Berlin 2005 – scientific programme

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SYOO: Organic Optoelectronics and Photonics

SYOO 2: Optoelectronic Properties

SYOO 2.4: Talk

Monday, March 7, 2005, 12:15–12:30, TU C130

Kelvin Probe Force Microscopy on Plastic Solar Cells — •Harald Hoppe¹, Thilo Glatzel², Michael Niggemann³, Andreas Hinsch³, Martha Ch. Lux-Steiner², and N. Serdar Sariciftci¹ — ¹Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz, Austria — ²Hahn-Meitner Institut, Glienicker Strasse 100, 14109 Berlin, Germany — ³Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstr. 2, D-79110 Freiburg, Germany

A comprehensive Kelvin probe force microscopy (KPFM) study in ultrahigh vacuum (UHV) has been performed on bulk heterojunction solar cells based on MDMO-PPV:PCBM (poly-[2-(3,7-dimethyloctyloxy)-5-methyloxy]-para-phenylene-vinylene: 1-(3-methoxycarbonyl) propyl-1-phenyl [6,6]C61) blends. The KPFM method yields both, topography and local work function at the nanometer scale. Experiments were performed under UHV conditions to extract absolute work function values of the different surfaces and were conducted either in the dark or with cw-laser illumination to get detailed information on the photoactivity of the films. We found considerable differences in the energetics on the surface of chlorobenzene and toluene cast blend films. We were able to interpret the KPFM results together with high resolution scanning electron microscopy (SEM) experiments. The results indicate a morphological hindrance for electron propagation towards the cathode in the case of toluene cast films.