LCD screen harvests energy from indoor and outdoor light

Liquid crystal displays (LCDs) work by using two polarised sheets that let only a certain amount of a device’s backlight pass through. Tiny liquid crystal molecules are sandwiched between the two polarisers and these crystals can be switched by tiny transistors to act as light valves. Manipulating each light valve, or pixel, lets a certain amount of the backlight escape; millions of pixels are combined to create images on LCDs.

From the perspective of energy use, current LCD polarisers are inefficient. A device’s backlight can consume 80 to 90 per cent of the device’s power. But as much as 75 per cent of the light generated is lost through the polarisers. A polarising organic photovoltaic LCD could recover much of that unused energy.

A team at the University of California Los Angles (UCLA) has created and tested a screen that it claims is the first such device to be able to simultaneously act as a polariser, a photovoltaic device and an ambient light or sunlight photovoltaic panel.