Enhancing the stability of methylammonium-based perovskite solar cells prepared in ambient conditions by adding formamidinium cations

Author(s)

Polimante, Lucas ; da Silva, Juliana Pereira ; Ferreira, Fabio Furlan ; Polo, Andre Sarto

• Document type: Journal article
• Source: SOLAR ENERGY MATERIALS AND SOLAR CELLS; v. 285, p. 8-pg., 2025-06-15.

Abstract

Perovskite solar cells (PSCs) represent an up-and-coming emerging technology for the future of clean and renewable energy generation. However, these devices still suffer stability and durability issues due to moisture when exposed and/or prepared under ambient conditions. Here, we investigate the influence of incorporating formamidinium cation into methylammonium-based lead iodide perovskite films to improve the stability of PSCs. The amount of FA+ ranges from 0 (pure MAPI) to 1 (pure FAPI) perovskite passing by different amounts (FA0.125MA0.875PI, FA0.25MA0.75PI, FA0.5MA0.5PI). All the solutions and deposition of each film are performed in an uncontrolled ambient atmosphere (relative humidity ranging from 40 % to 60 %), aiming to replicate scalable manufacturing environments. The perovskite films present high crystallinity and uniformity, confirmed by the Xray patterns, corroborating the predominantly photoactive FAPI alpha-phase or the MAPI cubic one. Scanning electron microscopy (SEM) images reveal that increasing FA+ content leads to larger grain sizes, reducing grain boundaries. Absorption spectra present a gradual red shift from MAPI to FAPI perovskites due to increased FA+ content, corresponding with the bandgap energy analysis. PSCs present photocurrent conversion efficiencies up to 13.4 %, and the photocurrent action spectra confirm the absorption observation, presenting energy conversion in higher wavelengths as the FA+ contents increase. A long-term stability experiment reveals that perovskites with more than 25 % FA+ maintain their efficiency over 80 % after 2160 h, a longer durability than MAPI PSCs. The durability improvement is ascribed to incorporating FA+ into the MAPI perovskite crystal lattice, which changes the grain size, surface area, and grain boundaries. (AU)

• FAPESP's process: 17/11986-5 - Generation and storage of New Energy: bringing technological development for the country
• Grantee: Ana Flávia Nogueira
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 23/09820-2 - Materials by design: from quantum materials to energy applications
• Grantee: Gustavo Martini Dalpian
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 22/07268-8 - Comprehending the charge recombination processes in perovskite solar cells
• Grantee: André Sarto Polo
• Support Opportunities: Regular Research Grants