The missing (solar) cell: Polish researcher improved the production of perovskites
Perovskites have a great chance to replace silicon in solar cells. Thanks to them, flexible and thin cells could be applied to clothing or plastic - believes Olga Malinkiewicz, who has developed a simple and inexpensive method to produce this remarkable material.
Inorganic perovskites are a group of chemical compounds that have been known since the nineteenth century (owing their fancy name to a Russian mineralogist Lev Perovski). However, only a few years ago it was discovered that they were ideal for the production of solar cells.
Perovskites occur in nature, for example in rock, but they can be also produced in a lab. "We do not need sophisticated equipment or expensive materials for that. I could make them at home, in the kitchen, if I wanted to" - said in an interview with PAP Olga Malinkiewicz, PhD student at the University of Valencia, who developed a simple method of production of these compounds.
Currently, photovoltaic solar cells primarily use silicon, a material which is not without drawbacks. High temperatures, around 1000°C are needed in the production of silicon photovoltaic cells, and silicon cells can not be directly applied to flexible materials, such as textiles or plastics.
Perovskites, like silicon, absorb visible light (300-800 nm length) in a way that allows to recover electricity. They also dissolve in solvents, so that they can be sprayed onto any surface. In addition, high temperatures are not needed for their preparation. The substance can be applied to any material: clothing, plastic, even paper. Moreover, the layer of this material may be up to 10 times thinner than the layer of silicon (e.g., 200-300 nm).
Olga Malinkiewicz believes that the possibilities of using solar cells with perovskites are almost limitless, in the future, for example, they could cover surfaces of houses, clothing or electronic devices that would charge with solar energy. Perovskites can even be used to make translucent layers. "Imagine that electricity can be produced by stickers applied onto the glass" - Malinkiewicz gave an example.
Perovskites are also a very efficient source of energy compared to silicon. Although the work on this material has only just begin, in the past few years researchers have improved the performance of perovskites several times, so that it is already better than the so-called amorphous silicon used in cheaper silicon cells.
Olga Malinkiewicz described that when she started working on perovskites, cells production method was very complicated: they could be produced only on thick glass, because one of the key components of the cell, titanium dioxide, was obtained at 500°C. In addition, the resulting layers had a lot of defects. "Layer of perovskites was very ugly, its properties were far from good. Therefore, it had to be coated with a thick layer of another, very expensive polymeric material" - the researcher told PAP.
"I developed a technique of forming a thin film of perovskites. My material was continuous, free of defects and smooth as a table. It did not have to be covered with thick polymer or produced on specific substrates" - described the scientist.
Olga Malinkiewicz started working on perovskites quite recently, last summer. When the head of her lab at the University of Valencia received a request from photovoltaics "guru" Michael Graetzel to produce perovskites as a gas, the task was entrusted to Malinkiewicz. She was the only one in the laboratory with experience in photovoltaics, the rest of the team specialised mainly in diodes and light emitting materials.
The researcher admityed that in her research on perovskites she used "what she found in the drawer", or materials useful in the application of LEDs. It turned out that these materials were perfect: at the end of the summer she had perovskites with excellent performance (12 percent). "We could not believe it was that simple" - said the researcher. The results were published in November in "Nature Photonics". Her individual study was awarded at the conference Photonics21 in late March.
For now, perovskites can be produced on small areas - a record size of the material is only 1 x 1 cm. These surfaces are not yet sufficiently large to use perovskites in large solar cells. However, this is only the beginning of research on this material.
" Polish laboratories should seize the opportunity and engage in research on perovskites. In these studies, everyone will have an equal start. Perovskites are thousand times easier to produce than graphene. Graphene production is very difficult, and perovskites - as it turns out - fabulously simple" - noted the PhD student.
PAP - Science and Scholarship in Poland, Ludwika Tomala
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