Dresden 2017 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 31: Organic Electronics and Photovoltaics III: Mobile and Trapped Charges
HL 31.1: Talk
Tuesday, March 21, 2017, 09:30–09:45, ZEU 260
A Kelvin-Probe study of the electrical transport in organic semiconductors — •Karl-Philipp Strunk1, Valeria Milotti1, Alexander Ullrich2, and Christian Melzer1 — 1Centre for Advanced Materials, University of Heidelberg, Germany — 2Chemiches Institut, Universität of Heidelberg, Germany
DC current-voltage measurements on organic field-effect transistors (organic FET or OFET) are commonly used to characterize the planar electrical transport in organic semiconductors. In this study we report an alternative AC dark-injection method giving likewise access to in-plane transport parameters of organic semiconductor thin films. Exposing a macroscopic FET-like structure to a periodic bias leads to a periodic change in surface potential which can be tracked via a Kelvin-Probe giving direct insight into the movement of lateral charge-carrier waves along the organic film. Tracking the temporal evolution of the surface potential distribution allows for the determination of the charge-carrier mobility at low currents, a regime which is conventionally hardly accessible. It will be shown that this regime allows for a mobility determination at P3HT based devices fairly independent on contact properties. In order to elucidate the influences of electrical properties like doping concentration, traps states and injection barriers on the device response, time-dependent finite-element simulations have been carried out.