Scientists in Singapore have developed a new type of ultrathin solar cell that is almost invisible and could one day turn windows, car sunroofs, and even smart glasses into clean energy generators.
The breakthrough was made by researchers at Nanyang Technological University in Singapore and published in ACS Energy Letters.
The research team, led by Annalisa Bruno, created ultrathin solar cells using a material called perovskite.
These new solar cells are about 10,000 times thinner than a human hair and roughly 50 times thinner than conventional perovskite solar cells.
Despite being so thin, the devices still showed impressive ability to convert sunlight into electricity.
The researchers say the technology could help integrate solar power into buildings and devices without changing their appearance very much.
One of the biggest advantages is that the solar cells are semi-transparent and nearly colorless.
This means they could potentially be built directly into windows and glass building façades while still allowing daylight to pass through.
Buildings account for a huge share of global energy use, and researchers believe windows and exterior glass surfaces could become an important new source of clean electricity in crowded cities where rooftop space is limited.
Unlike traditional silicon solar panels, these perovskite solar cells can also generate electricity under indirect sunlight and cloudy conditions. This is especially useful in dense urban areas like Singapore, where many building surfaces do not receive strong direct sunlight.
The researchers estimate that if the technology were scaled up, large glass office buildings could generate substantial amounts of electricity each year simply through their windows and façades. In some cases, the energy produced could equal the annual electricity use of around 100 four-room public housing apartments.
To manufacture the ultrathin solar cells, the scientists used a vacuum-based process called thermal evaporation. In this method, materials are heated until they turn into vapor inside a vacuum chamber. The vapor then settles onto a surface and forms an extremely thin and even film.
This technique avoids the use of toxic liquid solvents and helps reduce tiny defects that can lower solar-cell performance. It also allows scientists to carefully control how transparent the solar cells become.
The team successfully created solar cells with perovskite layers as thin as 10 nanometers. A nanometer is one-billionth of a meter.
One semi-transparent device allowed about 41% of visible light to pass through while still generating electricity efficiently. According to the researchers, this is among the best performances yet achieved for this type of transparent solar cell.
The scientists say the technology could eventually be used in windows, glass skyscrapers, vehicles, wearable electronics, and other surfaces that normally do not generate energy.
The team is now working with industry partners to improve the long-term durability and stability of the solar cells before commercial products become available.
Researchers believe the invention could help future cities generate more clean energy without needing extra land or large rooftop solar installations.
