A team of scientists from Japan-based research institute RIKEN and the University of Tokyo has developed a new type of ultra-thin organic photovoltaic cell which can continue to generate electricity from sunlight even when being soaked in water or being stretched and compressed and even after cleaning in the washing machine. Kenjiro Fukuda, a researcher at RIKEN and Takao Someya, an electrical engineering professor at the University of Tokyo led the team. The research was published on the website of Nature Energy, a British science journal on 18th September 2017.
This device can be stitched onto the clothing or attached to the shoulders or backside, or even on the hats. The batteries developed are only 3 micrometres thick. These solar cells are based on a material called PNTz4T, which was developed by the same team during their earlier research. These cells are coated with stretchable and waterproof transparent rubber films on both sides. This photovoltaic cell is almost about 2 times efficient in converting solar rays into electricity than the present ultra-thin solar batteries available in the market. The efficiency of the cells didn’t change even after washing with detergent either by hand or washing machine. Even light ironing didn’t affect the cell.
This solar cell has a strong energy efficiency of 7.9%, producing a current of 7.86 milliwatts per square centimetre, as the current density was 13.8 milliamperes per square centimetre at 0.57 volts, based on a simulated sunlight of 100 milliwatts per square centimetre. These washable, lightweight and stretchable organic photovoltaics are sure to open a new avenue as a long-term power source for health monitoring devices, sensors or smart gadgets like Fitbit or other portable electronic devices.