Perovskite cells retain 90% efficiency after 850 hours of operation

A perovskite solar cell retains its efficiency for a long time thanks to a new type of coating (photo: Nanyang Technological University, Singapore)

Researchers in Singapore have built a large-area perovskite photovoltaic panel that, according to the announcement, retains more than 90% of its original efficiency after more than 850 hours of operation. The scientists used a hydrophobic, all-organic salt to modify the top surface of the large-area perovskite layers.

Scientists describe the development as a “remarkable preservation of efficiency”. “Large-area perovskite solar modules have problems with their stability due to intrinsic defects and a mass of surface imperfections that occur during the manufacturing process,” said Prem Jyoti Singh Rana, one of the authors of the development.

The researchers used a hydrophobic, all-organic salt known as fluorinated anilinium benzylphosphonate (FABP) to modify the top surface of perovskite layers coated with methylammonium halide. The salt acts as a molecular “lock” that is capable of binding to both anionic and cationic free bonds, greatly increasing the inherent stability of the materials.

“This not only reduces the penetration of external influences such as oxygen and moisture, but also suppresses the escape of volatile organic components during the thermal stability test,” say the scientists. The absence of MA is a crucial factor due to its propensity for chemical reactions leading to volatile and electrochemically reactive products.

The research group built two different modules with an active area of ​​58.5 sq cm and 64 sq cm, respectively. The former achieved a power conversion efficiency of 19.28% and the latter achieved a power conversion efficiency of 17.62%.

“The unencapsulated FABP-based devices show excellent thermal stability, retaining 80% and 70% of their initial power conversion efficiency after 2700 hours and 1700 hours of operation at 65 degrees and 85 degrees, respectively,” the researchers explain.

“Unencapsulated FABP-based mini-modules show about 80% efficiency retention after 7,500 hours (313 days) at 30% relative humidity. They remarkably retain more than 90% of their original efficiency for over 850 hours while being measured continuously under illumination,” the scientists claim.