The route to cleaner e-cars - coupling perovskite solar cells

August 28, 2015 // By Paul Buckley
Researchers at Case Western Reserve University have wired four perovskite solar cells in series to enhance the voltage and directly photo-charged lithium batteries with 7.8 percent efficiency which the researchers believe is the most efficient reported to date.

The research, published in the Aug. 27 issue of Nature Communications, creates opportunities for cleaner transportation and novel home power sources.

"We found the right match between the solar cell and battery," explained Liming Dai, the Kent Hale Smith Professor of macromolecular science and engineering and leader of the research. "Others have used polymer solar cells to charge lithium batteries, but not with this efficiency."

In fact, the researchers say their overall photoelectric conversion and storage outperformed all other reported couplings of a photo-charging component with lithium-ion batteries, flow batteries or super-capacitors.

Perovskite solar cells have active materials with a crystalline structure identical to the mineral perovskite and are considered a promising new design for capturing solar energy. Compared to silicon-based cells, they convert a broader spectrum of sunlight into electricity.

Dai's lab made multilayer solar cells, which increases their energy density, performance and stability. Testing showed that, as desired, the three layers convert into a single perovskite film.

By wiring four lab-sized cells, about 0.1 centimeter square each, in series, the researchers further increased the open circuit voltage. The solar-to-electric power conversion efficiency was 12.65 percent.