Perovskites are great for making solar panels. They can be easily deposited on most surfaces, even flexible or textured. These materials are also cheap to produce and lightweight. Today, they would be as efficient as the leading photovoltaic materials, mostly silicon. They are attracting increasing investment and research due to their immense potential. But, before perovskite solar cells can become commercially viable, companies must overcome significant hurdles.
Two other major contenders in the field of photovoltaics are silicon and cadmium-telluride. On the other hand, the term perovskite refers to a whole group of compounds. Named after L.A. Perovski (a Russian mineralogist), the perovskite solar material family is named after its structural similarities to perovskite.
The original mineral perovskite as calcium titanium oxide (CaTiO 3). It has a unique crystal structure. It comprises three parts, which have been labeled A-B and X, respectively. The lattices for the various components are interwoven. The perovskites family includes all possible combinations of elements and molecules that could occupy any of the three components. They form a structure that is similar to the original perovskite. Some scientists may even break the rules and call other crystal structures with similar elements “perovskites,” but crystallographers frown on this.
You can combine atoms with molecules, but there are limits. You might distort the structure if you try and stuff a large molecule into it. You might eventually cause the 3D crystals to split into a 2D layered or lose their ordered structure altogether,” Tonio Buonassisi is a professor of mechanical engineering at MIT. He is also the director of the Photovoltaics Research Laboratory. “Perovskites are highly tunable, like a build-your-own-adventure type of crystal structure,” he says.
The structure of interlaced lattices is made up of ions or charged molecules. Two (A & B) are positively charged, while the other (X) is negatively charged. The A and B ions are usually of different sizes, with A being more common.
There are many perovskites within the general category, including metal oxide perovskites. These perovskites have been used in catalysis, energy storage and conversions such as fuel cells and metal-air batteries. Buonassisi states that the lead halide perovskites have been the main research focus for over a decade.
There are still many options within this category. Labs all over the globe are trying to find the best combination of efficiency, cost and durability. This is the most difficult of the three.
Many teams have focused on alternatives to reduce the environmental impact of lead. However, Buonassisi points out that lead-based devices’ performance has improved over time and that no other compositions have come close to it in terms of electronic performance. Work continues to explore alternatives, but for the moment, there is no way to beat the lead halide versions.
Buonassisi says that one of the greatest advantages of perovskites is their tolerance for defects in the structure. Perovskites can work with many imperfections and impurities, unlike silicon, which is extremely pure to function well within electronic devices.
It cannot be easy to find promising candidate compositions for perovskites. But researchers recently discovered a machine learning system that can significantly simplify this process. Buonassisi was a co-author of that research and believes this new approach will allow for the faster development of alternative solutions.
Perovskites are promising, and many companies are already preparing to start commercial production. However, durability is still a major problem. On the other hand, Perovskites lose much more power than silicon solar panels after 25 years. It has been a great leap forward. Initial samples only lasted a few hours. Then, they lasted for weeks or even months. However, new formulations can last up to a few more years and are suitable for certain applications that do not require longevity.
Buonassisi states that perovskites have several advantages. They are easy to create in the laboratory, and the chemical constituents can be assembled quickly. However, perovskites have a downside: While they can be assembled at room temperature, he said that it also breaks down at room temperatures. It’s easy to use!
Researchers are focusing on various types of protective materials that can protect the perovskite from moisture and air. Others are trying to find more robust formulations and treatments by studying the mechanisms that cause this degradation. The breakdown is mostly due to a process called Autocatalysis.
Autocatalysis works by allowing one component of material to begin to degrade. The reaction products then act as catalysts for the other parts to degrade. Similar problems were encountered in the early research on other electronic materials (OLEDs) and were eventually resolved by adding more purification steps to the raw materials. Buonassisi suggests that a similar solution could be found for perovskites.
Buonassisi and his co-researchers recently completed a Study showing how perovskites can be economically viable in replacing silicon in large-scale, utility-scale solar farms once they reach at least a decade. This is due to their lower initial cost.
He says that the progress made in developing perovskites is impressive and encouraging. It has achieved efficiency levels comparable to Cadmium Telluride (CdTe) after only a few years’ work. “The new material’s higher performance is almost unbelievable.” He compares the time it took to improve efficiency by comparing the amount of research done on perovskites with CdTe. He says that perovskites are “one of the reasons it’s so thrilling.”