Passivation breakthrough drives efficiency gains in perovskite silicon tandem solar cells

Passivation breakthrough drives efficiency gains in perovskite silicon tandem solar cells
by Sophie Jenkins
London, UK (SPX) Sep 07, 2025

An international team of researchers has achieved a major advance in perovskite silicon tandem solar cell technology by demonstrating effective passivation on textured silicon bottom cells, the industry standard. Their work shows that passivation of the perovskite top cell extends through the entire absorber layer, unlike silicon where it only impacts the surface, unlocking new efficiency potential.

The collaboration, involving KAUST, the University of Freiburg, and Fraunhofer Institute for Solar Energy Systems ISE, tackled one of the biggest hurdles for tandem solar cells - achieving high-quality passivation on silicon surfaces shaped with large pyramids to maximize light absorption. By depositing 1,3-diaminopropane dihydroiodide on the perovskite top cell, the team achieved excellent passivation, producing tandem devices with conversion efficiencies up to 33.1 percent and an open-circuit voltage of 2.01 volts.

Lead author Dr. Oussama Er-Raji of Fraunhofer ISE explained that earlier success in passivation was limited to flat-front cells, but this work proves that textured designs can also benefit. The scientists confirmed that passivation enhances conductivity and fill factor through a deep field effect that influences the entire perovskite absorber, rather than just the surface region.

"This realization provides a solid foundation for all future research in this area," said Prof. Stefaan De Wolf of KAUST. "It enhances our understanding of the processes occurring in the top cell while converting light into electricity, enabling scientists to leverage this knowledge to develop better tandem solar cells."

Prof. Stefan Glunz of the University of Freiburg and Fraunhofer ISE emphasized the industrial significance: "Surface passivation of solar cells is not just a nice-to-have feature; it is an essential booster for their efficiency and stability. For today's silicon solar cells, surface passivation was the key for high efficiencies in industrial production, and it is encouraging that the photovoltaic industry will benefit from these positive effects for perovskite silicon tandem solar cells as well."

The research builds on prior efforts within the Fraunhofer lighthouse project MaNiTU and the PrEsto and Perle projects, supported by Germany's Federal Ministry for Economic Affairs and Energy. Research Report:Electron accumulation across the perovskite layer enhances tandem solar cells with textured silicon