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To Succeed, Solar Perovskites Need to Escape the Ivory Tower

Solar perovskite cells, patterned with gold electrodes, await tests that measure their efficiency at converting sunlight into electricity

June 18, 2015

Solar perovskite cells, patterned with gold electrodes, await tests that measure their efficiency at converting sunlight into electricity
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What will tomorrow’s solar panels look like? This week, along with colleagues from Oxford and MIT, I published a feature in Scientific American making the case for cheap and colorful solar coatings derived from a new class of solar materials: perovskites. In this post, I’ll critically examine prospects for commercialization of solar perovskites, building on our article’s claim that this technology could represent a significant improvement over current silicon solar panels. We argue:

Perovskites are tantalizing for several reasons. The ingredients are abundant, and researchers can combine them easily and inexpensively, at low temperature, into thin films that have a highly crystalline structure similar to that achieved in silicon wafers after costly, high-temperature processing. Rolls of perovskite film that are thin and flexible, instead of thick and rigid like silicon wafers, could one day be rapidly spooled from a special printer to make lightweight, bendable, and even colorful solar sheets and coatings.

Still, to challenge silicon’s dominance, perovskite cells will have to overcome some significant hurdles. The prototypes today are only as large as a fingernail; researchers have to find ways to make them much bigger if the technology is to compete with silicon panels. They also have to greatly improve the safety and long-term stability of the cells—an uphill battle.

We wanted to write for a popular science magazine, with a general audience in mind, to share an exciting story of scientific discovery that has largely been confined to specialist journals. Indeed, for solar perovskites to overcome the odds stacked against an upstart clean technology breaking into the market, we believe the academic, private, and public sectors really need to pay more attention to each other.

The lack of awareness by the clean energy industry about solar perovskites, despite the commotion in the scientific community, demonstrates how scientific research can proceed in a bubble. Following the big announcement of a highly efficient solar perovskite from our research group in Oxford, hundreds of laboratories around the world jumped on the perovskite bandwagon, in many cases abandoning their research into other solar technologies. The race among labs to publish record solar efficiencies in the top journals involved international intrigue—the UK banded with Italy, trading records with the Swiss-Chinese coalition, and everyone was eventually upstaged by the South Koreans when they reported a 20 percent efficient solar cell late last year (for reference, silicon solar cells have plateaued at 25 percent efficiency, a target solar perovskites should soon surpass). The excitement and drama reflect the gravity of the perovskite discovery—time will tell, but many of us believe this is the field’s biggest breakthrough since the original invention of the solar cell sixty years ago.

Certified solar cell record efficiencies for silicon and perovskite technologies (date axis truncated to better show perovskite efficiency trajectory—silicon solar cells were invented in 1954; data from National Renewable Energy Laboratory)
Certified solar cell record efficiencies for silicon and perovskite technologies (date axis truncated to better show perovskite efficiency trajectory—silicon solar cells were invented in 1954; data from National Renewable Energy Laboratory)

However, when I talk to industry executives at major solar manufacturers and developers, very few have even heard of solar perovskites. This does not bother scientists, many of whom narrowly focus on demonstrating a higher efficiency solar perovskite, even if it is a fingernail-sized cell that degrades in hours. Some might argue that a scientist’s value is in basic inquiry and complementary to industry’s expertise, and they have a point. But aloof regard for real markets from the ivory tower leads many academics to naïvely assume that a superior technology will naturally make the leap from prototype to profitability.

In fact, broader feedback from professionals outside of research labs is integral to commercializing solar perovskites. Currently, solar perovskites can be worryingly unstable (although we’ve demonstrated longevity if they are properly sealed away from moisture). That’s a red flag for investors familiar with a mature, 50 billion dollar silicon solar panel industry in which every panel comes with a 25-year performance warranty. And because solar perovskites contain lead, a toxic element, any commercial product will need to undergo extensive safety testing, with which private industry veterans have experience. These professionals can guide research into the stability, safety, and real-world performance of solar perovskites, which are every bit as important as the efficiency under idealized lab conditions, the paramount academic metric.

Elsewhere in the physical sciences, the transition from basic research to product development is better institutionalized. This is one of the reasons why I have argued that Moore’s Law for computer chips, which predicts rapid deployment of scientific advances, does not apply to the solar panel industry, whose products have improved at a comparatively plodding pace. Whereas in computer chip development there are established conferences at every step of commercialization from basic device physics to chip integration that bring together scientists and industry, advanced solar technology development is confined almost exclusively to the realm of academia.

Fortunately, leading researchers in the United States and Europe are making a concerted effort to bridge the gap between academia and industry. For example, one of my co-authors and the leader of the Oxford research group, Henry Snaith, founded a company to tackle real-world deployment and commercialize solar perovskites. His strategy is actually to partner with the silicon solar panel companies, adding a perovskite coating on top of silicon to boost its performance. That approach seems prudent, because allying with powerful incumbents is easier than fighting them for market access. And through a partnership, his company will benefit from gaining access to experienced solar engineers, investors, and developers to guide the design and delivery of a compelling product.

Solar perovskites on glass—researchers can vary the color and transparency of the coatings, enabling new applications.
Solar perovskites on glass—researchers can vary the color and transparency of the coatings, enabling new applications (Plamen Petkov)

My co-authors and I do hope our article will bring professionals in the solar industry up to speed on the latest research, but our target audience is even broader. We envision architects reimagining the aesthetics and functionality of windows, roof shingles, and facades; policymakers tweaking green building codes and incentives; and the military investigating the use of solar perovskite coatings to power forward deployed bases. These applications may seem far-fetched, and they are—solar perovskites are still a risky bet to succeed in a monolithic market. But if scientists continue to broadly communicate our progress, those odds can only improve.

Read our feature, “Outshining Silicon,” in Scientific American’s July 2015 issue, here

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