New, flexible solar cells just 1 micrometer thick

GWANGJU, South Korea, June 20 (UPI) -- Researchers in South Korea have developed solar cells, or photovoltaics, so flexible and thin they they can be wrapped around a pencil. Scientists say they could power the next generation of wearable electronics.

Thinness is the key to the new solar cells' flexibility. The thinner a material, the more flexible it usually is.

"Our photovoltaic is about 1 micrometer thick," Jongho Lee, an engineer at the Gwangju Institute of Science and Technology in South Korea, said in a news release.

Most photovoltaic cells are several hundred times thicker, and even the thinnest solar cells are two to four times thicker than those developed by Lee and his colleagues.

Engineers built the solar cell using a production technique called "cold welding." First cells were stamped onto a flexible substrate layered with an electrode. When scientists applied intense pressure at a relatively high temperature -- 170 degrees Celsius -- a top layer on the substrate called the photoresist melted and became a temporary adhesive, affixing the cells to the electrode substrate. The photoresist was later peeled away, leaving a metal-to-metal bond.

The substrate's bottom metal layer helps reflect solar rays back toward the photovoltaic cells.

"The thinner cells are less fragile under bending, but perform similarly or even slightly better," Lee said.

While scientists have made similarly thin solar cells, researchers say their new technique -- detailed in the journal Applied Physics Letters -- is simpler and uses fewer materials, making it better suited for scaled production.