Solar energy has come a long way in recent decades. Silicon panels have steadily dropped in cost and risen in efficiency. But another class of materials, called perovskites, has been causing a stir in research circles. They promise even cheaper, more adaptable solar power, and they can be tuned to absorb parts of the sunlight that silicon can’t.
There’s just been one catch: perovskites don’t always behave themselves. In particular, wide-bandgap perovskites, the type best suited for stacking on top of silicon to make ultra-efficient tandem cells, suffer from a kind of internal squabble. When light shines on them, their atoms sometimes rearrange themselves in ways that sap efficiency, a process known as “phase segregation”.
A team of researchers from Northwestern Polytechnical University in Xi’an, China [34.2°N, 108.9°E] has now found an elegant way to calm things down, using light itself. Their new approach helps perovskites keep their structure stable under illumination, leading to more efficient and longer-lasting solar cells. They call it Photo-Homogenisation Assisted Segregation Easing Technique, or simply PHASET.
What’s New?
The brilliance of PHASET lies in how simple it is. By applying carefully controlled pulses of light during the device’s preparation, the researchers “train” the material into a more uniform, stable arrangement. This pre-conditioning makes the perovskite less prone to splitting into inefficient phases when it’s later exposed to sunlight in real-world use.
The results are striking: the treated solar cells achieved efficiencies above 20%, while maintaining their performance far longer than untreated versions. That combination of efficiency and stability is exactly what has been missing from wide-bandgap perovskites, and it is what makes them practical for scaling up.
TLDR: Training Solar Cells with Light
Wide-bandgap perovskite solar cells often lose efficiency when their atoms shift under sunlight; a flaw called phase segregation. Researchers have developed a simple fix: using short pulses of light during preparation to “train” the material into a stable form. This method, dubbed PHASET, keeps the cells efficient for longer. It’s a small tweak with big potential, paving the way for tandem perovskite-silicon solar panels that could push efficiency above 30%.
Why It Matters
For the sustainable energy transition, every incremental gain in solar performance counts. Wide-bandgap perovskites are the missing piece in creating tandem solar cells — layered devices where perovskite sits on top of silicon, together harvesting more of the sun’s spectrum than either could manage alone. Tandems could push solar efficiency beyond 30%, a figure that would dramatically lower the cost of clean electricity worldwide.
Until now, instability has held this vision back. If PHASET or similar methods can be integrated into manufacturing lines, we could see perovskite-silicon tandems moving from labs into the commercial market much sooner than expected.
Key Takeaway
Sometimes the best way to solve a problem in solar is not to add complexity, but to let light itself do the work. This is a kind of “Machine Learning” brought to hardware. By training perovskites for sunlight, PHASET sets up solar panels for better outdoor performance.
It means solar panel installers can offer better returns. But academics’ work is never done: This discovery opens up a new line of inquiry into how pre-conditioning can tame unstable materials. And for the rest of us, there’s all the more reason for solar to provide more of our electricity.
Source
Photo-homogenisation assisted segregation easing technique (PHASET) for highly efficient and stable wide-bandgap perovskite solar cells, Nature Energy, 2025-08-29
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