Scientists in China have developed a new way to make highly efficient perovskite solar cells that could help accelerate the future of low-cost solar energy.
The research team achieved a certified power conversion efficiency of 30.3% in rigid tandem solar cells and 28.0% in flexible versions, setting an important milestone for this rapidly developing technology.
The study was led by researchers at the Ningbo Institute of Materials Technology and Engineering, part of the Chinese Academy of Sciences.
Their findings were published in the journal Nature Nanotechnology.
Perovskite solar cells have attracted worldwide attention because they can potentially generate electricity more cheaply and efficiently than traditional silicon solar panels.
They can also be made using low-temperature solution processing, which could reduce manufacturing costs and allow lightweight, flexible solar panels to be produced more easily.
Among the most promising designs are “all-perovskite tandem” solar cells. These devices stack multiple layers of perovskite materials together so they can absorb different parts of sunlight more effectively than single-layer solar cells.
However, making these tandem cells is extremely challenging. The different ingredients inside the perovskite layers often crystallize at different speeds during manufacturing. This uneven crystal growth creates structural defects and unstable regions inside the material, reducing both efficiency and long-term durability.
To solve this problem, the researchers developed a new strategy based on a chemistry concept called hard-soft acid-base theory, or HSAB theory. Using this approach, they carefully selected chemical additives that help guide how the perovskite materials crystallize.
For wide-bandgap perovskites, the team used an additive called difluoro(oxalato)borate, while narrow-bandgap perovskites used tetrafluoroborate. These additives helped synchronize crystal formation throughout the material, creating smoother and more uniform films.
The researchers found that the improved crystal growth reduced defects, prevented uneven distribution of chemical components, and lowered internal stress inside the solar cells. This led to major improvements in performance.
The efficiency of wide-bandgap solar cells increased from 18.5% to 20.1%, while narrow-bandgap devices improved from 21.6% to 23.3%.
When combined into tandem devices, the results became even more impressive. The rigid tandem solar cells achieved a peak efficiency of 30.3%, meaning they converted nearly one-third of incoming sunlight into electricity. Flexible tandem devices reached 28.2% efficiency, with a certified efficiency of 28.0%.
The new devices also showed strong durability. The rigid solar cells retained 92% of their original efficiency after operating continuously for 1,000 hours. The flexible versions maintained more than 95% of their performance even after being bent 10,000 times.
The researchers say their new chemical-guided manufacturing strategy could help move perovskite solar technology closer to large-scale commercial use. In the future, lightweight flexible solar panels based on this technology could be used in buildings, portable electronics, vehicles, and many other applications.
