Smashing Solar Barriers: Low-Carbon Tandem Cells Hit 25.7% Efficiency

A new tandem solar cell developed by teams from the University of Potsdam and the Chinese Academy of Sciences achieves a 25.7% efficiency by combining perovskite with novel organic absorbers, setting a new standard in solar technology.

Improving the efficiency of solar cells to reduce dependence on fossil fuels is a major objective in solar cell research. Combining materials that selectively absorb short and long wavelengths—such as blue/green and red/infrared parts of the spectrum—is a well-known strategy to maximize the use of sunlight and increase efficiency.

The best absorbing parts of solar cells are currently made from traditional materials like silicon or CIGS (copper indium gallium selenide). However, these materials require high processing temperatures, which leads to a relatively high carbon footprint.

Breakthroughs in Solar Cell Efficiency

A team of researchers from the University of Potsdam and the Chinese Academy of Sciences has combined perovskite and organic solar cells—both of which are processed at low temperatures with a low carbon footprint—to create a tandem solar cell that achieves a record-breaking efficiency of 25.7%.

The team, led by physicist Dr. Felix Lang from the University of Potsdam, Prof. Lei Meng and Prof. Yongfang Li from the Chinese Academy of Sciences, Beijing, detailed their work in a study published in Nature.

Achieving a record level of 25.7 % efficiency for this new combination was not easy, says Lang: “This was only possible by combining two major breakthroughs.”

First, Meng and Li synthesized a novel red/infrared absorbing organic solar cell that extends its absorption further into the infrared. “Still, tandem solar cells were limited by the perovskite layer, which shows strong efficiency losses if adjusted to absorb only blue/green parts of the sun spectrum,” he explains. “To tackle this, we utilized a novel passivation layer applied to the perovskite that reduces material defects and improves the performance of the whole cell.”

Reference: “Isomeric diammonium passivation for perovskite–organic tandem solar cells” by Xin Jiang, Shucheng Qin, Lei Meng, Guorui He, Jinyuan Zhang, Yiyang Wang, Yiqiao Zhu, Tianwei Zou, Yufei Gong, Zekun Chen, Guangpei Sun, Minchao Liu, Xiaojun Li, Felix Lang and Yongfang Li, 14 October 2024, Nature.
DOI: 10.1038/s41586-024-08160-y

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