Solar panels made from silicon are already common on rooftops and in large solar farms.
They are reliable and proven, but they are also getting close to their maximum performance.
To make panels produce more electricity without taking up more space, scientists have been combining silicon with another powerful light-absorbing material called perovskite.
Together, these two materials form what is known as a perovskite–silicon “tandem” solar cell.
These advanced cells can capture more sunlight than ordinary panels and have reached efficiencies close to 35%, but their biggest weakness has been durability, especially in hot conditions.
A research team from the National University of Singapore has now found a way to make these high-performance solar cells last much longer.
Their study, published in the journal Science, focused on a very thin molecular layer that connects the perovskite and silicon parts of the cell.
Although this layer is extremely small, it plays a crucial role in moving electrical charge smoothly between the two materials. When it fails, the performance of the entire solar cell drops.
For a long time, scientists suspected that the perovskite material itself was the main cause of instability.
However, when the NUS team carefully tested perovskite–silicon cells under continuous light and heat, they discovered that the perovskite remained surprisingly stable. Instead, it was the tiny “contact” layer between the perovskite and the silicon that started to break down.
This layer, called a self-assembled monolayer, is made up of specially designed molecules that line up in an orderly way, a bit like a neatly woven carpet. When the temperature rises, many of these molecules begin to shift, curl up, or separate, creating gaps that block the flow of electricity.
To solve this problem, the researchers designed a new version of this molecular layer that can hold itself together more firmly. The new molecules form strong chemical links with one another as they arrange themselves, creating a tightly connected network that resists heat. In simple terms, they turned a delicate, loosely held layer into a tougher, more stable “molecular glue.” This change made the connection between the two materials much stronger and more reliable.
When tested, the improved tandem solar cells performed extremely well. They reached efficiencies above 34%, and one was officially certified at 33.6% by an independent testing center.
Even more importantly, the cells kept more than 96% of their original performance after 1,200 hours of continuous operation at 65 degrees Celsius. This level of stability is rare for perovskite-based solar cells and is a major step toward real-world use. Most conventional solar panels are expected to last 20 to 25 years, and matching that kind of reliability is essential for any new technology to succeed.
The researchers say this simple but effective improvement could help bring next-generation solar panels closer to the market. By strengthening the weakest link in the design, they have made it possible for these high-efficiency cells to work reliably for much longer periods.
The next step will be to test larger versions of these cells in real outdoor conditions, particularly in hot and humid climates like Singapore’s. If successful, this technology could allow future solar panels to generate much more electricity from the same amount of space, helping to accelerate the global shift to clean energy.
Source: National University of Singapore.
