A Perovskite solar cell prototype.Alain Herzog / EPFL
An international team of researchers has raised the efficiency of perovskite solar cells to nearly 27 percent after introducing a new interfacial coating between the top contact and the perovskite layer.
Led by the Helmholtz Zentrum Berlin (HZB), a world-class research center for energy materials research, the study involved scientists from China, Germany, Switzerland, and Italy.
Their innovative approach involved creating a thin, fluorinated molecular layer that acts as a chemical shield between the perovskite and its top contact layer, known as the buckyball (C60) layer.
The novel solution aims to improve the lifespan and reliability of perovskite solar cells under real-world conditions. It also addresses one of their biggest challenges that has limited their widespread commercial use.
Extending solar lifespan
Perovskite solar cells have long been hailed as a promising alternative for cheap, lightweight and highly efficient renewable energy. However, their instability has so far prevented them from taking over the market.
These next-generation cells tend to lose efficiency much faster than conventional silicon-based solar panels. This limits their commercial potential. Now, to tackle this challenge, the team applied a fluorinated coating to the interface between the perovskite surface and the top contact layer.
“We used a fluorinated compound that can slide between the perovskite and the buckyball (C60) contact layer, forming an almost compact monomolecular film,” Antonio Abate, PhD, a professor in the university’s department of novel materials and interfaces for photovoltaic solar cells, revealed.
A fluorinated compound between the perovskite and the buckyball (C60) contact layer forms an almost monomolecular film that acts as a chemical protective barrier and increases the stability of the cell. Image Credit: Guixiang Li / Nature Photonics 2025
The Teflon-like molecular layer pushed perovskite solar cells to an impressive 27 percent power conversion efficiency. The team discovered that the upgraded cells maintained this performance after 1,200 hours of continuous operation.
This is equivalent to a full year of natural sunlight exposure. In contrast, reference samples without the fluorinated layer lost around 20 percent of their performance after just 300 hours.
According to the scientists, the layer chemically isolates the perovskite from the contact layer. This, in turn, reduces defects and energy losses. It also strengthens the structure of both adjacent layers, particularly the C60 layer, making it more uniform and compact.
“It’s actually like the Teflon effect,” Abate explained. “The intermediate layer forms a chemical barrier that prevents defects while still allowing the electric contact.”
Stability through innovation
As per Guixiang Li, PhD, a professor at Southeast University in Nanjing, China, who led the study, the new coating does more than just maintain stability.
Li explained that the fluorinated compound enhanced the uniformity and density of the C60 contact layer. This resulted in improved charge transport and greater mechanical durability.
Meanwhile, cells produced using this approach showed virtually no performance loss under intense testing conditions. They reportedly withstood 1,800 hours of thermal aging at 185 degrees Fahrenheit and 200 temperature cycles ranging from -40 to 185 degrees Fahrenheit.
“The idea of using such Teflon-like molecules to form an intermediate film has been on my mind since my postdoctoral days in Henry Snaith’s lab, who did pioneer research on the perovskite materials,” Abate concluded in a statement.
Perovskite materials have evolved rapidly over the past decade, with efficiencies soaring from 15 percent in 2014 to nearly 30 percent today. Yet, their durability remained the key obstacle to commercial deployment.
The approach could bridge that gap, offering a scalable solution that combines high performance with long-term resilience. It could also speed up the creation of new solar technologies, from rooftop installations to flexible devices and tandem solar modules.
The study has been published in the journal Nature Photonics.
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