Halide perovskite solar cells are often described as one of the most exciting technologies of the new energy era. The reason is simple, they can achieve very high efficiencies while also offering the possibility of cheaper and simpler manufacturing than some of today’s standard solutions.
This is why scientists around the world view them as a serious contender for the future of solar energy. Yet one problem has been holding them back for years. These cells lose stability over time. The new paper published in Nature Energy now shows that this problem cannot be explained by a single “culprit,” but rather by a series of interconnected chemical processes taking place inside the cell while it is operating.
The paper was authored by an international team of scientists. The Ruđer Bošković Institute team includes Stjepan Dolić and Dr Vedran Kojić as first authors, Dr Andreja Gajović, and corresponding authors Dr Jasminka Popović and Dr Aleksandra B. Djurišić.
Why are halide perovskite solar cells so interesting?
Perovskite solar cells convert sunlight into electrical energy using a special class of photoactive materials known as halide perovskites. They have attracted both scientists and industry because, under laboratory conditions, they achieve very high efficiencies, higher than silicon cells, which currently dominate the market, and they can be produced in thin layers, opening the door to lighter, more flexible, and potentially cheaper solar devices.
Precisely because of this combination of high efficiency and lower production costs, perovskites have for years been regarded as one of the most serious candidates for the next generation of solar technologies.
The main obstacle, stability
Despite their enormous potential, perovskite solar cells have not yet seen widespread adoption because they lose stability over time. Their internal structure proves sensitive to the conditions under which they must operate, such as light, electrical voltage, and heat.
In other words, it is not enough for a solar cell to be highly efficient at the start. To be useful in real-world conditions, it must remain so over a long period of time, and that is precisely the greatest challenge for perovskite materials.
What does the new Perspective paper bring?
It is important to stress that this is not a conventional scientific article, but even less so a review paper. Perspective articles in Nature Energy are reserved for work that redefines the scientific narrative, in other words, work that challenges the currently prevailing scientific paradigm by arguing that the previous focus on certain processes is insufficient and that solutions lie in identifying and eliminating additional key parameters.
The authors broaden the current understanding of the degradation of perovskite solar cells. However, instead of focusing solely on iodide oxidation, which has so far received the most attention in this field, they also place irreversible reactions of the organic components of the material at the forefront, showing that these play a crucial role in the long-term stability of the device.
What is actually happening inside the cell?
Until now, the discussion has largely revolved around iodine, more specifically iodide, an important component of the perovskite material. When the solar cell is in operation, light and electrical voltage can trigger reactions in which iodide is oxidised. This then drives ion movement and disrupts the internal balance of the material.
But the authors show that the problem does not end there. After this initial step, the organic parts of the perovskite also begin to react, namely the small positively charged molecules that help maintain its structure. When these enter irreversible chemical reactions, volatile compounds are formed that can escape from the material. As a result, the perovskite gradually loses its own building blocks, and its crystal structure begins to break down.
Put simply, the problem is not only that some parts inside the cell start to move, but also that the chemical composition of the material changes in a way that can no longer be easily reversed.
Why is this perspective important?
This view changes the way degradation in perovskite solar cells is understood. Instead of a single isolated failure, the authors describe a chain of interconnected processes, from iodide oxidation and defect formation, through ion migration and the loss of organic components, to the eventual weakening and collapse of the material’s structure.
This is important because it shows that the solution is unlikely to come from a single measure, but rather from a combination of protective strategies targeting different chemical processes. Since unwanted photoelectrochemical and electrochemical reactions inside solar cells occur under the influence of light or electrical voltage, that is, under normal operating conditions, these cascading degradation processes are present even in the complete absence of oxygen and moisture, which would otherwise accelerate them. Consequently, these undesirable reactions can be slowed down, but they cannot be eliminated by encapsulation, because encapsulation only prevents moisture and air from entering from the outside, while the critical intrinsic processes take place within the material itself.
That is why the authors advocate a broader approach, namely the targeted design of organic components, the use of additives that can slow down undesirable reactions, optimisation of device architecture, and the development of methods that will enable these processes to be monitored in real time.
A step towards real-world application
Halide perovskite solar cells are no longer merely a laboratory curiosity. They are one of the most serious candidates for the next generation of solar technologies. If the stability problem can be solved, they could pave the way for more efficient and affordable solar panels, as well as new applications on surfaces and in conditions where today’s technologies are impractical.
The central message of the paper is therefore clear, if perovskite solar cells are truly to transform the energy sector, it is not enough to understand how they generate electricity, we must also understand how they age. It is precisely this deeper understanding of the chemical processes inside the material that could prove crucial in turning great laboratory promise into a stable technology of the future.
