Princeton Smart Window (VIDEO) Princeton University, Engineering School This video is under embargo. Please login to access this video. Caption A piece of the glass, which is shown in the video, harvests one portion of the light spectrum to control other parts of the spectrum. Specifically, it uses near-ultraviolet light to generate electricity, which powers chemical reactions that lighten or darken the glass as needed. When darkened, the window can block more than 80 percent of light. Credit Princeton University Usage Restrictions non-commercial use License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.