Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 92: Poster Session: Structure and transport in organic photovoltaics; Photovoltaics; Impurities/Amorphous semiconductors; New materials
HL 92.2: Poster
Donnerstag, 14. März 2013, 16:00–20:00, Poster A
Morphology and interdiffusion in organic donor-acceptor blends studied by analytical TEM — •Diana Nanova1,2,4, Dominik Daume2,4, Levin Dieterle1,3,4, Martin Pfannmöller3,4, Rasmus R. Schröder3,4, and Wolfgang Kowalsky1,4 — 1Institute for High-Frequency Technology, TU Braunschweig, Germany — 2Kirchhoff-Institute for Physics, Heidelberg University, Germany — 3CellNetworks, BioQuant, Heidelberg University, Germany — 4InnovationLab GmbH, Heidelberg, Germany
We present a combined study of the morphology and its relation to function on model devices of organic solar cells. The device characteristics acquired from impedance spectroscopy are correlated with the microstructural properties, obtained from analytical TEM. We found a novel morphology of P3HT:PCBM by applying electron energy loss spectroscopy and electron spectroscopic imaging in the low energy loss region. We observed a mixed-phase at the interface between the PCBM-rich and P3HT-rich phase, which seems to be crucial for efficient charge separation. To study the phase separation kinetics at the donor-acceptor interface, planar heterojunction samples of P3HT/PCBM bi-layer assemblies were prepared and annealed at various temperatures. In order to investigate the formation of a composite phase at the bi-layer interface via TEM, we prepared cross-sections by different methods, e.g. FIB-milling. We observed a change in the interface structure due to recrystallization and interdiffusion during annealing. This process leads to changes in the capacitance of the bi-layer devices, which can be derived from the measured impedance spectra.