Scientists have taken another important step toward making next-generation solar panels more powerful and longer lasting.
An international team of researchers has developed a new chemical treatment that helps perovskite solar cells convert sunlight into electricity more efficiently while also improving their durability.
The breakthrough allowed the experimental solar cells to reach a power conversion efficiency of 26.19%, placing them among the best-performing perovskite solar cells reported to date.
The study was carried out by researchers from Helmholtz Zentrum Berlin (HZB), Purdue University, Emory University, and several collaborating institutions. Their findings were published in the Journal of the American Chemical Society.
Perovskite solar cells have attracted worldwide attention because they are cheaper and easier to manufacture than traditional silicon solar cells while offering the potential for very high efficiency.
However, one of the biggest challenges has been making these devices stable enough for long-term use. Tiny defects that form during manufacturing can reduce performance and shorten the lifespan of the cells.
One common problem occurs after the perovskite layer is created. Small amounts of a material called lead iodide remain on the surface.
A little lead iodide can actually help the crystals form properly, but if it is unevenly spread across the surface, it creates tiny electrical weak spots. These weak spots trap electrical charges that should be flowing through the solar cell, reducing the amount of electricity the device can produce.
To solve this problem, the researchers designed a new type of molecule that attaches to the leftover lead iodide in a much more controlled way.
Unlike earlier molecules that connected through only one point, the new molecules grab onto the lead iodide at two different points. This stronger connection reorganizes the leftover material into a more stable and uniform structure without damaging the main perovskite layer underneath.
One of the newly developed molecules, called MeXT, performed especially well. It created a smoother and more even electronic surface, allowing electrical charges generated by sunlight to travel more easily through the solar cell instead of becoming trapped. As a result, less energy was lost during operation.
The best-performing solar cell achieved a certified efficiency of 26.19%, with a stabilized efficiency of 25.65% during continuous operation. Just as importantly, the treated devices showed impressive durability. After operating continuously under bright light at a temperature of 75 degrees Celsius (167 degrees Fahrenheit) for 1,000 hours, they still retained more than 80% of their original performance.
The researchers also used advanced imaging and electrical measurement techniques to understand exactly why the new treatment worked so well. These methods allowed them to watch how electrical charges moved inside the device. They found that the new molecular coating not only reduced defects but also improved the movement of positive charges while preventing electrons from becoming trapped at the interface between different layers of the solar cell.
The study demonstrates that carefully designing the chemistry at the boundary between materials can dramatically improve both efficiency and stability. Instead of simply covering up defects, the new approach creates a cleaner and more balanced electrical environment where charges can move more freely.
The researchers believe this strategy could help speed the commercial development of perovskite solar cells. They are also preparing a new fully automated robotic laboratory at Helmholtz Zentrum Berlin that will use robotics, advanced measurements, and artificial intelligence to rapidly test and optimize new solar cell materials.
By allowing robots to build, analyze, and improve devices automatically, the team hopes to accelerate solar cell research by roughly tenfold, bringing high-performance, low-cost solar technology closer to everyday use.
