Solar power is making huge strides as a reliable, renewable energy source, but there’s still a lot of untapped potential in terms of the efficiency of photovoltaic cells.
Solar cells are commonly used as power sources in several types of large electronics, but their use on consumer items, such as gadgets and even cars, has been limited.
As there is smaller area available to mount the cells and the fact that such products often have numerous curved surfaces.
To overcome those limitations, the team of researchers at the Gwangju Institute of Science and Technology in South Korea have developed solar cells thin enough they can be bend around a pencil.
This could possible by directly attaching the cells to the substrate without the use of an adhesive.
Ultra-thin solar cells are flexible enough to bend around small objects, such as the 1 mm-thick edge of a glass slide. (Image credit: Juho Kim, et al/ APL)
The cells could help usher in the use of solar energy in small portable gadgets where space is at a premium.
Standard photovoltaics are usually hundreds of times thicker, and even most other thin photovoltaics are 2 to 4 times thicker. The researchers made the ultra-thin solar cells from the semiconductor gallium arsenide.
They stamped the cells directly onto a flexible substrate without using an adhesive that would add to the material’s thickness. The cells were then “cold welded” to the electrode on the substrate by applying pressure at 170 degrees Celcius and melting a top layer of material called photoresist that acted as a temporary adhesive. The photoresist was later peeled away, leaving the direct metal to metal bond.
“Our photovoltaic is about 1 micrometer thick,” said Jongho Lee, an engineer at the Gwangju Institute of Science and Technology in South Korea. One micrometer is much thinner than an average human hair. Standard photovoltaics are usually hundreds of times thicker, and even most other thin photovoltaics are 2 to 4 times thicker., as reported by Science Daily.
The cells are fabricated onto a flexible substrate that is just a micrometer thick—one-half to one-quarter the thickness of other “thin” solar cells and hundreds of times thinner than conventional cells. A human hair, by comparison, is about 100 micrometers.
The scientists tested the cells and discovered they can almost be folded in half—wrapped around a radius as small as 1.4 millimeters, a paper describing the work was published in Applied Physics Letters, a journal of the American Institute of Physics.
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