Paul van Gerven
17 February 2020

With an externally verified efficiency of 29.15 percent, researchers at the Helmholtz Zentrum Berlin (HZB), along with colleagues from Kaunas University of Technology, have assembled a record-breaking silicon-perovskite solar cell. The previous record of 28 percent was held by British-German startup Oxford PV.

Most of the improvement was realized by tweaking material composition and improving fabrication techniques. A new element, however, was a self-assembling monolayer (SAM) as a hole transport layer. SAMs are formed simply by dipping the substrate in a solution, allowing dissolved molecules to anchor themselves to the surface. The resulting layer is as thin (1-2 nanometer) as the cross-section of the molecules involved.

The researchers are confident they can push through the 30 percent efficiency barrier. The practical efficiency limit of silicon-perovskite tandem cells is about 35 percent.