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Passivating Window and Capping Layers for Improved Photoelectrochemical (PEC) Efficiency and Durability

National Renewable Energy Laboratory

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Technology Marketing Summary

Hydrogen is a clean burning fuel that has been proposed as a substitute for gasoline in the transportation sector, as well as an important feedstock for ammonia fertilizers essential to the global fuel supply. Research firm Markets and Markets expects the global market for hydrogen generation to reach over $154.74 Billion by 2022, growing at a CAGR of 6.07% over the forecast period. Unfortunately, the current process which dominates hydrogen generation converts fossil fuels into hydrogen and releases significant amounts of carbon dioxide (CO2) and other greenhouse gases. In order for hydrogen to become a truly clean technology new methods of generation must be found. One promising early stage solution is the splitting of water into hydrogen and oxygen using solar energy from semiconductor cells.


Researchers at NREL have created a novel photoelectrochemical (PEC) cell which converts solar energy to stored energy in hydrogen bonds at an unprecedented efficiency of 16%. The device uses another NREL invention, the inverted metamorphic multijunction (IMM) cell, optimized for water-splitting to achieve the record efficiency. The use of an IMM cell with a transparent graded buffer allowed the researchers to vary the cell junction bandgaps independently to generate a higher photocurrent, which correlates directly with water-splitting conversion efficiency. This new high efficiency cell can reduce balance of system costs to make hydrogen production via PEC pathways more economic.

  • Emission-free hydrogen production
  • Storable solar energy
Applications and Industries
  • Hydrogen production
  • Hydrogen powered transportation
  • Hydrogen fuel cells
  • Fertilizer and agriculture
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Application 20180051379
An aspect of the present disclosure is a photoelectrochemical device that includes a first cell that includes a first semiconductor alloy, a capping layer that includes a second semiconductor alloy, and a passivating layer that includes a third semiconductor alloy, where the passivating layer is positioned between the first cell and the capping layer, and at least a portion of the capping layer is configured to be in direct contact with an electrolyte.
National Renewable Energy Laboratory 08/15/2017
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
NREL ROI 16-114, 14-37PrototypeAvailable08/23/201708/23/2017

Contact NREL About This Technology

To: Bill Hadley<>