OLED panel emits 20 percent more light thanks to a new electrode design

Engineers at the University of Michigan have created a new electrode that allows OLED panels to emit up to 20 percent more light. The researchers believe the breakthrough could help extend battery life for smartphones and laptops using the screen technology. The tech could also make next-generation TVs and displays more energy efficient.

Researchers delivered an approach that prevents light from being trapped in the light-emitting part of an OLED, enabling them to maintain brightness and use less power. The electrode is also easy to fit into an existing process for building OLED displays and light fixtures. University of Michigan researcher L. Jay Guo says that the team's approach allows construction in the same vacuum chamber used currently.

According to researchers, about 80 percent of the light produced by an OLED is trapped inside the device due to an effect known as waveguiding unless engineers take action. That means that light rays that don't come out of the device from an angle close to perpendicular get reflected and guided sideways inside the device and get lost inside the panel. A large portion of light lost is trapped between the two electrodes on either side of the light emitter.

Researchers say one of the biggest traps for light is the transparent electrode standing between the light-emitting material and the glass, usually made of indium tin oxide. Engineers swapped the indium tin oxide layer for a layer of silver only five nanometers thick deposited on a seed layer of copper. The process allows the team to maintain the electrode function while eliminating waveguiding in the OLED layers completely.

The team says that industry could liberate more than 40 percent of light, trading the conventional indium tin oxide electrodes for a nanoscale layer of transparent silver. The engineers note that despite the light no longer being guided in the OLED stack, the freed up light can still be reflected from the glass. Some researchers were able to free up about 34 percent of the light using unconventional materials with special emission directions or patterning structures. The new design technology has a patent applied for, and researchers intend to commercialize the technology.