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 6.27: Poster
Montag, 26. März 2012, 17:30–19:30, Poster A
Influence of Polarization on the Energy Landscape for Charge Transport in Organic Electronic Materials — •Falk May1, Björn Baumeier1, Denis Andrienko1, and Christian Lennartz2 — 1Max Planck Institute for Polymer Research, Mainz, Germany — 2BASF SE, GVC/E - B009, Ludwigshafen, Germany
Design of organic semiconductors for particular applications requires knowledge of the distribution of energy levels participating in charge transport. These levels are often approximated by EA/IP of single molecules in vacuum, while effects of the environment (broadening, shifts) are taken into account phenomenologically, using simple dielectric cavity or lattice models. Using a representative host-guest system of the active layer of an organic light emitting diode, we show that these approximations can be incompatible with the microscopic evaluation of site energy disorder in realistic morphologies. In a particular case of electron transport, microscopic polarization effects do not reduce the energetic disorder arising from static Coulomb interactions, in contradiction to the predictions of lattice models. Inclusion of polarization effects also leads to a relative shift of the guest and host distributions, which again cannot be rationalized within mesoscopic descriptions. Both effects lead to a strong overlap of site energy distributions and hence affect electron transport dynamics and the current distribution in the host-guest mixture.