High-Efficiency Tandem Absorbers for Economical Solar Hydrogen Production

Research output: NRELPresentation


The objective of this project is to develop a semiconductor-based device capable of over 20% solar-to-hydrogen efficiency with several thousand hours of stability under operating conditions. The ultimate system design will incorporate electrode components that can be fabricated cost-effectively and do not present a barrier to scale-up. Solar-to-hydrogen efficiency will be improved from our world-record holding 12.4% to over 20% by developing novel tandem semiconductor materials and configurations. Our approach focuses on classes of materials that have either demonstrated exceptionally high efficiency or theoretically can produce highly efficient materials. The four tandem-material approaches we will take are: III-Vs on GaAs, InGaN on Si, III-V-N on Si, and dual photoelectrode pairings. Durability will be enhanced from a few hundred hours to nearly 1000 hours, with a stretch target of 3500 hours, through catalytic nitride, oxide, and sulfide-based semiconductor surface modifications. Economical hydrogen production is attainable using high-efficiency III-V photoelectrochemical materials with cost reductions from emerging epitaxial synthesis technologies such as spalling, epitaxial lift-off, or close-space vapor transport. We will address synthesis cost, in a limited capacity, by investigating novel material configurations. The expected outcome is a prototype photoreactor that produces 3 L of standard hydrogen within an 8-hour period under moderate solar concentration (10x), which can be accomplished using only 6 cm2 of a 20% STH material. Inputting attainable performance metrics from our approach into the H2A Central Production Model 3.0 shows a clear pathway to hydrogen production cost of <$2/gge.
Original languageAmerican English
Number of pages29
StatePublished - 2017

Publication series

NamePresented at the U.S. Department of Energy Hydrogen and Fuel Cells Program 2017 Annual Merit Review and Peer Evaluation Meeting, 5-9 June 2017, Washington, D.C.

NREL Publication Number

  • NREL/PR-5900-68489


  • epitaxial synthesis technologies
  • hydrogen
  • photoelectrochemical water spitting


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