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| Home > Publications database > Efficient multijunction thin film silicon based photocathodes for hydrogen production via photoelectrochemical water splitting |
| Conference Presentation (Other) | FZJ-2015-03193 |
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2015
Abstract: We report on the application of multijunction thin film silicon based photocathodes for solar water splitting. Multijunction solar cells allow for high photovoltages, well above the thermodynamically required 1.23 V to drive the oxygen and hydrogen evolution reactions. However, the use of such solar cells in integrated water splitting devices imposes considerable challenges, in particular at the solar cell/electrolyte interface concerning catalysis and chemical stability. In this regard, we integrate different metal layers at the solar cell/electrolyte interface and evaluate their catalytic and stability properties.The performance of the photocathodes, with respect to photocurrent densities and onset potentials for cathodic current were evaluated in a 3-electrode configuration. By using tandem, triple and quadruple junction photocathodes, the onset potentials can be tuned between 1.3 V and 2.5 V vs. RHE. We demonstrate, that the high excess-voltage allows for the substitution of precious metal catalysts, like platinum, by more abundant materials, like nickel, without impairing the device performance. The ability to provide self-contained solar water splitting over a prolonged period of time is demonstrated in a 2-electrode configuration with an impressive solar-to-hydrogen efficiency of 8.6 %.Modeling the current-voltage characteristics of the water splitting device shows good agreement with experimental results and allows for an analysis of the relevant system losses.
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