a temperature dependent mobility. We show how disorder influence thermalization, non-geminate recombination and transport. For instance the recombination rate strongly increases with increasing energetic disorder or decreasing temperature, which reproduces the experimentally observed deviations from the Langevin theory [1]. Furthermore, the model is capable to describe temperature dependent transient absorption measurements on poly(3-hexyl thiophene-2,5-diyl) (P3HT) blended with [6,6]-phenyl-C₆₁ butyric acid methyl ester (PCBM).
[1] P. Langevin, Ann. Chim. Phys. 28, 433, 1903.