Insect eyes inspire new solar cell design

Researchers at Stanford University have designed a new solar cell inspired by the compound eyes of insects. The design could help them overcome a major obstacle to the development of solar panels based on perovskite.

Packing tiny solar cells together, like micro-lenses in the compound eye of an insect, could pave the way to a new generation of advanced photovoltaics, say Stanford University scientists.

In a new study, the Stanford team used the insect-inspired design to protect a fragile photovoltaic material called perovskite from deteriorating when exposed to heat, moisture or mechanical stress.

“Perovskites are promising, low-cost materials that convert sunlight to electricity as efficiently as conventional solar cells made of silicon,” Reinhold Dauskardt, senior author of the study, said in a statement.

“The problem is that perovskites are extremely unstable and mechanically fragile. They would barely survive the manufacturing process, let alone be durable long term in the environment.”

To make them more durable, the Stanford team turned to nature: the compound eye of the fly with its hundreds of tiny segment eyes.

“It 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,” explained Dauskardt.

Using the compound eye as a model, the researchers created a compound solar cell consisting of a vast honeycomb of perovskite microcells, each encapsulated in a hexagon-shaped scaffold just 500 microns wide.

“The scaffold is made of an inexpensive epoxy resin widely used in the microelectronics industry,” said co-lead author Nicholas Rolston. “It’s resilient to mechanical stresses and thus far more resistant to fracture.”

Tests conducted during the study revealed that the scaffolding had little effect on how efficiently perovskite converted light into electricity.

“We got nearly the same power-conversion efficiencies out of each little perovskite cell that we would get from a planar solar cell,” Dauskardt said.

The researchers then exposed encapsulated perovskite cells to temperatures of 85 degrees Celsius and 85 per cent relative humidity for six weeks to test their ability to withstand the types of conditions that conventional rooftop solar panels endure.

With success: despite the extreme conditions, the cells continued to generate electricity at relatively high rates of efficiency.

 

Image credit: Thomas Shahan via Flickr/CC BY-NC-ND 2.0

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