Flexible perovskite solar cells show great potential for applications that require lightweight and adaptable solutions; however, their vulnerability to humidity and temperature presents significant challenges for prolonged use. In response, a group of researchers has undertaken an extensive study to evaluate how these solar modules degrade under extreme heat and moisture conditions. Their accelerated tests unveiled the influence of the water vapor transmission rates of barrier films on the stability of the modules, providing essential information for developing more durable solar cells.
Perovskite solar cells (PSCs) represent a groundbreaking advancement in renewable energy technologies, boasting high efficiency, light weight, and flexibility. Nevertheless, their widespread use is often limited by their sensitivity to changes in the environment, such as heat and moisture.
A research team led by Professor Takashi Minemoto, a Fellow at the Ritsumeikan Advanced Research Academy in the College of Science and Engineering at Ritsumeikan University in Japan, alongside Dr. Abdurashid Mavlonov from the same university and Dr. Akinobu Hayakawa from Sekisui Chemical Co., Ltd., has embarked on innovative research to assess the durability of these PSC modules in extreme environmental conditions. This research was published online on December 17, 2024, and appeared in Volume 286 of Solar Energy on January 15, 2025.
Professor Minemoto explained the purpose of the study, stating, “Perovskite solar cells are notably promising due to their low-temperature wet-coating process and compatibility with flexible substrates, which opens up new possibilities for the solar industry. However, their stability is considerably weaker compared to traditional materials, which can be enhanced through methods like encapsulation using barrier films.”
To assess the durability of flexible PSC modules, the research team employed PSC modules made from methylammonium lead iodide (MAPbI₃), encapsulated with a polyethylene terephthalate substrate featuring barrier films with different rates of water vapor transmission (WVTR). The modules underwent a damp heat test, exposing them to a temperature of 85 °C at 85% relative humidity, simulating prolonged outdoor conditions.
After 2,000 hours of exposure, the researchers evaluated the photovoltaic (PV) performance of the modules and confirmed degradation by analyzing current-voltage characteristics, spectral reflectance, and electroluminescence.
The findings revealed that high humidity resulted in the breakdown of the MAPbI₃ layer into lead iodide, thereby impeding charge transport between the layers. This degradation significantly reduced the efficiency of the PSC modules, underscoring the harmful effects of moisture on their performance.
Additionally, the study highlighted that the quality of the barrier film was crucial to the stability of the modules. Notably, the module with the lowest WVTR of 5.0 × 10⁻³ g/m²/day maintained 84% of its power conversion efficiency, while modules with higher WVTRs experienced quick deterioration, failing after only 1,000 hours.
“Our research is the first to document the durability of encapsulated flexible MAPbI3-based PSC modules. With applications for solar energy in buildings with weight restrictions or on mobile platforms, flexible PSCs serve as an excellent alternative to conventional silicon panels. Insights from our study could aid industries in optimizing these modules for enhanced stability and durability,” Prof. Minemoto explains.
This study underscores the significance of barrier films in preserving the long-term reliability of flexible PSC modules, marking a transformation in the photovoltaic industry. Furthermore, providing energy generation across various locations can alleviate stress on energy grids. Enhancing the durability of PSC modules could also broaden the adoption of renewable energy, enabling their use in diverse environments and accelerating the global transition towards cleaner and more sustainable energy solutions.
