Ultra-slim transparent solar panels offer the potential for invisible charging solutions for wearables, vehicles, and residential spaces.

      A new type of nearly invisible solar cell may someday enable common glass surfaces to produce electricity, including car windows, sunroofs, smart glasses, wearables, building façades, and residential windows.

      Researchers at Nanyang Technological University (NTU) in Singapore have created ultrathin, transparent perovskite solar cells that are approximately 10,000 times thinner than a human hair and about 50 times thinner than standard perovskite solar cells. The NTU research team, led by Associate Professor Annalisa Bruno, detailed their findings in ACS Energy Letters (as reported by TechXplore).

      Could solar cells be integrated into regular glass?

      These solar cells are semi-transparent and color-neutral, allowing them to be incorporated into glass without resembling conventional solar panels. This innovation may be particularly beneficial in urban areas where rooftops are already utilized for solar energy, while windows and vertical glass façades remain largely untapped.

      Globally, researchers are seeking ways to simplify the adoption of solar technology and make it more visually appealing to everyday users. Some are focusing on colorful solar cells to enhance the aesthetics of solar panels on homes, while NTU's method aims for solar cells to blend seamlessly with glass. If successfully scaled, it could address a significant challenge for solar energy by generating clean power without necessitating changes to the visual appearance of homes, vehicles, or devices.

      NTU claims these cells can produce electricity even under indirect and diffuse light, which is advantageous for densely populated urban buildings with limited access to direct sunlight. If scaled effectively, large glass-fronted structures could potentially generate several hundred megawatt-hours of electricity annually, based on their orientation and the area of usable glass.

      What obstacles remain before commercialization?

      The team produced the cells using thermal evaporation, a method that involves heating material in a vacuum chamber until it vaporizes and then deposits as an ultra-thin layer. NTU states that this process creates uniform layers over larger surfaces, avoids toxic solvents, and allows researchers to control the transparency of the solar cells.

      The most effective outcome was achieved with the 60 nanometer opaque cell, which attained around 12% efficiency. Thinner opaque versions reached approximately 11% efficiency at 30 nanometers and 7% at 10 nanometers. The 60 nanometer semi-transparent variant permitted about 41% of visible light to pass through while achieving 7.6% efficiency.

      In comparison, traditional rooftop solar panels are considerably more efficient, with many commercial home panels converting about 18% to 24% of sunlight into electricity. The aim of NTU’s semi-transparent cell isn't to surpass these panels in raw efficiency but to capitalize on surfaces where conventional solar panels are not practical or desired.

      This research is currently in the laboratory stage and not yet a viable product for windows, vehicles, or wearables. NTU has applied for a patent and is engaging with companies to refine the manufacturing process. The researchers still need to demonstrate that the cells can maintain stability, withstand long-term use, and perform effectively when produced on a larger scale.