A new breed of cell phone screens is emerging and they can stay on all day without sucking the juice out of the battery. It turns out backlight that is hard on batteries - consuming up to 90% of the power supplied to the display. The display itself can eat more than 30% of the phone's energy supply. The next-gen screens do not require backlighting but are primarily illuminated by sunlight or the movement of liquids inside the screen.

Qualcomm's iMod screen acts as a a complex mirror. The phone creates images which become visible when sunlight or artificial light strikes the screen. What happens if there's not enough light? An integrated light kicks in to illuminate the screen but still consumes far less energy than regular phone LCDs.

Liquavista's version of the green cell phone screen is the liquid-filled screen that uses electrowetting. Each pixel contains water and a droplet of dyed oil. An electric charge applied to the outside surface of the pixel attracts water to the surface forcing the oil to the side. This makes the pixel take on the color of the lower surface of the pixel. When the charge is reversed, the pixel takes on the color of the dyed oil.

With these energy-misers in place cell phones don't have to shut down its screen after a few seconds. They could continually broadcast stock quotes, news stories or show a music video to go along with a built-in MP3 player. The new screen technology, which can also replace laptop and notebook screens, will be available as soon as phone manufacturers adopt them.