Korean Team Sets World Record of 26.7% for <1 cm² Perovskite-CIGS Tandem Solar Cell

en.Wedoany.com Reported - The Korea Institute of Energy Research (KIER) has achieved a tandem solar cell efficiency of 26.7% by combining a perovskite top cell with a copper indium gallium selenide (CIGS) bottom cell. This record has been confirmed by Germany's Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) and listed in the "Best Research-Cell Efficiency Chart" maintained by the U.S. Department of Energy's National Renewable Energy Laboratory, setting a new efficiency record for perovskite-CIGS tandem solar cells with an area of less than 1 cm².

Both light-absorbing materials used in the tandem device can be fabricated as thin films, giving this structure the potential to achieve both high efficiency and a lightweight, flexible form factor. The KIER team stated that when integrating the two types of cells, the perovskite light-absorbing layer may degrade, and some component layers may unnecessarily absorb light, thereby reducing overall performance. To address this, the team analyzed loss sources item by item, developed interfacial materials and processing techniques to mitigate damage to the perovskite layer, and optimized the structure of the top transparent electrode and charge transport layers to reduce parasitic light absorption and minimize photocurrent loss.

The research team measured an efficiency of 27% for this cell in the laboratory but did not disclose further details. Principal researcher In-Young Jeong noted that after suppressing interfacial and optical losses during the integration of perovskite and CIGS, both efficiency and stability improved simultaneously. This efficiency value has been verified by globally recognized certification bodies and confirmed as a record-breaking value, providing objective validation of the technology's competitiveness.

The previous world record in the same size category was 26.3%, set by the Korea Institute of Science and Technology (KIST) in July 2025.

The current world record for perovskite-CIGS tandem cells with an area larger than 1 cm² is 25.5%, held by Germany's Helmholtz-Zentrum Berlin (HZB) and Humboldt-Universität zu Berlin, a result that has been confirmed by the European Solar Test Installation (ESTI).

HZB researcher Farias Basulto previously stated in an interview with pv magazine that the physics behind the current cell architecture indicates that 25.5% is only the first milestone, as internal test efficiencies for similar designs have already reached 27.5%. This record-breaking 25.5% result has also been included in the "Solar Cell Efficiency Tables."