A team of scientists and researchers recently developed a new photovoltaic microfilm that may soon be used in clothing and wearable devices. What separates the new development from previous iterations is its elasticity and capacity to remain functional even after getting soaked in water.
The team, which was composed of RIKAN and University of Tokyo scientists, created a solar cell that can be fitted in an ultrathin microfilm. Once successfully integrated into clothing, this microfilm would have the ability to power certain wearable gadgets and sensors.
According to Nature where the project was first published, the new solar device can improve the functionality and longevity of gadgets and sensors that are worn all over the body for health purposes.
Some of the health sensors currently in the market measure certain bodily functions such as heartbeats per second, as well as body temperature. Takao Someya, team leader of the group, said these pieces of data are crucial in providing early warnings for various medical conditions.
In order to come up with the thin, waterproof solar cell, members of the group used a material called PNTz4T, which the team developed in a previous project. The team then deposited the solar cell in an inverse architecture, which is also a product of an earlier work.
After getting placed onto a 1-um-thick parylene film, the device was then transferred to an acrylic-based elastomer. The team coated both sides of the microfilm with identical elastomer, preventing water to pass through. This elastomer enables the microfilm to allow light to enter, while keeping water and air away from the solar cells.
The research team then ran some tests to check the efficiency and durability of the newly developed solar microfilm. The results were impressive considering how thin it was. The device reportedly had 7.9 percent of energy efficiency, and produced 7.86 milliwatts per square centimeter. For the purposes of the tests, the density of the solar device was 13.8 milliamperes per square centimeter at 0.57 volts, with simulated sunlight of 100 milliwatts per square centimeter.
For the water resistance test, researchers submerged the solar microfilm in water for two hours. The report said that even after prolonged contact with water, the device’s efficiency went down by only 5.4 percent. Finally, the team subjected the ultrathin solar cell in a durability test where they compressed it by nearly half for twenty cycles. Even after the compression, the solar cell still had 80 percent of its original efficiency.
Kenjiro Fukuda of the RIKEN Center for Emergent Matter Science was thrilled by the success of the new solar device. He said the team managed to come up with a solar cell that has ‘environmental stability’, ‘good efficiency’, and ‘mechanical robustness.’
“We very much hope that these washable, lightweight and stretchable organic photovoltaics will open a new avenue for use as a long-term power source system for wearable sensors and other devices,” he added.