Pure phase 2D/3D tin-based perovskite solar cells

• Metastable quasi-2D perovskite films exhibit reduced light absorption capabilities and degraded charge transfer kinetics, with irreversible changes in composition and structure under external stress. Developing high-quality pure-phase 2D/3D perovskite films is of great significance for perovskite photovoltaic power generation, but it is also full of challenges.

  
  

  Yin Longwei of Shandong University, Ya-Nan Zhang of Taishan University, and Enyan Guo of Qilu University of Technology introduced 4,4-difluoropiperidine (DFPD+) cations with high positive charge density at the cation end, and tightly coupled with the Sn-I component. One-pot solution process for constructing phase-pure DFPD2SnI4/FASnI3 2D/3D perovskite films. The good lattice matching between DFPD2SnI4 and FASnI3 perovskite and the preferential formation of DFPD2SnI4 precursor effectively regulate the film crystallization and promote the directional growth of FASnI3 (h00) plane.

  
  

  In addition, strong DFPD2SnI4 perovskite with hydrogen bonds in the organic spacer is distributed along the grain boundaries to stabilize the edge lattice of FASnI3 grains, suppress defect generation and improve environmental stability. The optimized device achieves a best-in-class efficiency of 13.34% and exhibits enhanced storage and operational stability.

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