Layering an organic material on top of 2D materials achieves stable, fast phosphorescent light emission without using expensive and hazardous heavy metals.
News by Patricia DeLacey
Screens for TVs, smartphones or other displays could be made with a new kind of organic LED material developed by an international team, co-led by University of Michigan engineers. The material maintains sharp color and contrast while replacing the heavy metal with a new hybrid material.
Curiously, the material also seemed to break a quantum rule.
OLED devices currently on the market include heavy metal components like iridium and platinum, which improve the efficiency, brightness and color range of the screen. But they come with drawbacks—significantly higher cost, a shorter device lifetime and increased health and environmental hazards.
In OLEDs, light emission through the more energy-efficient phosphorescence is preferred over fluorescence, but phosphorescence happens more slowly, taking milliseconds or longer without the heavy metal component. Speeding up phosphorescence to happen in microseconds is necessary to keep up with modern displays, which operate at 120 frames per second, without producing a lingering “ghost” image. This is a key role of the heavy metals.
“We found a way to make a phosphorescent organic molecule that can emit light on the microsecond scale, without including heavy metals in the molecular framework,” said Jinsang Kim, U-M professor of materials science and engineering and co-corresponding author of the study published in Nature Communications.
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