Displays that Generate Electricity
Liquid Crystal Displays (LCDs) work by shining light through a polarizer, the liquid crystals, and another polarizer. The two polarizers are perpendicular to each other, so light travelling directly through both will first be reduced by half by the first polarizer, and then reduced even further by the second. When light shines through a polarizer some of it is absorbed and what is left has a single orientation dependent on the polarizer. What the liquid crystals do is twist the light from the first polarizer so it can line up with the second and not be reduced again. The concept of an LCD is dependent on light being lost so a display’s backlight has to be very bright, which means the screen as a whole has to draw a lot of power; as much 80-90% of a device’s power. Researchers at University of California Los Angeles have developed a material that may potentially return as much as 75% of that.
Instead of letting the energy of the blocked light be wasted, the team have created polarizing organic photovoltaics to recapture some of the energy and feed it back to the device when the display is on. When the display is off, the screen can act as a solar cell and recharge the battery. The team hopes to make their polarizing organic photovoltaics more efficient and achieve the 75% energy return for when they become used in consumer LCDs.