Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 44: Organic Thin Films I

DS 44.3: Talk

Friday, March 26, 2010, 10:45–11:00, H8

In-situ Photoconduction Measurements of Mixed Films to Detect Isolated Clusters of Molecular Semiconductors — •Dominik Klaus, Christopher Keil, and Derck Schlettwein — Institute of Applied Physics, Justus-Liebig-University Giessen, Germany. email:schlettwein@uni-giessen.de

A cone-shaped subphthalocyanine (SubPcBCl) absorbing in the green was used as an electron donor and a planar perfluorinated phthalocyanine (F₁₆PcCu) absorbing in the red as an electron acceptor to discuss their applicability as a photosensitive material. Mixed thin films (60 nm) of increasing contents of SubPcBCl were studied that were prepared by physical vapour deposition on electrode structures on glass. Conduction measurements were performed under illumination at three distinct wavelengths across the visible range of the solar spectrum during growth and conditioning of the films. Photocurrents were observed that indicated the expected contributions to the net photoconduction of both molecules but also anomal, negative contributions were found, leading to a decreased conduction under illumination, showing the presence of isolated clusters for films rich in SubPcBCl. This behaviour indicates a light-induced trapping of electrons in insulating pockets under illumination with green and blue light.