Regensburg 2013 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Focus Session: Thin Film Photovoltaic Materials and Solar Cells I

DS 17.3: Topical Talk

Wednesday, March 13, 2013, 10:30–11:00, H32

Photoelectrochemical Water Splitting with Complex Metal Oxides: the Role of Defects — •Roel van de Krol — Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany

Transition metal oxides are promising candidates for the conversion of solar energy to chemical fuels. They combine reasonable semiconducting properties with excellent chemical stability and low cost. As such, they can bridge the gap between conventional PV semiconductors and molecular/biological systems. Although exciting progress has been made in the past 5 years on e.g. Fe2O3 and Cu2O, further improvement of these binary oxides is severely hampered by intrinsic materials limitations. To broaden the scope of suitable materials, research efforts are currently shifting towards multinary (complex) oxides such as InVO4 and BiVO4. In InVO4, ionic point defects are found to enhance the visible light absorption, but they also cause extensive recombination. In contrast, BiVO4 is found to be a much more defect-tolerant material, showing internal QEs above 90% when prepared with a low-cost spray pyrolysis technique. We will discuss how photo-electrochemical measurements can be used to determine the performance-limiting factors in this material. This provide valuable guidelines to improve the photoresponse, resulting in a stand-alone water splitting device based on a BiVO4 photoanode and a thin film double-junction a-Si cell with a solar-to-hydrogen efficiency of 4.3%.