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These solar cells are so flexible they can wrap around a pencil

The cells are 1 micrometre thick and are made from gallium arsenide

20 Jun 2016
Solar cells


Juho Kim et al/APL

Scientists in South Korea have made ultra-thin solar cells flexible enough to wrap around an average pencil - and the bendy panels could soon be used to could power fitness trackers, smart glasses or be woven into clothes to help power phones on the go.

The cells are around a single micrometre thick and are made from the semiconductor gallium arsenide. Researchers, from the Gwangju Institute of Science and Technology, stamped the cells directly onto a flexible surface without using an adhesive.

The cells were then "cold welded" to an electrode by applying pressure at 170 degrees Celcius and melting a top layer of material called photoresist that acted as a temporary glue. The photoresist was later peeled away, leaving the direct metal to metal bond.

The metal bottom layer also served as a reflector to direct stray photons back to the solar cells. The researchers tested the efficiency of the cells at converting sunlight to electricity and found that it was comparable to similar thicker photovoltaics. They performed bending tests and found the cells could wrap around a radius as small as 1.4 millimetres.

"Our photovoltaic is about 1 micrometre thick - much thinner than an average human hair," said researcher and engineer Jongho Lee. "The thinner cells are less fragile under bending, but perform similarly or even slightly better," Lee added.

Standard photovoltaics are typically hundreds of times thicker, and even most other thin photovoltaics are two to four times thicker.



The research is published in the journal Applied Physics Letters, from AIP Publishing.