Tandem Solar Cells Achieve Record 25.7% Efficiency

Researchers from Germany and China achieve a great efficiency in tandem solar cells, combining perovskite and organic materials for low-carbon energy solutions.

Researchers from the University of Potsdam, Germany and the Chinese Academy of Sciences (CAS), Beijing have achieved a major milestone in solar technology. They have developed a tandem solar cell combining perovskite with innovative organic absorbers, setting a new efficiency record of 25.7%. The research highlights the potential of low-carbon alternatives for more sustainable energy solutions.

Maximising solar cell efficiency is key to reducing reliance on fossil fuels. Tandem cells, which merge materials that selectively capture different parts of sunlight—such as blue/green and red/infrared wavelengths—offer a promising approach. Traditional solar cells, made of silicon or CIGS (copper indium gallium selenide), perform well but require high processing temperatures, which lead to a significant carbon footprint. The improved tandem design is expected to attract interest from industries prioritising sustainability, such as renewable energy developers, eco-conscious businesses, and governments working toward carbon neutrality goals.

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The tandem cells use the unique properties of perovskite and organic materials. Unlike conventional options, these materials can be processed at low temperatures, significantly reducing environmental impact. Dr Felix Lang, University of Potsdam explained, “This was only possible by combining two major breakthroughs.”

The first innovation came from Lei Meng, professor and researcher, Shandong University and Yongfang Li, professor, CAS who developed an advanced organic material capable of absorbing red and infrared light more efficiently. This enabled the solar cell to extend its absorption range deeper into the infrared spectrum.

The second breakthrough involved addressing a common limitation in perovskite layers, which often lose efficiency when adjusted for blue and green light absorption. To overcome this, the researchers introduced a novel passivation layer that minimises defects in the perovskite material and enhances the overall performance of the tandem cell.

By combining unique materials, this achievement not only showcases a step forward in solar technology but also opens new possibilities for cost-effective, low-carbon energy solutions tailored for diverse applications, including residential, commercial, and large-scale power projects.