Regensburg 2019 – scientific programme
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O: Fachverband Oberflächenphysik
O 60: Organic Molecules on Inorganic Substrates IV: Electronic Properties, Excitations, Dynamics
O 60.6: Talk
Wednesday, April 3, 2019, 16:15–16:30, H24
Adsorption of phosphonate functionalized porphyrin molecules on TiO2(110) surfaces — Cynthia Fernandez1, Daniel Weschler2, Hans-Peter Steinrück2, Ole Lytken2, and •Federico Williams1,2 — 1Departamento de Química Inorgánica, Analítica y Química Física, Universidad de Buenos Aires, Argentina — 2Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Erlangen, Germany
Solar energy technologies including dye-sensitized solar cells and water-splitting photoelectrochemical cells are constructed linking chromophores to semiconductor surfaces. Promising systems are based on porphyrins bonded to TiO2 surfaces. One of the critical factors affecting device performance is the molecular adsorption geometry. Therefore, fundamental research studying the interaction of porphyrins with TiO2 surfaces is important. Here, we studied the bonding and adsorption geometry of tetraphenyl porphyrin molecules containing one or four phosphonate groups. The investigation was carried out by means of synchrotron radiation X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) measurements. Our results show that the number of linker groups have a great influence on the adsorption geometry. Molecules with one phosphonate group adsorb with the macrocycle tilted away from the surface whereas molecules with four phosphonate groups adsorb with the macrocycle close to the surface. This is an important finding for the design of dye-sensitized solar and photoelectrochemical cells. This project is supported by the DFG through FOR 1878 (funCOS).