Preparation of phase-pure FAPbI3 perovskite in air

• Formamidine-lead triiodide (FAPbI3 ) perovskite is expected to become a leading candidate in the field of perovskite photovoltaics . However, the photoactive α-FAPbI3 phase exists in a metastable state, can only be observed at high temperatures, and can easily degrade to the δ phase in ambient air. Therefore, obtaining phase-stable α-FAPbI3 under ambient conditions has become an important goal of perovskite research.

  
  

  Here, Pengwei Li, Yiqiang Zhang from Zhengzhou University, and Yanlin Song from the Institute of Chemistry of the Chinese Academy of Sciences proposed a process to efficiently convert PbI2 to α-FAPbI3 perovskite in ambient air. This conversion is facilitated by the introduction of chelating molecules, which interact with PbI2 to form an intermediate phase. This stable intermediate phase directly transforms to α-FAPbI3 after deposition from an organic cation solution, effectively bypassing the formation of δ-FAPbI3, due to a reduced formation barrier caused by an altered reaction pathway.

  
  

  As a result, the FAPbI3 perovskite solar cells (PSCs ) fabricated in air exhibited an excellent power conversion efficiency of 25.08% and a high open-circuit voltage of 1.19 V. In addition, the unencapsulated devices exhibited excellent environmental stability. Notably, this innovative approach is expected to be widely applicable to various chelating molecules, opening up new avenues for further progress in the ambient air fabrication of FAPbI3 PSCs.

  
  

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• Shiheng Wang, Zhipeng Miao, Jing Yang, Zhenkun Gu, Pengwei Li, Yiqiang Zhang, Yanlin Song, Angew. Chem. Int. Ed. 2024, e202407192.

  
  

  https://onlinelibrary.wiley.com/doi/10.1002/anie.202407192