Solar-powered vests take limelight at Osaka Expo 2025

As temperatures soar near 37.8°C (100°F) in Osaka this summer, Expo 2025 staff aren’t just sweating it out — they’re solar-cooling it out.

Thanks to a futuristic vest developed by Toyoda Gosei, in partnership with solar startup Enecoat Technologies and textile maker Seiren, workers are staying cool using sunshine. 

These smart utility vests come equipped with ultra-thin, flexible perovskite solar cells — each one lighter than a single sheet of paper — which power neck fans to beat the heat.

Perovskite: Star of solar power

And yes, these aren’t your average rooftop silicon panels. 

The star here is perovskite, a family of lightweight, crystal-based materials that can absorb a broader range of light, even on cloudy days or in the shade.

These cells are ultra-thin, lightweight, and can be integrated onto various surfaces, making them ideal for wearables, portable electronics, and building-integrated photovoltaics (BIPV).

Shinichiro Fuki, Toyoda Gosei’s project director, said they hope people working in places without easy access to power can benefit from the technology.

In lab tests, Enecoat’s solar film hits 21.2% efficiency — and Expo staff are now helping test its real-world performance, including how fast its mobile battery charges (around 5–10 hours).

Why Perovskite?

Perovskites are flexible, lightweight, and easier to install in places traditional solar can’t go — like curved rooftops, delicate fabrics, or even smartphones. 

Unlike bulky silicon panels that can weigh over 20 kg, perovskite solar films are featherlight and can even harvest power indoors from LED and fluorescent lighting.

Expo star

At Expo 2025, perovskites are everywhere: Polish company Saule is using them in smart street poles powering lights, cameras, and signage. 

Sekisui Chemical is showing off one-millimeter-thick solar film on bus station roofs. Over at the Panasonic Pavilion, transparent solar cells are built into the glass facade — a blend of art and energy.

“We need a balance between design and efficiency,” said Yoshiteru Hara, Panasonic’s technical director.

The catch? Durability

Despite their promise, perovskites can degrade quickly when exposed to heat, moisture, or UV light — lasting months instead of years. 

But researchers like Dr. Hashini Perera at the University of Surrey are working on fixes, including protective coatings and additives that could extend lifespan tenfold.

Also, perovskites contain a small amount of lead, raising environmental concerns. Still, experts say the risk is low with proper encapsulation.

Even so, perovskites are already making silicon panels better: companies like Oxford PV have launched perovskite-silicon hybrid panels, boosting efficiency by up to 20%.

The future could see solar you wear, use, and barely notice, says Tamotsu Horiuchi of Enecoat.

“Think watches, phones — even your clothes.”

Flexible perovskite solar cells (FPSCs) are experiencing rapid advancements, with several key developments in efficiency, durability, and real-world applications over the past year.

Power conversion efficiencies (PCEs) for flexible perovskite solar cells have surged, with recent certified values approaching 24.9%, according to Nature. Flexible perovskite-silicon tandem cells have also achieved notable efficiency milestones, such as 26.5%.

Perovskite might just be the spark for the wearable energy revolution.