The days of silicon remaining the top dog in commercial solar have never looked so numbered. The University of California, Berkeley, and Lawrence Berkeley National Laboratory have developed new perovskite solar cells that achieve an average steady-state efficiency of 18.4 percent, with a high of 21.7 percent.
Even the lower figure of 18.4 percent puts the devices in competition with most commercially available silicon cells and some expect perovskite-based solar devices will reach the market soon. But a great thing about perovskite crystals is that they’re inexpensive and easy to produce. They’re made of a mix of organic molecules and inorganic elements and can be placed on flexible materials, unlike silicon.
“This has a great potential to be the cheapest photovoltaic on the market, plugging into any home solar system,” said Onur Ergen, the lead author of the research, which appeared in the journal Nature Materials, and a UC Berkeley physics graduate student.
The new cells developed by UC Berkeley and LBL also reached a peak efficiency of 26 percent. “We have set the record now for different parameters of perovskite solar cells, including the efficiency,” said Alex Zettl, a UC Berkeley professor of physics and senior author of the research. “The efficiency is higher than any other perovskite cell—21.7 percent—which is a phenomenal number, considering we are at the beginning of optimizing this.”
Indeed. Research into their photovoltaic properties is relatively new. For instance, the National Renewable Energy Laboratory only began adding them to its Research Cell Record Efficiency Chart in 2013 and already they’re about as efficient as thin-film solar records and close to that of silicon records.
The new cells combine two perovskite solar cell materials, with each layer tuned to absorb a different color of sunlight into a “graded bandgap” solar cell. The resulting device absorbs nearly the entire spectrum of visible light, the university stated.
“This is realizing a graded bandgap solar cell in a relatively easy-to-control and easy-to-manipulate system,” Zettl said. “The nice thing about this is that it combines two very valuable features–the graded bandgap, a known approach, with perovskite, a relatively new but known material with surprisingly high efficiencies–to get the best of both worlds.”Tweet