Efficient LEDs to extend smartphone battery life

In what could lead to longer battery life in smartphones and produce better TV display screens, researchers at University of Michigan have extended the lifetime of blue organic light emitting diodes (OLEDs).

Blue OLEDs are colours used in screen displays in smartphone and high-end TVs.

The improvement means that the efficiencies of blue OLEDs in these devices could jump from about five percent to 20 percent or better in the near future.

"Phosphorescent OLEDs, also known as PHOLEDs, produce light through a mechanism that is four times more efficient than fluorescent OLEDs," said Stephen Forrest, a Paul G. Goebel professor of engineering at University of Michigan.

Green and red PHOLEDs are already used in new TVs - as well as in Samsung and LG smartphones - but the blues are fluorescent.

"Having a blue phosphorescent pixel is an important challenge but they have not lived long enough," Forrest added.

The efficient blues will make a significant dent in power consumption for large-screen TVs and extend battery life in smartphones.

The lifetime improvement will also help prevent blue from dimming relative to red and green over time.

"In a display, it would be very noticeable to your eye," Forrest noted.