Perovskite Solar Cell to Increase Efficiency

Stanford postdoctoral scholar Tomas Leijtens and professor Mike McGehee work together to examine perovskite tandem solar cells. Photo Credit: L.A. Cicero
Stanford postdoctoral scholar Tomas Leijtens and professor Mike McGehee work together to examine perovskite tandem solar cells. Photo Credit: L.A. Cicero

STANFORD, Calif. — Researchers at both Stanford and Oxford Universities have created a new solar cell by combining two perovskite solar materials. The new solar cells are designed to increase a building’s energy efficiency and lower its carbon footprint.

“When used together with another perovskite semiconductor that specializes in harvesting visible photons, we are able to convert solar energy into electricity with 20 percent efficiency,” said Tomas Leijtens, co-lead author of the Science Journal Paper in a statement. “We think we are going to be able to increase the efficiency to 30 percent, which could revolutionize the solar industry.”

According to a statement from Stanford University, the new device consists of two perovskite solar cells stacked in tandem. Each cell is printed on glass, but the same technology could be used to print the cells on plastic.

Previous studies from Stanford and Oxford showed that adding a layer of perovskite can improve the energy-efficiency of silicon solar cells. But a tandem device consisting of two all-perovskite cells would be cheaper and less energy-intensive to build, according to a statement from the authors.

“Perovskite cells can be processed in a laboratory from common materials like lead, tin and bromine, then printed on glass at room temperature,” said co-lead author Tomas Leijtens in a statement.

Building an all-perovskite device posed a difficult challenge to researchers. The main problem is creating stable perovskite materials capable of capturing enough energy from the sun to produce a decent voltage.

According to a statement from the authors of the study, a typical perovskite cell harvests photons from the visible part of the solar spectrum. Higher-energy photons can cause electrons in the perovskite crystal to jump across an “energy gap” and create an electric current.

A solar cell with a small energy gap can absorb most photons but produces a very low voltage. A cell with a larger energy gap generates a higher voltage, but lower-energy photons pass right through it.

Funding for this project was provided by the European Union-based Graphene Flagship, London-based Leverhulme Trust, U.K. Engineering and Physical Sciences Research Council, European Union’s Seventh Framework Programme, European Union-based Horizon 2020, the U.S. Office of Naval Research and the Global Climate and Energy Project at Stanford.