Today’s OLED displays have a challenge in terms of blue light sources. Although there are high performance red and green organic light emitting diodes, there is no blue light source with similar performance. Researchers at Kyushu University in Japan used a new combination of emitter molecules and demonstrated a new way to overcome this challenge. The pure blue OLED splits the energy conversion and emission process between two different molecules.
Using this method, researchers can produce an efficient pure blue light emission, which can maintain brightness for a relatively long time, and the device does not use any expensive metal atoms.
Blue and green emitting devices are a growing challenge for researchers. Efficiency, color purity, cost, and lifetime have always been weighed against each other, and blue emitters usually have a short working life and must use expensive metals such as iridium or platinum.
Researchers at the organic Photonics and Electronics Research Center (Opera) of Kyushu University have developed luminescent molecules based on thermally activated delayed fluorescence processes. The process can achieve the same efficiency without metal atoms, and show the ability to emit multiple colors.
The researchers used a bimolecular method called superfluorescence, which allowed the team to achieve a longer working life at higher brightness than previously reported high-efficiency OLEDs with similar color purity. Their approach is basically to stack two devices together to effectively double the emission at the same current. As a result, the lifetime is almost doubled at high brightness.
The researchers estimate that the device can maintain 50% brightness for more than 10000 hours at milder intensities. The team hopes their OLED will replace the blue part of OLED used in current displays in the future.