Berlin 2018 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 77: Organic Electronics and Photovoltaics - Transport and Doping
CPP 77.12: Talk
Friday, March 16, 2018, 12:45–13:00, C 243
Photoinduced Charge Carrier Transport at (001) Pentacene/Perfluoropentacene Crystal Interfaces — •Sebastian Hammer1 and Jens Pflaum1,2 — 1Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — 2Bavarian Center for Applied Energy Research (ZAE Bayern), 97074 Würzburg
Mixed Pentacene:Perfluoropentacene (P:PFP) thin films have been reported archetypical donor-acceptor heterojunctions for examining the optical characteristics of charge transfer states [1]. However, aiming for possible effects on charge carrier transport at P/PFP interfaces, thin film boundaries impose severe limitations and thus, require the examination of photoinduced effects on the interface conductivity by means of well-defined crystal surfaces. For this purpose, pentacene single crystals were grown by horizontal physical vapor deposition with the (001) orientation of the crystal surface being confirmed by X-ray diffraction. PFP layers of various thicknesses between 5 to 50 nm were evaporated on top of the (001) surface and their morphology was analyzed by complementary AFM and XRD measurements. Illuminating the (001) P/PFP interface with a 532 nm cw-laser we observed a pronounced increase of the interface conductivity by up to 50% with respect to the neat pentacene crystal depending on the PFP top layer thickness as well as on the electric field applied. Utilizing different illumination geometries and temperature dependent measurements we will discuss the origin of the conductivity increase and its relation to charge transfer states and injection effects.
[1] Anger, F., et. al., JCP 136, 054701 (2012)