Can the most exciting new solar material live up to its hype?
Testing perovskite solar cells in the lab used to require a decent pair of running shoes. The materials fell apart so quickly that scientists would bolt from where they made the cells to where they tested them, trying to measure their performance before the cells degraded in their handsusually within a couple of minutes. Perovskites have long enchanted researchers with the promise of producing inexpensive, ultra-efficient solar cells. And now several companies are making major strides toward producing commercial perovskite solar cells at scale. But the materials instability has threatened to derail their path to rooftops and power plants. Though a few companies say theyve solved the challenge, at least well enough to bring preliminary products to market within the year, some researchers are still skeptical. People want me to say I know for sure this is going to be stable, and it's going to be efficient and were going to conquer the world, says Joseph Berry, who leads the perovskite research program at the US National Renewable Energy Laboratory. And part of me believes that, but part of me as a scientist says, I don't have the data.  Soaking up the sun  Perovskites are synthetic materials, inexpensive and relatively simple to produce even in large quantities. Common perovskites used in photovoltaics are typically something like methylammonium lead halide, but the perovskite family includes thousands of materials that share the same crystal structure. Coated onto a flexible base, they can produce thin-film solar cells that are light and bendable. While several new photovoltaic materials have emerged in recent decades, none has made much of a dent in the market, which is dominated by silicon. It is found in around 95% of existing solar cells. Some perovskite companies, like Saule Technologies in Warsaw, are trying to leave silicon behind altogether. The company, founded in 2014, developed an ink-jet printing process for manufacturing perovskite solar cells encased in a flexible plastic. A panel containing Saules cells is about a tenth as heavy as a silicon panel of the same size. In May, Saule opened a factory that can produce around 40,000 square meters of panels annually. Thats enough to generate around 10 megawatts of power (some factories that produce silicon cells are hundreds of times larger).