Dresden 2014 – scientific programme
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DS: Fachverband Dünne Schichten
DS 13: Organic semiconductors: Photovoltaics (Jointly with HL, CPP)
DS 13.5: Talk
Tuesday, April 1, 2014, 11:00–11:15, POT 081
Imaging the origin of S-shaped current-voltage characteristics of organic solar cells by scanning Kelvin probe microscopy — •Christian Müller1,2,3, Rebecca Saive1,2,3, Janusz Schinke1,3, Robert Lovrincic1,3, and Wolfgang Kowalsky1,2,3 — 1InnovationLab GmbH, Heidelberg, Germany — 2Kirchhoff-Institut für Physik, University Heidelberg, Germany — 3Institut für Hochfrequenztechnik, Technische Universität Braunschweig, Germany
We investigated organic bilayer solar cells consisting of poly(3-hexylthiophene)/1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 (P3HT/PCBM). Scanning Kelvin probe microscopy (SKPM) was performed on the solar cell cross sections which were exposed with a focused ion beam. We prepared the P3HT/PCBM bilayer solar cells by solution processing. These bilayer solar cells showed normal and anomalous, S-shaped current-voltage characteristics. Using SKPM on the device cross sections, we found that in normal bilayer solar cells the potential dropped at the ITO/PEDOT:PSS contact and over the active area, whereas in S-shaped bilayer solar cells the potential dropped exclusively at the aluminium contact. This behavior confirms the assumption that S-shaped curves are caused by hindered charge transport at electrode interfaces.