Perovskite Solar Panels

A substance known to scientists for more than a hundred years, only today, at the beginning of the XXI century, it turned out to be very promising material for the production of cheap and effective solar cells. Perovskite, or calcium titanate, first found in the form of a mineral by the German geologist Gustav Rosa in the Ural Mountains back in 1839, and named after Count Lev Alekseevich Perovsky, a glorious statesman and collector of minerals, the hero of the Patriotic War of 1812, turned out to be the most suitable contender for the role of the alternative to silicon in the production of solar cells.

As a substance, until recently, calcium titanate was widely used only as a dielectric for multilayer ceramic capacitors. And now they are trying to apply it to build highly efficient solar panels, since it turned out that this material perfectly absorbs light.

Ordinary, long traditional silicon solar panels at a thickness of 180 microns, they absorb as much light as perovskite will absorb at a thickness of only 1 micron. Perovskite, just like silicon, is a semiconductor, and it transfers electric charge in the same way under the influence of light, but the spectrum of light converted to electricity in perovskite is wider than that of silicon.

The structure of the crystalline substance of calcium titanate is identical to the structure of the perovskite mineral, therefore their name is the same. And it is this substance that is today at one of the leading places in the ranking of optimization paths for solar energy.

The thing is that silicon-based solar panels cost an average of 75 cents per 1 kW today, and perovskite-based solar panels will reduce their cost to 10-15 cents per 1 kW, that is, perovskite solar technology in 5-7 times cheaper than silicon both in the production of batteries and in their operation, and the amount of electricity produced is the same.

And this despite the fact that energy industry analysts claim that already at a cost of 50 cents per 1 kW, solar energy becomes competitive with fossil fuels. That is, the transition to perovskite on a global scale will reduce the cost of electricity production at times, while the production process of the panels themselves will be very simple.

Studies to evaluate and improve the efficiency of perovskite-based solar cells are being carried out in many countries: in Australia, Martin Green, in Switzerland, Michael Gretzel, in the USA, Henry Saint, Felix Deshler, Leaming Day, and Korea, Sok Sang Il. Researchers unanimously declare the low cost and high efficiency of promising technology.

Michael Gretzel argues that his efficiency of 15% can easily be increased to 25%, and inexpensive solar cells from the currently available do not reach 15%. For the first time, in 2009, when they were just talking about the possibilities of using perovskite for solar energy, an efficiency of 3.5% was obtained, and the cells were short-lived, since the liquid electrolyte dissolved perovskite, and as soon as scientists had time to measure, the battery stopped working.

However, after three years, the liquid electrolyte was replaced by a solid one, and the cells became more stable, and the efficiency first doubled, and then doubled again. Several electrically conductive substrate layers, one of which was coated with a pigment, solved the problem and opened up the prospect. Steps to improve efficiency do not stop to this day, scientists use, among other things, standard optimization methods that served to improve silicon precursors.

Michael Gretzel is sure 25% efficiency will lead to a revolution in solar energy.A professor from Australia, Martin Green, one of the pioneers in research, claims that silicon-free batteries are so simple to manufacture and efficient to operate that there is definitely confidence that the future of solar panels on Perovskite is bright, because preliminary estimates already predict a huge reduction in price - at 7 time.

A group of researchers from Korea, led by Sok Sang Il, developed their own formula by mixing lead ammonium bromide with lead formamidine iodide, scientists achieved such a perovskite structure that they set a record efficiency of 17.9%. Using the mixture will allow the printing of solar cells, and their cost will be further reduced. The problem remains - the material dissolves in water, in addition, the size of the cells in the tests did not exceed 10 square mm, so research continues.

The process of manufacturing perovskite solar cells seems to researchers quite simple. The liquid is simply sprayed onto the surface or applied in the form of steam, which is very simple to realize technologically. Several layers of materials are applied to metal foil or glass, one of which is perovskite.

Other materials are needed here to facilitate the movement of electrons within the element. The manufacturing process is close to ideal. Oxford University physicist Henry Saint, who works on developing perovskite cells in the United States, is confident that layers of the solar panel will be applied as easily as with a regular paint on a surface.

Despite the emerging prospects, scientists were divided into two camps. The former advocate the improvement of silicon batteries that have already become traditional, while the others advocate the creation of completely new, more efficient ones. So, Martin Green believes that perovskite can be used as an addition to silicon batteries by combining silicon with perovskite, and thus reduce the cost of a watt of electricity produced without significant losses for the silicon industry. Michael Gretzel, on the contrary, is convinced that new developments are important, and the cost of increasing the efficiency of new photocells will pay off many times.

Many companies are already working on the commercial implementation of the product, because despite the fact that the possibilities of perovskite are just beginning to be realized, leading experts in the field of solar energy have already turned their attention to the future. Australian and Turkish companies together actively approached the commercialization of perovskite solar panels, and according to forecasts, by 2018 they will be presented on the world market.

Despite the optimism of some companies, experience shows that it usually takes ten years for a new technology to go from the laboratory to the market, and during this time, silicon batteries may well overtake perovskite. Gretzel, by the way, is selling a license for new technology to companies that intend to follow the traditional way of silicon.

The competition in the solar energy market is also high, and every new player is faced with it. The cost of silicon panels is reduced, and according to some analysts, it can drop to 25 cents per 1 kW, which completely deprives the benefits of perovskite technology.

The presence of a small amount of lead in the pigment, which is toxic, remains a problem. Experimental studies are coming up that will reveal how toxic perovskite is. It is worth paying attention to the disposal of used batteries, as is the case with starter car batteries. But in principle, tin or something similar can be used instead of lead.

Meanwhile, researchers from Ohio, led by Leaming Dai, set about electrifying electric cars using perovskite solar panels. They developed the most beneficial combination of solar panels with electric car batteries than ever before.

By connecting four perovskite batteries to a lithium battery, scientists achieved an efficiency of 7.8% in the most efficient configuration to date, which surpassed previous solutions for combining solar cells with supercapacitors and batteries.

Multilayer panels have increased the density and stability of energy received from the sun. Tests have shown that three layers of perovskite are transformed, if desired, into one film. With a single-cell area of ​​not more than 10 square mm, the researchers achieved an efficiency of 12.65% of a coin-sized converter, but taking into account the conversion and storage of energy, the efficiency was 7.8% in cyclic mode.

Such systems, according to developers, will be able in the future not only to charge electric cars, but will also be installed in the form of a flexible film on bodies. The technology seems ideal for electric vehicles.

Remarkable is the ability of perovskite to reemission. A scientist at the University of Cambridge, Felix Deschler, discovered that perovskite has a unique property. When light enters the material, the photon energy is not just converted into electricity, part of the charge is converted back into photons.

If the panel can reuse these photons, then the collected energy will become even greater. Deshler's group conducted an experiment in which the laser beam was concentrated on a 0.5 micron thick perovskite section, and light was re-emitted elsewhere in the sample. Silicon, for example, does not have the ability to transfer energy within itself and again emit it.

Thus, the prospects for perovskite are enormous, and who knows, it may be just around the time when every house and every car will be equipped with perovskite batteries, since it will become economically unprofitable and not advisable to pollute the environment with fossil fuel combustion products.