Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 55: Photovoltaics: mainly Technology and Photon Management
HL 55.12: Talk
Wednesday, March 16, 2011, 17:30–17:45, FOE Anorg
Defect and charge transfer studies on hybrid solar cells with silicon nanocrystals — •Sabrina Niesar1, Daniel Herrmann2, Wolfgang Fabian1, Nadine Erhard1, Andre Stegner1, Rui Pereira3, Hartmut Wiggers4, Martin Brandt1, Eberhard Riedle2, and Martin Stutzmann1 — 1Walter Schottky Institut, Technische Universität München, 85748 Garching — 2Ludwig-Maximilians-Universität München, 80538 München — 3University of Aveiro, 3810-193 Aveiro, Portugal — 4Institut für Verbrennung und Gasdynamik, Universität Duisburg-Essen, 47057 Duisburg
Hybrid inorganic nanoparticle-polymer solar cells are a promising alternative to purely organic devices due to the broad spectral range of absorption of the inorganic material. In this work, a combination of P3HT and silicon nanocrystals (Si-ncs), which are synthesized in a microwave plasma reactor, is studied. In particular, we focus on methods to decrease the concentration of silicon dangling bond defects which negatively affect the electronic properties of the hybrid solar cells. HF etching in combination with vacuum annealing at 200°C leads to the lowest defect densities. Conductivity measurements in vacuum show that the defect reduction results in improved electrical properties of Si-nc thin films. Electron paramagnetic resonance and Fourier transform infrared spectroscopy are used to study the stability of the different post-growth treatments. The charge transfer across the organic-inorganic interface is investigated via broadband-femtosecond optical pump-probe spectroscopy. We find that the addition of the Si-ncs leads to an increase of the charge separation as compared to pure P3HT.