Scientists are one step closer to spray-on solar power. Instead of traditional bulky solar cells encased in glass—which can be awkward to put in places other than a roof, and take a lot of energy to produce—we may someday be able to easily spray paint low-cost, low-energy solar cells on everything from a pair of jeans, to a car, to the side of a skyscraper.
Research on painted solar cells isn't new, but it has been challenging to make these solar cells efficient enough to actually be useful. Now, scientists in a lab at the University of Sheffield have discovered a trick to making them work better: A material called perovskite, which can be almost as efficient as silicon, but cheaper to make and, in theory, more environmentally friendly.
Making silicon—the main component in most solar cells today—takes a huge amount of energy as silica rock is heated up to about 3,000 degrees. Ironically, solar-cell manufacturing is usually powered by coal or other fossil-fuel-powered plants. Perovskite, by contrast, takes little energy to produce, and spraying it on saves even more energy.
It's going to take a little longer in the lab before it's actually ready to use, however. At the moment, the spray-on solar being tested at the University of Sheffield is only about 11% efficient—a huge step up from the 1% efficiency of similar spray-on solar a couple of years ago, but far from perovskite's potential of 19%, or silicon at 25%.
It also doesn't last as long as conventional solar cells, so it's unlikely to start replacing rooftop solar panels anytime soon. But it may start to show up on different types of products where traditional solar panels wouldn't work as well.
"First applications could be in more low-lifetime products in which long-term stability is not required, i.e. on clothing, or for various indoor applications to scavenge energy," says lead researcher David Lidzey. Later, the technology might be used in stable places like the gap between two windows, and eventually, on the facade of buildings.
For now, the researchers are working on making the technology more efficient. Perovskite may keep evolving as well. Today, it's made from a not-so-environmentally-friendly lead chloride, and other researchers are working on finding a better material.
The fact that perovskite is so cheap might mean that it can help bring solar power to people who might not otherwise have been able to afford it. "The technology offers the ultimate potential of very low-cost solar energy, with photovoltaic devices built into many varied environments," Lidzey says. "This will be particularly important in the developing world, where access to low-cost, carbon-free energy will be an important part of making sure that economic and population growth happens in a sustainable fashion."