Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 26: Organic-inorganic hybrid systems and organic films III

O 26.10: Talk

Tuesday, March 13, 2018, 12:45–13:00, MA 042

Protoporphyrin IX functionalized GaN surfaces as a model system for photocatalytic hybrid devices — Felix Eckmann, •Jennifer Padberg, and Martin Stutzmann — Walter Schottky Institut und Physik-Department, Technische Universität München, Am Coulombwall 4, 85748 Garching

Efficient photocatalytic conversion of carbon dioxide into solar fuels constitutes an attractive option to reduce the problem of energy storage present in today's renewable energy technology. Although extensive research efforts have already been made, the conversion efficiencies and long-term stability of current devices are still far from feasible for large scale applications. In the current work, gallium nitride surfaces functionalized with protoporphyrin IX self-assembled monolayers are investigated as a model system to gain insights into future photocatalytic devices using similar functionalized surfaces. Sulfo-NHS activated protoporphyrin IX monolayers were created by adsorption from solution or by Langmuir-Blodgett deposition onto aminopropyltriethoxysilane-functionalized gallium nitride surfaces in order to create a chemisorbed monolayer. Thermally programmed desorption studies are carried out to gain information on the binding energy of the molecules on the surface. Polarized FTIR and AFM studies give indications on molecule orientation and layer morphology. Additionally, fluorescence spectroscopy and optical absorption spectroscopy highlight the changing optical properties accompanied by the transition from solved molecules to a chemisorbed solid monolayer.