Perovskite solar cells have the potential to make solar power cheaper, lighter and more versatile.
But one major problem has held them back: they tend to lose performance over time, especially when exposed to moisture, oxygen and heat.
Now, researchers have developed a surprisingly simple solution that could make these next-generation solar cells more stable and practical.
Scientists at Kaunas University of Technology (KTU) and their international partners found that turning an acidic material inside the solar cell into a neutral salt can protect the device from damage.
Their study, published in Nature Communications, showed that the approach can improve both efficiency and long-term stability.
A perovskite solar cell is made from several extremely thin layers, each with a different job. KTU researcher Dr. Kasparas Rakštys compares the structure to a multilayered sandwich. For the solar cell to work well, the layers must connect properly so electrical charges can move through the device.
One particularly important layer contains molecules known as self-assembled monolayers, or SAMs. These molecules help move positive electrical charges toward an electrode. Although this layer is only a few nanometers thick, problems within it can reduce the performance of the entire solar cell.
Researchers discovered that conventional SAM molecules have an important weakness: they are acidic. Over time, this acidity can damage nearby materials and create tiny defects that interfere with the movement of electrical charges.
The KTU team tackled the problem by chemically changing the acidic part of the molecules into neutral salts. The modified molecules still attach strongly to the surface underneath them, but they are much less likely to cause damaging chemical reactions.
There is another advantage. The new salt-based materials dissolve in water, allowing manufacturers to apply them without some of the potentially harmful solvents normally used during production.
The researchers also wanted to know whether the technology could work beyond tiny laboratory devices. Working with partners in China, they successfully applied the new material to larger solar modules, producing an even, high-quality coating.
The approach also performed well in tandem solar cells, which combine materials that capture different parts of sunlight. Using the new method, the researchers achieved a power conversion efficiency of more than 29%.
Better stability could eventually help perovskite cells find uses in places where traditional silicon panels are difficult to install. Because perovskite devices can be thin, lightweight and flexible, they could potentially be incorporated into building walls, windows and even textiles.
The technology may also have an unusual advantage in space. Perovskite cells are extremely lightweight and appear to tolerate radiation better than conventional silicon cells. Space also lacks moisture and oxygen, two major causes of perovskite degradation on Earth.
The researchers are now working toward commercialization. A patent application has been filed, and the team says its neutral SAM salts are expected to become commercially available.
If the technology proves durable on a large scale, this small chemical change could help remove one of the biggest obstacles standing between perovskite solar cells and widespread use.
Source: KSR.
