Tapping Solar Power with Perovskites
July 4, 2014
A Polish physicist has developed a simple and inexpensive method of producing perovskites, a class of remarkable materials that could replace silicon in solar panels. In recognition of her work, Olga Malinkiewicz was named the winner of an annual competition held by the European Commission.
Perovskites are a group of chemical compounds named after Russian mineralogist Lev Perovski that have been known since the 19th century. But it was not until a few years ago that researchers discovered that these materials are ideal for the production of solar cells.
Perovskite is the term used for a particular mineral crystal structure, most commonly a calcium titanium trioxide (CaTiO3) mineral, and is applied to anything that adopts this same structure.
Perovskites occur in nature, for example in rock, but they can also be produced artificially in a laboratory. A perovskite is simply everything that takes on a specific crystalline structure—the spatial arrangement of an atomic lattice, researchers say. Depending on what atoms are put in the lattice, it is possible to shape the properties of the material, such as conductivity, light absorption, flexibility, and solubility. Naturally occurring perovskites are minerals.
After perovskites were discovered in the early 19th century, the scientists of the time tried, with little success, to use them as a source of light in diodes. But the real breakthrough came about two years ago when it turned out that this material is ideal for solar panels.
“Perovskites absorb lots of light in very thin layers,” says Malinkiewicz, who studied in Spain and is pursuing her scientific career at the University of Valencia. “They absorb and convert into electricity the entire solar spectrum in all of its colors. That’s why solar cells appear to be very dark, almost black.”
Initially perovskites used in solar cells were about 10 percent efficient. Today, this has increased to 15 percent and continues to grow. It’s no wonder then that there is increasingly talk about using perovskites instead of silicon in solar panels.
Although work is still in its early stages, over the past several years researchers have improved the performance of perovskites so much that these materials are already far more efficient than so-called amorphous silicon used in cheaper silicon cells.
Malinkiewicz’s method makes it possible to produce cheaper and more universal solar cells than those pioneered by researchers at Britain’s Oxford University.
“I considerably simplified the design of typical perovskite cells by removing from their architecture expensive materials and replacing these with much cheaper ones,” says Malinkiewicz. “I managed to get rid of problematic components, such as titanium dioxide, which requires very high temperatures of around 500 degrees Celsius and thus limits the choice of the surface for such a cell practically to glass only.”
Cheap solar cells should be built from inexpensive materials. Lower temperatures (of up to around 100 degrees Celsius) significantly reduce the cost of producing solar cells and make it possible to integrate them with film and other substrates that do not like high temperatures, thereby extending the number of potential applications.
Solar cells made with the method Malinkiewicz has developed are flexible as well as light. Solar panels made from such cells could be placed on the roof of a car, house, sports arena or office building.
It is possible to make partially transparent cells and integrate them with a building’s windows, in addition to putting them up on the roof.
Malinkiewicz and her colleagues filed for a patent immediately after developing their method for producing perovskite-based cells.
“We are looking for a way to make further progress,” says Malinkiewicz. “So far, we have created efficient perovskite cells on ultra-thin film. We have yet to test fabrics. But I see no reason we should not succeed with such a substrate.”
Most solar panels used today are made from crystalline silicon, but scientific research continues into new materials that would be more efficient, cheaper, readily available, solid and durable under prolonged exposure to sunlight and weather.