A study conducted at UFABC presents a new way to mitigate the rapid degradation of perovskite solar cells. The problem, which limits the use of these devices in everyday life, has been challenging researchers in the field in search of viable solutions.

Currently, perovskite solar cells are a very promising photovoltaic technology. They are as efficient as silicon cells and have lower production costs. In addition, they are light, flexible and semi-transparent, which opens up numerous possible applications, such as windows, clothing or tents capable of generating electricity from sunlight.

However, the commercialization of these cells is hindered by their low durability, caused by the degradation that materials in the perovskite family undergo when exposed to humidity and ambient temperature conditions, either during their production or during their use. This deterioration impacts the performance of the solar cells and, therefore, their durability.

In a scientific article published in the journal Solar Energy Materials and Solar Cells, the UFABC team presented a new way to produce more durable perovskite solar cells. The biggest advantage of the process is that it can be carried out without the strict humidity and temperature control that exists in laboratories dedicated to researching these devices.

“The solar cells in this work were obtained under ambient conditions, without extensive humidity controls, which may be more compatible with industrial preparation conditions,” says Professor André Sarto Polo (UFABC), a CINE researcher who led the work.

Modulating the composition of perovskites

The perovskite family includes materials with diverse chemical compositions. They all share the same structure, composed of positively charged ions (cations) and negatively charged ions (anions). Perovskites based on methylammonium (MA⁺) and formamidinium (FA⁺) cations are the most studied for use in solar cells.

In this new CINE study, the authors incorporated increasing amounts of formamidinium cations into methylammonium-based perovskites. They characterized each of the resulting materials and used them to assemble solar cells. The production and characterization of the materials and devices were carried out in environments with relative humidity levels between 40% and 60%.

To test their stability, these solar cells were exposed to ambient temperature and humidity for 90 days. During this period, the researchers systematically studied the properties of all the devices to investigate the influence of adding formamidinium on the performance of the solar cells.

While the solar cells without FA⁺ experienced a sharp drop in efficiency soon after assembly and stopped functioning within 30 days, those with more than 25% FA⁺ retained 80% of their original efficiency at the end of the 90-day period.

“This work demonstrates how incorporating formamidinium cations into methylammonium-based perovskites leads to increased durability in perovskite solar cells that are fabricated and measured under ambient conditions,” summarizes Professor Polo.

According to him, this improvement occurs because the addition of formamidinium increases the size of the grains that form the crystalline structure of the perovskite, reducing the total length of the grain boundaries. Since grain boundaries are points where moisture tends to accumulate, the perovskite undergoes less degradation, allowing the solar cell to maintain its performance for a longer time.

The research opens up prospects for developing more durable perovskite solar cells that can be produced at lower costs in conditions that are more friendly to the industrial environment.

The work was carried out as part of Lucas Polimante’s doctoral research and was funded by Fapesp, Shell, CNPq and Capes, in addition to strategic support from ANP.

Paper reference: Lucas Polimante, Juliana Pereira da Silva, Fabio Furlan Ferreira, Andre Sarto Polo. Enhancing the stability of methylammonium-based perovskite solar cells prepared in ambient conditions by adding formamidinium cations. Solar Energy Materials and Solar Cells 285 (2025). https://doi.org/10.1016/j.solmat.2025.113522

CINE members who authored the paper: Lucas Polimante (PhD student) and André Sarto Polo (researcher of the Energy Generation program).