As the scorching summer temperatures in Osaka, Japan, inch closer to 100 degrees Fahrenheit, a groundbreaking innovation is helping Expo 2025 staff combat the heat. This initiative revolves around solar-powered utility vests developed through a partnership between the Toyota Group company, Toyoda Gosei, the startup Enecoat Technologies specializing in solar cells, and textile manufacturer Seiren. These utility vests are equipped with remarkably thin and flexible solar panels, weighing less than four grams each, surprisingly lighter than a single sheet of paper. These panels efficiently power neck fans, delivering a refreshing breeze to the wearer.
The solar films incorporated in these vests differ significantly from the traditional silicon panels commonly seen on rooftops and solar farms, which dominate 98% of the current solar energy market. Instead, these innovative films are crafted from perovskites—a family of crystalline materials recognized for their unique structural characteristics. Perovskite solar cells stand out thanks to their lightweight composition, low production costs, and versatility in absorbing a broader spectrum of light, encompassing visible light and near-infrared radiation. This technology even allows for charging under shaded conditions or during rainy weather, as noted by Shinichiro Fuki, the director of the team from Toyoda Gosei responsible for this project.
In laboratory settings, Enecoat’s solar film has reached an efficiency level of 21.2%, meaning approximately one-fifth of the captured solar energy is converted into usable electricity. The current focus lies in real-world testing at the Expo, with daily data collection on the film’s responsiveness to varying environmental conditions, such as solar radiation and temperature. The performance of the connected mobile battery is also being monitored, with an expected charging duration of five to ten hours. Fuki highlights the project as a world-first approach to integrating perovskite solar cells into wearable technology, aiming to benefit those working in locations without easy access to power sources.
Perovskites can be either naturally occurring or synthesized in laboratories, with their application in solar cells first demonstrated by researchers in Japan back in 2009. Within controlled lab environments, perovskite cells have exhibited power conversion efficiencies exceeding 26%, rivaling the performance of the top-tier silicon solar panels that are nearing their efficiency limits. According to Tamotsu Horiuchi, the chief technology officer at Enecoat Technologies, a major advantage of perovskites lies in their ability to generate power even in low-light or indoor conditions. For instance, LED and fluorescent lighting can also be harnessed to produce electricity.
However, the innovative vests are just one of the many demonstrations of perovskite technology at the Expo. Polish company Saule Technologies has introduced curved solar cells within “smart poles,” powering street lights, security cameras, digital signage, and wireless charging solutions. Similarly, Japanese firm Sekisui Chemical is showcasing a one-millimeter-thick solar film atop its bus terminus roof. At the Panasonic Group pavilion, perovskite cells embedded between glass layers have been creatively utilized to illustrate the aesthetic possibilities of the technology. Yoshiteru Hara, the technical director of the Panasonic pavilion, emphasizes the challenges faced with traditional silicone panels in terms of installation and the delicate balance required between design and energy efficiency.
Japan is heavily investing in perovskite technology, aiming to achieve ambitious goals of generating 20 gigawatts of solar energy by 2040—equivalent to the output of about 20 conventional nuclear power plants. The nation ranks as the second-largest producer of iodine, an essential component in creating perovskites. Traditional solar farms require substantial flat land for installation, which presents difficulties given Japan’s mountainous terrain. Despite the many benefits of perovskites, they do come with challenges, particularly their susceptibility to degradation from heat, moisture, and UV rays, which can diminish their efficiency over months or even weeks.
Dr. Hashini Perera, a postgraduate research fellow at the University of Surrey’s Advanced Technology Institute studying perovskites, affirms that current research is focused on developing stability, which is the main shortcoming of perovskite materials compared to silicon. Efforts are underway to enhance the durability of these solar cells through stabilizing agents or protective encapsulation methods. Perera’s research even identified a technique that could potentially lengthen the lifespan of perovskites tenfold.
Another concerning aspect is the presence of lead in some perovskite materials, which poses an environmental risk if damaged. However, experts believe that the risk of lead leakage remains low, particularly when robust encapsulation strategies are employed. The commercialization of pure perovskite solar cells may still be a challenge, but significant advancements are being made in enhancing existing solar panel technologies. A notable example is Oxford PV, a spinoff from the University of Oxford’s physics department, which last year introduced the first commercial perovskite-on-silicon tandem panels in the U.S., achieving energy outputs that are
