The new borders of the wearable pv!

We usually use to think about pv technology in different forms: tandem, offshore, walls or windows. This time we are talking about something very different from this. Have you ever wondered to wear pv cells? It’s not a joke, today it is possible thanks to a Japanese research. The wearable pv is made by organic pv cells, which have a lot of applications. These cells are very thin and stretchable, suitable to wearable devices.

Moreover, these pv cells are waterproof. This is very important to for washable electronic textile applications. There are some essential features for textile applications: environmental stability, sufficient energy efficiency and mechanical robustness.

The structure

The team leader of this research of the University of Tokyo and RIKEN is Takao Someya. The innovative material employed in wearable cells is called PNTz4T. It is a
crystalline polymer organic semiconductor. The device is deposed on a 1 micrometer thick parylene film, usually used in biomedical devices. The parylene makes the structure flexible and it protects the cell from environmental agents. But how they made it waterproof? The ultra-thin device was placed onto acrylic-based elastomer on both sides of the device, giving it a coating on both sides to prevent water infiltration. From studies, it results that, soaking the cell, the efficiency decreases of only 2%.

Efficiency and applications

The efficiency of this pv cells is of 7,9 %, that becomes 5,4% in case of soaking for 2 hours. The production is of 7.86 mW per square centimeter, as the current density was 13.8 mA per square centimeter at 0.57 volts, based on a simulated sunlight of 100 mW per square centimeter. Moreover, after compressing, it still had 80 percent of the original efficiency. Anyway, the applications of this technology don’t require high level of power.  Let’s think about sensor for biomedical applications or the well-known Internet of Things.

Kenjiro Fukuda from the “RIKEN Center for Emergent Matter Science” states:

“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.”