Foldable Solar Cells Can Be Bent without Breaking

Foldable Solar Cells Can Be Bent without Breaking

When thinking of solar panels, people usually imagine a solid square plate. However, this technology is becoming more and more flexible. Engineers at Pusan National University in South Korea developed foldable prototypes of solar cells. Rigid solar cells can be stuck to roofs and huge solar farms. This technology can bring more flexibility to make it easier to transport, or apply the technology to vehicles, cell phones, indoor equipment and even clothing.
In recent years, flexible solar cells have shown promise in all these types of applications. They are typically made of thin-film materials such as graphene, tungsten diselenide, or copper indium gallium selenide (CIGS), and deposited on flexible substrates such as polymers or even paper. As a result, solar cells can be bent to a limited extent like a card.
However, they haven't been able to be fully folded in half without breaking. Some electronic devices start to gain this ability. For example, Samsung's Galaxy Fold phone can be opened and closed like a book.
"Unlike purely flexible electronics, foldable devices need to bear more severe deformations, with folding radii as small as 0.5mm. This is not possible with conventional ultra-thin glass substrates and metal oxide transparent conductors, which can be made flexible but can never be fully folded" Professor Il Jeon, the author of the study said.
To solve this problem, the researchers used conductive films made of single-walled carbon nanotubes (SWNTs). They embedded the film on a polyimide substrate and then doped molybdenum oxide to improve its conductivity. In the end, the researchers were able to create solar cells with a thickness of just 7 micrometers that could be folded in cells with a radius of just 0.5 millimeters. They were able to withstand over 10,000 folding cycles without breaking. Of course, they also functioned well as solar cells, having 15.2% power conversion efficiency and 80% transparency. "The obtained results were some of the best reported for flexible solar cells to date, both in terms of efficiency and mechanical stability," Jeon said. The research results were published in the journal Advanced Science.