This title appears in the Scientific Report :
2014
Silicon thin film photoelectrodes for efficient hydrogen production: Interface design and corrosion stability
Silicon thin film photoelectrodes for efficient hydrogen production: Interface design and corrosion stability
This contribution focuses on the utilization of thin film Si tandem junction photocathodes for the application in an integrated photoelectrochemical water splitting device. Silicon based thin film technology presents a promising pathway to sustainable solar hydrogen production due to its earth abund...
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Personal Name(s): | Becker, Jan Philipp (Corresponding Author) |
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Urbain, Felix / Smirnov, Vladimir / Rau, Uwe / Ziegler, Jürgen / Kaiser, Bernhard / Jaegermann, Wolfram / Finger, Friedhelm | |
Contributing Institute: |
Photovoltaik; IEK-5 |
Published in: | 2014 |
Imprint: |
2014
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Conference: | 20th International Conference on Conversion and Storage of Solar Energy, Berlin (Germany), 2014-07-27 - 2014-08-01 |
Document Type: |
Conference Presentation |
Research Program: |
Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) Thin Film Photovoltaics |
Publikationsportal JuSER |
This contribution focuses on the utilization of thin film Si tandem junction photocathodes for the application in an integrated photoelectrochemical water splitting device. Silicon based thin film technology presents a promising pathway to sustainable solar hydrogen production due to its earth abundance, low cost, and non-toxicity. The combination of amorphous hydrogenated Si (a-Si:H) and microcrystalline Si (µc-Si:H) thin films in tandem junction devices allows for the efficient utilization of the solar spectrum and the generation of a voltage well above 1.23 V which is the thermodynamic potential to drive the oxygen and hydrogen evolution reactions. The band gap of the light harvesting layers can be continuously adjusted by tuning the plasma enhanced chemical vapor deposition (PECVD) process. Optimized a-Si:H/µc-Si:H and a-Si:H/a-Si:H tandem solar cells with photovoltaic efficiencies of η > 10% and open circuit voltages Voc in the range between 1.4 V and 1.9 V are used within this study. Their performance as photocathodes is evaluated in a photoelectrochemical 3-electrode setup by means of voltammetric and galvanometric measurements. A metallic layer at the solid/electrolyte interface between the solar cell and the electrolyte was implemented for multiple purposes: (i) it functions as a back reflector for transmitted photons and thereby increases the probability of photon absorption and charge carrier generation which enhances the photo current of the device, (ii) it forms a good electronic contact to the silicon semiconductor and provides an efficient charge transfer at the solid/electrolyte interface, (iii) it protects the silicon solar cell against corrosion, and (iv) it can provide catalytic activity and thus lowers the overpotential for hydrogen evolution. Considering this broad range of demands, care has to be taken when it comes to choosing the right candidates. Here, we systematically evaluate thin layers (approx. 250 nm) of Cr, Ti, Pd, Ni, Ag and Pt on glass substrates as well as attached to the photocathodes with regards to their electrochemical stability and catalytic activity. All films were deposited by electron beam evaporation. The electrochemical experiments were conducted in acidic and alkaline solutions (sulfuric acid and potassium hydroxide, respectively) because both the stability against corrosion and the catalytic activity depend on the pH of the used electrolyte. |