Perovskite solar cells are widely considered one of the most exciting technologies in the future of renewable energy. They can convert sunlight into electricity with very high efficiency, while also offering advantages that traditional silicon solar panels cannot easily provide. They can be made extremely thin, lightweight and flexible, and their manufacturing process could require less energy and potentially lower production costs.
But one major problem has slowed their journey toward widespread commercial use: stability.
Perovskite solar cells can gradually lose performance when exposed to moisture, oxygen and high temperatures. Now, researchers at Kaunas University of Technology (KTU) and their international collaborators have developed a promising solution to one of the key causes of this degradation.
Their research, published in Nature Communications, focuses on something incredibly small but extremely important—the molecular interface between the different layers of a solar cell.
The Hidden Weak Point Inside a Solar Cell
A perovskite solar cell is not made from a single material. Instead, it contains several thin layers, and each layer has a specific job.
Dr. Kasparas Rakštys of KTU compares the structure to a multilayered sandwich. The different layers must work together perfectly for electricity to move efficiently through the device.
One particularly important layer is only a few nanometers thick. It helps transport positive charge carriers, known as holes, toward the electrode.
Even though this layer is almost unimaginably thin, problems inside it can affect the performance of the entire solar cell.
Researchers have previously used special materials called self-assembled monolayers (SAMs) to create this connection. These molecules work almost like molecular glue, helping connect the solar cell's layers and allowing electrical charges to move efficiently.
SAMs developed by Professor Vytautas Getautis's research group at KTU became an important development in perovskite solar technology after their introduction in 2018.
However, researchers later discovered a weakness.
Some of these molecules are acidic. Over time, their acidic nature can attack nearby layers and create defects at the interface. These defects interfere with charge movement, causing the solar cell to become less efficient and shortening its working lifetime.
In other words, a material designed to improve the solar cell could eventually contribute to its degradation.
A Simple Chemical Solution
The KTU researchers decided to address the problem by changing the chemistry of the molecules.
Instead of allowing the molecules to remain acidic, they chemically converted the acidic group into an ionic salt.
The result was a more chemically neutral interface.
According to the researchers, this seemingly simple change has several important advantages. The modified molecules can still attach strongly to metal oxide surfaces, but they are much less aggressive toward the surrounding materials.
Another benefit is that the salt-based molecules are water-soluble. This means they can potentially be deposited without relying on toxic organic solvents, offering an additional advantage for manufacturing.
The researchers were therefore able to address two major goals at once: maintaining high efficiency while improving stability.
That combination is particularly important because achieving high efficiency and achieving long-term durability are often difficult to accomplish simultaneously in emerging solar technologies.
Why Interfaces Matter So Much
The breakthrough demonstrates an important lesson in materials science: sometimes the biggest problem is not the main material but the boundary where two materials meet.
Perovskite itself can absorb sunlight extremely well. However, if electrons or holes encounter defects while moving through the solar cell, some of the electrical energy can be lost.
Imagine a highway with excellent roads but several damaged bridges. The quality of the highway does not matter if vehicles cannot move smoothly between sections.
The same principle applies inside a solar cell. Improving the interface can therefore improve the performance of the entire device.
The researchers' approach essentially creates a cleaner and more stable connection between the layers.
From Tiny Laboratory Cells to Larger Solar Modules
A major challenge in solar technology is moving from laboratory experiments to practical devices.
A small solar cell can sometimes achieve impressive efficiency under carefully controlled laboratory conditions. But producing a large-area device with the same quality is much harder.
The KTU team therefore tested whether its new molecular approach could work over larger areas.
Working with international partners in China, the researchers demonstrated that their new molecules could produce a uniform and high-quality coating on larger solar modules.
This is an important step because commercial solar panels require large, consistent surfaces rather than tiny laboratory samples.
The researchers also tested the approach in perovskite tandem solar cells.
Tandem cells combine different light-absorbing materials so that they can capture more portions of the Sun's spectrum. This can potentially push solar efficiency beyond the limits of conventional single-junction cells.
Using their new approach, the researchers achieved more than 29% power conversion efficiency in perovskite tandem solar cells, representing one of the high efficiency levels reported for this type of technology.
Could Perovskites Change the Future of Solar Power?
If stability problems can be solved, perovskite solar cells could become useful in applications where conventional solar panels are difficult to install.
Because they can be thin and lightweight, they could potentially be incorporated into building surfaces, windows and even flexible materials such as textiles.
This could transform solar energy from something mainly installed on rooftops and large solar farms into a technology that can be integrated into everyday objects and structures.
The researchers are already working toward commercialization. The KTU team has filed a patent application and is continuing to develop neutralized SAM materials and new molecules that could provide even better performance.
The team has also begun commercialization efforts and hopes its SAM salt technology will become available to other research groups and eventually reach the global market.
A New Opportunity for Solar Power in Space
Interestingly, the potential applications of perovskite solar cells extend far beyond Earth.
The space industry is becoming increasingly interested in lightweight and radiation-resistant solar technologies. Satellites need reliable power sources, but traditional space solar cells can be extremely expensive.
Perovskites offer several potentially important advantages.
First, they are exceptionally thin and lightweight. Second, research has shown that they can tolerate high levels of radiation better than conventional silicon solar cells.
Space also provides an unusual advantage for perovskites: the environment lacks the moisture and oxygen that can accelerate degradation on Earth.
According to the researchers, recent studies indicate that some perovskite solar cells can retain more than 90% of their efficiency after radiation exposure that would severely damage silicon solar cells.
Their extremely low weight is another major advantage. The researchers say perovskite cells could potentially offer a power-to-weight ratio 10 to 20 times higher than today's expensive multijunction solar cells used in satellites.
KTU researchers are exploring this opportunity through their spinout company, SantakaPV, which focuses on space applications.
From a Tiny Molecule to a Big Energy Opportunity
The latest breakthrough shows how a small chemical change can have a major impact on an emerging technology.
By replacing an acidic molecular group with a neutral salt, researchers have created a more stable interface that could help perovskite solar cells maintain their efficiency for longer.
The technology still needs further development, testing and large-scale validation before it can become a mainstream replacement or complement to silicon solar panels. But the progress is encouraging.
Perovskites already offer the possibility of highly efficient, lightweight and flexible solar power. If their long-standing stability challenge can be overcome, they could open the door to a new generation of solar technologies—not only for homes and buildings, but potentially for wearable devices, vehicles, satellites and future space missions.
What makes this breakthrough particularly exciting is that the solution did not require completely redesigning the solar cell. Sometimes, the key to a major technological breakthrough can be hidden in a layer only a few nanometers thick.
Reference: Yang, Y., Krisiune, D., Xu, Y. et al. Ionic self-assembled monolayers enable neutral interfaces and synergistic charge extraction in high-efficiency perovskite solar cells. Nat Commun 17, 7906 (2026). https://doi.org/10.1038/s41467-026-74288-2
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