Quantum Wells Enable Record-Efficiency Two-Junction Solar Cell
With a Sandwich of 80 Ultrathin Quantum Well Layers, New Solar Cell Unlocks World Record and a Path to Further Improvements
Researchers from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and the University of New South Wales achieved a new world-record efficiency for two-junction solar cells, creating a cell with two light-absorbing layers that converts 32.9% of sunlight into electricity.
Key to the cell’s design is a series of more than 150 ultrathin layers of alternating semiconductors that create quantum wells in the cell’s bottom absorber, allowing it to capture energy from a key range of the solar spectrum. While the new record only improves modestly on the previous 32.8% efficiency record, it is the first record-efficiency multijunction solar cell to use a strain-balanced structure—a design that holds promise for further improvements.