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Stanford solar researchers put contract out to assassin flies – aiming for 26.4% solar cells

Stanford University has found design inspiration with solar cell material perovskites by analyzing the microlenses in the compound eye of an assassin fly. By utilizing the hexagonal substructures of the fly eye – they’ve strengthened and stabilized the nascent solar material.

Perovskite is the solar power media darling that is slowly inching toward the marketplace. Constant and quick evolution has earned it outsized attention. An Electrek revisit seems timely as some are suggesting pilot products in 2018 and the product recently broke 26.4% efficiency in labs.

The California researchers created a compounded solar cell consisting of perovskite microcells encapsulated in a hexagon-shaped scaffold. Professor of Materials Science and Engineering and senior author of the study, Reinhold Dauskardt explained,

“Perovskite would barely survive the manufacturing process, let alone be durable long-term in the environment. (Our research) has a beautiful honeycomb shape with built-in redundancy: If you lose one segment, hundreds of others will operate. Each segment is very fragile, but it’s shielded by a scaffold wall around it.”

The honey comb shielded perovskite cells got nearly the same power-conversion efficiencies compared to a standard photovoltaic cell, and held onto relatively high rates of efficiency after stress testing with extreme temperature (185F) and relative humidity over a six-week period.

One of the main reasons perovskite is cheaper than silicon solar cells it that you can manufacture the material at temperatures far below that of the silicon. The cost of the energy to push the high temperatures needed to create the solar power grade silicon is a main driver of the cost of the product. The main challenges, so far for perovskite, have been the above noted fragility and a tendency to lose efficiency very quickly.

The solar window featured on Electrek a few days ago is a perovskite based material.

Electrek’s Take

There is reason to expect some real action in the perovskite marketplace in the upcoming year, partially because there are enough start-up and global level companies aiming for some sort market success.

The apparent leader in the race to bring the material to market – Oxford PV – wishes to build a perovskite-silicon tandem solar cell. The company has stated:

“We expect to have a product that meets industry requirements by the end of 2017,” said Frank Averdung, chief executive officer at Oxford PV.  “Adding some time for qualification, certification and production, our first product could be commercially available towards the end of 2018.”

At the beginning of October, it was announced that the company received a €15m loan from the European Investment Bank to build out that pilot line. They’ve also signed a joint development agreement (JDA) with an unidentified global manufacturer of solar cells and modules.

In a partnership with solar industry heavyweight’s Suntech and Trina Solar, Australia National University achieved 26.4% efficiency also in a stacked configuration with silicon solar cells.

JinkoSolar and Greatcell are also in a business relationship. Jinko delivers 2GW of solar panels per quarter.

And while these market players are looking to build manufacturing lines – the research labs are continuing their push. A Korean group recently pushed the efficiency of the material on its own to 22.1% efficiency. Another group is working at getting lead out of the product. Others have grown the product stability for the course of a year.

Martin Green, a professor at the University of New South Wales who also studies perovskite, said that as the product crossed the 10% threshold, attention levels changed – “All of a sudden you got about 10,000 researchers switching over to this field overnight.” Part of this is that conventional solar cells have slowly risen toward their 22-23% record efficiencies. Most of perovskite’s rise has occurred since 2009, with a jump from 15% to 22% happening in the last three years.

Jinsong Huang, an associate professor of mechanical and materials handling, who is moving his research effort to the University of North Carolina, estimated that continued development could raise the efficiency level of perovskite-coated films to 25% “within three to five years.”

Still other research, using the same silicon stacking technique as above, projects efficiencies possible up to 32.9%.

Its seems the most logical path for this material in the short to medium term, is in the tandem structures with current manufactured solar panels. If someone can insert a few machines into current manufacturing lines, versus rebuilding the global infrastructure, we’ll save a great deal of time. At the end of 2017 though, we’re still in vapor ware space…our breath bated.

Interestingly – on Twitter early yesterday, we got to see a book on the new science float by. Anyone have feedback on it?

Header image credit to: Thomas Shahan/Creative Commons

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