Perovskite: A Quantum Leap for Solar?

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The new solar cell material is showing promise, but will it live up to the hype?

XPrize CEO Peter Diamandis

XPrize CEO Peter Diamandis


Recently, The Huffington Post ran an article by X-Prize CEO Peter Diamandis entitled Disrupting Solar. In the first installment in the two-part series, Diamandis writes glowingly of perovskite, a new and promising solar material. Diamandis writes that “Many entrepreneurs and investors are cautious about solar after having been burned in the early 2010s, when a string of solar companies took in considerable capital before shuttering their operations.

That being said, there has been a resurgence of promising startups developing commercially viable solar solutions – and we believe we’ll see perovskite solar cells as early as next year.”

Diamandis, a notable Silicon Valley futurist, entrepreneur and co-founder (with Ray Kurzweil) on Singularity University, has been a big proponent of perovskite in recent years. At this year’s Abundance 360 summit, Diamandis’ annual $12k per seat meeting of “curated entrepreneurs,” perovskite was touted as the “next big thing” in solar generation.

In his article, Diamandis rightly notes that “…Estimates suggest that perovskite solar panels could cost just 10 to 20 cents per watt, compared to 75 cents per watt for traditional silicon based panels — anywhere from 3X to 8X cost savings — making solar panels much more affordable for the average consumer.” Also, that “…the theoretical limit of perovskite’s conversion efficiency is about 66 percent, compared to silicon’s theoretical limit of about 32 percent.”  Diamandis goes as far as to write that “…could enable solar to reach a scale that eventually eliminates dependence on fossil fuels entirely.”

That is a pretty bold claim. This isn’t unusual, though, for Diamandis, who loves to extrapolate, and a claim that is welcome to those eager for a glimpse of “nextgen” solar technology. However, Diamandis’ track record as a prognosticator is a little shaky. After all, in his 2012 book Abundance, he predicted clean, safe “nextgen” nuclear reactors would be coming online soon as well. Techno-Utopians like Diamandis have an attractive message and his optimism is contagious, but how realistic is it?

First off, let’s back up and talk a little about exactly what perovskite is.  Named for a 19th Century Russian mineralogist, L.A. Perovski, perovskite structures are any material with the same type of crystal structure as calcium titanium oxide (CaTiO3). A perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer. Perovskite materials such as methylammonium lead halides are cheap to produce and simple to manufacture.Solar cell efficiencies of devices using these materials have increased from 3.8% in 2009 to 22.1% in early 2016,making this the fastest-advancing solar technology to date.

Schematic of a sensitized perovskite solar cell in which the active layer consist of a layer of mesoporous TiO2 which is coated with the perovskite absorber.

Schematic of a sensitized perovskite solar cell in which the active layer consist of a layer of mesoporous TiO2 which is coated with the perovskite absorber.

Just days before the publishing of the Diamandis piece on The Huffington Post, Scientific American published it’s own article on Perovskite entitled Solar Cell “Wonder Material”—Perovskite—Falls Short of Expectations.  Ironically, this article refutes nearly every claim that Mr. Diamandis makes in his article.  The damning subtitle reads: “New materials may never become efficient for real power, new report says.” The story is reprinted from work originally appearing on Chemistry World, a website of the Royal Society of Chemistry.

Essentially, the article states that the promising perovskite technology works well in theory, but not in practical applications.  The article quotes Robert Palgrave of the University College London, UK, who has has reassessed the validity of the tolerance factor in predicting new hybrid perovskite structures.  “The rapid advance of hybrid solar cells is an amazing story,’ Palgrave says. “Having worked on oxide perovskites before, I was sure there would be many more hybrid perovskites to find.” But following failed synthesis attempts in the lab, the team realised “the tolerance factor simply doesn’t work for iodide perovskites.” Ending on a positive note the article states: “Palgrave remains optimistic about prospects in discovering new solar cell materials. ‘It is quite liberating after trying to make new perovskites – now we can use pretty much any organic and inorganic ions we like!”

Meanwhile, scientists outside of the UK are less ready to pronounce perovskites a dead end. A new study by researchers from Brown University, the National Renewable Energy Laboratory (NREL) and the Chinese Academy of Sciences’ Qingdao Institute of Bioenergy and Bioprocess Technology published in the Journal of the American Chemical Society is much more optimistic about bringing perovskite solar cells to the mass market.

“We’ve demonstrated a new procedure for making solar cells that can be more stable at moderate temperatures than the perovskite solar cells that most people are making currently,” said Nitin Padture, professor in Brown’s School of Engineering, director of Brown’s Institute for Molecular and Nanoscale Innovation, and the senior co-author of the new paper. “The technique is simple and has the potential to be scaled up, which overcomes a real bottleneck in perovskite research at the moment.” Padture continues… “The simplicity and the potential scalability of this method was inspired by our previous work on gas-based processing of MAPbI3 thin films, and now we can make high-efficiency FAPbI3-based perovskite solar cells that can be thermally more stable. That’s important for bringing perovskite solar cells to the market.”

For the time being, the dire predictions of UK scientists seem premature in light of the momentum behind perovskite’s popularity in the solar research community. However, Mr. Diamandis might want to revise his prediction of commercial perovskite panels in 2016.

 

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