Kelly McSweeney

Apr 29th 2019

When Will Perovskites Give Solar Cells a Boost?


Perovskites, a class of compounds that have a certain type of crystal structure, are a hot topic in research today. Even though they are still in the research phase, the rate of progress is astounding. Perovskite solar cells could be an alternative to silicon that could make solar power inexpensive enough for widespread use. The big question for this emerging technology is: When will it be ready for commercialization? The answer is sooner than you might think, possibly even later this year.

Why Are Scientists So Excited?

Solar power is a great alternative energy source, but today’s silicon-based solar panels are bulky and can be expensive to install. Perovskite solar modules are more flexible and less expensive. The first perovskite solar cells were created 10 years ago by a research team at Toin University in Japan. Those early prototypes were unstable and had an efficiency of only 3.8 percent, but now most stability concerns have been addressed, and the efficiency of these cells is as much as 23.3 percent. Other technologies have taken more than 30 years of research to reach the same level, according to Yabing Qi, a researcher at Okinawa Institute of Science and Technology, who described perovskite advances in Science Daily.

The original perovskite mineral was discovered in 1839, according to IEEE Spectrum, but the term is now broadly used to describe a compound made of an organic molecule, a metal and a halogen. Researchers worldwide are still perfecting the recipe to come up with the right combination of ingredients that will achieve the three basic criteria for commercialization: stability, efficiency and scalability.

Benefits and Challenges

Perovskites gained attention because they are theoretically more conductive than silicon, meaning they’re better at converting photons into electricity. They’re also more versatile and easier to manufacture. Plus, perovskite solar compounds are a flexible, nearly transparent material that could be sprayed onto existing infrastructure. This could be an ideal formula for cheap solar power.

Silicon has to be pure and perfect, but perovskites are less prone to defects, IEEE Spectrum reports. The material isn’t as fragile as silicon, so it can be handled and still perform. This means it could be easy to manufacture, which means cheaper solar cells. The solar cells we use today are made of silicon, which has to be processed at temperatures above 1,400 degrees Celsius, MIT News notes. Whereas silicon manufacturing requires expensive equipment to handle high temperatures, perovskite compounds can be processed at temperatures as low as 100 degrees using inexpensive equipment.

Joseph Berry, who leads the perovskite solar team at the National Renewable Energy Laboratory, told IEEE Spectrum that he predicts building a perovskite solar factory will cost about one-tenth what it costs to build a comparable silicon solar panel factory.

Tomorrow’s Alternative Energy Source

This industry, born just a decade ago, shows great potential. Perovskites are a very active research area, with academic papers on this topic coming out frequently. A Pubmed search of “perovskite” yields nearly 8,000 results, with the bulk of the research being published in the last five years.

This year could be a turning point, with at least two companies setting up production lines and anticipating selling their first perovskite solar cells within the next year or so, according to MIT News. Major players include university spin-offs, startups and well-established corporations. Renewable energy sources such as wind, sun and water aren’t just good for the environment; they are actually becoming cheaper than traditional options.

“We’re at a disruption point in history,” Chris Case, Oxford PV’s chief technology officer, told IEEE Spectrum. “Right now, in most places in the world, solar PV without subsidies is cheaper than any other form of electrical generation.”

Coming Sooner: Tandem Solar Cells

While researchers continue to investigate and improve pure perovskite cells, tandem solar cells could offer a compromise. Companies like Oxford PV are combining layers of silicon and a perovskite into one cell. These solar cells can be manufactured with existing methods, but with the added benefit of a perovskite layer that absorbs sunlight at wavelengths that silicon doesn’t.

Despite the many benefits of perovskite solar cells, skeptics have pointed out that the material is prone to instability and weakness. MIT News suggests that there’s still more work to do to make perovskite solar cells durable enough for commercial use. Critically, the material absolutely must be stable enough for manufacturers to be willing to try a perovskite cell. Some solar researchers say that perovskites are sensitive to moisture, oxygen and light. However, perovskite champions say that instability is a misconception and insist that not all perovskite compounds have that flaw. Oxford PV told IEEE Spectrum that their cells have been engineered for stabilities and extensively tested, and suggested they will produce the first modules in 2019, working with a “major manufacturer of silicon solar cells and modules.” If that comes to pass, it will be great news for alternative energy.