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Engineers let the sunshine in

A research team at The Ohio State University is working to bring readily available solar cells closer to the gold standard of efficiency. 

Tyler Grassman, assistant professor of materials science and engineering, and Steven Ringel, Neal Smith Endowed Chair and professor of electrical and computer engineering, will expand their efforts on a new type of high-efficiency solar cell — a silicon-based tandem cell — closer to commercialization using highly scalable manufacturing processes. 

Tandem, or multijunction, solar cells combine multiple semiconducting materials into a single device that’s able to subdivide and make more efficient use of the solar spectrum than single-junction, single-material devices.

Grassman and Ringel have already developed pioneering prototype cells that layer III-V compound semiconductors gallium indium phosphide (GaInP) or gallium arsenic phosphide (GaAsP) with silicon (Si). These silicon-based tandem solar cells combine the affordability and manufacturability of silicon with the exceptional efficiencies achievable with III-V elements.

The materials are produced and integrated together in a single process. Grassman and Ringel’s prototypes pave the way for solar cells that are significantly more efficient and affordable to produce than the current state-of-the-art III-V multijunction solar cells, which are used almost exclusively in the space industry, powering satellites and exploration spacecraft.

“The pure silicon cells typically found in photovoltaic solar panels convert only about 20% of the light that strikes through them into electricity,” Grassman said. “Our goal is to take silicon to the next level.”

The project will create a manufacturing process for silicon-based tandem cells with an efficiency of at least 30%, while still maintaining a commercially favorable cost structure. This combination of improved efficiency and economical manufacturing is key for ultimately reducing the cost of solar-generated electricity.

The project is part of an $11 million suite of projects funded by the Energy Department’s Office of Energy Efficiency and Renewable Energy intended to develop innovative, early-stage solutions in both photovoltaics and concentrating solar power. The Ohio State effort received $1.125 million. 

Grassman said he’s been an environmentalist and solar power enthusiast his whole life, but it took a while before it evolved into a career path. He began working on photovoltaics during his postdoctoral research at Ohio State. His concern for sustainability and his scholarly interests finally intersected with what he described as something that’s “both a really important topic and a difficult materials science challenge.”

Article via Ohio State Department of Materials Science Engineering