Liquid crystal displays (LCDs) are widely used in modern visual appliances such as smart phone touch screens or high definition television screens. The display consists of liquid crystals that are activated by electric current. Depending on the activation state of the crystals, they block or allow polarized light to pass through. Polarizing films are used to increase the visibility of the image created on the LCD, by polarizing light so that it has a constant and precisely defined direction.
Iodine containing polarizing films are made by adsorbing iodine onto a stretched polyvinyl alcohol surface.