Modeling and practical realization of thin film silicon-based integrated solar water splitting devices

• Published in: Physica status solidi. A, Applications and materials science Vol. 213; no. 7; pp. 1738 - 1746
• Main Authors: Becker, Jan-Philipp, Urbain, Félix, Smirnov, Vladimir, Rau, Uwe, Ziegler, Jürgen, Kaiser, Bernhard, Jaegermann, Wolfram, Finger, Friedhelm
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.07.2016; Wiley Subscription Services, Inc
• Subjects: Catalysis; Catalysts; Devices; Evolution; Mathematical models; Oxygen; Photocathodes; Photovoltaic cells; silicon; Silicon wafers; Solar cells; solar fuels; Thin films; water splitting
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201533025

An integrated solar water splitting device based on thin film silicon multijunction photocathodes is presented. A graphical representation of the photovoltaic current–voltage data is introduced which allows for an estimation of the maximum achievable solar‐to‐hydrogen efficiency of the integrated device. Furthermore, a simple yet very useful series circuit model is used to predict the photoelectrochemical performance of the integrated device in a more elaborate way when the j–V characteristics of the individual components are known. Within the model, the j–V characteristics of each component can be either modeled with parameters from the literature or measured. The photocathode, the electrolyte concentration, and the hydrogen and oxygen evolving catalysts were varied exemplarily and the impact of each component on the integrated device performance was evaluated. A maximum solar‐to‐hydrogen efficiency of 9.5% was found using a triple junction solar cell functionalized with a Pt catalyst for the hydrogen evolution and a RuO2 catalyst for the oxygen evolution reaction in a 1 M KOH electrolyte. This result was confirmed experimentally and is compared to efficiencies reported in the literature.