When the Biden government announced a $ 128 million initiative in late March to improve the cost of solar energy, a significant portion of the money went to research on materials named after an obscure 19th-century Russian geologist and nobleman: Lev Perovski.
Among the projects mentioned: $ 40 million for research and development of so-called perov shooting materials that scientists use to shift the limits of how efficient and adaptable solar power can be.
And although perovskites are nothing new – they were first found in the Ural Mountains in Russia in 1839, and this is relatively common, their recent applications in solar technology have given rise to the hope that people will use it to kill the thousands better to utilize megawatts. energy of the sun falling on the earth every hour.
“Perovskites are, in my opinion, one of the most exciting opportunities for solar cells in the immediate future,” said David Mitzi, a professor of mechanical engineering and materials science at Duke University, who has been studying materials since the 1990s.
Any new solar technology had to compete with silicon solar cells, a entrenched technology that has been used for more than 50 years, Mitzi said. But perovskites had the potential to both improve the efficiency of silicon cells and perhaps compete directly with it: “I think there are definitely opportunities.”
Efficiency is just one of the characteristics. Perovskite cells can be easily manufactured in a variety of electricity-generating materials, and at much lower temperatures – and therefore possibly lower costs – than silicone. However, attention must be paid to the stability and durability of perovskite cells before they can replace silicone.
Scientists have now discovered a whole class of perovskite material that has a specific structure, containing three different chemicals in a cubic crystal form. They realized years ago that some perovskites are semiconductors, like the silicon used in electronics. But only in 2009 did researchers find that perovskites can also be used to build solar cells, which convert sunlight into usable electricity.
The first perovskite cells had very low efficiency, so most of the sunlight that fell on them was not used. But they improved rapidly.
“The efficiency with which solar cells carrying this perovskite material convert sunlight into electrons has increased at an incredible rate, to such an extent that the efficiency is now close to silicon solar cells in the laboratory,” said Lynn Loo, a professor said. chemical engineering at Princeton University and the director of the Andlinger Center for Energy and the Environment. “That’s why we’re so excited about this class of materials.”
Perovskite solar cells can also be made relatively easily – unlike silicone cells, which have to be refined at very high temperatures and therefore require a lot of energy to make. Perovskites can be made as thin sheets at low temperatures, or as ink that can be effectively ‘printed’ on the substrate of other materials, such as flexible plastic rolls.
This can lead to its use on surfaces where silicone solar cells would not be practical, such as the exterior of cars or trucks; or they can even be printed on cloth to power portable electronics. Another possibility is to apply thin films of perovskites to the window glass, where they transmit most of the light while using part of it to generate electricity.
But one of the most promising uses of perovskite cells is to combine them with silicone cells so that they use more of the solar energy than silicone alone. The best silicone cells approach their theoretical maximum efficiency of about 29 percent. But perovskite cells can be set to generate electricity from wavelengths of light that silicon cells do not use – and thus covering the silicon solar cells with semi-transparent films of perovskite cells can overcome the fundamental limit.
Physicist Henry Snaith at Oxford University, a leading researcher in perovskite solar cells, sees this as a way to combine the industrial dominance of silicone with the technological advantages of perovskites. He believes that ‘tandem’ silicone and perovskite cells with efficiencies of more than 40 percent can spread commercially within ten years, and that this could soon be followed by multilayer cells with more than 50 percent efficiencies.
The potential of perovskite solar panels has also attracted the government’s attention, both here and abroad. In addition to creating new commercial opportunities for U.S. companies, perovskites can become a relatively inexpensive way to challenge solar power to challenge fossil fuels for electricity generation. “I think a lot of us have the drive for technology to really address some of the climate change issues that need to be addressed by 2050,” said physicist Joe Berry, who conducts research on solar perovskites at the National Renewable Energy Laboratory in Golden, Colorado.
However, Perovskite solar cells still have problems, and the most important of these is the problem of stability. Partly because it is easy to make, perovskite cells also decay rapidly from humidity and heat. Some experimental perovskite cells have remained stable for tens of thousands of hours, but they still have a long way to go to reach the 25 or 30 years of use of silicone cells, Snaith said.
Some of the most promising materials for solar power also contain lead that can be released into the environment when the perovskite cells break down. Researchers are studying alternatives to lead-based perovskites, such as tin-based perovskites, and similar crystal structures containing other, safer substances.
“I think there are some challenges ahead,” Loo said. ‘Or [perovskites] is going to play an important role depends on whether we can overcome these challenges. ‘