At Matria I can across Priva-lite glass from Saint-Gobain. Remember its not magic but innovation!
About the product:
PRIVA-LITE technology is a thermal and sound-insulating laminated glazing solution incorporating a liquid crystal film that can manage transparency on demand, changing instantly from clear state to translucent, and vice versa. The liquid crystals align when the electrical current is switched on, causing the glass to turn transparent instantly. When the power is switched off, the glass has a naturally opaque appearance, blocking vision (total privacy), yet permitting light to pass through (translucent).