A team of researchers at Stanford University has used an 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. However, the problem is that perovskites are extremely unstable and mechanically fragile.
While most solar devices, like rooftop panels, use a flat, or planar, design, that approach doesn't work well with perovskite solar cells.
"We were inspired by the compound eye of the fly, which consists of hundreds of tiny segmented eyes," explained Reinhold Dauskardt, a professor of materials science and engineering at Stanford and senior author of a study published in the journal Energy & Environmental Science (E&ES). "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."
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 0.02 inches, or 500 microns, wide.
"The scaffold is made of an inexpensive epoxy resin widely used in the microelectronics industry," graduate student Nicholas Rolston, a co-lead author of the study, was quoted as saying in a news release this week. "It's resilient to mechanical stresses and thus far more resistant to fracture."
Tests revealed that the scaffolding had little effect on how efficiently perovskite converted light into electricity.
In addition, to test against extreme conditions, the researchers exposed encapsulated perovskite cells to temperatures of 185 degrees Fahrenheit, or 85 degrees Celsius, and 85 percent relative humidity for six weeks, only to find that the cells continued to generate electricity at relatively high rates of efficiency.