It’s getting close to every day that perovskite crystals are becoming the next likely solar superstar with the low-cost materials getting ever closer to commercial production and potentially even supplanting silicon-based photovoltaics as the dominant form of solar power generation. Most recently a cross-Atlantic team of researchers from Stanford and Oxford Universities have produced a dual-layer, perovskite crystal-based solar cell that’s 20.3 percent efficient in laboratory testing. That’s nearly as efficient as many of the leading silicon-based solar cells commercially available in 2016.
“Perovskite semiconductors have shown great promise for making high-efficiency solar cells at low cost,” said study co-author Michael McGehee, a professor of materials science and engineering at Stanford. “We have designed a robust, all-perovskite device that converts sunlight into electricity with an efficiency of 20.3 percent, a rate comparable to silicon solar cells on the market today.”
“The all-perovskite tandem cells we have demonstrated clearly outline a roadmap for thin-film solar cells to deliver over 30 percent efficiency,” added co-author Henry Snaith, a professor of physics at Oxford. “This is just the beginning.”
The new research from the universities was published in the journal Science where researchers explained how they used tin and other earth-abundant elements to create the cells. Their solar cells use stack two perovskite solar cells on top of each other to absorb photons from different spectra of sunlight. The upper layer of the device is brown and captures low-energy lightwaves, while the lower, red layer of the cell captures high-energy lightwaves. In testing the cells are printed on glass, but researchers said they could also be printed on plastic.
By creating a solar device that’s ‘printable’ researchers are able to create a much less expensive device. “A silicon solar panel begins by converting silica rock into silicon crystals through a process that involves temperatures above 3,000 degrees Fahrenheit (1,600 degrees Celsius),” said co-lead author Tomas Leijtens, a postdoctoral scholar at Stanford. The processing and need for high temperatures add expense to the manufacturing process.
“Perovskite cells can be processed in a laboratory from common materials like lead, tin and bromine, then printed on glass at room temperature,” Leijtens said. That makes it much less expensive to produce.
However, thus far, perovskites have suffered from instability and most devices have degraded quickly. Silicon solar panels are expected to last 25 or more years. The researchers said they subjected their device to temperatures of 212 degrees Fahrenheit (100 degrees Celsius) for four days.
“Crucially, we found that our cells exhibit excellent thermal and atmospheric stability, unprecedented for tin-based perovskites,” the authors wrote in the journal.
Now the researchers will work to optimize the devices to absorb more light and generate an even higher current, according to Snaith. “The versatility of perovskites, the low cost of materials and manufacturing, now coupled with the potential to achieve very high efficiencies, will be transformative to the photovoltaic industry once manufacturability and acceptable stability are also proven,” he said.Tweet