Use of Quantum Engineering Increases Tandem Solar Cells’ Conversion Efficiency by Nearly 50%

Achievement date: 
2016
Outcome/accomplishment: 

Researchers at the NSF-funded Quantum Energy and Sustainable Solar Technologies (QESST) Engineering Research Center (ERC) have designed a tandem cell conversion device using dilute nitrogen alloys that improves practical solar energy conversion efficiencies by 44 percent.

Impact/benefits: 

The tandem solar cell conversion device allows for a near-ideal conversion of sunlight into electricity. By integrating these tandem solar cell configurations into other devices, engineers can achieve practical power conversion efficiencies of close to 50% from a renewable energy source. 

Explanation/Background: 

Tandem devices based on III-V semiconductors have shown excellent promise for boosting solar cell conversion efficiencies. Led by Dr. Alex Freundlich from the University of Houston, QESST researchers have designed a breakthrough device that uses a bottom subcell made with dilute nitrogen alloys of these semiconductors in a 3-cell series-connected tandem configuration. By incorporating these sets of carefully crafted ultra-thin nanostructures – resonantly coupled multi-quantum wells – of dilute nitrides, the team has demonstrated 1.05 and 1.25 electronvolt (eV) devices with open circuit voltages that significantly exceed prior practical solar conversion efficiencies to the range of 44 percent. Until now, relatively poor open-circuit voltages associated with dilute nitride solar cells have limited access to higher efficiencies in this material system.