A simple salt could be the key to making solar power cheaper, stronger, and longer-lasting.
Researchers at University College London (UCL) have discovered that a salt called guanidinium thiocyanate can help improve a new type of solar technology known as perovskite solar cells.
Perovskites are a class of semiconductors that have been attracting huge attention over the past decade as a possible replacement—or partner—for the silicon used in today’s solar panels.
Like silicon, they can turn sunlight into electricity, but they can be made with less energy and at lower cost.
They can also be tuned to capture different parts of sunlight, which makes them especially promising for “tandem” solar cells—cells with more than one layer stacked together to squeeze more energy from the sun.
The UCL team found that by adding guanidinium thiocyanate during the manufacturing process, they could slow down and control how perovskite crystals form.
This makes the crystal layers smoother and more uniform, reducing tiny defects that usually limit performance and shorten lifespan.
In tests, their perovskite cells achieved an efficiency of 22.3%, which is very close to the best reported results for this type of material.
For comparison, the best silicon cells in labs reach about 27%, and most panels installed on rooftops today are around 22%.
What makes tandem perovskite cells so exciting is that they can already surpass 30% efficiency in labs—well beyond standard silicon panels.
If the salt treatment is applied to the bottom layer of these tandem cells, researchers believe the efficiency could be pushed even higher. That means more power from the same amount of sunlight, and potentially lower costs for consumers.
One of the biggest hurdles for perovskite solar cells has been stability—making them last long enough to compete with silicon.
By controlling crystal growth with this salt, the cells become not only more efficient but also more durable. This insight gives scientists a powerful new tool to fine-tune the material’s structure for long-term use.
Perovskites also have practical manufacturing advantages. They can be processed at relatively low temperatures and made into lightweight, flexible panels. That opens the door to solar cells that can be used on rooftops, vehicles, or even clothing.
The study shows that sometimes small changes—in this case, a pinch of salt—can make a big difference. As the world races to expand clean energy, discoveries like this bring us closer to solar panels that are cheaper, more powerful, and built to last.
