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HL: Fachverband Halbleiterphysik

HL 64: Poster: Photovoltaics and Optics

HL 64.21: Poster

Mittwoch, 22. März 2017, 15:00–19:00, P1C

Charge carrier mobility in fullerene-blended squaraine thin films and the impact of correct layer thickness determination — •Majvor Mack¹, Matthias Schulz², Arne Lützen², and Manuela Schiek¹ — ¹Energy and Semiconductor Research Laboratory, Institute of Physics, University of Oldenburg, D-26111 Oldenburg, Germany — ²Kekulé Institute for Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany

Squaraine-based solar cells suffer from a low fill factor which leads to a small efficiency. A possible reason for this could be the built up of space charges due to imbalanced hole and electron mobility. To address this issue, the mobility is determined from I-V-measurements of single carrier devices, which follow the Mott-Gurney law for space-charge-limited current (SCLC). Under these circumstances the current has a quadratic dependence of the voltage and an inversely cubic dependence of the organic layer thickness. Thus, the determination of the layer thickness is important. Two methods for the thickness measurement are opposed: atomic force microscopy (AFM) as a tactile method and spectroscopic ellipsometry (SE) as contactless, optical method. Topographic AFM images across scratches in the organic film are evaluated with the software Gwyddion and compared to the result obtained by modeling and fitting of ellipsometric data with the software WVASE32.