Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 65: Poster: Organic electronics and photovoltaics (CPP; jointly with HL, O)
HL 65.12: Poster
Mittwoch, 13. März 2013, 16:30–18:30, Poster C
Surface Structure of organic solar cells based on PBDTTT-C and PC70BM — •Mario Zerson1, Andreas Zusan2, Carsten Deibel2, and Robert Magerle1 — 1Chemische Physik, Technische Universität Chemnitz, Chemnitz, Germany — 2Experimental Physics VI, Julius-Maximilians-University of Würzburg, Würzburg, Germany
We study the surface structure of organic heterojunction solar cells based on blends of poly[4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3, 4-b]thiophene))-2,6-diyl] (PBDTTT-C) and Phenyl-C70-butyric acid methyl ester (PC70BM) with a weight ratio of 1:1,5. The additive diiodooctane (DIO) is used with ratios between 0% and 10% to increase the compatibility of the two components. We investigate the surface structure of the devices with amplitude modulation atomic force microscopy (AFM). Conventional AFM height and phase images are complemented with data obtained from maps of amplitude-phase-distance (APD) curves. This allows us to determine the unperturbed (true) surface and the mechanical properties of the soft surface layer of the specimen. The AFM height and phase images of PBDTTT-C:PC70BM blends produced with different ratio of DIO indicate, that the additive plays a fundamental role in the structure formation process. Blends with DIO ratios between 1,8% and 5% show the best power conversion efficiency (PCE) up to 6,9%. We discuss the structure and the structure of the interface between donor and acceptor components in view of their impact on charge carrier dynamics and solar cell performance.