PEROVSKITE SOLAR CELLS A Better Method for Producing Perovskite Solar Cells
Researchers at Stanford University in California, USA, say that they have developed a new perovskite solar cell manufacturing process that is both cheaper and four times faster than traditional manufacturing methods.
Solar Cells (PSCs) are thin films of synthetic crystalline made from cheap, abundant chemicals such as lead, carbon, and iodine. They’re lightweight, bendable, and can be grown in open-air laboratories, unlike silicon-based solar cells that must be fabricated in controlled clean rooms.
They’re also quickly catching up to silicon in terms of their efficiency, too, going from four percent efficiency in 2009 to over 20 percent efficiency earlier this year, closing in on silicon’s record of around 25 percent efficiency. One area where they’ve always somewhat fallen behind, however, is that of production speed. It takes time to manufacture PSCs, and this is a challenge for large-scale production.
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Now, researchers at Stanford University in California say that they’ve developed a new manufacturing method that can produce up to 40 feet (12 meters) of PSCs per minute, even faster than silicon production.
An alternative to silicon-based solar cells
The desire for switching to PSCs from silicon is born from that of energy consumption and the overall environmental impact of the Silicon Solar Cell (SSC) production process. Factories producing SSCs consume a huge amount of energy and also produce a huge amount of carbon dioxide because of the 3,000 ºF furnaces required to refine them.
In an effort to combat this challenge, scientists have turned to PSCs as a greener alternative to silicon-based cells. They offer manufacturers a way of reducing energy consumption and production costs while producing close to zero carbon dioxide solar cells because of the open-air production process that takes place at temperatures near to the boiling point of water.
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Despite all the benefits that PSCs bring, however, research has shown that they’re relatively unstable. When you try and make PSCs bigger, deformities can be created which decrease their efficiency, this doesn’t happen with silicon. And when they’re exposed to heat and moisture, PSCs can degrade over time whereas SSCs can last for decades.
The Stanford researchers say that they’ve solved this problem with a new method that can manufacture stable PSCs in useful amounts at practical speeds.
‘Rapid-spray plasma processing’
Known as ‘rapid-spray plasma processing’, a new patented technology, the method uses a robot with two nozzles. The first nozzle sprays a liquid mixture of perovskite precursors onto a glass sheet, then the second nozzle sprays the liquid with plasma, quickly converting it into a thin perovskite film.
Using this method, the Stanford team says that the perovskite film can be produced at a rate of 40 feet per minute. This is a record-breaking production rate that is around four times faster than SSC manufacturing. It’s also got a power conversion efficiency of 18 percent and is very cheap, with the researchers estimating that modules could be made for around US$0.25 per square foot, roughly one-tenth of the price of silicon.
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To ready their perovskite modules for commercial markets, the Stanford researchers made them so that they’re able to operate at 15.5 percent efficiency, even when they’ve been sitting around on the shelf for five months. In the future, the team hopes to make their modules more resilient and durable so that they can be used for production at scale.
“We achieved the highest throughput of any solar technology,” says Nick Rolston, co-author of the study. “You can imagine large panels of glass placed on rollers and continuously producing layers of perovskite at speeds never accomplished before.”
“If we can build a perovskite module that lasts 30 years, we could bring down the cost of electricity below 2 cents per kilowatt-hour,” says Rolston. “At that price, we could use perovskites for utility-scale energy production. For example, a 100-megawatt solar farm.”