Heat cycles shape perovskite cell durability

Metal-halide perovskites can achieve efficiencies up to 27% while requiring minimal material and energy during fabrication, a factor that could substantially reduce the cost of solar energy. Nonetheless, the ambition to secure a stable energy yield for 20 to 30 years in outdoor settings remains unfulfilled, underscoring the need for more robust materials.

The collaborative study brought together experts from China, Italy, Spain, the UK, Switzerland and Germany. In partnership with Prof Meng Li of Henan University, the research documented years of investigation showing that drastic temperature fluctuations critically undermine the performance of metal-halide perovskite solar cells.

In real-world conditions solar modules face daily and seasonal temperature swings. As Abate states, "When used outdoors, solar modules are exposed to the weather and the seasons," indicating that even with effective moisture protection the cells endure significant thermal variations from minus 40 degrees Celsius to plus 100 degrees Celsius in some regions.

To mimic even harsher conditions the study subjected the cells to extreme temperature cycles from minus 150 degrees Celsius to plus 150 degrees Celsius repeatedly. Dr Guixiang Li examined how these cycles altered the microstructure of the perovskite layer and disrupted its interactions with adjacent layers.

These severe temperature swings induce stress within the perovskite film as well as at the interfaces between dissimilar materials. As Abate explains, "In a perovskite solar cell, layers of very different materials need to be in perfect contact; unfortunately, these materials often have quite different thermal behaviours," leading to poorer interlayer adhesion, local phase transitions and the diffusion of elements.

Drawing on these insights the researchers propose measures to enhance long-term stability. As Abate states, "Thermal stress is the key," and the study advocates for improving the crystalline quality of the perovskite structures and employing suitable buffer layers to mitigate thermal strain. The team also calls for standardized test protocols to enable effective comparisons of durability results.

Research Report:Resilience Pathways for Halide Perovskite Photovoltaics Under Temperature Cycling