A team of scientists in China has developed a targeted passivation technique that significantly improves the performance of perovskite/silicon tandem solar cells. The new development could help to address a key barrier to the commercial viability of perovskite/silicon tandem solar panels.

These are next-generation photovoltaic technologies that stack a perovskite solar cell on top of a conventional silicon solar cell to capture more of the sun’s spectrum and achieve higher efficiencies than silicon alone.

China’s new solar cell formula

For the new technique, the researchers focused on mitigating electrical leakage resulting from uneven perovskite layer deposition on industrial silicon substrates.

Perovskite/silicon tandem cells stack a perovskite top cell, which efficiently captures high-energy photons, atop a silicon bottom cell optimized for lower-energy light. 

This configuration can, in theory, surpass the efficiency limits of single-junction silicon cells. This could ultimately lead to the development of lighter, more powerful solar cells, making the technology more accessible and widespread.

Industrial silicon wafers used in solar cells typically feature pyramid-textured surfaces to reduce reflection and improve light absorption. While effective for conventional silicon cells, these textures complicate uniform perovskite coating, creating defect sites prone to localized leakage currents. This problem reduces overall efficiency and stability.

Researchers from the Ningbo Institute of Materials Technology and Engineering (NIMTE) under the Chinese Academy of Sciences, working with colleagues at Soochow University and Taizhou University in Jiangsu Province, devised a peak-selective passivation strategy to tackle this problem.

They employed polystyrene nanospheres as a template to apply a thin insulating layer of aluminum oxide specifically to the peaks of the silicon pyramids. This approach blocks leakage pathways without interfering with the bulk of the surface needed for effective charge transport.

A simple strategy

To test their technique, the team used a device with an active area of about one square centimeter. This yielded a power conversion efficiency of approximately 33 percent. During the tests, the cell retained roughly 90 percent of its initial efficiency after 1,000 hours of continuous operation, indicating strong operational stability.

“This strategy is simple and compatible with existing industrial production lines, bringing perovskite/silicon tandem solar cells a step closer to commercial applications,” said Ye Jichun, a corresponding author of the study, according to a state-owned media report.

The global solar industry is seeking methods that enable higher efficiencies beyond the roughly 22-24 percent range common in mass-produced silicon modules.

Tandem architectures represent one of the most promising routes. However, scaling these has proven challenging due to interface and deposition issues on textured substrates.

By focusing passivation only where defects are most problematic, the new method avoids the performance trade-offs often seen with broader surface treatments. Its compatibility with established manufacturing processes could accelerate adoption, potentially lowering costs for high-performance solar installations in utility-scale, rooftop, and specialized applications.

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