Rooftop arrays are perhaps the most common use for solar cells. But what if they could be used to power smaller things, like wearables? That’s exactly what scientists from a couple of South Korean universities are pursuing. They designed super thin, flexible solar cells that can wrap around a pencil for potential use in items like smart glasses or fitness trackers.
The researchers recently detailed the innovative process they created to make such flexible cells in Applied Physics Letters. Others have made thin cells before, but have utilized etching to produce their photovoltaics. The South Korean researchers used transfer printing. They stamped the cells right onto a flexible metal electrode, and didn’t use an adhesive, which would make the cells that much thicker. Instead, the cells were “cold welded” using pressure and another layer of material, which helped the solar cell stick to the electrode before it was peeled off.
There’s another big difference: not only is their solar cell super thin, it’s thinner than most other competing thin cells. The researchers made a solar cell that’s one micrometer thick. Other thin cells are two to four times that thickness, and most photovoltaics are “hundreds of times” thicker. The unique process also allows the scientists to use less materials.
The new thin cell still works well, converting sunshine to electricity at an efficiency similar to other thin solar cells. The team tested their technology against cells that are 3.5 micrometers thick, and found sometimes theirs actually functioned better. Jongho Lee, one of the paper’s co-authors, said, “The thinner cells are less fragile under bending, but perform similarly or even slightly better.”
Lee said they envision their cells incorporated into glasses frames or fabric to generate power for wearable electronics.