Ultra-thin transparent solar cells promise invisible charging for wearables, cars, and homes

A new kind of near-invisible solar cell could one day help everyday glass surfaces generate electricity. This could include car windows and sunroofs, smart glasses, wearables, building façades, and home windows.

Scientists at Nanyang Technological University, Singapore, have developed ultrathin transparent perovskite solar cells that are about 10,000 times thinner than a strand of human hair and around 50 times thinner than conventional perovskite solar cells. The NTU research team, led by Associate Professor Annalisa Bruno, published the findings in ACS Energy Letters (via TechXplore).

Can solar cells disappear into everyday glass?

These solar cells are semi-transparent and color-neutral, so they could potentially be added to glass without making it look like traditional solar panels. This could be useful in cities where rooftops are already used for solar, but windows and vertical glass façades remain mostly untapped.

Researchers around the world are trying to make solar technology easier to adopt and more appealing to everyday users. Some are working on colorful solar cells that could make panels look better on homes, while NTU’s approach focuses on making solar cells almost disappear into glass. If it works at scale, it could help solve one of solar’s biggest challenges by generating clean power without asking people to change the way their homes, cars, or devices look.

NTU says the cells can generate electricity under indirect and diffuse light, making them useful for dense urban buildings with limited direct sunlight. If scaled successfully, large glass-fronted buildings could theoretically generate several hundred megawatt-hours of electricity a year, depending on orientation and usable glass area.

What challenges remain before commercial use?

The team made the cells using a process called thermal evaporation, where material is heated inside a vacuum chamber until it turns into vapor, then settles as an extremely thin layer. NTU says this helps create even layers over larger areas, avoids toxic solvents, and lets researchers control how clear the solar cells are.

The best result came from the 60 nanometer opaque cell, which reached about 12% efficiency. Thinner opaque versions reached about 11% efficiency at 30 nanometers and 7% at 10 nanometers. The 60 nanometer semi-transparent version allowed about 41% of visible light to pass through while reaching 7.6% efficiency.

For comparison, regular rooftop solar panels are far more efficient, with many commercial home panels converting roughly 18% to 24% of sunlight into electricity. NTU’s semi-transparent cell is not trying to beat those panels on raw power. Its advantage is that it can tap into surfaces where regular solar panels would be impractical or undesirable.

This is still lab-stage research, not a product ready for windows, cars, or wearables. NTU has filed a patent and is talking to companies to validate the manufacturing process. The researchers still need to prove that the cells can remain stable, survive long-term use, and perform well when produced over larger areas.