Ultra-Thin Solar Cells That Are Tinier Than Human Hair

Rapid advances are happening in solar tech, as engineers from South Korea unveiled the thinnest solar cells yet constructed. The micro-thin photovoltaic cells are even slimmer than the ones recently developed by MIT Research, which were so tiny they could alight on a soap bubble without popping it.

The cells built by MIT had a thickness of 1.3 micrometers. The researchers at the Gwangju Institute of Science and Technology produced cells no more than 1 micrometer thick, they reported in a paper in Applied Physics Letters. In contrast, a strand of human hair would typically measure around 100 micrometers in diameter.

Such ultra-thin solar cells could power future mobile devices and invigorate the wearable gadget industry. Not only are the solar panels thin, they are extremely flexible and can be safely wrapped around a pencil, said the American Institute of Physics in EurekAlert. This makes them ideal for integrating mobile tech into eyeglass frames, sheer fabrics, and tiny accessories.

The Gwangju Institute team observed that their photovoltaics could handle stress more readily than could comparable cells that were 3.5 times thicker. The thinner cells performed just as effectively while showing less fragility on being bent. They could be wrapped around an object with a 1.4-millimeter radius without faltering.

The Korean researchers manufactured the super-compact solar cells using the technique of transfer printing. This involved imprinting the cells directly onto a flexible metallic substrate under high temperature (170 degrees Celsius). The cells bonded to the material without the need for an adhesive, which would have added to the thickness.

That so-called "cold welding" process did make use of a temporary adhesive, a substance known as a photoresist. But this photoresist was then peeled off, leaving only a pure metal on metal bond. The method makes it possible to manufacture more flexible photovoltaics while using fewer materials.