Foldable solar cells could bring renewable energy to new products

Pusan National University

Researchers are developing thin, lightweight and foldable solar cells that could open up a whole new range of use for solar power

Spotter: We are used to thinking of solar panels as flat, rigid structures propped on rooftops or arrayed in rows on solar farms. But what if a solar panel could be almost any shape? That could open up a whole new range of uses, including in phones, vehicles, and even clothing.  A research group at Pusan National University has recently developed a way to make bendable solar cells.

One roadblock to developing bendable solar cells has been the need for a conductor that could withstand the pressure of bending within a very small radius while maintaining its strength and integrity. This conductor would need to be not only thin and resilient, but also transparent. Ultra-thin glass substrates and transparent metal oxides have been proposed for this, but they could not be made fully foldable.

However, the researchers, led by Professor Il Jeon, found a solution in the use of single-walled carbon nanotube (SWNT) films as a conducting layer. These are embedded into a polyimide substrate, which fills the spaces between the nanotubes. Small impurities are introduced into the nanocomposite in order to reduce the energy needed for electrons to move across the structure, so that more charge can be generated for a given amount of current.

In testing, the researchers were able to make a solar cell just seven micrometers thick that could fold to a radius of just 0.5 mm. The cells could also withstand more than 10,000 folding cycles without breaking. The foldable cells also had a power conversion efficiency of 15.2 per cent. Professor Jeon pointed out that this was the highest efficiency ever achieved using carbon nanotube conductors, saying, “The obtained results are some of the best among those reported thus far for flexible solar cells, both in terms efficiency and mechanical stability.”

Solar power has a number of limitations, including their relatively heavy weight and opacity, which limits the number of ways they can be used. This is why a growing number of researchers are working to address these issues. Recent innovations in solar technology include transparent solar panels for on-the-go power, and windows that can act as solar cells.

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