Li Yongfang and Meng Lei’s research group at the Institute of Chemistry of the Chinese Academy of Sciences (ICCAS) has made significant progress in wide bandgap perovskite solar cells (pero-SCs) by using 1,4-cyclohexanediamine iodide (CyDAI₂) with cis-trans isomerism to passivate interface defects.

Pero-SCs have gained attention because of their potential in the photovoltaic field. By developing tandem solar cells (TSCs) that combine perovskites with other photovoltaic materials efficiency limits are enhanced. Among them, perovskite-organic TSCs, which use wide bandgap pero-SC as a front cell and narrow bandgap organic solar cell (OSC) as a rear cell, stand out for their higher stability and solution-processable active layers.

Studies indicate that the front wide bandgap perovskites serve as UV filters, protecting the more delicate rear organic layers from damage caused by short-wavelength light. Additionally, the rear organic layers block moisture and oxygen, enhancing the stability of the front pero-SC. The interconnect layer (ICL) in TSCs also helps mitigate ion diffusion issues related to the electron-transporting layer in pero-SC, further improving stability.

Enhancing the voltage and efficiency of wide-bandgap pero-SCs is crucial for perovskite-organic TSCs. However, the interface between wide-bandgap perovskites and the C₆₀ layer in the ICL often experiences electron recombination, leading to voltage losses. Addressing this issue requires effective methods to minimize these losses and boost overall TSC performance.

The researchers discovered that the cis configuration of CyDAI₂ (cis-CyDAI₂) outperforms the trans configuration, yielding a higher theoretical voltage and reduced energy loss. They achieved a high open circuit voltage of 1.36 V and a power conversion efficiency (PCE) of 18.4 percent for wide bandgap pero-SCs. By combining this with a ternary OSC as a rear cell, the group set a record PCE of 26.4 percent for perovskite-organic TSCs.

Chemical structure of CyDAI2, analysis of voltage loss, structure of perovskite-organic tandem solar cells and the photovoltaic performance [IMAGE: ICCAS]

Their paper, titled “Isomeric diammonium passivation for perovskite-organic tandem solar cells”, was published in Nature (DOI:10.1038/s41586-024-08160-y) with Jiang Xin and Dr. Qin Shucheng at ICCAS as co-first authors, and Professor Meng Lei, Professor Felix Lang from the University of Potsdam, and Professor Li Yongfang as corresponding authors.

For more information, please contact:

Professor Meng Lei

E-mail: menglei@iccas.ac.cn

Professor Li Yongfang

E-mail: liyf@iccas.ac.cn

Institute of Chemistry,

Chinese Academy of Sciences

Source: Institute of Chemistry,

Chinese Academy of Sciences