Alkylammonium Spacer Engineering in 2D/3D Perovskite Solar Cells

Alkylammonium Spacer Engineering in 2D/3D Perovskite Solar Cells

• Autor
• Bárbara Scola Rodrigues
• Co-autores
• Lucas Polimante , André Sarto Polo
• Resumo

• Perovskite solar cells (PSCs) have emerged as promising candidates for high-efficiency, low-cost solar energy conversion [1], yet their long-term operational stability remains a major limitation [2, 3]. Here, we compare two alkylammonium spacers: butylammonium iodide (BAI), a monovalent cation associated with the Ruddlesden-Popper (RP) phase, and butyl-1,4-diammonium diiodide (BDAI2), a divalent cation forming the Dion-Jacobson (DJ) phase, in CH3NH3PbI3-based 3D perovskite films.

  Spacer incorporation results in two distinct regimes. At higher concentrations (BAI 50 mmol/L, BDAI 2.5 mmol/L), 2D phase formation is observed, evidenced by an absorption band around 500 nm and characteristic X-ray diffraction (XRD) peaks. At lower concentrations (BAI 5 mmol/L, BDAI2 0.5 mmol/L), the spacers primarily act as passivating agents, resulting in smoother film surfaces, as confirmed by scanning electron microscopy (SEM).

  Despite these similarities, the two spacers exhibit markedly different stability trends. BAI-modified CH3NH3PbI3 films display improved long-term stability, even at low concentrations. In contrast, BDAI2-modified devices degrade more rapidly than expected, despite initial improvements in charge transfer and reduced recombination. UV-vis analysis reveals that films with 50 mmol/L BAI undergo phase evolution from n = 1 to n = 2, indicating structural adaptability. Conversely, films with 5 mmol/L BDAI2 show a progressive loss of the 2D absorption feature, consistent with degradation of the DJ phase. These results suggest that the presence of non-2D species compromises the stability of BDAI2-modified systems.

  Additionally, neither spacer leads to significant improvements in electrical conductivity at high concentrations, indicating that excessive 2D phase formation does not translate into enhanced charge transport.

  These findings underscore the critical role of spacer concentration in balancing structural stability and efficiency in 2D/3D PSCs. By optimizing spacer incorporation, device durability can be enhanced without compromising performance, paving the way for more stable perovskite solar cells.

  1 Rodrigues B.S., et al, ACS Omega, 11, 5, 8061-8073 (2026).

  2 Goetz K. P. et al, ACS Appl Mater Interfaces, 13, 1 -17 (2021).

  3 Niu T. et al, Adv Energy Mater, 12, 2102973 (2022).

• Palavras-chave
• alkylammonium spacers, perovskite solar cell, degradation
• Modalidade
• Pôster
• Área Temática
• Materiais Avançados