Thin Films for Efficient Solar Driven Water Splitting and Water Electrolysis
(Room Room 104-A)
29 Apr 19
1:40 PM
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2:20 PM
Tracks:
Coatings for Energy Conversion and Related Processes
About half of the energy in the solar spectrum is in the IR region and results in a mismatch between the solar energy distribution and the energetic requirements for performing the full water splitting reaction. Very modest efficiencies have so far been achieved in single band gap devices where devices with multiple band gaps instead have been utilized for absorption of IR photons, improved photovoltage, and providing high efficient solar driven water splitting. Large scale applications of tandem approaches, however, are limited by the manufacturing complexity and have the same difficulties with cost-per-performance as the tandem approach in conventional PV-industry. Utilization of serial interconnected photo-absorber with a buried junction approach is an alternative and cost-effective solution to the spectral mismatch problem. Taking losses due to charge carrier separation and overpotential for catalysis into account, the maximum STH-efficiency for a series interconnected solar splitting device is 24.6 %, compared to 32.0 % for an optimum double junction tandem device at 1 sun (Air Mass 1.5, 1000 W/m2). Water splitting devices based on modified Cu-In-Ga-Se2 (CIGS) are presented and span all the way from classical photoelectrochemical cells (PECs) immersed in water to PV/PEC hybrid devices. The approach allows utilization of photons up to 1200 nm in the solar spectrum and converts this energy into solar fuel with 10% to 12.7 % solar-to-hydrogen (STH) efficiency. Results from varying Ga-contents in the CIGS thin films as well as surface coatings of Ni-Fe and Ni- Mo based catalysts for the hydrogen evolution and oxygen evolution reaction are presented and discussed in terms of their performance.