Perovskite solar cells are often called the future of solar energy.
They promise higher efficiency and lower costs than today’s panels, and when combined with silicon in “tandem” cells, they could generate record-breaking amounts of clean electricity.
But there has been one big obstacle: stability. These promising devices often don’t last long enough under real-world conditions to be practical for widespread use.
A new study published in Materials Futures sheds light on why that happens—especially in a special class of perovskites known as wide-bandgap perovskites, which are crucial for tandem solar cells.
Researchers from imec, Hasselt University, and Ghent University in Belgium have mapped out the major ways these devices degrade, giving scientists clearer targets for improvement.
The team focused on how thermal stress—exposure to heat—affects perovskite cells in both dark and illuminated conditions.
Under dark heat stress, known as ISOS-D2 testing, the weak spot turned out to be the charge transport layers, which move electricity through the device.
But under light plus heat stress, called ISOS-L2, the real culprit was the perovskite absorber itself—the part of the cell responsible for capturing sunlight.
This difference is crucial. It shows that “stability” in perovskite solar cells is not a single, fixed concept but depends heavily on the environment in which the devices are tested. Many earlier studies overlooked this, leading to an incomplete picture of how and why these cells fail.
Wide-bandgap perovskites are especially tricky. While they have excellent optoelectronic properties that make them perfect as the top layer in tandem cells, they suffer from phase segregation.
This means the bromide and iodide components in the crystal structure separate under heat and light, damaging the stability of the material.
Until now, solutions to this problem have mostly been demonstrated in lab-scale experiments, using techniques like spin-coating that are not suitable for industrial-scale production.
By conducting a side-by-side comparison between wide-bandgap perovskites and more stable, narrower-bandgap versions, the Belgian team was able to pinpoint how and where failures occur. Their work followed international testing standards, which strengthens its relevance for the solar industry.
Looking ahead, the researchers stress that more work is needed before wide-bandgap perovskites can be scaled up for commercial use. They call for deeper investigations at the nanoscale to fully understand degradation, as well as a broader set of stress tests, including outdoor field trials that mimic real-world conditions.
They also highlight the urgent need for clear industry standards that define what “stable” really means in the context of perovskite solar cells.
This study marks an important step forward. By uncovering the key pathways of degradation, scientists are now closer to solving the stability problem that has long stood in the way of perovskite commercialization.
If successful, this research could help unlock the next generation of ultra-efficient solar technology, bringing us closer to a future powered by abundant, reliable, and affordable renewable energy.
