Officially Listed on NREL Chart — Korea Expected to Lead Next-Generation Photovoltaic Technology
A team of South Korean researchers has set a new world record in power conversion efficiency* for perovskite/CIGS (copper indium gallium selenide) tandem solar cells**, demonstrating the country’s technological leadership in next-generation photovoltaic (PV) systems.
* Power conversion efficiency: The rate at which a solar cell converts sunlight into electricity.
** Perovskite/CIGS tandem solar cell: A two-layer thin-film solar cell combining two different types of solar cells that absorb different wavelength ranges of slight energy. This configuration can generate more electricity than conventional single-junction cells, making it a strong candidate for next-generation PV technology.
According to the National Research Foundation of Korea (NRF), the research team led by Professor Jin Young Kim at Seoul National University’s Department of Materials Science and Engineering, and the team led by Dr. Jeung Hyeon Jeong at the Advanced Photovoltaics Research Center of Korea Institute of Science and Technology (KIST), developed a technology that minimizes energy loss in perovskite/CIGS tandem solar cells—setting a new world record with a power conversion efficiency of 26.3%.
Solar power is essential for achieving the carbon neutrality goal by 2050. However, Korea faces limitations due to its high population density and limited land area, making it difficult to secure large-scale sites for solar farms. In this context, thin-film perovskite/CIGS tandem solar cells offer a highly promising alternative. Their lightweight and flexible nature allows them to be applied like stickers to a variety of surfaces—including building exteriors, windows, car roofs, and soundproof walls—thus maximizing land use efficiency.
The joint research team combined the low-cost, easy-to-fabricate perovskite solar cell with a CIGS cell that can absorb a broader range of the solar spectrum. The result achieved high efficiency in thin-film integration, comparable to that of silicon-based tandem solar cells.
SNU’s team developed advanced materials and fabrication processes to reliably stack perovskite top cells onto the rough surface of CIGS bottom cells. This innovation ensured effective contact between the two solar cells, maximizing photovoltaic performance. KIST’s team optimized the interconnecting layer that bridges the two solar cells to minimize energy loss, enabling the solar cells to achieve maximum power output.
This joint effort led to a record-breaking power conversion efficiency of 26.3%, surpassing the previous record of 24.6% held by a German research institute—an increase of 1.7%. The achievement was officially listed in April 2025 on the certified Best-Research-Cell Efficiency Chart maintained by the U.S. National Renewable Energy Laboratory (NREL).
Commenting on the significance of the achievement, Dr. Jeung Hyeon Jeong stated, “This achievement not only reached the state-of-the-art efficiency but also demonstrated the potential of thin-film tandem technology, which can be applied to various fields such as buildings, automobiles, and aerospace—where conventional silicon-based high-efficiency technologies have inherent limitations.”
Professor Jin Young Kim added, “Being listed on the NREL chart is a major milestone that places Korea at the forefront of perovskite/CIGS tandem solar cell technology. We believe this breakthrough will accelerate development in a field that has seen relatively slow progress and mark a turning point toward broader commercial adoption.”
The research was supported by South Korea’s Ministry of Science and ICT and the National Research Foundation under the Leap-Forward Carbon Neutral Technology Development Program and the Climate Change Response Technology Development Project.
This chart, maintained by the U.S. National Renewable Energy Laboratory (NREL) in Golden, Colorado, shows the world record efficiencies for different types of solar cells. The efficiency of 26.3% achieved by Seoul National University and KIST for perovskite/CIGS tandem solar cells was added in June 2025.
(Source: https://www.nrel.gov/pv/cell-efficiency)
This plot is courtesy of the National Renewable Energy Laboratory, Golden, CO.
[Contact Information]
Sojeong Park, Researcher, Department of Materials Science and Engineering, Seoul National University / szpark@snu.ac.kr
