To Reach a Solar Boom, We Must Say Goodbye to Silicon, Claim Cornell Engineers

August 18, 2020 by Luke James

When it comes to the future of solar energy cells, some engineers think that we should be waving goodbye to silicon and replacing it with calcium titanium oxide, also known as perovskite.

We should do away with silicon and instead look to perovskite to answer our solar energy prayers, claim research engineers at Cornell University.

In their latest works, the researchers have found that photovoltaic wafers in solar panels that are composed of all-perovskite structures outperform photovoltaic cells made from current cutting-edge crystalline silicon. In fact, the all-perovskite structures were found to outperform even perovskite-silicon tandem cells, which are stacked in a way that enables them to absorb light better. 


The Rise of Perovskite

Since researchers discovered that perovskite could be used as a solar material in the mid-2000s, there have been several leaps and bounds with the technology—going from an efficiency level of just 2% in 2006 to 25.2% in 2020 in single-junction architectures (and, in silicon-based tandem cells, to 29.1%).


Perovskite solar cells

Perovskite solar cells are said to be more energy-efficient when used in solar panels. Image used courtesy of Dennis Schroeder and Cornell University

In the last few years especially, perovskite has started to gain recognition as something of a wonder material. Today, research teams the world over, like those recently at UC Berkeley, are making ground-breaking discoveries about perovskite that could help us achieve the so-called solar boom.

Even government-backed research institutions and agencies are getting involved; the U.S. created the U.S. Manufacturing of Advanced Perovskites Consortium (US-MAP) while the EU has established the European Perovskite Initiative.


A Sustainable Future for Solar Energy?

In addition to offering a quicker return on investment than silicon-based solar panels, all-perovskite cells may consume less energy during manufacturing, according to the Cornell research, which was published in Science Advances. The paper analyzes the energy life-cycle and environmental impacts of modern tandem solar cells made of silicon and perovskites. 

According to the Cornell team’s study, silicon photovoltaics require an expensive initial energy outlay, and it takes around 18 months on average to see a return. In contrast, a solar cell wafer with an all-perovskite tandem configuration provides an energy payback on the initial investment in four months—a reduction by a factor of 4.5. 


 Review of the energy consumption and environmental impact of three types of solar cells

Review of the energy consumption and environmental impact of three types of solar cells: SHJ, perovskite-silicon tandem, and perovskite-perovskite tandem. Image used courtesy of Science Advances

However, solar panels don’t last forever. Over time, they become less efficient and must be replaced. And just like in the manufacturing phase, the breaking down and recycling of silicon panels are very energy-intensive whereas perovskite cells can be recycled more easily. 

To illustrate their point, the Cornell engineers used the analogy of a car. While using silicon solar cells is akin to replacing the entire car at the end of its useful life, replacing perovskite solar cells is like installing a new battery. 

"Perovskite cells are promising, with a great potential to become cheaper, more energy-efficient, scalable, and longer-lasting," said Fengqi You, a professor in energy systems engineering at Cornell. "Solar energy's future needs to be sustainable."