Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 23: POSTER Functional Organic Thin Films
CPP 23.15: Poster
Donnerstag, 30. März 2006, 17:00–19:00, P2
Field-Effect Mobility in n-doped C60 Thin Films: Dependency on Gate Bias and Temperature — •Kentaro Harada1, Fenghong Li1, Martin Pfeiffer1, Ansgar G. Werner2, and Karl Leo1 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden, Germany — 2Novaled GmbH, Tatzberg 49, 01307 Dresden, Germany
We study the gate bias and temperature dependence of field-effect mobility in n-doped C60 thin films with different doping concentrations of Acridine Orange Base (AOB, C17H19N3). The n-doping of AOB enhances the bulk conductivity of C60, whereas the application of a gate bias leads to an increase of transverse conductance between source and drain. For a heavily doped C60 sample, the field-effect mobility has already reached its maximum without gate bias, and an increase of the gate bias does not give a contribution to the mobility at all. Yet, an elevation of temperature from 180 K to 340 K does give rise to the activation of the field-effect mobility until a clear transition to the saturation regime appears around 270 K; thereafter the mobility stays nearly constant at 0.13 cm2/Vs. On the other hand, for a lightly doped sample, the field-effect mobility is gate bias dependent within the measured bias and temperature range, indicating that both the field induced and the thermally activated carrier density play a role in mobility enhancement. We discuss these phenomena in accordance with the trap-filling models that have been proposed to explain the charge transport mechanism in organic materials.