Korean researchers crack perovskite solar cell's biggest weakness — water

South Korean researchers have solved one of the most persistent obstacles to commercializing next-generation perovskite solar cells: poor moisture stability.

The National Research Foundation of Korea announced Tuesday that a research team led by Kim So-yeon and Lim Dong-chan, principal researchers at the Korea Institute of Materials Science, developed a technology that forms a molecular network modeled on a fishing net at the perovskite interface to block moisture from penetrating the cell.

Perovskite solar cells have drawn growing attention in recent years for their ability to match the efficiency of conventional silicon solar cells while being far cheaper to produce.

The material's critical weakness, however, is its extreme vulnerability to moisture and oxygen. Exposure to rain or humidity causes a sharp drop in performance, a flaw that has long stood in the way of commercial deployment.

Until now, the dominant approach has been to seal cells behind thick protective layers — a method that raises manufacturing costs and reduces flexibility.

The research team took a different approach: instead of blocking water from the outside, they made the material itself resistant to water.

Using copper ions (Cu2+) as linking agents, the team bonded a rigid organic molecule (BCP) with a flexible polymer (PEIE) to form a tightly woven molecular network — like a fishing net — directly at the perovskite interface.

The structure simultaneously blocks moisture from penetrating the cell and suppresses ion migration, a key driver of performance degradation.

The team verified the technology's water resistance by repeatedly submerging perovskite solar cells in water.

The cells, fabricated in open air without a glovebox, achieved a light-conversion efficiency of more than 26 percent and demonstrated strong water resistance by recovering their performance even after repeated submersion.

If commercialized, the technology would allow solar cells to operate reliably in humid or water-adjacent environments where conventional cells have struggled. Potential applications include self-powered outdoor and underwater IoT sensors for real-time monitoring of water temperature, quality and ion concentration at open-field farms, smart farms, aquaculture facilities, and riverbanks or reservoirs. Extending the technology to lightweight, flexible solar cells would also open the door to building-integrated photovoltaics (BIPV) on exterior walls and windows, vehicle-integrated photovoltaics (VIPV) on car bodies and curved structures, wearable and portable power sources, and standalone power supplies for smart factories.

"The most important distinction of this research is that we made the solar cell material itself resistant to water," Kim and Lim said. They added that the team plans to apply the technology to large-area coating processes and roll-to-roll continuous production, and to pursue modular research tailored to real-world applications including flexible solar cells, BIPV, VIPV, and self-powered IoT sensors for outdoor and underwater use.

The research was supported by the Ministry of Science and ICT and the National Research Foundation of Korea through a future-convergence technology pioneer project. The findings were published July 17 in the international journal Nano-Micro Letters, which covers nanoscience, nanotechnology and materials science.