Researchers from the University of Tokyo, Japan, and Johannes Kepler University, Austria, have created the world’s thinnest and lightest solar battery.

With a thickness of only 1.8 micrometers, the solar batteries are thin enough to wrap around a human hair. Thinner than a skein of spider silk, the thin-film device comprises of electrodes on a plastic foil, and is a tenth of the size of the thinnest solar cells currently available.

In order to create the battery, the scientists applied ink containing an organic semiconductor to plastic film that measures 1.4 micrometers in thickness. According to the researchers, the thinnest battery to date was 25 micrometers.

One gram of the solar battery produces 10 watts of energy. The efficiency of conversion from solar power to electricity is 4.2 percent, substantially lower than typical solar panels. However, the new battery can function without conversion rate drops when folded or bent. According to the team, the spider-silk soar batteries can also be made cheaply.

It is hoped the ultra-thin solar cells can be used in order to monitor health by the general public. Tsuyoshi Sekitani from the University of Tokyo, one of the researchers said:

“Being ultra-thin means you don’t feel its weight, and it is elastic.
You could attach the device to your clothes like a badge to collect electricity (from the sun) .. Elderly people who might want to wear sensors to monitor their health would not need to carry around batteries.”

As the device is soft, it is possible to make the cells bigger — and its flexible nature means it is less prone to damage by bending. The team hopes that once the rate of electricity conversion has been increased and developed further, the cells could be put into practical use within five years.