Development of a Highly Efficient Perovskite Solar Cell with Triple the Lifespan

UNIST and Korea University Professors Develop Solar Cell Additive That Replaces Cause of Durability Loss
Maintains 80% Initial Efficiency for 3,000 Hours and Withstands Extreme Temperature Stress
Published in Nature Energy

A highly efficient perovskite solar cell with a lifespan more than three times longer than previous versions has been developed.

This breakthrough was made possible by creating a new material that can replace additives which increase cell efficiency but shorten its lifespan.

The team led by Professors Changdeok Yang and Seungjae Shin from the Department of Energy and Chemical Engineering at Ulsan National Institute of Science and Technology (UNIST), together with Professor Hanul Min's team from Korea University, announced on September 22 that they developed a solid additive called 4CP to replace the liquid tBP additive. By applying this to perovskite solar cells, they achieved a high power conversion efficiency of 26.2% and secured long-term stability for 3,000 hours.

Research team, (from left) Sangjin Yang, researcher at Ulsan National Institute of Science and Technology (UNIST); Changdeok Yang, professor at UNIST; Hanul Min, professor at Korea University; Kihoon Kim, researcher at Korea University. Provided by UNIST

tBP (4-tert-butylpyridine) is an additive used in solar cells to evenly distribute lithium ions, thereby increasing the efficiency of converting sunlight into electricity. However, because it is in liquid form, it easily volatilizes at high temperatures. During this process, it fails to retain lithium ions effectively, resulting in by-products or microscopic pinholes inside the cell. These are major factors that reduce the lifespan of the cell.

The newly developed 4CP (4-(N-carbazolyl)pyridine) is a solid additive that fundamentally prevents these issues due to its non-volatile nature. In addition to its outstanding stability at high temperatures, it creates a uniform interface between the cell layers, facilitating smooth charge transfer. As a result, the power conversion efficiency is also enhanced.

In experiments, perovskite solar cells using 4CP achieved a power conversion efficiency of 26.2% (certified at 25.8%), and demonstrated excellent long-term performance. While the efficiency of conventional tBP-based cells dropped to 60% of the initial value within 1,000 hours, 4CP-based cells maintained 80% of their initial efficiency for over 3,000 hours-effectively tripling the lifespan.

The benefits were also clear under high-temperature and extreme conditions. Cells with 4CP retained 80% of their initial efficiency for over 400 hours at 85°C. In contrast, cells using tBP saw their output drop to less than half within 120 hours under the same conditions. Furthermore, even after 200 cycles of temperature stress tests alternating between -80°C and 80°C, the cells maintained over 90% of their initial efficiency.

The joint research team stated, "This study demonstrates that simply replacing the additive, without altering the manufacturing process, can effectively solve the biggest weakness of next-generation perovskite solar cells-limited lifespan. Since performance was maintained even under extreme temperature fluctuations, this paves the way for using perovskite solar cells in space and other harsh environments."

The team added, "Because the technology is compatible with existing manufacturing processes, the barrier to mass production is low. We plan to fabricate large-area modules to verify performance for commercialization."

Chemical Structure and Performance of the Developed Solid Additive.

This research was co-led by Sangjin Yang, researcher at UNIST, and Kihoon Kim, researcher at Korea University, as first authors.

The results were published in Nature Energy, a sister journal of Nature, on September 10.

This content was produced with the assistance of AI translation services.