Harnessing solar energy to drive photoelectrochemical reactions is widely studied for sustainable fuel production and versatile energy storage over different timescales. However, the majority of solar photoelectrochemical cells cannot drive the overall photosynthesis reactions without the assistance of an external power source. A device for simultaneous and direct production of renewable fuels and electrical power from sunlight is now proposed. This hybrid photoelectrochemical and photovoltaic device allows tunable control over the branching ratio between two high-value products of solar energy conversion, requires relatively simple modification to existing photovoltaic technologies, and circumvents the photocurrent mismatches that lead to significant loss in tandem photoelectrochemical systems comprising chemically stable photoelectrodes. Our proof-of-concept device is based on a transition metal oxide photoanode monolithically integrated onto silicon that possesses both front- and backside photovoltaic junctions. This integrated assembly drives spontaneous overall water splitting with no external power source, while also producing electricity near the maximum power point of the backside photovoltaic junction. The concept that photogenerated charge carriers can be controllably directed to produce electricity and chemical fuel provides an opportunity to significantly increase the energy return on energy invested in solar fuels systems and can be adapted to a variety of architectures assembled from different materials.
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The data that support the findings within this paper are available from the corresponding author upon request.
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This material is based on work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the US Department of Energy under award no. DE-SC0004993. G.S. acknowledges support by the Israeli Ministry of National Infrastructure, Energy and Water Resources under the programme for post-doctoral fellowships.
The authors declare no competing interests.
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Segev, G., Beeman, J.W., Greenblatt, J.B. et al. Hybrid photoelectrochemical and photovoltaic cells for simultaneous production of chemical fuels and electrical power. Nature Mater 17, 1115–1121 (2018). https://doi.org/10.1038/s41563-018-0198-y