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D1.05 - Artificial Photosynthesis from a Silicon Based Monolithic PV/PEC Device 
April 22, 2014   9:45am - 10:00am

Hydrogenated amorphous silicon carbide (a-SiC:H) has shown promising activities as a photocathode for photoelectrochemical (PEC) water splitting. This material has many promising advantages for large-scale utilization since it is compromised entirely of earth abundant materials and can be fabricated in industrial processing techniques. Therefore, it is of paramount importance to identify and overcome the performance limitations for this material in order to address the global environmental and energy demands.One limitation for a-SiC:H photocathodes is the non-ideal alignment of the conduction and valence band edge positions. This requires a bias voltage to be applied to drive water splitting, which can be overcome by integrating a PV cell under the photocathode. The challenges for this PV/PEC integration require matching the Vop and Jsc of the PV cell with the Vonset and Jplateua of the photocathode, while at the same time managing the spectral utilization of the sun. To improve the PV matching with the PEC films, we have fabricated several unique single and tandem junction PV cells with both amorphous silicon and nano-crystalline silicon, showing enhanced current matching and performance.In addition, we have utilized several surface passivation techniques to reduce corrosion during the PEC testing. Using both ALD and RF sputtering depositions, we deposited thin transparent conducting layers on the surface of the a-SiC:H photocathode, which showed improved onset potentials, saturated photocurrent densities and enhanced stability.Finally, we have investigated various hydrogen evolution catalysts deposited on the passivated a-SiC:H photocathodes, showing significantly enhanced water splitting capabilities at reduced bias potentials. Electronic band diagrams have been developed to explain the activity (or non-activity) of different catalysts.Overall, we have been able to identify and address significant hurdles in the development a-SiC:H photocathodes for solar water splitting, and herein report our recent advances with regards to PV integration, surface passivation, and hydrogen evolution catalysis.

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Keynote Address
Panel Discussion - Different Approaches to Commercializing Materials Research
Business Challenges to Starting a Materials-Based Company
Fred Kavli Distinguished Lectureship in Nanoscience
Application of In-situ X-ray Absorption, Emission and Powder Diffraction Studies in Nanomaterials Research - From the Design of an In-situ Experiment to Data Analysis