North of 49 degrees, solar power is often said to be better suited to sunnier lands. Yet advances in materials science are reshaping that perception. Among the most promising candidates are perovskite solar cells, a family of crystalline materials that, in theory, could outperform silicon while being cheaper and lighter to produce.
But brilliance has its fragility. A new study led by researchers at Hasselt University in Diepenbeek, Belgium [50.9°N, 5.4°E], together with colleagues across Europe, has taken a hard look at where these cutting-edge cells begin to falter. Their focus: the wide bandgap perovskite, a variety tuned to capture high-energy sunlight and designed to pair elegantly with conventional silicon cells in “tandem” architectures. Together, such pairings could lift solar panels to efficiencies unimaginable a decade ago.
The researchers found that the cells are more robust under some stresses than many expected, but also more vulnerable in others — and in ways that reveal how far the field still has to travel.
Light, Heat, and Their Unwelcome Alliance
The team fabricated solar cells using scalable industrial methods rather than delicate laboratory techniques — an important step towards real-world application. They then subjected the devices to a series of internationally recognised stress tests: prolonged exposure to light, exposure to heat, and finally, both together.
The results carried a certain irony. Under light alone, the wide bandgap cells showed only modest decline, retaining much of their performance after 60 hours. Heat alone was harsher, sapping efficiency until only 80 per cent remained after 95 hours. But the most punishing was the combination. Light and heat together cut the cells down swiftly, leaving them at 80 per cent of their original efficiency in just 35 hours.
In these conditions, the very heart of the perovskite absorber began to degrade, its crystal structure splintering into less useful forms. Where light alone had seemed tolerable, heat joined forces with it to accelerate collapse.
The Interfaces Tell a Story
Perhaps most striking was the conclusion that degradation often did not stem from the perovskite material itself, but from the interfaces — the thin boundary layers where the perovskite meets the transport layers that shuttle charges out of the cell. Here, invisible barriers can arise, impeding the flow of electricity and eroding performance.
This finding matters because it directs attention not merely to the perovskite composition, but to the way it is integrated with surrounding materials. In a field often obsessed with the absorber crystal, it is a reminder that success rests on the harmony of the whole stack.
Why This Matters Beyond the Lab
For policy-makers and investors in the global north, the message is clear. Perovskites are not a mirage — they truly can endure light, and with refinement, they may yet endure heat. But accelerated tests reveal that what is often labelled “stability” is not a single trait. Cells may resist one stress while succumbing quickly to another. To reach the rooftops of Oslo, Montreal or Reykjavik, these devices must be engineered to cope with the real outdoors, where sunlight rarely comes without temperature swings.
The study also underscores the importance of testing cells under combined conditions. It is no longer enough to demonstrate resilience under light or heat alone. Real-world deployment demands resilience against their partnership.
Towards a Durable Future
The optimism lies not in denying the difficulties, but in naming them clearly. The researchers suggest new directions: redesigning interfaces, exploring fresh material combinations, and subjecting prototypes to a wider range of stresses — including outdoor trials, where the complexity of weather and time cannot be simulated in the lab.
If progress continues, wide bandgap perovskites could soon be the crown jewel in tandem solar cells that push efficiencies beyond 30 per cent. That, in turn, could transform the economics of solar power in northern latitudes — where every photon counts, and durability is as precious as efficiency.
Source
In-depth study of degradation in scalable wide bandgap perovskite cells, Materials Futures, 2025-09-16
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