Chinese Researchers Uncover Aging Mechanism of Perovskite Solar Cells

Chinese researchers have unveiled the “aging mechanism” of perovskite solar cells, according to a report from Nanjing University of Aeronautics and Astronautics. The team, led by Professors Guo Wanlin and Zhao Xiaoming, has successfully identified the aging process of these solar cells and proposed a cost-effective solution to extend their lifespan, which could accelerate the commercialization of next-generation photovoltaic technology.

The related paper was published online on May 30, 2025, in the prominent international academic journal Science.

Zhao Xiaoming explained that perovskite is a key candidate material for next-generation photovoltaic technology. China is at the forefront of research in this area, with some small-sized perovskite solar cells achieving a power conversion efficiency exceeding 27%, comparable to that of commercial crystalline silicon solar cells. However, to transition perovskite from the laboratory to production lines and gain market acceptance, challenges such as low conversion efficiency and short lifespan for larger perovskite solar cells must be overcome.

On May 30, 2025, Zhao Xiaoming (center) and team members, including Sun Xiangnan (second from the right), discussed the preparation process for large-sized perovskite solar cells. (Image courtesy of Nanjing University of Aeronautics and Astronautics)

In the industry, the lifespan of a photovoltaic cell is typically defined as the time required for its conversion efficiency to degrade to 80% of its initial state. The team previously developed a gas-phase fluorination technique that effectively improves conversion efficiency and extends lifespan, but it requires significant modifications to existing photovoltaic production lines, increasing the financial burden on companies.

“To optimize the technology, we needed to understand the essence of efficiency degradation,” Zhao Xiaoming noted. The team discovered that, with the cycle of day and night, perovskite solar cells exhibit a phenomenon of “reversible degradation”—the efficiency lost during the day partially recovers after a night of “rest.”

“It’s like a person who, after a tiring day, feels refreshed after a good night’s sleep,” said Sun Xiangnan, the paper’s lead author. Further investigation revealed that this phenomenon is linked to the movement of iodide ions—during the day, under sunlight, these ions move around within the perovskite film, causing tiny defects on the film’s surface, which in turn leads to efficiency degradation.

If the iodide ions only move within the perovskite layer, the degraded efficiency can automatically recover at night. However, if these ions migrate to the charge transport layer or electrodes, they cannot return to the perovskite layer, resulting in a permanent loss of efficiency.

Identifying the root cause, the team developed a “gas-phase-assisted surface reconstruction” technology that creates tiny isolation chambers on the surface of the perovskite film, confining the troublesome iodide ions and restricting their movement.

Experimental data showed that a large-sized perovskite solar cell, measuring 785 cm² and treated with surface reconstruction technology, experienced only a 3% loss in conversion efficiency after undergoing 101 cycles of simulated day-night transitions at 50°C.

“This means it could operate stably outdoors for 25 years,” Zhao Xiaoming stated. To further test the cell’s performance, the team exposed the perovskite cell alongside commercial crystalline silicon cells to both a 45-day high-temperature, high-humidity summer environment and an 18-day low-temperature winter environment. The results indicated that the perovskite cell outperformed the crystalline silicon cell in both scenarios.

Importantly, the new technology is compatible with existing photovoltaic production lines, effectively controlling the costs associated with modifications.

Guo Wanlin emphasized that this research has achieved a closed loop from fundamental theory to practical application. It not only clarifies the reasons behind the irreversible degradation of conversion efficiency in perovskite solar cells but also addresses a critical bottleneck for the industrialization of large-sized perovskite photovoltaic technology. The team has applied for ten patents and is currently improving device fabrication processes and material systems to expedite the launch of larger-scale perovskite solar cell pilot projects.