College of Engineering
Researchers believe the patent-pending technology could dramatically reduce solar energy material costs. [View Image]
Researchers believe the patent-pending technology could dramatically reduce solar energy material costs.

VCU invention improves solar cell light harvesting

Researchers believe the patent-pending technology could dramatically reduce solar energy material costs.

Researchers at Virginia Commonwealth University have developed a new material they believe could deliver solar energy at a lower cost. The innovation harvests sunlight using a more affordable material that could address a long-standing barrier to solar power’s viability as a cost-efficient energy source.

Current solar-cell technology features thick layers of light-absorbing material (silicon or germanium) to improve light-matter interactions. It absorbs light poorly as a consequence of using a method known as “indirect-energy gap semi-conduction.” The cost of this traditional silicon-based approach multiplies in order to use enough material to scale the collection of light for conversion into power.

Seeking to make absorption more efficient — and reduce the amount of material to gather and transport light — researchers in VCU’s College of Humanities and Sciences and College of Engineering produced a direct-energy gap solar absorber in place of traditional indirect-gap silicon and germanium solar cells currently available.

Using direct-energy gaps and unique advantages of nanomaterials’ design/fabrication, this innovation enables solar energy to be more efficient than current photovoltaics — and more competitive with fossil fuels.

“Unlike indirect-energy gaps, which require a photon and a phonon, these direct-energy gaps only require a photon. This allows for significantly higher absorption cross-section in the visible to near [infrared] spectrum,” said Indika Arachchige, Ph.D., associate professor in the Department of Chemistry. “The technology is also compatible with existing silicon electronics. With these two advantages, this invention provides a low-cost solution that greatly increases efficiency.”

Arachchige invented the technology alongside Denis Demchenko, Ph.D., associate professor in the Department of Physics; Venkatesham Tallapally, Ph.D., in the Department of Chemistry; Ümit Özgür, Ph.D., professor in the Department of Electrical and Computer Engineering; and Tanner Nakagawara in the College of Engineering.

“The benefits of this material are significant both technologically and economically,” said Brent Fagg, technology manager at VCU Innovation Gateway. “Our research team discovered the nanostructure of the material could be tuned, so the absorption and emission profiles meet the needs of any desired technology, including solar cells, light-emitting diodes and optical sensors. The overall effect is an increased conversion rate of solar to electric, coupled with a reduced cost of solar energy.”

For more information, contact Brent Fagg, technology manager with VCU Innovation Gateway, at or (804) 827-2211.

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