Petr Liška's penchant for sci-fi led him to study physics, and although today he admits that he sees a lot of pseudo-scientific nonsense in his favourite series, he has not given up on his beloved genre. But perhaps he has started to be even more fascinated by the real secrets of nature. As part of his PhD studies, he is engaged in research of so-called perovskites – nanomaterials that have the potential to bring breakthroughs, for example, in photovoltaics.
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Petr Liška loved series like the aforementioned Stargate. These, combined with inspirational teachers, led Petr to study physics at the Faculty of Mechanical Engineering. However, the study brought an unpleasant disillusionment from what was wrong in his dream worlds. "At first, I was disappointed that space was much less interesting than I imagined because of science fiction. But when you delve deeper into physics, you find that the real world is much more complex and adventurous than any science fiction," says the young scientist, who works at the Institute of Physical Engineering and CEITEC BUT.
Today in the laboratory he is studying the so-called perovskites, artificially created materials that have an interesting structure and no less interesting properties. "Structurally, they resemble the natural mineral perovskite. They have an interesting crystalline grid, different from the one we commonly see in nature. Thanks to this, they have properties that are relatively unprecedented, and, at the microscopic level, we still do not fully understand why they behave the way they do," Liška describes.
| Perovskite was discovered in the Urals in 1839 by the German chemist Gustav Rose, who found, described and named the calcium titanate compound in crystalline form after the Russian mineralogist and diplomat Lev Alekseevich Perovsky. A number of other compounds with a similar crystalline structure can be artificially created, which are referred to as perovskites. |
As an example, he points at photoluminescence, the so-called luminescence of the material. "Luminescent materials – phosphors – have their characteristic absorption energy. All photons that have an energy lower than this "absorption edge" cannot be absorbed by the phosphors. Simply put, for these photons the phosphors are transparent. However, some perovskites are able to absorb such photons and consume some of their internal heat in the process. They emit photons with energy higher than they have absorbed and cool down at the same time. It's like the sun shining on you, but instead of a warm feeling, you would soon start to get really cold. So far, we understand this phenomenon macroscopically, that is, we know what the result of the process is. But what we don't know is why such a process is happening, and moreover with such a huge probability," says Liška about the problem he is trying to solve in the laboratory.
Perovskites can be used in a wide range of areas. Photovoltaics, where they could increase the efficiency of solar panels, or energy or high-speed communication in general, seem to be very promising. Perovskite is a semiconductor. Monocrystalline perovskites appear to be effective and stable, but so far they have only been worked with in laboratory conditions, and scientists are still searching for a way to "tame" this material and transfer it to mass production.
"I am specifically engaged in the study of advanced nanomaterials for so-called smart wearable devices. Imagine, for example, many times smaller and smarter "smart" watch. There is a wide range of possible uses. The milestone we would like to achieve in our laboratory is a tuneable optical metasurface that would work similarly to a mobile phone lens, but would be many times lighter, take up less space and would be tuneable by light, heat and electricity," explains Liška.
In nanomaterials, the young scientist sees huge potential, but also a number of questions that the new technology brings along. "Like fire, nanomaterials can be a good servant but a bad master. Nanoparticles are so small that we cannot filter them out of groundwater, for example. I am researching perovskite CsPbBr3, which contains lead, which is a problem for commercial use in terms of European legislation. The good news is that we are able to replace many substances. And although this may reduce the efficiency of the material, if we look at factors such as price/performance ratio, quality or safety, they can be more than sufficient for commercial use," adds Liška.
Petr Liška's enthusiasm for his scientific work is infectious. That is probably why he also devotes himself to the popularization of science. "I'm a relatively closed person, but on the other hand, I'm very aware of how important it is to show people what I'm working on. Even if I excite one single person and motivate them to watch a popularization video or read something, it will make me very happy. In my opinion, it is a wonderful way to escape from everyday worries, for which we often do not even have time to think about how the world actually works. But when we realize that "above" and "below" is just our construct, because we float on a space rock in the void like a small blue dot, completely different horizons open up for us. Perhaps they will then realize that our mere existence is a miracle for which we should be grateful. The fact that a person explores the world around him and constantly asks "why" is, in my opinion, human nature," concludes Liška.