New approach stacks up for multi-junction solar cells

This is the claim of researchers from North Carolina State University (NC State) whose proof-of-concept paper - A New Approach for Multi-Junction Solar Cells from Off-the-Shelf Individual Cells: GaAs/Si - was presented on June 19 at the IEEE Photostatic Specialist Meeting in Chicago.

Multi-junction solar cells – which convert up to 45 per cent of the solar energy they absorb into electricity - are made by stacking semiconductors with varying bandgaps on top of one another. This allows cells to absorb differing wavelengths of solar radiation but makes them more expensive to produce than less efficient thin solar films.

“We want to create high-efficiency solar cells at a reasonable cost,” said Salah Bedair, Distinguished Professor of Electrical and Computer Engineering at NC State and lead author of the research. “Silicon-based thin solar cells are very popular because the material has around 20 per cent efficiency and the cells cost about 1/10^th what a multi-junction solar cell costs. And other low cost, lower efficiency materials are gaining popularity as well. If we could create stacked solar cells using this existing technology we would be well on our way to reaching our goal.”