International. Researchers at the University of Notre Dame develop a window coating that blocks heat-generating ultraviolet and infrared light and lets visible light through no matter its angle.
The coating can be incorporated into existing or car windows. It can reduce air-conditioned cooling costs by more than a third in hot weather.
"The angle between the sun and your window is always changing," said Tengfei Luo, a professor at the University of Notre Dame and leader of the study. "Our coating maintains functionality and efficiency regardless of the sun's position in the sky."
Luo and his postdoctoral associate Seongmin Kim previously fabricated a clear window covering by stacking ultra-thin layers of silica, alumina, and titanium oxide on a glass base. A micrometer-thick silicon polymer was added to improve the cooling power of the structure by reflecting thermal radiation through the atmospheric window and into outer space.
"Further optimization of the order of the layers was needed to ensure that the coating could adapt to multiple angles of sunlight. However, a trial-and-error approach was impractical, given the immense number of possible combinations," Luo continued.
Recent studies on the subject are optimized for light entering a room at a 90-degree angle. This coating maintains transparency regardless of the angle of the sun. The team used quantum computing, or more specifically, quantum annealing, and validated their results experimentally.
"Like polarized sunglasses, our coating reduces the intensity of incoming light, but, unlike sunglasses, our coating remains clear and effective even when you tilt it at different angles," Luo added.
Their model produced a coating that maintained both transparency and temperature reduction at 5.4 to 7.2 degrees Celsius in a model room, even when light was transmitted over a wide range of angles. The active learning and quantum computing scheme developed to create this coating can be used to design a wide range of materials with complex properties.
